Guide to Space Archives

June 24, 2015February 27, 2017 by Fraser Cain

Will We Ever Reach Another Star?

We hear about discoveries of exoplanets every day. So how long will it take us to find another planet like Earth?

There are two separate parts of your brain I would like to speak with today. First, I want to talk to the part that makes decisions on who to vote for, how much insurance you should put on your car and deals with how not paying taxes sends you to jail. We’ll call this part of your brain “Kevin”.

The rest of your brain can kick back, especially the parts that knows what kind of gas station you prefer, whether Lena Dunham is awesome or “the most awesome”, whether a certain sports team is the winningest, or believes that you can leave a casino with more money than you went in with. We will call this part “Other Kevin”, in honor of Dave Willis.

Okay Kevin, you’re up. I’m going to cut to the gut punch, Kevin. Between you and me, it is my displeasure to inform you that science fiction has ruined “Other Kevin”. Just like comic books have compromised their ability to judge the likelihood of someone acquiring heat vision, science fiction has messed up their sense of scale about interstellar travel.

But you already knew that. Not like “Other Kevin”, you’re the smart one. In the immortal words of Douglas Adams, “space is big”. But when he said that, Douglas was really understating how mind-bogglingly big space really is.

The nearest star is 4 light years away. That means that light, traveling at 300,000 kilometers per second would still need 4 YEARS to reach the nearest star. The fastest spacecraft ever launched by humans would need tens of thousands of years to make that trip.

But science fiction encourages us to think it’s possible. Kirk and Spock zip from world to world with a warp drive violating the Prime Directive right in it’s smug little Roddenberrian face. Han and Chewy can make the Kessel run in only 12 parsecs, which is confusing and requires fan theories to resolve the cognitive space-distance dissonance, and Galactica, The SDF 3, and Guild Navigators all participate in the folding of space.

And science fiction knows everything that’s about to happen, right? Like cellphones. Additionally Kevin, I know what you’re thinking and I’m not going to tear into Lucas on this. It’s too easy, and my ilk do it a little too often. Plus, I’m saving it up for Abrams. Sorry Kevin. Got a little distracted there.

The point is, science fiction is doing colossal hand waving. They’re glossing over key obstacles, like the laws of physics.

Stay with me here.This isn’t like jaywalking bylaws that “probably don’t apply to you at that very moment”, these are the physical laws of the universe that will deliver a complete junk-kicking if you try and pretend they’re not interested in crushing your little atmosphere requiring, century lifespan, conventional propulsion drive dreams.

So let’s say that we wanted to actually send a spacecraft to another star, whilst obeying the laws of physics. We’ll set the bar super low. We’re not talking about massive cruise ships filled with tourists seeking the delights of the super funzone planetoid, Itchy and Scrachylandia Prime.

David Hardy's illustration of the Daedalus Project envisioned by the British Interplanetary Society: a spacecraft to travel to the nearest stars. (Credit: D. Hardy) — David Hardy’s illustration of the Daedalus Project envisioned by the British Interplanetary Society: a spacecraft to travel to the nearest stars. (Credit: D. Hardy)

I’m not talking about sending a crack team of power armored space marines to defend colonists from xenomorphs, or perhaps take other more thorough measures.

No, I’m talking about getting an operational teeny robotic spacecraft from Earth to Alpha Centauri. The fastest spacecraft we’ve ever launched is New Horizons. It’s currently traveling at 14 kilometres per second. It would take this peppy little probevette 100,000 years to get to the nearest star.

This is mostly due to our lack of reality shattering propulsion. Our best propellant option is an ion engine, used by NASA’s Dawn spacecraft. According to much adored Ian “Handsome” O’Neill from Discovery Space, we’d be looking at 19,000 years to get to Alpha Centauri if we used an ion engine and added a gravitational assist from the Sun.

Just think of what we could do with those 81,000 years we’d be saving! I’m going to learn the dulcimer!
We can start shearing back the reality curtain and throw money and resources to chase nearby speculative propulsion tech. Things like antimatter engines, or even dropping nuclear bombs out the back of a spacecraft

The best idea in the hopper is to use solar sails, like the Planetary Society’s Lightsail.
Use the light from the Sun as well as powerful lasers to accelerate the craft.

Ion Propulsion System Test for Deep Space 1. Image Credit: NASA/JPL

But if we’re going to start down that road, we could also send microscopic lightsail spacecraft which are much easier to accelerate. Once these miniprobes reached their target, they could link up and form a communications relay, or even robotic factories.

Sorry, I think that was my “Other Kevin” talking. So where are we at, fo’ reals?

Harold “Sonny” White, a researcher with NASA announced that they’ve been testing out a futuristic technology called an EM drive. They detected a very slight “thrust” in their equipment that might mean it could be possible to maybe push a spacecraft in space without having to expel propellent like a chemical rocket or an ion drive.

What’s that, Kevin? Yes, you should totally be skeptical. You’re right, that last bit was a salad of weasel words.

Even if this crazy drive actually works, it still needs to obey the laws of physics. You couldn’t go faster than the speed of light and you would need a remarkable source of energy to power the reactor. Also, yes, Kevin, you’re right NASA is working on a warp drive. There’s no need to yell.

NASA is also working on an actual warp drive concept known as an alcubierre drive. It would actually do what science fiction has claimed: to warp space to allow faster than light travel. But by working on it, I mean, they’ve done a lot of fancy math.

But once they get all the math done, they can just go build it right? This concept is so theoretical that physicists are still arguing whether powering an alcubierre drive would take more energy than contained within the entire Universe. Which, I think we can call an obstacle.

Oh, one more thing. “Other Kevin”, thanks for being so patient. Here’s your reward. Unicorns are real, and Kevin has been lying to you this whole time. Go get ‘em tiger. Place your bets. When do you think we’ll send our first probe towards another star? Predict the departure date in the comments below.

June 24, 2015December 23, 2015 by Matt Williams

What Is a Tsunami?

11 March 2011: The wave from a tsunami crashes over a street in Miyako City, Japan Credit: REUTERS/Mainichi Shimbun

For people living in oceanfront communities, the prospect of a tsunami is a frightening one. Much like earthquakes, volcanoes, hurricanes and tornadoes, tsunamis are one of the most destructive natural forces on the planet. And much like these other phenomena, they require the right conditions to happen and are more common in some areas of the world than others.

Knowing how and when a tsunami will strike has therefore a subject of great interest for scientists over the ages. But for anyone who has lived in certain parts of the world where “tsunami zones” are common – namely Japan and the South Pacific – it is a matter of survival.

Definition:
Numerous terms are used in the English language to describe large waves created by the displacement of water, with varying degrees of accuracy. The term tsunami, for example, is literally translated from Japanese to mean “harbor wave”. There are only a few other languages that have an equivalent native word, though similar meanings can be found in Indonesia, Sri Lanka, and the Indian Subcontinent.

The term tidal wave has also been used, which is derived from the most common appearance of a tsunami – an extraordinarily high tidal bore. However, in recent years, the term “tidal wave” has fallen out of favor with the scientific community because tsunami actually have nothing to do with tides, which are produced by the gravitational pull of the moon and sun rather than the displacement of water.

*Tsunamis initiate when an earthquake causes the seabed to rupture, which leads to a rapid decrease in sea surface height directly above it. Credit: howitworksdaily.com*

The term seismic sea wave also is used to refer to the phenomenon, due to the fact that the waves most often are generated by seismic activity such as earthquakes. However, like “tsunami,” “seismic sea wave” is not a completely accurate term, as forces other than earthquakes – including underwater landslides, volcanic eruptions, underwater explosions, land or ice slumping into the ocean, meteorite impacts, or even sudden changes in weather – can generate such waves by displacing water.

Causes:
The principal cause of a tsunami is the displacement of a substantial volume of water or perturbation of the sea. This is usually the result of earthquakes, landslides, volcanic eruptions, glacier calvings, or more rarely by meteorites and nuclear tests. The waves formed in this way are then sustained by gravity.

Tectonic earthquakes trigger tsunamis when the sea floor abruptly deforms and vertically displaces the water above. More specifically, a tsunami can be generated when thrust faults associated with convergent or destructive plate boundaries move abruptly and displace water.

Tsunamis have a small amplitude (wave height) offshore, and a very long wavelength (often hundreds of kilometers long), and only grow in height when they reach shallower water. Once there, the wavelength shortens as the wave encounters resistance, thus increasing the amplitude increases and causing the wave to rears up in a massive tidal bore.

In the 1950s, it was discovered that tsunamis larger than what had previously been believed possible could be caused by giant submarine landslides. These rapidly displace large water volumes, as energy transfers to the water at a rate faster than the water can absorb. Their existence was confirmed in 1958, when a giant landslide in Lituya Bay, Alaska, caused the highest wave ever recorded (524 meters/1700 feet).

A village near the coast of Sumatra that was devastated by the 2004 Tsunami. Credit: US Navy — *A village near the coast of Sumatra that was devastated by the Tsunami that struck South-East Asia in 2004. Credit: US Navy/Public Domain*

In general, landslides generate displacements mainly in the shallower parts of the coastline, such as in closed bays and lakes. But an open oceanic landslide large enough to cause a tsunami across an ocean has not yet happened since the advent of modern seismology, and only rarely in human history.

Meteorological phenomena, such tropical cyclones, can generate a storm surge that will cause sea levels to rise, often in coastal regions. These are what is known as meteotsunamis, which are tsunamis triggered by sudden changes in weather. When such tsunamis reach shore, they rear up in shallows and surge laterally, just like earthquake-generated tsunamis.

Tsunamis can also be triggered by external factors, such as meteors or human intervention. For instance, when a meteor of significant strikes a region of the ocean, the resulting impact is enough to displace high volumes of water, thus triggering a tsunami. There has also been much speculation since World War II of how a nuclear detonations have trigger a tsunami, but all attempts at research (especially in the Pacific) have yielded poor results.

Characteristics and Effects:
Tsunamis can travel at well over 800 kilometers per hour (500 mph), but as they approach the coast, wave shoaling compresses the wave and its speed decreases to below 80 kilometers per hour (50 mph). A tsunami in the deep ocean has a much larger wavelength of up to 200 kilometers (120 mi), but diminishes to less than 20 kilometers (12 mi) when it reaches shallow water.

When the tsunami’s wave peak reaches the shore, the resulting temporary rise in sea level is termed run up. Run up is measured in metres above a reference sea level. A large tsunami may feature multiple waves arriving over a period of hours, with significant time between the wave crests.

Tsunamis cause damage by two mechanisms. First, there is the smashing force of a wall of water traveling at high speed, while the second is the destructive power of a large volume of water draining off the land and carrying a large amount of debris with it.

It is often difficult for people to recognize a tsunami in the open ocean because the waves are much smaller further out at sea than they are close to shore. As with earthquakes, several attempts have been made to set up scales of tsunami intensity or magnitude to allow comparison between different events.

Ships try to extinguish a blaze at oil refinery tanks in Ichihara, Chiba Prefecture, which has been burning since Friday's earthquake and tsunami Read more: http://www.dailymail.co.uk/news/article-1366395/Japan-tsunami-earthquake-Rescuers-pick-way-apocalypse-wasteland.html#ixzz3dvVfz0hr Follow us: @MailOnline on Twitter | DailyMail on Facebook Credit: EPA — *Ships try to extinguish a blaze at oil refinery tanks in Ichihara, Chiba Prefecture, after the tsunami that struck in March, 2011. Credit: EPA*

The first scales used routinely to measure the intensity of tsunami were the Sieberg-Ambraseys scale, used in the Mediterranean Sea and the Imamura-Iida intensity scale, used in the Pacific Ocean. This latter scale was modified by Soloviev to become the Soloviev-Imamura tsunami intensity scale, which is used in the global tsunami catalogs compiled by the NGDC/NOAA and the Novosibirsk Tsunami Laboratory as the main parameter for the size of the tsunami.

In 2013, following the intensively studied tsunamis in 2004 and 2011, a new 12 point scale was proposed, known as the Integrated Tsunami Intensity Scale (ITIS-2012). This scale was intended to match as closely as possible to the modified ESI2007 and EMS earthquake intensity scales.

Tsunamis throughout History:
Japan and the Pacific Ocean may have the longest recorded history of tsunamis, but they are an often underestimated hazard in the Mediterranean Sea region and Europe in general. In his History of the Peloponnesian War (426 BCE), Greek historian Thucydides offered what could be considered the first recorded speculation about the causes of tsunamis – where he argued that earthquakes at sea were the reason for them.

An aerial view of tsunami damage in T?hoku. Credit: US Navy — *An aerial view of tsunami damage in Tohoku. Credit: US Navy*

After the tsunami of 365 CE devastated Alexandria, Roman historian Ammianus Marcellinus described the typical sequence of a tsunami. His descriptions included an earthquake and the sudden retreat of the sea, followed by a gigantic wave.

More modern examples include the 1755 Lisbon earthquake and tsunami (which was caused by activity in the Azores–Gibraltar Transform Fault); the 1783 Calabrian earthquakes, which caused several ten thousand deaths; and the 1908 Messina earthquake and tsunami – which caused 123,000 deaths in Sicily and Calabria and is considered one of the most deadly natural disasters in modern European history.

But by far, the 2004 Indian Ocean earthquake and tsunami was the most devastating of its kind in modern times, killing around 230,000 people and laying waste to communities throughout Indonesia, Thailand, and Southern Asia.

In 2010, an earthquake triggered a tsunami which devastated several coastal towns in south-central Chile, damaged the port at Talcahuano and caused 4334 confirmed fatalities. The earthquake also generated a blackout that affected 93 percent of the Chilean population.

In 2011, an earthquake off the Pacific coast of Tohoku led to a tsunami that struck Japan and led to 5,891 deaths, 6,152 injuries, and 2,584 people to be declared missing across twenty prefectures. The tsunami also caused meltdowns at three reactors in the Fukushima Daiichi Nuclear Power Plant complex.

Tsunamis are a force of nature, without a doubt. And knowing when, where, and how severely they will strike is intrinsic to ensuring that we can limit the damage they do cause.

Universe Today has articles on about tsunamis and causes of tsunamis.

For more information, try tsunami and causes of tsunamis.

Astronomy Cast has an episode on Earth.

Source:
Wikipedia

June 24, 2015July 20, 2017 by Matt Williams

What is the Biggest Planet in the Solar System?

Jupiter and Io — Io and Jupiter as seen by New Horizons during its 2008 flyby. (Credit: NASA/Johns Hopkins University APL/SWRI).

Ever since the invention of the telescope four hundred years ago, astronomers have been fascinated by the gas giant of Jupiter. Between it’s constant, swirling clouds, its many, many moons, and its Giant Red Spot, there are many things about this planet that are both delightful and fascinating.

But perhaps the most impressive feature about Jupiter is its sheer size. In terms of mass, volume, and surface area, Jupiter is the biggest planet in our Solar System by a wide margin. But just what makes Jupiter so massive, and what else do we know about it?

Size and Mass:

Jupiter’s mass, volume, surface area and mean circumference are 1.8981 x 10²⁷ kg, 1.43128 x 10¹⁵ km³, 6.1419 x 10¹⁰ km², and 4.39264 x 10⁵ km respectively. To put that in perspective, Jupiter diameter is roughly 11 times that of Earth, and 2.5 the mass of all the other planets in the Solar System combined.

But, being a gas giant, Jupiter has a relatively low density – 1.326 g/cm³– which is less than one quarter of Earth’s. This means that while Jupiter’s volume is equivalent to about 1,321 Earths, it is only 318 times as massive. The low density is one way scientists are able to determine that it is made mostly of gases, though the debate still rages on what exists at its core (see below).

Composition:

Jupiter is composed primarily of gaseous and liquid matter. It is the largest of the gas giants, and like them, is divided between a gaseous outer atmosphere and an interior that is made up of denser materials. Its upper atmosphere is composed of about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules, and approx. 75% hydrogen and 24% helium by mass, with the remaining one percent consisting of other elements.

*This cut-away illustrates a model of the interior of Jupiter, with a rocky core overlaid by a deep layer of liquid metallic hydrogen. Credit: Kelvinsong/Wikimedia Commons*

The atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds as well as trace amounts of benzene and other hydrocarbons. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur. Crystals of frozen ammonia have also been observed in the outermost layer of the atmosphere.

The interior contains denser materials, such that the distribution is roughly 71% hydrogen, 24% helium and 5% other elements by mass. It is believed that Jupiter’s core is a dense mix of elements – a surrounding layer of liquid metallic hydrogen with some helium, and an outer layer predominantly of molecular hydrogen. The core has also been described as rocky, but this remains unknown as well.

In 1997, the existence of the core was suggested by gravitational measurements, indicating a mass of from 12 to 45 times the Earth’s mass, or roughly 4%–14% of the total mass of Jupiter. The presence of a core is also supported by models of planetary formation that indicate how a rocky or icy core would have been necessary at some point in the planet’s history in order to collect its bulk of hydrogen and helium from the protosolar nebula.

However, it is possible that this core has since shrunk due to convection currents of hot, liquid, metallic hydrogen mixing with the molten core. This core may even be absent now, but a detailed analysis is needed before this can be confirmed. The Juno mission, which launched in August 2011, is expected to provide some insight into these questions, and thereby make progress on the problem of the core.

The temperature and pressure inside Jupiter increase steadily toward the core. At the “surface”, the pressure and temperature are believed to be 10 bars and 340 K (67 °C, 152 °F). At the “phase transition” region, where hydrogen becomes metallic, it is believed the temperature is 10,000 K (9,700 °C; 17,500 °F) and the pressure is 200 GPa. The temperature at the core boundary is estimated to be 36,000 K (35,700 °C; 64,300 °F) and the interior pressure at roughly 3,000–4,500 GPa.

Moons:

The Jovian system currently includes 67 known moons. The four largest are known as the Galilean Moons, which are named after their discoverer, Galileo Galilei. They include: Io, the most volcanically active body in our Solar System; Europa, which is suspected of having a massive subsurface ocean; Ganymede, the largest moon in our Solar System; and Callisto, which is also thought to have a subsurface ocean and features some of the oldest surface material in the Solar System.

Then there’s the Inner Group (or Amalthea group), which is made up of four small moons that have diameters of less than 200 km, orbit at radii less than 200,000 km, and have orbital inclinations of less than half a degree. This groups includes the moons of Metis, Adrastea, Amalthea, and Thebe. Along with a number of as-yet-unseen inner moonlets, these moons replenish and maintain Jupiter’s faint ring system.

Jupiter also has an array of Irregular Satellites, which are substantially smaller and have more distant and eccentric orbits than the others. These moons are broken down into families that have similarities in orbit and composition, and are believed to be largely the result of collisions from large objects that were captured by Jupiter’s gravity.

*Illustration of Jupiter and the Galilean satellites. Credit: NASA*

Interesting Facts:

Much like Earth, Jupiter experiences auroras near its northern and southern poles. But on Jupiter, the auroral activity is much more intense and rarely ever stops. The intense radiation, Jupiter’s magnetic field, and the abundance of material from Io’s volcanoes that react with Jupiter’s ionosphere creates a light show that is truly spectacular.

Jupiter also has a violent atmosphere. Winds in the clouds can reach speeds of up to 620 kph (385 mph). Storms form within hours and can become thousands of km in diameter overnight. One storm, the Great Red Spot, has been raging since at least the late 1600s. The storm has been shrinking and expanding throughout its history; but in 2012, it was suggested that the Giant Red Spot might eventually disappear.

The discovery of exoplanets has revealed that planets can get even bigger than Jupiter. In fact, the number of “Super Jupiters” observed by the Kepler space probe (as well as ground-based telescopes) in the past few years has been staggering. In fact, as of 2015, more than 300 such planets have been identified.

Notable examples include PSR B1620-26 b (Methuselah), which was the first super-Jupiter to be observed (in 2003). At 12.7 billion years of age, it is also the third oldest known planet in the universe. There’s also HD 80606 b (Niobe), which has the most eccentric orbit of any known planet, and 2M1207b (Lerna), which orbits the brown dwarf Fomalhaut b (Illion).

Scientist theorize that a gas gain could get 15 times the size of Jupiter before it began deuterium fusion, making it a brown dwarf star. Good thing too, since the last thing the Solar System needs if for Jupiter to go nova!

Jupiter was appropriately named by the ancient Romans, who chose to name after the king of the Gods (Jupiter, or Jove). The more we have come to know and understand about this most-massive of Solar planets, the more deserving of this name it appears.

If you’re wondering, here’s how big planets can get with a lot of mass, and here’s what is the biggest star in the Universe. And here’s the 2nd largest planet in the Solar System.

Here’s another article about the which is the largest planet in the Solar System, and here’s what’s the smallest planet in the Solar System.

We have recorded a whole series of podcasts about the Solar System at Astronomy Cast. Check them out here.

Sources:

June 22, 2015February 27, 2017 by Fraser Cain

What Are The Biggest Mysteries in Astronomy?

Black Holes? Dark Energy? Dark Matter? Alien Life? What are the biggest mysteries that still exist out there for us to figure out?

“The more I learn, the more I realize how much I don’t know.” These are the words of Albert Einstein. I assume he was talking about Minecraft, but I guess it applies to the Universe too.

There are many examples: astronomers try to discover the rate of the expansion of the Universe, and learn a dark energy is accelerating its expansion. NASA’s Cassini spacecraft finally images Saturn’s moon Iapetus, and finds a strange equatorial ridge – how the heck did that get there? Did the Celestials forget to trim it when it came out of the packaging?

There have always been, and, let’s go as far as to say that there always will be, mysteries in astronomy. Although the nature of the mysteries may change, the total number is always going up.

Hundreds of years ago, people wanted to know how the planets moved through sky (conservation of angular momentum), how old the Earth was (4.54 billion years), or what kept the Moon from flying off into space (gravity). Just a century ago, astronomers weren’t sure what galaxies were (islands of stars), or how the Sun generated energy (nuclear fusion). And just a few decades ago, we didn’t know what caused quasars (feeding supermassive black holes), or how old the Universe was (13.8 billion years). Each of these mysteries has been solved, or at least, we’ve a got a pretty good understanding of what’s going on.

Science continues to explore and seek answers to the mysteries we have, and as it does it opens up new brand doors. Fortunately for anyone who’s thinking of going into astronomy as a career, there are a handful of really compelling mysteries to explore right now:

Is the Universe finite or infinite? We can see light that left shortly after the Big Bang, 13.8 billion years in all directions. And the expansion of the Universe has carried these regions more than 45 billion light-years away from us. But the Universe is probably much larger than that, and may be even infinite.

Images from the Hubble Space Telescope showing a gravitational lensing effect. Credit: NASA/ESA.

What is dark matter? Thanks to gravitational lensing, astronomers can perceive vast halos of invisible material around all galaxies. But what is this stuff, and why doesn’t it interact with any other matter?

What is dark energy? When trying to discover the expansion rate of the Universe, astronomers discovered that the expansion is actually accelerating? Why is this happening? Is something causing this force, or do we just not understand gravity at the largest scales?

There are supermassive black holes at the heart of pretty much every galaxy. Did these supermassive black holes form first, and then the galaxies around them? Or was it the other way around?

The Big Bang occurred 13.8 billion years ago, and the expansion of the Universe has continued ever since. But what came before the Big Bang? In fact, what even caused the Big Bang? Has it been Big Bangs over and over again?

The Universe 590 million years after the Big Bang. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.

Are we alone in the Universe? Is there life on any other world or star system? And is anyone out there we could talk to?

Shortly after the Big Bang, incomprehensible amounts of matter and antimatter annihilated each other. But for some reason, there was a slightly higher ratio of matter – and so we have a matter dominated Universe. Why?

Is this the only Universe? Is there a multiverse of universes out there? How do I get to the Whedonverse?

In the distant future, after all the stars are dead and gone, maybe protons themselves will decay and there will be nothing left but energy. Physicists haven’t been able to catch a proton decaying yet. Will the ever?

And these are just some of the big ones. There are hundreds, thousands, millions of unanswered questions. The more we learn, the more we discover how little we actually understand.

Whenever we do a video about concepts in astronomy where we have a basic understanding, like gravity, evolution, or the Big Bang, trolls show up and say that scientists are so arrogant. That they think they know everything. But scientists don’t know everything, and they’re willing to admit when something is a mystery. When the answer to the question is: I don’t know.

What’s your favorite unanswered question in space and astronomy? Give us your best mystery in the comments below.

June 21, 2015May 6, 2016 by Matt Williams

How Many Moons Does Uranus Have?

Uranus and Moons — Uranus and its system of Moons. Credit: NASA/JPL

In the outer Solar System, there are many worlds that are so large and impressive to behold that they will probably take your breath away. Not only are these gas/ice giants magnificent to look at, they are also staggering in size, have their own system a rings, and many, many moons. Typically, when one speaks of gas (and/or ice) giants and their moons, one tends to think about Jupiter (which has the most, at 67 and counting!).

But have you ever wondered how many moons Uranus has? Like all of the giant planets, it’s got rather a lot! In fact, astronomers can now account for 27 moons that are described as “Uranian”. Just like the other gas and ice giants, these moons are motley bunch that tell us much about the history of the Solar System. And, just like Jupiter and Saturn, the process of discovering these moons has been long and involved on multiple astronomers.

Continue reading “How Many Moons Does Uranus Have?”

June 20, 2015November 19, 2017 by Matt Williams

Uranus’s Moon Oberon

Oberon, as imaged by the Voyager 2 probe during its flyby on Jan. 24, 1986. Credit: NASA

In 1610, Galileo’s observed four satellites orbiting the distant gas giant of Jupiter. This discovery would ignite a revolution in astronomy, and encouraged further examinations of the outer Solar System to see what other mysteries it held. In the centuries that followed, astronomers not only discovered that other gas giants had similar systems of moons, but that these systems were rather extensive.

For example, Uranus has a system of 27 confirmed satellites. Of these, Oberon is the outermost satellite, as well as the second largest and second most-massive. Named in honor of a mythical king of fairies, it is also the ninth most massive moon in the Solar System.

Discovery and Naming:

Discovered in 1787 by Sir William Herschel, Oberon was one of two major satellites discovered in a single day (the other being Uranus’ moon of Titania). At the time, he reported observing four other moons; however, the Royal Astronomical Society would later determine that these were spurious. It would be almost five decades after the moons were discovered that an astronomer other than Herschel observed them.

Initially, Oberon was referred to as “the second satellite of Uranus”, and in 1848, was given the designation Uranus II by William Lassell. In 1851, Lassell discovered Uranus’ other two moons – later named Ariel and Miranda – and began numbering them based on their distance from the planet . Oberon was thus given the designation of Uranus IV.

Size comparison between the Earth, the Moon, and Saturn's moon of Oberon. Credit: Tom.Reding/Public Domain — *Size comparison between the Earth, the Moon, and Uranus’ moon of Oberon. Credit: Tom.Reding/Public Domain*

By 1852, Herschel’s son John suggested naming the moon’s his father observed Oberon and Titania, at the request of Lassell himself. All of these names were taken from the works of William Shakespeare and Alexander Pope, with the name Oberon being derived from the King of the Fairies in A Midsummer Night’s Dream.

Size, Mass and Orbit:

With a diameter of approx. 1,523 kilometers, a surface area of 7,285,000 km², and a mass of 3.014 ± 0.075 x 10²¹ kilograms, Oberon is the second largest, and second most massive of Uranus’ moons. It is also the ninth most massive moon in the solar system.

At a distance of 584,000 km from Uranus, it is the farthest of the five major moons from Uranus. However, this distance is subject to change, as Oberon has a small orbital eccentricity and inclination relative to Uranus’ equator. It has an orbital period of about 13.5 days, coincident with its rotational period. This means that Oberon is a tidally-locked, synchronous satellite with one face always pointing toward the planet.

Since (like all of Uranus’ moons) Oberon orbits the planet around its equatorial plane, and Uranus orbits the Sun almost on its side, the moon experiences a rather extreme seasonal cycle. Essentially, both the northern and southern poles spend a period of 42 years in complete darkness or complete sunlight – with the sun rising close to the zenith over one of the poles at each solstice.

Voyager 2:

So far, the only close-up images of Oberon have been provided by the Voyager 2 probe, which photographed the moon during its flyby of Uranus in January 1986. The images cover about 40% of the surface, but only 25% of the surface was imaged with a resolution that allows geological mapping.

In addition, the time of the flyby coincided with the southern hemisphere’s summer solstice, when nearly the entire northern hemisphere was in darkness. This prevented the northern hemisphere from being studied in any detail. No other spacecraft has visited the Uranian system before or since, and no missions to the planet are currently being planned.

Composition:

Oberon’s density is higher than the typical density of Uranus’ satellites, at 1.63 g/cm³. This would indicate that the moon consists of roughly equal proportions of water ice and a dense non-ice component. The latter could be made of rock and carbonaceous material including heavy organic compounds.

Spectroscopic observations have confirmed the presence of crystalline water ice in the surface of the moon. It is believed that Oberon, much like the other Uranian moons, consists of an icy mantle surrounding a rocky core. If this is true, then the radius of the core (480 km) would be equal to approx. 63% of the radius of the moon, and its mass would be around 54% of the moon’s mass.

A computer-projected false-color image of Oberon. The white region has not yet been photographed by a spacecraft. The large crater with the dark floor (right of center) is Hamlet; the crater Othello is to its lower left, and the 'canyon' Mommur Chasma is at upper left. Credit: USGS Astrogeology Research Program — *False-color image of Oberon, showing the Hamlet and Othello craters (right of center and lower left) and the Mommur Chasma (upper left). Credit: USGS Astrogeology Research Program*

Currently, the full composition of the icy mantle is unknown. However, it it were to contain enough ammonia or other antifreeze compounds, the moon may possess a liquid ocean layer at the core–mantle boundary. The thickness of this ocean, if it exists, would be up to 40 km and its temperature would be around 180 K.

It is unlikely that at these temperatures, such an ocean could support life. But assuming that hydrothermal vents exist in the interior, it is possible life could exist in small patches near the core. However, the internal structure of Oberon depends heavily on its thermal history, which is poorly known at present.

Interesting Facts:

Oberon is the second-darkest large moon of Uranus (after Umbriel), with a surface that appears to be generally red in color – except where fresh impact deposits have left neutral or slightly blue colors. In fact, Oberon is the reddest moon amongst its peers, with a trailing hemisphere that is significantly redder than its leading hemisphere.

The reddening of the surfaces is often a result of space weathering caused by bombardment of the surface by charged particles and micrometeorites over many millions of years. However, the color asymmetry of Oberon is more likely caused by accretion of a reddish material spiraling in from outer parts of the Uranian system.

Oberon’s surface is the most heavily cratered of all the Uranian moons, which would indicate that Oberon has the most ancient surface among them. Consistent with the planet’s name, these surface features are named after characters in Shakespearean plays. The largest known crater, Hamlet, measures 206 kilometers in diameter, while the Macbeth, Romeo, and Othello craters measure 203, 159, and 114 km respectively.

*Uranus and its five major moons. Credit: space.com*

Other prominent surface features are what is known as chasmata – steep-sided depressions that are comparable to rift valleys or escarpments here on Earth. The largest known chasmata on Oberon is the Mommur Chasma, which measures 537 km in diameter and takes its name from the enchanted forest in French folklore that was ruled by Oberon.

As you can plainly see, there is much that remains unknown about this satellite. Much like its peers, how they came to be, and what secrets may lurk beneath their surfaces, is still open to speculation. One can only hope that future generations will choose to mount another Voyager-like expedition to the Outer Solar System for the sake of studying the Uranian satellites.

We have written many interesting articles on the moons of Uranus here at Universe Today. Here’s How Many Moons Does Uranus Have? and Interesting Facts About Uranus.

For more information, check out NASA’s Solar System Exploration page on Oberon and Nine Planet’s page on Oberon.

Astronomy Cast also has a good episode on the subject. Here’s Episode 62: Uranus.

Sources:

June 18, 2015February 27, 2017 by Fraser Cain

When Will We Find Another Earth?

We hear about discoveries of exoplanets every day. So how long will it take us to find another planet like Earth?

Back in the olden days, astronomers could only guess if there were planets orbiting other stars.

These were the days when we had to wait at the bank to pay our bills, nobody carried computers in their pockets and those computers gave direct connections to everyone else’s pockets because pocket connectivity is highly important, school was uphill both ways, the number 6 was brand new, we recorded images on thin sheets of transparent plastic, 5 bees were worth a quarter and I had an onion tied to my belt, as was the style at the time.

With the discovery of a mega Jupiter-sized world orbiting the star 51 Pegasi in 1995, the floodgates opened up. In the years that followed, dozens more planets were discovered. Then hundreds, and now, we know about thousands orbiting other stars.

The bad news is we can’t get to any of them. The good news is most of these worlds suck. You don’t want any part of them. For starters their wifi is terrible.

Consider Kepler-70b. This world orbits its star 4 times in a 24 hour period. This means it’s super close, and a great place to really quickly win all the human torch cosplay competitions. The surface temperature is a completely unreasonable 7200 Kelvin, hotter than the surface temperature of the Sun.

There’s the planets orbiting pulsar PSR B1257+12, a millisecond pulsar in the constellation of Virgo. As they whip around their exotic host, they’re bathed in intense radiation. Which is generally considered bad for creatures who need functioning organs.

Perhaps HD 106906 b, orbiting its star 650 times more distantly than we orbit the Sun. You’d spend every second of your short life on that planet inventing new words for cold. And then you’d die. Cold.

Imagine a world that orbits a star like our Sun. A world made of about an Earth’s worth of rocky material that you could stand on, at just the right distance from its star that water can exist as a liquid.

This is what astronomers search for, the tri-wizard cup of extrasolar planetary research. Earth 2? Terra Nova? The Gaia part le deux.

Here’s the exciting part. Astronomers have found each of these characteristics in a planet, but never all together. They’ve found plenty of stars similar to our Sun, with planets orbiting them. In fact, the star HD 10180 is incredibly similar to the Sun, and astronomers have discovered 9 planets orbiting it so far. Which does have a familiar ring to it. No word so far on which ones are about to be demoted to dwarf planets.

Sizes and temperatures of Kepler discoveries compared to Earth and Jupiter

They’ve found planets roughly the same mass as the Earth. Kepler-89, with 98% the mass of the Earth. So close! Sadly, it’s way too close to its parent hydrogen furnace to be habitable.

They’ve found planets in the habitable zone. Here on Earth, the global average temperature is -18 degrees C. Sounds cold, but the wintery nights in Antarctica absolutely wreck our GPA.

The closest analog discovered is Kepler-22b, with a global average temperature of -11C. So, it should feel downright balmy. Except, it’s about 2.4 times bigger than Earth and orbits a nasty red dwarf star.

Astronomers have even matched up two criteria at the same time. Earth-sized world orbiting around a Sun-like star, but it’s hellishly hot. Wrong flavor star but with the right temperature and size, it’s a veritable tic tac toe board of near wins.

So far, there hasn’t been a single extrasolar planet discovered that meets all three criteria. An Earth-sized world, orbiting a Sun-like star inside the habitable zone where liquid water could be present.

Astronomers were hoping that NASA’s Kepler spacecraft would have been the first to discover Earth 2.0. It had already turned up thousands of planets, including many of the ones I’ve already mentioned.

Artist's conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech — Artist’s conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech

Sadly, just a few years into the mission, it lost too many reaction wheels, which allow the spacecraft to change direction. It wasn’t able to make enough observations to help confirm a true Earth 2.0. Kepler is still searching for planets, but with a reduced ability to point, it’s only looking at red dwarf stars.

Don’t worry, NASA’s Transiting Exoplanet Survey Satellite will launch in 2017, and will survey a region of the sky 400 times larger than Kepler did. It should turn up thousands of planets, Earth-sized and larger.

Once we actually find New Terra, things get really interesting. Astronomers will search those planets for life. I know it sounds almost impossible to see life from this distance, but astronomers know that if they can analyze the atmosphere of these worlds, they can detect life flourishing there.

They might even be able to detect the pollution from their alien cars and heavy industry, contributing to their CO2 levels, and learn we’re not so different after all. Even if they’re icky bug people.

At the time I’m recording this video, no analog Earth planet has been discovered so far. But it’s just a matter of time. In the next few decades astronomers are going to find that first Earth 2.0, and then dozens, then hundreds, and even figure out which ones have life on them.

It’s a great time to be alive. Place your bets. Predict the date astronomers announce that we’ll find Earth 2.0. Put your guess into the comments below.

June 17, 2015January 8, 2017 by Matt Williams

Mir: Russia’s Space Station

The Mir space station hangs above the Earth in 1995 (photo by Atlantis STS-71, NASA)

The Mir Space Station was Russia’s greatest space station, and the first modular space station to be assembled in orbit. Commissioned in 1986, the name can be translated from Russian as “peace”, “world”, and even “village” – alluding to the spirit of international cooperation that led to its creation. Owned and operated by the Soviet Union, it became the property of the Russian Federal Space Agency (Roscosmos) after 1991.

The space station was intended to advocate world peace and hosted international scientists and NASA astronauts. In this respect, Mir was very much the curtain-raiser for the International Space Station, which succeeded it as the largest satellite in Earth’s orbit after 2001.

Origin:

During the 1960s and 70s, when the United States was largely focused on Apollo and the Space Shuttle program, Russia began to focus on developing expertise in long-duration spaceflight, and felt that a larger space station would allow for more research in that area. Authorized in February 1976 by a government decree, the station was originally intended to be an improved model of the Salyut space stations.

The original plan called for a core module that would be equipped with a total of four docking ports, but eventual grew to include several ports for crewed Soyuz spacecraft and Progress cargo spaceships. By August 1978, the plan had grown to the final configuration of one aft port and five ports in a spherical compartment at the forward end of the station.

The Mir Space Station and Earth limb observed from the Orbiter Endeavour during NASA's STS-89 mission in 1998. Credit: NASA — *The Mir Space Station and Earth limb observed from the Orbiter Endeavour during NASA’s STS-89 mission in 1998. Credit: NASA*

Two would be located at either end of the station (as with the Salyut stations) with an additional two on either side of a docking sphere at the front of the station to enable further modules to expand the station’s capabilities. These docking ports would each accommodate 20-tonne space station modules based on the TKS spacecraft – a previous generation of space craft used to bring cosmonauts and supplies to the Salyut space stations.

Work began on the station in 1979, and drawings were released in 1982 and 83. By early 1984, work had ground to a halt as virtually all of Russia’s space resources were being put into the Buran program – a Soviet and later Russian reusable spacecraft project. Funding resumed in early 1984 when the Central Committee became determined to orbit Mir by early 1986, just in time for the 27th Communist Party Congress.

Deployment:

On February 19th, 1986, the assembly process began with the launching of Mir’s core module on a Proton-K rocket into orbit. Between 1987 and 1996, four of the six modules were launched and added to the station – Kvant-2 in 1989, Kristall in 1990, Spektr in 1995 and Priroda in 1996. In these cases, the modules were sent into orbit aboard a Proton-K, chased the station automatically, and then used their robot Lyappa arms to mate with the core.

Soviet/Russian space station Mir, after completion in 1996. The date shown for each module is its year of launch. Docked to the station are a Soyuz TM manned spacecraft and an unmanned Progress resupply ferry. Credit: Encyclopedia Britannica — *Soviet/Russian space station Mir, after completion in 1996. The date shown for each module is its year of launch. Credit: Encyclopedia Britannica*

Kvant-1, having no engines of its own, was delivered by a TKS spacecraft in 1987, while the docking module was brought to the station aboard Space Shuttle Atlantis (STS-74) in 1995. Various other external components, including three truss structures, several experiments and other unpressurized elements, were also mounted to the exterior of the station over the course of its history.

The station’s assembly marked the beginning of the third generation of space station design, being the first to consist of more than one primary spacecraft. First generation stations such as Salyut 1 and Skylab had monolithic designs, consisting of one module with no resupply capability, while second generation stations (Salyut 6 and Salyut 7) comprised a monolithic station with two ports to allow resupply cargo spacecraft (like Progress).

The capability of Mir to be expanded with add-on modules meant that each could be designed with a specific purpose in mind, thus eliminating the need to install all the station’s equipment in one module. After construction was finished, Mir had a collection of facilities. At 13.1 meters (43 feet) long, the “core” module of the station was the main area where the cosmonauts and astronauts did their work. It also housed the main computer and vital space station parts, such as communications.

In addition to solar arrays and a docking port, the station had several facilities for orbital science. These included, but were not limited to, the two Kvant modules (where astronomy and other scientific research was conducted), the Kristall module (which had a facility for microgravity manufacturing) and Spektr (focused on Earth work).

*A view of the Russian space station Mir on 3 July 1993 as seen from Soyuz TM-17. Credit: spacefacts.de*

Missions:

During its 15-year spaceflight, Mir was visited by a total of 28 long-duration, or “principal”, crews. Expeditions varied in length, but generally lasted around six months. Principal expedition crews consisted of two to three crew members, who often launched as part of one expedition but returned with another.

As part of the Soviet Union’s manned spaceflight program effort to maintain a long-term research outpost in space, operated by the new Russian Federal Space Agency after 1991, the vast majority of the station’s crew were Russian. However, through international collaborations, the station was made accessible to astronauts from North America, several European nations and Japan.

Collaborative programs included the Intercosmos, Euromir and Shuttle-Mir programs. Intercosmos, which ran from 1978-1988, involved astronauts from other Warsaw Pact Nations, other socialist nations – like Afghanistan, Cuba, Mongolia, and Vietnam – and pro-Soviet non-aligned nations such as India, Syria, and even France.

Euromir, which began in the 1990s, was a collaborative effort between the Russian Federal Space Agency and the European Space Agency (ESA) to bring European astronauts to the space station. With help provided by the NASA Space Shuttle program, the goal was to recruit and train European astronauts for the then-planned International Space Station.

Meanwhile, the Shuttle–Mir Program was a collaborative space program between Russia and the United States, and involved American Space Shuttles visiting the space station, Russian cosmonauts flying on the shuttle, and an American astronaut flying aboard a Soyuz spacecraft to engage in long-duration expeditions aboard Mir.

*A view of the US Space Shuttle Atlantis and the Russian Space Station Mir during STS-71 as seen by the crew of Mir EO-19 in Soyuz TM-21. Credit: NASA*

By the time of the station’s deorbit, it had been visited by 104 different people from twelve different nations, making it the most visited spacecraft in history (a record later surpassed by the International Space Station).

Decommissioning:

When it was launched in 1986, Mir was only supposed to have a life span of about five years, but it proved to have a greater longevity than anyone expected. Unfortunately, a series of technical and structural problems eventually caught up with the station; and in November 2000, the Russian government announced that it would decommission the space station.

This began on Jan. 24th, 2001, when a Russian Progress cargo ship rendezvoused with the station carrying twice its normal amount of fuel. The extra fuel was intended to fire the Progress’ thrusters once it had docked with Mir and push the station into a controlled descent through the Earth’s atmosphere.

The Russian government purchased insurance just in case the space station hit any populated area when it crashed to Earth. Luckily, the station ended up crashing into the South Pacific Ocean, landing about 2,897 kilometers from New Zealand. In 2001, former RKA General Director Yuri Koptev estimated that the cost of the Mir program to be $4.2 billion (including development, assembly and orbital operation).

Legacy:

The Mir Space Station endured for 15 years in orbit, three times its planned lifetime. It hosted scores of crew members and international visitors, raised the first crop of wheat to be grown from seed to seed in outer space, and served as a symbol of Russia’s past glories and it’s potential as a future leader in space exploration.

*Jerry Linenger dons a mask during his mission on Mir in 1997. Credit: NASA*

In addition, the station was a source of controversy over the years, due to the many accidents and hazards it endured. The most famous of these took place on February 24, 1997 during mission STS-81. On this occasion, which saw the Space Shuttle Atlantis delivering crew, supplies, and conducting a series of tests, the worst fire aboard an orbiting spacecraft broke out.

This caused failures in various on-board systems, a near collision with a Progress resupply cargo ship during a long-distance manual docking system test, and a total loss of station electrical power. The power failure also caused a loss of attitude control, which led to an uncontrolled “tumble” through space. Luckily, the crew managed to suppress the fire and regain control before long.

Another major incident took place on June 25th, when a Progress resupply ship collided with solar arrays on the Spektr module, creating a hole which caused the station to lose pressure. This was the first orbital depressurization in the history of spaceflight to take place. Luckily, no astronauts were lost while serving aboard the station.

Mir is also famous for hosting long-duration missions during its early years in space. Topping the list was Russian cosmonaut Valeri Polyakov, who spent nearly 438 days aboard Mir and landed on March 22, 1995. The station itself orbited the Earth more than 86,000 times during its lifespan, and was also the largest orbiting object in the Solar System.

But most importantly of all, Mir served as the stage for the first large-scale, technical partnership between Russia and the United States after a half-century of mutual antagonism. Without it, there would be no ISS today, and numerous joint-research efforts between NASA, the ESA, Russia, and other federal space agencies, would not have been possible.

We have written many interesting articles about space stations here at Universe Today. Here’s What is the International Space Station?, Fire! How the Mir Incident Changed Space Station History, The Mir Space Station: An Unlikely Place for a Beautiful Art Exhibit, and Mir’s Fiery Re-entry, March 23, 2001.

For more information, check out the Mir Space Station and Shuttle-Mir.

And Astronomy Cast has a wonderful episode on Mir, titled Episode 297: Space Stations, Part 2: Mir

Source:

June 16, 2015March 11, 2016 by Matt Williams

What Is The Kuiper Belt?

Hubble Finds Smallest Kuiper Belt Object. Credit: NASA

Dr. Mike Brown is a professor of planetary astronomy at Caltech. He’s best known as the man who killed Pluto, thanks to his team’s discovery of Eris and other Kuiper Belt Objects. We asked him to help us explain this unusual region of our solar system.

Soon after Pluto was discovered by Clyde Tombaugh on February 18th, 1930, astronomers began to theorize that Pluto was not alone in the outer Solar System. In time, they began to postulate the existence of other objects in the region, which they would discover by 1992. In short, the existence of the Kuiper Belt – a large debris field at the edge of the Solar System – was theorized before it was ever discovered.

Definition:

The Kuiper Belt (also known as the Edgeworth–Kuiper belt) is a region of the Solar System that exists beyond the eight major planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, in that it contains many small bodies, all remnants from the Solar System’s formation.

But unlike the Asteroid Belt, it is much larger – 20 times as wide and 20 to 200 times as massive. As Mike Brown explains:

The Kuiper Belt is a collection of bodies outside the orbit of Neptune that, if nothing else had happened, if Neptune hadn’t formed or if things had gone a little bit better, maybe they could have gotten together themselves and formed the next planet out beyond Neptune. But instead, in the history of the solar system, when Neptune formed it led to these objects not being able to get together, so it’s just this belt of material out beyond Neptune.

Discovery and Naming:

Shortly after Tombaugh’s discovery of Pluto, astronomers began to ponder the existence of a Trans-Neptunian population of objects in the outer Solar System. The first to suggest this was Freckrick C. Leonard, who began suggesting the existence of “ultra-Neptunian bodies” beyond Pluto that had simply not been discovered yet.

That same year, astronomer Armin O. Leuschner suggested that Pluto “may be one of many long-period planetary objects yet to be discovered.” In 1943, in the Journal of the British Astronomical Association, Kenneth Edgeworth further expounded on the subject. According to Edgeworth, the material within the primordial solar nebula beyond Neptune was too widely spaced to condense into planets, and so rather condensed into a myriad of smaller bodies.

In 1951, in an article for the journal Astrophysics, that Dutch astronomer Gerard Kuiper speculated on a similar disc having formed early in the Solar System’s evolution. Occasionally one of these objects would wander into the inner Solar System and become a comet. The idea of this “Kuiper Belt” made sense to astronomers. Not only did it help to explain why there were no large planets further out in the Solar System, it also conveniently wrapped up the mystery of where comets came from.

In 1980, in the Monthly Notices of the Royal Astronomical Society, Uruguayan astronomer Julio Fernández speculated that a comet belt that lay between 35 and 50 AU would be required to account for the observed number of comets.

Following up on Fernández’s work, in 1988 a Canadian team of astronomers (team of Martin Duncan, Tom Quinn and Scott Tremaine) ran a number of computer simulations and determined that the Oort cloud could not account for all short-period comets. With a “belt”, as Fernández described it, added to the formulations, the simulations matched observations.

*The bodies in the Kuiper Belt. Credit: Don Dixon*

In 1987, astronomer David Jewitt (then at MIT) and then-graduate student Jane Luu began using the telescopes at the Kitt Peak National Observatory in Arizona and the Cerro Tololo Inter-American Observatory in Chile to search the outer Solar System. In 1988, Jewitt moved to the Institute of Astronomy at the University of Hawaii, and Luu later joined him to work at the University’s Mauna Kea observatory.

After five years of searching, on August 30th, 1992, Jewitt and Luu announced the “Discovery of the candidate Kuiper belt object” (15760) 1992 QB1. Six months later, they discovered a second object in the region, (181708) 1993 FW. Many, many more would follow…

In their 1988 paper, Tremaine and his colleagues referred to the hypothetical region beyond Neptune as the “Kuiper Belt”, apparently due to the fact that Fernández used the words “Kuiper” and “comet belt” in the opening sentence of his paper. While this has remained the official name, astronomers sometimes use the alternative name Edgeworth-Kuiper belt to credit Edgeworth for his earlier theoretical work.

However, some astronomers have gone so far as to claim that neither of these names are correct. For example, Brian G. Marsden – a British astronomer and the longtime director of the Minor Planet Center (MPC) at the Harvard-Smithsonian Center for Astrophysics – claimed that “Neither Edgeworth nor Kuiper wrote about anything remotely like what we are now seeing, but Fred Whipple (the American astronomer who came up with the “dirty snowball” comet hypothesis) did”.

The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA — *The layout of the solar system, including the Kuiper Belt and the Oort Cloud, on a logarithmic scale. Credit: NASA*

Furthermore, David Jewitt commented that, “If anything … Fernández most nearly deserves the credit for predicting the Kuiper Belt.” Because of the controversy associated with its name, the term trans-Neptunian object (TNO) is recommended for objects in the belt by several scientific groups. However, this is considered insufficient by others, since this can mean any object beyond the orbit of Neptune, and not just objects in the Kuiper Belt.

Composition:

There have been more than a thousand objects discovered in the Kuiper Belt, and it’s theorized that there are as many as 100,000 objects larger than 100 km in diameter. Given to their small size and extreme distance from Earth, the chemical makeup of KBOs is very difficult to determine.

However, spectrographic studies conducted of the region since its discovery have generally indicated that its members are primarily composed of ices: a mixture of light hydrocarbons (such as methane), ammonia, and water ice – a composition they share with comets. Initial studies also confirmed a broad range of colors among KBOs, ranging from neutral grey to deep red.

This suggests that their surfaces are composed of a wide range of compounds, from dirty ices to hydrocarbons. In 1996, Robert H. Brown et al. obtained spectroscopic data on the KBO 1993 SC, revealing its surface composition to be markedly similar to that of Pluto, as well as Neptune’s moon Triton, possessing large amounts of methane ice.

8 largest Kuiper Belt Objects — *Artist’s comparison of the eight largest Kuiper Belt Objects. Credit: Lexicon/NASA Images*

Water ice has been detected in several KBOs, including 1996 TO₆₆, 38628 Huya and 20000 Varuna. In 2004, Mike Brown et al. determined the existence of crystalline water ice and ammonia hydrate on one of the largest known KBOs, 50000 Quaoar. Both of these substances would have been destroyed over the age of the Solar System, suggesting that Quaoar had been recently resurfaced, either by internal tectonic activity or by meteorite impacts.

Keeping Pluto company out in the Kuiper belt, are many other objects worthy of mention. Quaoar, Makemake, Haumea, Orcus and Eris are all large icy bodies in the Belt. Several of them even have moons of their own. These are all tremendously far away, and yet, very much within reach.

Exploration:

On January 19th, 2006, NASA launched the New Horizons space probe for the sake of studying Pluto, its moons and one or two other Kuiper Belt objects. As of January 15th, 2015, the spacecraft began its approach to the dwarf planet, and is expected to make a flyby by July 14th, 2015. When it reaches the area, astronomers are expecting several interesting photographs of the Kuiper Belt as well.

Even more exciting is the fact that surveys of other solar systems indicate that our Solar System isn’t unique. Since 2006, there have been other “Kuiper Belts” (i.e. icy debris belts) discovered around nine other star systems. These appear to fall into two categories: wide belts, with radii of over 50 AU, and narrow belts (like our own Kuiper Belt) with radii of between 20 and 30 AU and relatively sharp boundaries.

According to infrared surveys, an estimated 15-20% of solar-type stars are believed to have massive Kuiper-Belt-like structures. Most of these appear to be fairly young, but two star systems – HD 139664 and HD 53143, which were observed by the Hubble Space Telescope in 2006 – are estimated to be 300 million years old.

Vast and unexplored, the Kuiper Belt is the source of many comets, and is believed to be the point of origin for all periodic or short-period comet (i.e. ones with an orbit lasting 200 years or less). The most famous of these is Halley’s Comet, which has been active for the past 16,000–200,000 years.

Future of the Kuiper Belt:

When he initially speculated about the existence of a belt of objects beyond Neptune, Kuiper indicated that such a belt probably did not exist anymore. Of course, subsequent discoveries have proven this to be wrong. But one thing that Kuiper was definitely right about was the idea that these Trans-Neptunian Objects won’t last forever. As Mike Brown explains:

We call it a belt, but it’s a very wide belt. It’s something like 45 degrees in extent across the sky – this big swath of material that’s just been churned and churned by Neptune. And these days, instead of making a bigger and bigger body, they’re just colliding and slowly grinding down into dust. If we come back in another hundred million years, there’ll be no Kuiper Belt left.

Given the potential for discovery, and what up-close examination could teach us about the early history of our Solar System, many scientists and astronomers look forward to the day when we can examine the Kuiper Belt in more detail. Here’s hoping that the New Horizons mission is just the beginning of future decades of research into this mysterious region!

We have many interesting articles here at Universe Today on the subject on the Outer Solar System and Trans-Neptunion Objects (TNOs).

And be sure to check out this article on the planet Eris, the latest dwarf planet and the largest TNO to be discovered.

And astronomers are expecting to discover two more large planets in our Solar System.

Universe Today also has a full-length interview with Mike Brown from Caltech.

June 14, 2015December 23, 2015 by Matt Williams

Edwin “Buzz” Aldrin – The Second Man on the Moon

Astronaut Edwin E. Aldrin, Jr. Credit: NASA

Astronaut, engineer, author, and actor, Edwin “Buzz” Aldrin is what you might call a living legend. As the Lunar Module Pilot aboard the Apollo 11 mission, and second man to walk on the Moon, he is exceeded only by Neil Armstrong when it comes to the most famous astronauts that have ever lived.

And much like all astronauts who left an indelible mark on history, the path that brought Aldrin to the Moon began early in his life. And since achieving the dream of countless generations, he has gone on to inspire others to make similar leaps, advocating space exploration, and a mission to Mars.

Early Life:
Born Edwin Eugene Aldrin on January 20th, 1930, in Montclair, New Jersey to a military family, Aldrin picked up his famous nickname from the younger of his two elder sisters. Unable to pronounce brother, he let her call him “buzzer”, which was eventually shortened to “Buzz”. During his childhood, Aldrin was also a boy scout, earning the rank of Tenderfoot Scout.

After graduating from high school, Aldrin wanted to follow in his father’s footsteps. As such, he turned down a scholarship to the Massachusetts Institute of Technology (MIT) and instead enrolled in the United States Military Academy at West Point, New York. He would later enroll at MIT to complete his studies, but not before going off to war.

Military Career:
Upon graduating in 1951 from West Point with a Bachelors of Science in Mechanical Engineering, Aldrin was commissioned as a 2nd Lieutenant in the United States Air Force. During the Korean War, he served as a jet fighter pilot, flying 66 combat missions in F-86 Sabres and shooting down two MiG-15 aircraft.

After the war, he was assigned as an aerial gunnery instructor at Nellis Air Force Base in Nevada before becoming a flight commander at Bitburg Air Base in West Germany, where he flew F-100 Super Sabres with the 22nd Fighter Squadron.

F-86 Sabre Pilot Lieutenant Buzz Aldrin of 16th FS, 51st FW, Korea, 1953. Credit: openroadmedia.kinja.com — *Buzz Aldrin in the cockpit of an F-86 Sabre while serving as part of the 16th FS, 51st FW, in Korea, 1953. Credit: openroadmedia.kinja.com*

After completing his military service, Aldrin returned to MIT to receive his Doctor of Science degree in Aeronautics. In 1963, he was assigned to the Gemini Target Office of the Air Force Space Systems Division in Los Angeles, and began to pursue a career in space exploration. Initially, his application was rejected since he had never been a test pilot. However, that prerequisite was lifted when Aldrin re-applied, and he was accepted into the third group of astronauts in October of 1963.

Gemini Program:
Aldrin was initially selected to participate in the Gemini program, and after the deaths of the original Gemini 9 prime crew (Elliot See and Charles Bassett) Aldrin and Jim Lovell were promoted to backup crew for the mission. The main objective of the revised mission (Gemini 9A) was to rendezvous and dock with a target vehicle.

When this failed, Aldrin improvised an effective exercise for the craft to rendezvous with a co-ordinate in space. On his next mission – Gemini 12, which took place in 1966 – Aldrin served as the pilot and set a record for extra-vehicular activity (EVA), demonstrating that astronauts could work outside spacecraft.

*Photograph of Major Edwin E. Aldrins helmet taken during the Gemini XII mission during orbit no. 14 on November 12,1966. Credit: NASA*

Apollo 11:
As the Lunar Module Pilot of the Apollo 11 mission, Aldrin became the second astronaut to walk on the Moon on July 21st, 1969. Aldrin’s first words on the Moon were “Beautiful view. Magnificent desolation.” As a Presbyterian, Aldrin decided to hold a religious ceremony on the Moon, and became the first man to do so.

Using a home communion kit given to him, he reciting words used by his pastor at Webster Presbyterian Church (Rev. Dean Woodruff). The ceremony was not communicated back to Earth and was a private affair. However, after landing on the Moon, Aldrin radioed Earth and said:

I’d like to take this opportunity to ask every person listening in, whoever and wherever they may be, to pause for a moment and contemplate the events of the past few hours, and to give thanks in his or her own way.

In later years, Aldrin expressed some regret, thinking that a Christian service may not have been in keeping with the spirit of going to the Moon for all of humanity. However, for him personally, it was a significant event and in keeping with his personal faith.

According to different NASA accounts, it had originally been proposed that Aldrin be the first to step onto the Moon’s surface. But due to the physical positioning of the astronauts inside the compact lunar landing module, it was easier for the commander, Neil Armstrong, to be the first to exit the spacecraft.

Buzz Aldrin on the Moon — *The iconic photo of Buzz Aldrin walking on surface the Moon as part of the Apollo 11 mission. Credit: NASA*

Retirement:
After leaving NASA in 1971, Aldrin was assigned as the Commandant of the U.S. Air Force Test Pilot School at Edwards Air Force Base, California. In March 1972, Aldrin retired from active duty after 21 years of service, due to personal issues stemming from clinical depression and alcoholism. Afterward, he sought treatment for these problems, and his life improved considerably.

Following his retirement, Aldrin remained active in promoting space. He created a nonprofit organization named ShareSpace which supports space education, has written several books, and even released a CD with Snoop Dogg and other rappers in order to promote space. He has been very vocal regarding his belief that NASA should be moving ahead with a manned mission to Mars.

Since retiring from NASA, he has also had an impressive career in television and film, appearing on multiple episodes of hit TV shows, TV movies, documentaries, and as a contestant on Dancing with the Stars. He has also done extensive voice-over work for animated shows, movies, and the video game Mass Effect 3.

Like Neil Armstrong, Buzz Aldrin has received numerous medals and awards for his service – including the Presidential Medal of Freedom, the Air Force Distinguished Service Medal, three Air Medals, the NASA Distinguished Service Medal, the NASA Exceptional Service Medal, two NASA Space Flight Medals, and the Harmon International Trophy. He has also received honorary degrees from six colleges and universities.

Aldrin has been married three times and has three children and one grandson.

Universe Today has articles on Buzz Aldrin and Buzz Aldrin raps with Snoop Dogg.

For more information, try Buzz Aldrin and Snoop Dogg and biography of Buzz Aldrin.

Astronomy Cast has episodes on the Moon.

Source: NASA