Astronomy Archives

December 13, 2016December 15, 2016 by Matt Williams

Martian Mineral Points Toward Past Habitability

Curiosity picture showing color variations on Mount Sharp, Mars. Credit: NASA/JPL

For over a year, the Curiosity rover has been making its way up the slopes of Mount Sharp, the central peak within the Gale Crater. As the rover moves higher along this formation, it has been taking drill samples so that it might look into Mars’ ancient past. Combined with existing evidence that water existed within the crater, this would have provided favorable conditions for microbial life.

And according to the most recent findings announced by the Curiosity science team, the upper levels of the mountain are rich in minerals that are not found at the lower levels. These findings reveal much about how the Martian environment has changed over the past few billion years, and are further evidence that Mars may have once been habitable.

The findings were presented at the Fall meeting of the American Geophysical Union (AGU), which began on Monday, Dec. 12th, in San Fransisco. During the meeting, John Grotzinger – the Fletcher Jones Professor of Geology at Caltech and the former Project Scientist for the Curiosity mission – and other members of Curiosity’s science team shared what the rover discovered while digging into mineral veins located in the higher, younger layers of Mount Sharp.

This pair of drawings depicts the same location at Gale Crater on at two points in time: now and billions of years ago. Water moving beneath the ground, as well as water above the surface in ancient rivers and lakes, provided favorable conditions for microbial life, if Mars has ever hosted life. Credit: NASA/JPL-Caltech — *Artist’s illustration showing the Gale Crater as it appears today, with the Curiosity rover climbing Mount Sharp. Credit: NASA/JPL-Caltech*

To put it simply, mineral veins are a great way to study the movements of water in an area. This is due to the fact that veins are the result of cracks in layered rock being filled with chemicals that are dissolved in water – a process which alters the chemistry and composition of rock formations. What the rover found was that at higher layers hematite, clay minerals and boron are more abundant than what has been observed at lower, older layers.

These latest findings paint a complex picture of the region, where groundwater interactions led to clay-bearing sediments and diverse minerals being deposited over time. As Grotzinger explained, this kind of situation is favorable as far as habitability is concerned:

“There is so much variability in the composition at different elevations, we’ve hit a jackpot. A sedimentary basin such as this is a chemical reactor. Elements get rearranged. New minerals form and old ones dissolve. Electrons get redistributed. On Earth, these reactions support life.”

At present, no evidence has been found that microbial life actually existed on Mars in the past. However, since it first landed back in 2012, the Curiosity mission has uncovered ample evidence that conditions favorable to life existed billions of years ago. This is possible thanks to the fact that Mount Sharp consists of layered sedimentary deposits, where each one is younger than the one beneath it.

*The Gale Crater, billions of years ago, showing how the circulation of groundwater led to chemical changes and deposits. Credit: NASA/JPL-Caltech*

These sedimentary layers act as a sort of geological and environmental record for Mars; and by digging into them, scientists are able to get an idea of what Mars’ early history looked like. In the past, Curiosity spent many years digging around in the lower layers, where it found evidence of liquid water and all the key chemical ingredients and energy needed for life.

Since that time, Curiosity has climbed higher along Mount Sharp and examined younger layers, the purpose of which has been to reconstruct how the Martian environment changed over time. As noted, the samples Curiosity recently obtained showed greater amounts of hematite, clay minerals and boron. All of these provide very interesting clues as to what kinds of changes took place.

For instance, compared to previous samples, hematite was the most dominant iron oxide mineral detected, compared to magnetite (which is a less-oxidized form of iron oxide). The presence of hematite, which increases with distance up the slope of Mount Sharp, suggests both warmer conditions and more interaction with the atmosphere at higher levels.

The increasing concentration of this minerals – relative to magnetite at lower levels – also indicates that environmental changes have occurred where the oxidation of iron increased over time. This process, in which more electrons are lost via chemical exchanges, can provide the energy necessary for life.

*Hi-resolution pictures showing the Curiosity rover’s various drilling sites, up until Nov. 2016. Credit: NASA/JPL*

In addition, Curiosity’s Chemistry and Camera (ChemCam) instrument has also noted increased (but still minute)) levels of borons within veins composed primarily of calcium sufate. On Earth, boron is associated with arid sites where water has evaporated, and its presence on Mars was certainly unexpected. No previous missions have ever detected it, and the environmental implications of it being present in such tiny amounts are unclear.

On the one hand, it is possible that evaporation within the lake bed created a boron-deposit deeper inside Mount Sharp. The movement of groundwater within could have then dissolved some of this, redepositing trace amounts at shallower levels where Curiosity was able to reach it. On the other hand, it could be that changes in the chemistry of clay-bearing deposits affected how boron was absorbed by groundwater and then redeposited.

Either way, the differences in terms of the composition of upper and lower levels in the Gale Crater creates a very interesting picture of how the local environment changed over time:

“Variations in these minerals and elements indicate a dynamic system. They interact with groundwater as well as surface water. The water influences the chemistry of the clays, but the composition of the water also changes. We are seeing chemical complexity indicating a long, interactive history with the water. The more complicated the chemistry is, the better it is for habitability. The boron, hematite and clay minerals underline the mobility of elements and electrons, and that is good for life.”

It seems that with every discovery, the long history of “Earth’s Twin” is becoming more accessible, yet more mysterious. The more we learn about it past and how it came to be the cold, desiccated place we know today, the more we want to know!

Further Reading: NASA

December 13, 2016 by Matt Williams

Hubble Watches Spinning Black Hole Swallow a Star

Close-up of star near a supermassive black hole (artist’s impression). Credit: ESA/Hubble, ESO, M. Kornmesser

In 2015, the All-Sky Automated Survey for Supernovae (aka. ASAS-SN, or Assassin) detected something rather brilliant in a distant galaxy. At the time, it was thought that the event (named ASASSN-15lh) was a superluminous supernova – an extremely bright explosion caused by a massive star reaching the end of its lifepsan. This event was thought to be brightest supernova ever witnessed, being twice as bright as the previous record-holder.

But new observations provided by an international team of astronomers have provided an alternative explanation that is even more exciting. Relying on data from several observatories – including the NASA/ESA Hubble Space Telescope – they have proposed that the source was a star being ripped apart by a rapidly spinning black hole, an event which is even more rare than a superluminous supernova.

According to the ASAS-SN’s findings – which were published in January of 2016 in Science – the superluminous light source appeared in a galaxy roughly 4 billion light-years from Earth. The luminous source was twice as bright as the brightest superluminous supernova observed to date, and its peak luminosity was 20 times brighter than the total light output of the entire Milky Way.

Credit: ESA/Hubble, ESO, M. Kornmesser — *This artist’s impression depicts a rapidly spinning supermassive black hole surrounded by an accretion disc. Credit: ESA/Hubble, ESO, M. Kornmesse*

What seemed odd about it was the fact that the superluminous event appeared within a massive, red (i.e. “quiescent”) galaxy, where star formation has largely ceased. This was in contrast to most super-luminous supernovae that have been observed in the past, which are typically located in blue, star-forming dwarf galaxies. In addition, the star (which is Sun-like in size) is not nearly massive enough to become an extreme supernova.

As such, the international team of astronomers – led by Giorgos Leloudas of the Weizmann Institute of Science in Israel and the Dark Cosmology Center in Denmark – conducted follow-up observations using space-based and Earth-based observatories. These included the Hubble Space Telescope, the Very Large Telescope (VLT) at the ESO’s Paranal Observatory and the New Technology Telescope (NTT) at the La Silla Observatory.

With information from these facilities, they arrived at a much different conclusion. As Dr. Leloudas explained in a Hubble press release:

“We observed the source for 10 months following the event and have concluded that the explanation is unlikely to lie with an extraordinary bright supernova. Our results indicate that the event was probably caused by a rapidly spinning supermassive black hole as it destroyed a low-mass star.”

The process is colloquially known as “spaghettification”, where an object is ripped apart by the extreme tidal forces of a black hole. In this case, the team postulated that the star drifted too close to the supermassive black hole (SMBH) at the center of the distant galaxy. The resulting heat and the shocks created by colliding debris led to a massive burst of light – which was mistakenly believed to be a very bright supernova.

Multiple lines of evidence support this theory. As they explain in their paper, this included the fact that over the ten-months that they observed it, the star went through three distinct spectroscopic phases. This included a period of substanial re-brightening, where the star emitted a burst of UV light that accorded with a sudden increase in its temperature.

Combined with the unlikely location and the mass of the star, this all pointed towards tidal disruption rather than a massive supernova event. But as Dr. Leloudas admits, they cannot be certain of this just yet. “Even with all the collected data we cannot say with 100% certainty that the ASASSN-15lh event was a tidal disruption event.” he said. “But it is by far the most likely explanation.”

As always, additional observations are necessary before anyone can say for sure what caused this record-breaking luminous event. But in the meantime, the mere fact that something so rare was witnessed should be enough to cause some serious excitement! Speaking of which, be sure to check out the simulation videos (above and below) to see what such an event would look like:

Further Reading: Hubble Space Telescope

December 13, 2016 by Bob King

All I Want for Christmas is a Green Laser: How to Choose and Use One

When it comes to helping others find something in the night sky, a green laser makes it a piece of cake. Credit: Bob King

Devious humans have given green lasers a bad name. Aiming a laser at an aircraft or the flight path of an aircraft is illegal according to a 2012 U.S. federal law. Jail time awaits offenders. Don’t point at a police officer either. To get a taste of the dark side of green lasers, check out these rap sheets.

asdf — A standard 5 milliwatt (mW) laser can cause temporary flashblindness or at the very least distract a pilot up to around 11,000 feet (3,350 meters). Beyond that, it’s indistinguishable from other ground lighting. Credit: Wikipedia

But if you mind your manners, a green laser is one of the best tools available to amateur astronomers eager to share the wonders of the night sky with the public. There’s simply nothing better to point out constellations, comets, individual stars and satellites in the night sky. Amateurs love ’em! So does the public. Go to a star party and pop out the laser, and you’ll get everyone’s attention. There’s magic in being able to point out our favorite points of light with a beam of light.

Not only are lasers helpful when pointing out stars, many amateurs use them to point to and find deep sky objects with their telescopes. Credit: Bob King — Not only are lasers helpful when pointing out stars, many amateurs use them to point zero in on deep sky objects with their telescopes. Credit: Bob King

First, let’s look at laser etiquette to ensure the safety of our fellow stargazers:

* Always gather the group around you first, raise the laser above the crowd and ask everyone to look up. Then turn on the beam and aim. That way no one will accidentally face into the light. This is crucial when aiming low above the horizon, where the beam, nearly horizontal, has a better chance of striking someone in the eye. Take extra precaution to make sure the group is close. The closer the gathering, the brighter and easier the beam will be to see. Viewers too far off to one side or another will see a weaker, less intense light.

* Green lasers often use AAA batteries and draw a good amount of power especially on chilly nights. You’ll only get a few minutes of operation if you leave it out in the cold. Store your laser in an inside pocket to keep it warm until you need it. Tuck it back in between pointing sessions. Have a fresh pair of batteries around and keep those in your pocket, too!

* If you see an airplane headed in your direction, avoid using the laser light for a couple minutes just to be on the safe side.

* Never give your laser to someone in the dark to “try out.” Especially a child! They won’t be familiar with its safe use.

* Store your laser in a safe place when not in use, so kids can’t accidentally find it.

Red, green and violet lasers with a high enough output to trace a line in the night sky are all available now for reasonable prices. These three beams come from 50 mW lasers. Credit: Bob King — Red, green and violet lasers with a high enough output to trace a line in the night sky are all available these days for reasonable prices. These three beams come from 50 mW lasers. Multiple rays result from the subject not being able to hold the lasers steady during the time exposure! Credit: Bob King

The most common green laser available is rated at 5 milliwatts (mW), just adequate for night sky pointing. That said, be aware that brightness from one manufacturer to another can vary. Some 5mW pointers produce nearly as much light as a 30 mW model, practically a light saber! Others, like my first green laser, did the job on moonless nights, but proved too weak by first quarter phase. 30mW and 50mW are much better and significantly amp up the wow factor when you’re out with the crowd. They’re also much easier to see for larger groups and remain visible even in bright moonlight.

Back in olden days, 5 mW red and green lasers were as bright as they came, and the green ones were pricey. But nowadays, you can get powerful pointers in green, red, blue and violet. All will trace a visible beam across the night sky with green the brightest by far because our eyes are most sensitive to green light.

Green, violet and red lasers. Lasers emit very specific colors of light. Green appears brightest and sharpest; red and blue beams look fuzzier to our eyes. Credit: Pang Ka kit / CC BY-SA 3. — Green, violet and red lasers. Lasers emit very specific colors of light. Green appears brightest and sharpest; red and blue beams look fuzzier to our eyes. Credit: Netweb01 / CC BY-SA 3 / Wikimedia

I should add that yellow lasers have also recently become available. Like green, they’re superb for long-distance applications, but prices — oh, my — will burn a hole in your wallet. How about 300 bucks! You can get a 5 mW green laser for $5-10 that’s similarly bright. No matter what kind of laser pen you buy, they all operate on the same principle: a laser diode, related to an LED (light-emitting diode), powered by AA batteries emits a narrow, coherent beam of light when switched on.

Coherent light is light of a single wavelength where all the crests and troughs (remember, light is a wave) are in lockstep with one another. Each crest precisely overlaps the next; each trough snugly fits within the other. Regular light contains a garden salad mix of every wavelength each vibrating out of stop, to its own drummer as it were. Because laser light is coherent, it stays focused over great distances, forming a narrow beam ideal for pointing.

Lasers form visible beams because they scatter off air molecules, water vapor and dust in the air. In this photo, I spun the beam around the planet Jupiter on a humid, slightly foggy night. Credit: Bob King — Laser light literally illuminates the air and anything in it. The intense beam scatters off air molecules, water vapor and dust in the air. In this photo, I spun the beam around the planet Jupiter on a humid, slightly foggy night. Dust and water vapor illuminated by the beam creates a mesmerizing sparkle effect you have to see to believe. Credit: Bob King

Lasers are not only rated by power (milliwatts) but also the specific wavelength they emit. Green lasers beam light at 532 nanometers (nm), blue at 445 nm, violet at 405 nm, red at 650 nm and yellow at 589 nm. Green laser pointers generate their light from an infrared laser beam within the pen’s housing. Normally, any infrared light should be filtered from the final beam but in the majority of inexpensive laser pointers, it beams out right along with the green. We can’t see it, but concentrated infrared laser light poses an additional hazard when directed into the eyes. When you hear of lasers being used to pop balloons or light a match, it’s the leaky infrared that’s doing the popping. Yet another reason to use your laser with care!

Lasers can be artistic tools, too. Every year, a friend holds a star party near a towering grain silo. Late at night, we take a break, open the camera shutter and paint the silo with laser light. In this case - a rocket. Credit: Bob King — Lasers can be artistic tools, too. Every year, a friend holds a star party near a towering grain silo. Late at night, we take a break, open the camera shutter and paint the silo with laser light. In this case — a rocket. Credit: Bob King

Lower-powered laser pointers use AAA batteries. For instance, both my 5 mW and 55 mW green lasers use AAA batteries. Higher-powered pointers in the 5-watt range use a single #18650 (or 16340) 3.7 volt lithium ion rechargeable battery. You can either purchase these online (Orbitronics makes an excellent one for $12.99) or at your local Batteries Plus store. You’ll need a charger, too, which runs anywhere from about $8 for a single battery model to around $30 for a multiple battery version with different charging speeds. Be sure you get one with an LED light that will alert you when the batteries are done charging.

Whether sold in the U.S. or elsewhere, nearly every laser comes from China. We’ll talk about that in a minute, but if you purchase a laser that uses rechargeable batteries, beware of no-name chargers and off-brand batteries that lack safeguards. Some of these inexpensive batteries have been known to explode!

What to buy? I can’t speak to every firm that offers laser pointers, and there are many, but some of the more popular ones include:

* Wicked Lasers
* Z-Bolt
* Optotronics
* LED Shoppe

I’ve bought from Optotronics, based in Colorado and the LED Shoppe, out of Hong Kong. I took a chance on the LED Shoppe’s lasers and have been pleasantly surprised at the low cost, free shipping and good customer service. While power ratings can vary from what the label reads, I’ve been especially pleased with both the 55 mW from Optotronics and the 5-watt (yes, FIVE WATTS) green and red pointers from the LED Shoppe. Their 50 mW green version does a great job, too. Just a disclaimer — I don’t work for and am not associated with either company.

Bottom line: If you’re looking for a effective pointer for public star parties, I recommend a 50 mW or higher green pointer. Anything in that range will provide a lovely bright beam you can use to literally dazzle your audience when sharing the beauty of the night. Before you make your decision, check your country or state’s laser use laws where for the U.S. or worldwide. If buying in the U.S., speak to the business owner if you have any questions.

Have a Merry Green, Red, Blue and Violet Christmas!

December 12, 2016December 13, 2016 by Matt Williams

What is an Orrery?

Mechanical orrery by Gilkerson, in Armagh Observatory. Credit: star.arm.ac.uk

For thousands of years, humans have been studying the heavens, seeking to find patterns and predictability in their movements. This tradition goes all the way back to prehistory, where hunter-gatherer societies assigned characteristics to asterisms and celestial bodies. And from the 2nd millennium onward, magi and astronomers began recording the movements of the constellations and the planets through the zodiac.

By classical antiquity, attempts began to create astrolabes and other devices that would allow astronomers to know where the stars and planets were at any given time. These would eventually culminate in the creation of the orrery, a mechanical device that attempts to recreate the Solar System and the movements of its planets and moons around our Sun.

Definition:

Traditionally, an orrery is a mechanical model of the Solar System, or at least the major planets. This device is driven by a clockwork mechanism that simulates the motion of the planets (and, in some cases, major moons) around the Sun. This last feature is key, since most known orreries were produced during the early modern period and after, when the Heliocentric model of the Solar System came to be the accepted one.

Orreries are typically driven by a clockwork mechanism with a globe representing the Sun at the center, and with a planet at the end of each of the arms. They are usually not to scale, partly because of the difficulty of mechanically modeling the distances involved, the eccentricity of various planets’ orbits, and the planets’ massive differences in terms of size.

Though many working planetaria were created during Classical Antiquity, the first orrery of the modern era was produced in 1704 by clock makers George Graham and Thomas Tompion. The name is derived from Charles Boyle, the 4th Earl of Orrery, England, who commissioned famed instrument maker John Rowley to build one in 1713 based on the design of Graham and Tompion.

Early Examples:

The Antikythera mechanism, which is dated to ca. 150 – 100 BCE, may be considered the first orrery that is still in existence. Discovered in the wreck of a ship in 1900 off the Greek island of Antikythera (hence the name), this device consisted of hand-driven mechanisms that represented the diurnal motions of the Sun, the Moon, and the then-known five known planets (Mercury, Venus, Earth, Mars, Jupiter).

The Antikythera Mechanism may be the world's oldest computer. Image: By Marsyas CC BY 2.5 — *The Antikythera Mechanism may be the world’s oldest computer. Credit: Wikipedia Commons/Marsyas*

Reflecting the cosmological view of the Greeks, the device was geocentric in nature and was used as a mechanical calculator designed to determine astronomical positions. According to Roman philosopher Cicero (106 – 43 BCE), the Syrian-born Greek philosopher Posidonius of Rhodes (ca. 135 – 51 BCE ) built a planetary model as well. With the fall of the Roman Empire, the art would not be resurrected until the late Medieval Period.

In 1348, Italian doctor and clock maker Giovanni Dondi built the first known clock-driven mechanism which displayed the position of Moon, Sun, Mercury, Venus, Mars, Jupiter and Saturn along the ecliptic – according to the Ptolemaic (geocentric) model of the Solar system. At present, only a written account survives, but it is extremely detailed in its description of the mechanisms involved.

During the 16th century, two astronomical clocks were built for the court of William IV, Langrave of Hesse-Kassel (in modern day Bavaria, Germany). These showed the motions of the Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn based on the Ptolemaic system. These clocks are now on display at the Museum of Physics and Astronomy and the Royal Cabinet of Mathematical and Physical Instruments (in Kassel and Dresden, respectively).

Modern Examples:

Thanks to Copernicus’s proposal of the Heliocentric model of the Universe, Isaac Newton’s Law of Universal Gravitation, and other discoveries that took place during the Scientific Revolution, orreries changed significantly by the early modern period. In essence, the Heliocentric model simplified the apparent orbits of the planets around the Sun, to the point that they could be represented as simple circles or ellipses.

*A Philosopher Lecturing on the Orrery (ca. 1766) by Joseph Wright of Derby. Credit: Public Domain*

As noted, the first modern orrery was created in 1704 in England by clock makers George Graham and Thomas Tompion. This design was given to instrument maker Jon Rowely, who then produced a copy for the Prince Eugene of Savoy and was commissioned by his patron – Charles Boyle – to build them for himself and his son John – who would go on to become the 5th Earl of Orrery (and the 5th Earl of Cork).

Between 1665 and 1681, while in Paris, Christiaan Huygens created a heliocentric planetary machine that represented a year and the cycles of the then-known planets. He would go on to publish papers describing its functions by 1703. The painting “A Philosopher giving a Lecture on the Orrery in which a lamp is put in place of the Sun”, which Jospeh Wright completed in 1766, features a brass orrery as its centerpiece.

Between 1774 and 1781, Eisinga’s Planetarium was built in Franeker, in the Netherlands by amateur Frisian astronomer Eise Eisinga. Central to the planetarium is an orrery which shows the orbits of the planets across the width of the room’s ceiling. The clockwork machine that powers it has been in almost continuous operation since it first opened.

In 1764, Benjamin Martin invented a new type of orrery that relied on three parts – the planetarium where the planets revolved around the Sun; the tellurion, which showed the inclined axis of the Earth and how it revolved around the Sun; and the lunarium which showed the eccentric rotations of the Moon around the Earth. This allowed for a more accurate representations of the Solar System, which included the planet’s inclinations, relative to the Sun.

Orreries Today:

Today, with immense amounts of low-cost computing power available, software has been developed to calculate the relative positions and motions of Solar System bodies. Examples of these “digital orreries” include a java applet used at the Department of Physics at the University of Texas at Austin, and Orrery, a Solar System Visualizer from The Geometry Center at the University of Minnesota (which relies on Unix).

There is also the Digital Orrery, a special-purpose computer designed to model the long term motions of the outer planets of the Solar System. Constructed in 1985, it was built to answer a long-standing question about the Solar System, which is whether or not it is stable (invariably, the answer was a big no). This device is now at the Smithsonian Institution in Washington, DC.

And in 2013, the first virtual orrery was created by the Cattle Point Foundation at the DARK SKY Urban Star Park, located in Oak Bay, British Columbia. The orrery is called “The Salish Sea Walk of the Planets“, and was built with Google Maps to avoid negatively impacting the park and the nearby Orca and wildlife sanctuaries. This orrery has now extended beyond the Star Park to become the world largest, covering a distance of over 8,500 km (5,300 mi).

*The Sun and Cairn, part of “The Salish Sea Walk of the Planets” in Oak Bay, BC. Credit: attlepointstarpark.org*

The Sun is located in the Star Park in Oak Bay (shown above) while Pluto (the most distant “planet”) is located in Bamfield on the western side of Vancouver Island, BC. The Kuiper Belt Objects are situated north in the small towns of Ucluelet and Tofino while the farthest object within our Solar System – the Oort Cloud – is across the sea at the Canadian Embassy in Beijing, China.

Meanwhile, physical orreries still exist in many locations. For example, there’s The York Solar System Model Orrery, a special bike path constructed in 1999 and maintained by York University in the UK. Spread out along 10.3 km (6.4 miles) of the old East Coast main-line railway, this scale model of the Solar System contains all the planets of the Solar System, as well as models of the Cassini and Voyager spacecraft.

There is also the “Path of the Planets Uetliberg–Felsenegg“, which follows a hiking trail along the Albis (a chain of hills in Switzerland). The path was designed by Arnold von Rotz to be a 1:1 billion scale model of the Solar System (where 1 meter equals 1 billion km). The path runs from the towns of Uetliberg to Felsenegg (which is about 2 hours away on foot) and opened on April 26th, 1979.

Each planet is represented by a large orb that is mounted to a boulder or affixed inside one (depending on their size) and has a sign that includes the body’s place in the Solar System and their basic info (like equatorial diameter, rotational speed, etc.)

*The bronze orb representing the Sun along the “Passauer Footpath of the Planets”, in Lower Bavaria, Germany. Credit: uetliberg.ch*

There’s also The Human Orrery, which is located at Armagh Observatory, in Northern Ireland. This orrery allows people to play the part of the planets of Mercury, Venus, Earth, Mars, Jupiter, and Saturn, as well as Ceres and two comets (1P/Halley and 2P/Encke). Due to their immense distance, and the fact the orrery is to scale, Uranus and Neptune are not included.

From our humble beginnings as hunter-gatherers who looked up at the stars and discerned patterns in their appearance, humanity has come a long way in terms of its understanding of the Universe. As we invented devices to look deeper into the night sky, and even explore space directly, our models have matured accordingly, growing in terms of accuracy and complexity.

That tradition continues, with more mission to study and explore the outer Solar System proceeding apace. Future orreries are likely to take advantage of all this, leveraging new technologies and new information to create even more detailed and interesting representations of our cosmic background!

We have written many interesting articles about the planets here at Universe Today. Here’s The Solar System Guide, What is the Geocentric Model of the Universe?, What is the Heliocentric Model of the Universe?, What is the Difference Between the Geocentric and Heliocentric model of the Solar System?, and How Many Planets are in the Solar System?

Source:

December 12, 2016 by David Dickinson

This Week: Occultations of Aldebaran, Regulus vs. the Supermoon

Aldebaran Occultation — The Moon about to occult Aldebaran on December 23rd, 2015. Image credit and copyright: Paul Campbell.

It’s a busy week for the Moon. While our large solitary natural satellite reaches Full and interferes with the 2016 Geminids, it’s also beginning a series of complex bright star occultations of Aldebaran and Regulus, giving us a taste of things to come in 2017.

First up, here’s the lowdown on this week’s occultation of Aldebaran by the Moon, coming right up tonight:

The 99% illuminated waxing gibbous Moon occults the +0.9 magnitude star Aldebaran on Monday, December 12^th. The Moon is just 19 hours and 30 minutes before reaching Full during the event. Both are located 167 degrees east of the Sun at the time of the event. The central time of conjunction is 4:37 Universal Time (UT). The event occurs during the daylight hours over Hawaii at dusk during Moonrise, and under darkness for Mexico, most of Canada and the contiguous United States. The event also includes the United Kingdom and southwestern Europe at Moonset near early dawn. This is the final occultation of Aldebaran by the Moon for 2016; The Moon will next occult Aldebaran on January 9^th, 2017. This is occultation 26 in the current series of 49, running from January 29^th, 2015 to September 3^rd, 2018.

Moon Gibraltar — The view from Gibraltar just prior to this week’s occultation of Aldebaran by the Moon. Credit: Stellarium.

Four 1^st magnitude stars are along the Moon’s path in the current epoch: Regulus, Aldebaran, Antares and Spica. In the current century, (2001-2100 AD) the Moon occults Aldebaran 247 times, topped only by Antares (386 times) and barely beating out Spica (220 times). The Moon also occults Regulus 220 times this century, and occultations of Spica and Antares resume on May 2024 and July 2023, respectively.

And yes, this Supermoon 3 of 3 for 2016, though actual perigee occurs at 23:28 UT tonight, 39 minutes past our own ’24 hour from Full’ rule. The Moon reaches Full on Wednesday, December 14^th at just past midnight at 00:07 UT. This is also the closest Full Moon to the December 21^st winter solstice next week, and the Full Moon will ride high in the sky this week for northern hemisphere observers on long winter nights.

Keep an eye out for Geminid meteors tonight as well… sure, 2016 may be an off year for this usually spectacular shower, but a few brighter fireballs may still punch through the lunar light pollution.

Clouded out? Be sure to catch the Supermoon action tomorrow night live online starting at 16:00 UT, courtesy of Gianluca Masi and the Virtual Telescope Project.

And there’s more. This coming weekend marks the start of an upcoming new cycle of occultations of Regulus by the Moon. These run right through 2018, as the Moon visits the bright star Regulus five days after crossing the Hyades and occulting Aldebaran for every lunation pass in 2017.

Here’s the specifics for Sunday’s event:

Moon Regulus — The footprint for Sunday’s occultation of Regulus by the Moon. You can find specific ingress and egress times for major cities near you on the IOTA event page. Credit: Occult 4.2.

The 73% illuminated waning gibbous Moon occults the +1.4 magnitude star Regulus on Sunday, December 18^th. The Moon is just four days past Full during the event. Both are located 117 degrees west of the Sun at the time of the event. The central time of conjunction is 18:38 Universal Time (UT). The event occurs during the daylight hours over Tasmania, and under darkness for the southwestern tip of Australia, including Perth. The Moon will next occult Regulus on January 15^th, 2017. This is the first occultation in a new series of nineteen, running from this weekend to April 24^th, 2018.

It’s worth noting that the graze line for Sunday’s occultation of Regulus by the Moon runs just north of the Australian city of Perth and the Perth Observatory… let us know if anyone ‘Down Under’ witnesses the first occultation of Regulus in the new cycle.

Can you spy Regulus’ white dwarf companion? Located 77 light years distant, the Regulus system has at least four components: a B/C pair shining at a combined magnitude of +8, with an apparent separation of 3”, (5,000 AU physical distance in a ~600 year orbit) and an unseen white dwarf companion in a tight 40 day orbit. We know that said white dwarf companion exists from spectroscopic analysis… and it would shine at an easy magnitude +13, were it not near dazzling Regulus shining over 10,000 times brighter. Could this elusive companion turn up just moments before the reappearance of Regulus from behind the Moon? Remember, the dark limb of the Moon leads the way during waxing phases, then trails as the Moon wanes. These and other amazing facts are included in our forthcoming free guide to 101 Astronomical Events to watch out for in 2017.

Regulus occultations — Every occultation of Regulus for the upcoming cycle. Credit: Occult 4.2.

Follow that Moon, and don’t miss these fine astro-events coming to sky above you this week!

December 10, 2016December 15, 2016 by Matt Williams

Showcasing the Benefits of NASA Technology Here on Earth

Every year, NASA showcases how the technology it develops for exploring space and studying other worlds has applications here on planet Earth. It’s what known as Spinoff, an annual publication that NASA’s Technology Transfer Program has been putting out since 1976. Since that time, they have showcased over 2000 examples where NASA technology was used for the sake of creating products that had wide-ranging benefits.

For Spinoff 2017, NASA selected 50 different companies that are using NASA technology – which included innovations developed by NASA, those made with the help of NASA funding, or those produced under contract with the agency. With examples ranging from GPS and satellite imaging, to light detection and ranging (Lidar) and biomedical devices, the list of commercial applications for this year is quite impressive!

For over 50 years, the NASA Technology Transfer Program has share NASA resources with private industries, a process which is colloquially referred to as “spin-offs”. In finding the widest possible applications for NASA technology and leveraging partnerships and licensing agreements with industry, they ensure that the large investments made in space exploration find additional uses that benefit humanity here on Earth.

*Spinoff is an annual publication exploring the many applications NASA technology has. Credit: NASA*

In the past, spin-offs have included memory foam, freeze-dried food, emergency thermal blankets, Dustbusters, cochlear implants, and numerous other application that have benefited the computer, medical, transportation, manufacturing and safety industries – thought not Velcro or Tang (contrary to popular conception). As Dan Lockney, the executive of NASA’s Technology Transfer program, told Universe Today via email:

“Spinoff is NASA’s annual publication featuring technologies that have left NASA’s launchpads and laboratories and moved into the public sector. We’ve published Spinoff each year since 1976, featuring about 50 of the best examples of commercialized NASA technologies each year. These range from consumer goods to public safety and medical equipment to advances in round and aire transportation.

“These commercialized technologies are often a direct outcome of the work that NASA’s Technology Transfer Program conducts. Our Tech Transfer Program works to get the technolgoes developed for NASA missions out to industry so that they can have second lives as new products and services.”

This year’s spinoffs were certainly numerous, but some are particularly worthy of mention. For instance, there is the metal oxide semiconductor (CMOS) image sensor that was developed by NASA’s Jet Propulsion Laboratory. Since its creation, it has become one of NASA’s most ubiquitous technologies, leading to the development of DSLR cameras, camera phones, and digital cameras that are available on every handheld device on the market.

And then there’s the GPS technology NASA began developing back in the 1990s, which included software capable of correcting for GPS signal errors and enabling incredible accuracy. John Deere recently acquired this technology and used it to develop a popular class of self-driving farm tractors. Today, as much as 70% of North American farmland is cultivated by self-driving tractors that rely on this technology.

Aerial photograph of a forest in Connecticut (left), and bare-earth lidar image beneath the overgrown vegetation (right) showing the remnants of stone walls, building foundations, abandoned roads and what was once cleared farm land. Credits: NASA/Katharine Johnson

And then there is the spinoff involving NASA-developed laser imaging and ranging technology (Lidar). This technology allowed the Pheonix Lander to detect snow falling from the skies of Mars, and will be used to OSIRIS-REx mission to land on an asteroid in the coming decade. And recently, this same technology was used by a team of archaeologists to map prehistoric sites in North America where hunter-gatherers hunted bison en masse.

In addition, “Robotics Spinoffs” get a special mention in this year’s report, with homage being paid to missions like Curiosity and Juno (which have explored the surfaces and atmospheres of other planets) and space-based observatories like Spitzer, Chandra and Hubble – which have looked deep into the cosmic field. The technologies used by these missions has also had an impact in virtually every sector of the world’s economy.

The publication also includes a section called “Spinoffs of Tomorrow“, which highlights 20 technologies that are especially well-suited for commercial adaptation. These include thin-film piezoelectric and composite materials that could be used in wind turbines to generate more electricity and improve electrode durability, as well as in personal devices to generate power from mere movement.

There’s also the new Armstrong wing design that lower drags, which could make airplanes and wind turbines more efficient. The Glenn Research Center is also cited for their development of a suite of materials and methods that optimize the performance of nanomaterials by making them tougher, more resistant, and easier to process. This could be used to build super-resilient fabrics and consumer products.

NASA's Juno spacecraft launched on August 6, 2011 and should arrive at Jupiter on July 4, 2016. Credit: NASA / JPL — NASA’s Juno spacecraft launched on August 6, 2011 and should arrive at Jupiter on July 4, 2016. Credit: NASA / JPL

Then there’s an underwater vehicle developed by JPL that uses thermally-generated changes in buoyancy to generate electricity and recharge its batteries. This technology, which enables submarines to remain underwater for years at a time, could lead to the creation of nearly self-sufficient undersea drones – something that has applications in everything from sea exploration to pipeline monitoring.

The section also makes mention of an easy-to-use device that separates DNA, RNA, and proteins outside a traditional lab environment. Originally intended for use aboard the ISS, this device could be a boon for developing nations where medical infrastructure may be limited. And there’s also a system that autonomously detects faulty wiring and reroutes around it.

As always, the development of cutting-edge technologies can have applications that go far beyond the purpose for which they were originally intended. Whether it is robotic landers or probes, miniaturized cameras, improved electronics, or advanced materials, commercial industries here on Earth have always benefited from the research, development and exploration efforts of the space industry.

And as our efforts to send astronauts to Mars, return to the Moon, and explore the outer Solar System andbeyond continue, who knows what commercial applications will emerge as a result? And in the meantime, be sure to enjoy this video which explains how NASA technology is licensed through the TTP:

Further Reading: NASA

December 9, 2016 by David Dickinson

101 Astronomical Events for 2017: A Teaser

A partial solar eclipse rising over the VAB. Image by author.

It’s that time of year again… time to look ahead at the top 101 astronomical events for the coming year.

And this year ’round, we finally took the plunge. After years of considering it, we took the next logical step in 2017 and expanded our yearly 101 Astronomical Events for the coming year into a full-fledged guide book, soon to be offered here for free download on Universe Today in the coming weeks. Hard to believe, we’ve been doing this look ahead in one form or another now since 2009.

This “blog post that takes six months to write” will be expanded into a full-fledged book. But the core idea is the same: the year in astronomy, distilled down into the very 101 best events worldwide. You will find the best occultations, bright comets, eclipses and much more. Each event will be interspersed with not only the ‘whens’ and ‘wheres,’ but fun facts, astronomical history, and heck, even a dash of astronomical poetry here and there.

It was our goal to take this beyond the realm of a simple almanac or Top 10 listicle, to something unique and special. Think of it as a cross between two classics we loved as a kid, Burnham’s Celestial Handbook and Guy Ottewell’s Astronomical Calendar, done up in as guide to the coming year in chronological format. Both references still reside on our desk, even in this age of digitization.

And we’ve incorporated reader feedback from over the years to make this forthcoming guide something special. Events will be laid out in chronological order, along with a quick-list for reference at the end. Each event is listed as a one- or two-page standalone entry, ready to be individually printed off as needed. We will also include 10 feature stories and true tales of astronomy. Some of these were culled from the Universe Today archives, while others are new astronomical tales written just for the guide.

Don’t miss 2017’s only total solar eclipse, crossing the United States! Image credit: Michael Zeiler/The Great American Eclipse.

The Best of the Best

Here’s a preview of some of the highlights for 2017:

-Solar cycle #24 begins to ebb in 2017. Are we heading towards yet another profound solar minimum?

-Brilliant Venus reaches greatest elongation in January and rules the dusk sky.

-45P/Honda-Mrkos-Pajdusakova passes 0.08 AU from Earth on February 11^th, its closest passage for the remainder of the century.

-An annular solar eclipse spanning Africa and South America occurs on February 26^th.

A sample occultation map from the book. Image credit: Occult 4.1.2.

-A fine occultation of Aldebaran by the Moon on March 5^th for North America… plus more occultations of the star worldwide during each lunation.

-A total solar eclipse spanning the contiguous United States on August 21^st.

-A complex grouping of Mercury, Venus, Mars and the Moon in mid-September.

-Saturn’s rings at their widest for the decade.

Getting wider... the changing the of Saturn's rings. Image credit and copyright: Andrew Symes (@FailedProtostar). — Getting wider… the changing face of Saturn’s rings. Image credit and copyright: Andrew Symes (@FailedProtostar).

-A fine occultation of Regulus for North America on October 15^th, with occultations of the star by the Moon during every lunation for 2017.

-Asteroid 335 Roberta occults a +3^rd magnitude star for northern Australia…

And that’s just for starters. Entries also cover greatest elongations for the inner planets and oppositions for the outer worlds, the very best asteroid occultations of bright stars, along with a brief look ahead at 2018.

Get ready for another great year of skywatching!

And as another teaser, here’s a link to a Google Calendar download of said events, complied by Chris Becke (@BeckePhysics). Thanks Chris!

December 8, 2016February 8, 2023 by Matt Williams

ESO Survey Shows Dark Matter to be Pretty “Smooth”

The technique of gravitational lensing relies on the presence of a large cluster of matter between the observer and the object to magnify light coming from that object. Credit: NASA

Dark Matter has been something of a mystery ever since it was first proposed. In addition to trying to find some direct evidence of its existence, scientists have also spent the past few decades developing theoretical models to explain how it works. In recent years, the popular conception has been that Dark Matter is “cold”, and distributed in clumps throughout the Universe, an observation supported by the Planck mission data.

However, a new study produced by an international team of researchers paints a different picture. Using data from the Kilo Degree Survey (KiDS), these researchers studied how the light coming from millions of distant galaxies was affected by the gravitational influence of matter on the largest of scales. What they found was that Dark Matter appears to more smoothly distributed throughout space than previously thought.

Continue reading “ESO Survey Shows Dark Matter to be Pretty “Smooth””

December 8, 2016 by Bob King

Why Does Siberia Get All the Cool Meteors?

Children ice skating in Khakassia, Russia react to the fall of a bright fireball two nights ago on Dec.6

In 1908 it was Tunguska event, a meteorite exploded in mid-air, flattening 770 square miles of forest. 39 years later in 1947, 70 tons of iron meteorites pummeled the Sikhote-Alin Mountains, leaving more than 30 craters. Then a day before Valentine’s Day in 2013, hundreds of dashcams recorded the fiery and explosive entry of the Chelyabinsk meteoroid, which created a shock wave strong enough to blow out thousands of glass windows and litter the snowy fields and lakes with countless fusion-crusted space rocks.

Documentary footage from 1947 of the Sikhote-Alin fall and how a team of scientists trekked into the wilderness to find the craters and meteorite fragments

Now on Dec. 6, another fireball blazed across Siberian skies, briefly illuminated the land like a sunny day before breaking apart with a boom over the town of Sayanogorsk. Given its brilliance and the explosions heard, there’s a fair chance that meteorites may have landed on the ground. Hopefully, a team will attempt a search soon. As long as it doesn’t snow too soon after a fall, black stones and the holes they make in snow are relatively easy to spot.

This photo shows trees felled from a powerful aerial meteorite explosion. It was taken during Leonid Kulik's 1929 expedition to the Tunguska impact event in Siberia in 1908. Credit: Kulik Expedition — This photo shows trees felled from a powerful aerial meteorite explosion. It was taken during Leonid Kulik’s 1929 expedition to the Tunguska impact event in Siberia in 1908. Credit: Kulik Expedition

OK, maybe Siberia doesn’t get ALL the cool fireballs and meteorites, but it’s done well in the past century or so. Given the dimensions of the region — it covers 10% of the Earth’s surface and 57% of Russia — I suppose it’s inevitable that over so vast an area, regular fireball sightings and occasional monster meteorite falls would be the norm. For comparison, the United States covers only 1.9% of the Earth. So there’s at least a partial answer. Siberia’s just big.

A naturally sculpted iron-nickel meteorite recovered from the Sikhote-Alin meteorite fall in February 1947. The dimpling or "thumb-printing" occurs when softer minerals are melted and sloughed away as the meteorite is heated by the atmosphere while plunging to Earth. Credit: Svend Buhl — A naturally sculpted iron-nickel meteorite recovered from the Sikhote-Alin meteorite fall in February 1947. The dimpling or “thumb-printing” occurs when softer minerals are melted and sloughed away as the meteorite is heated by the atmosphere while plunging to Earth. Credit: Svend Buhl

Every day about 100 tons of meteoroids, which are fragments of dust and gravel from comets and asteroids, enter the Earth’s atmosphere. Much of it gets singed into fine dust, but the tougher stuff — mostly rocky, asteroid material — occasionally makes it to the ground as meteorites. Every day then our planet gains about a blue whale’s weight in cosmic debris. We’re practically swimming in the stuff!

Meteors are pieces of comet and asteroid debris that strike the atmosphere and burn up in a flash. Credit: Jimmy Westlake A brilliant Perseid meteor streaks along the Summer Milky Way as seen from Cinder Hills Overlook at Sunset Crater National Monument—12 August 2016 2:40 AM (0940 UT). It left a glowing ion trail that lasted about 30 seconds. The camera caught a twisting smoke trail that drifted southward over the course of several minutes. — Meteors are pieces of comet and asteroid debris that strike the atmosphere and burn up in a flash. Here, a brilliant Perseid meteor streaks along the Summer Milky Way this past August. Credit: Jeremy Perez

Most of this mass is in the form of dust but a study done in 1996 and published in the Monthly Notices of the Royal Astronomical Society further broke down that number. In the 10 gram (weight of a paperclip or stick of gum) to 1 kilogram (2.2 lbs) size range, 6,400 to 16,000 lbs. (2900-7300 kilograms) of meteorites strike the Earth each year. Yet because the Earth is so vast and largely uninhabited, appearances to the contrary, only about 10 are witnessed falls later recovered by enterprising hunters.

A couple more videos of the Dec. 6, 2016 fireball over Khakassia and Sayanogorsk, Russia

Meteorites fall in a pattern from smallest first to biggest last to form what astronomers call a strewnfield, an elongated stretch of ground several miles long shaped something like an almond. If you can identify the meteor’s ground track, the land over which it streaked, that’s where to start your search for potential meteorites.

Meteorites indeed fall everywhere and have for as long as Earth’s been rolling around the sun. So why couldn’t just one fall in my neighborhood or on the way to work? Maybe if I moved to Siberia …

December 8, 2016December 22, 2016 by Ken Kremer

Fabulous Florida Nighttime Blastoff Delivers Highest-Capacity US Air Force Satcom to Orbit

A United Launch Alliance (ULA) Delta IV rocket carrying the WGS-8 mission lifts off from Space Launch Complex-37 at 6:53 p.m EDT on Dec. 7, 2016 from Cape Canaveral Air Force Station, Fla. Credit: Ken Kremer/kenkremer.com

A United Launch Alliance (ULA) Delta IV rocket carrying the WGS-8 mission lifts off from Space Launch Complex-37 at 6:53 p.m EDT on Dec. 16, 2016 from Cape Canaveral Air Force Station, Fla. Credit: Ken Kremer/kenkremer.com — A United Launch Alliance (ULA) Delta IV rocket carrying the WGS-8 mission lifts off from Space Launch Complex-37 at 6:53 p.m EDT on Dec. 7, 2016 from Cape Canaveral Air Force Station, Fla. Credit: Ken Kremer/kenkremer.com

CAPE CANAVERAL AIR FORCE STATION, FL – The highest-capacity US Air Force communications system thundered to orbit during a fabulous nighttime blastoff from the Florida Space Coast, Wednesday evening offering a picture perfect spectacle in addition to a significant boost to military point to point communications.

Hordes of spectators lined space coast beaches and viewing areas to witness the dinnertime launch of the Wideband Global SATCOM (WGS-8) mission for the U.S. Air Force on a United Launch Alliance Delta IV Medium+ rocket at 6:53 p.m. EST on Wednesday, Dec. 7, 2016.

The on time Delta liftoff took place from Space Launch Complex-37 at Cape Canaveral Air Force Station, Florida at the opening of the 49 minute long launch window.

United Launch Alliance (ULA) Delta IV rocket carrying the WGS-8 mission for the U.S. Air Force launches at 6:53 p.m EDT on Dec. 16, 2016 from Cape Canaveral Air Force Station, Fl. Credit: Ken Kremer/kenkremer.com — United Launch Alliance (ULA) Delta IV rocket carrying the WGS-8 mission for the U.S. Air Force launches at 6:53 p.m EDT on Dec. 7, 2016 from Cape Canaveral Air Force Station, Fl. Credit: Ken Kremer/kenkremer.com

“Thank you to the U.S. Air Force and industry team whose flawless execution enabled today’s successful launch of the WGS-8 mission,” said Laura Maginnis, ULA vice president of Custom Services, in a statement.

“Last week ULA celebrated our anniversary and 10 years of 100% mission success. This evening’s launch epitomizes why our customers continue to entrust ULA to deliver our nation’s most crucial space capabilities.”

WGS-8 was delivered to a supersynchronous transfer orbit atop the United Launch Alliance Delta IV Medium+ rocket.

WGS-8 is the first in a newly upgraded series of a trio of WGS satellites built by Boeing that will nearly double the communications bandwidth of prior WGS models.

The major upgrade is inclusion of the Wideband Digital Channelizer, awarded to Boeing in June 2012.

“Boeing’s eighth Wideband Global SATCOM (WGS) satellite will provide nearly twice as much communications bandwidth as previous WGS satellites due to an upgraded digital payload,” said Boeing in a statement.

The Wideband Digital Channelizer will provide a 90 percent improvement in satellite bandwidth for US military forces.

“Using leading commercial digital circuit technology, the newly upgraded satellite will aid in fulfilling the increasing demand for high-data rate communications of warfighters around the globe.”

WGS-8 was also built for a significantly cheaper price compared to the prior WGS series. WGS-8 cost about $426 million vs. about $570 million for the WGS 7 satellite.
“Not only does WGS-8’s cutting edge digital payload nearly double the satellite’s bandwidth, but the U.S. government was able to realize more than $150 million in savings for WGS-7 through WGS-10 through fixed-price block purchases and commercial operating practices,” said Dan Hart, Boeing vice president, Government Satellite Systems, in a statement.

“We’ve been able to both increase the capability and reduce the per-unit cost with each new WGS satellite we’ve delivered, making WGS, by far, the most cost-effective asset for military communications.”

The 217 foot tall Delta IV Medium+ rocket launched in the (5,4) configuration with a 5 meter diameter payload fairing and powered by one common booster core and four solid rocket motors built by Orbital ATK to augment the first stage.

The common booster core was powered by an RS-68A liquid hydrogen/liquid oxygen engine producing 705,250 pounds of thrust at sea level. A single RL10B-2 liquid hydrogen/liquid oxygen engine powered the second stage.

The booster and upper stage engines are both built by Aerojet Rocketdyne. ULA constructed the Delta IV Medium+ (5,4) launch vehicle in Decatur, Alabama.
The is the sixth flight in the Medium+ (5,4) configuration; all of which were for prior WGS missions.

ULA Delta IV rocket poised for blastoff with the WGS-8 mission for the U.S. Air Force from pad 37 on Cape Canaveral Air Force Station, Fl, on Dec. 7, 2016. Credit: Ken Kremer/kenkremer.com

WGS-8 also counts as the first of three launches from the Cape this December. A Pegasus XL rocket will launch on Dec. 12 carrying NASA’s CGYNSS hurricane monitoring satellites. And an Atlas V will launch on Dec. 12 with the EchoStar 23 comsat.

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer