A beautiful display of the aurora borealis on June 6 this year. The line of light is the International Space Station; an airplane is off to the left. Credit: Bob King
As an amateur astronomer, two of the most frequently questions I’m asked are “When is the best time to see the aurora borealis and where is the best place?” In terms of place, two locations comes to mind: Churchill, Manitoba and Tromso, Norway. But until such time as the transporter is invented, most of us will be staying closer to home. The simple answer is north and the farther north the better.
As for the time, in the northern border states of the US, auroras occur fairly regularly around the time of solar maximum, when the sun peaks in storm activity. The current solar cycle tops out this summer and fall, so your chances at seeing northern lights are far better now than a year and a half ago when solar activity saw a steep decline during a protracted minimum.
No answers today, only a question. But it’s one of the most interesting and meaningful questions we can possibly ask.
Where does life come from?
How did we get from no life on Earth, to the rich abundance we see today?
Charles Darwin first published our modern theories of evolution – that all life on Earth is related; adapting and changing over time. Look at any two creatures on Earth and you can trace them back to a common ancestor. Humans and chimpanzees share a common ancestor from at least 7 million years ago.
Trace back far enough, and you’re related to the first mammal who lived 220 million years ago. In fact, you and bacteria can trace a family member who lived billions of years ago. Keep going back, and you reach the oldest evidence of life on Earth, about 3.9 billion years ago.
But that’s as far as evolution can take us.
The Earth has been around for 4.5 billion years, and those early years were completely hostile to life. The early atmosphere was toxic, and a constant asteroid bombardment churned the landscape into a worldwide ocean of molten rock.
As soon as the environment settled down to be relatively habitable, life appeared. Just half a billion years beyond the formation of the Earth.
So how did life make the jump from raw chemicals to the evolutionary process we see today? The term for this mystery is abiogenesis and scientists are working on several theories to explain it.
One of the first clues is amino acids, the building blocks of life. In 1953, Stanley Miller and Harold Urey demonstrated that amino acids could form naturally in the environment of the early Earth. They replicated the atmosphere and chemicals present, and then used electric sparks to simulate lightning strikes.
Amazingly, they found a variety of amino acids in the resulting primordial soup.
Other scientists replicated the experiment, even changing the atmospheric conditions to match other models of the early Earth. Instead of water, methane, ammonia and hydrogen, they wondered what would happen if the atmosphere contained hydrogen sulfide and sulfur dioxide from volcanic eruptions. Environments around volcanic vents at the bottom of the ocean might have been the perfect places to get life started, introducing heavier metals like iron and zinc. Perhaps ultraviolet rays from the younger, more volatile Sun, or abundant radiation from natural uranium deposits played a role in pushing life forward into an evolutionary process.
Artists concept of shredded asteroid around white dwarf (NASA/JPL-Caltech)What if life didn’t start on Earth at all? What if the building blocks came from space, drifting through the cosmos for millions of years. Astronomers have discovered amino acids in comets, and even alcohol floating in distant clouds of gas and dust
Maybe it wasn’t the organic chemicals that came first, but the process of self organization. There are examples of inorganic chemicals and metals that can organize themselves under the right conditions. The process of metabolism came first, and then organic chemicals adopted this process.
Thermophilic (heat-loving) bacteria may be among the last living creatures on Earth, the study suggests. Credit: Mark Amend / NOAA Photo LibraryIt’s even possible that life formed multiple times on Earth in different eras. Although all life as we know it is related, there could be a shadow ecosystem of microbial life forms in our soil or oceans which is completely alien to us.
So how did life get here? We just don’t know.
Maybe we’ll discover life on other worlds and that will give us a clue, or maybe scientists will create an experiment that finally replicates the jump from non-life to life.
Up until 20 years ago, the only planets astronomers were aware of were within our Solar System. They assumed others were out there, but none had ever been detected.
Today we know of almost a thousand planets orbiting other stars. They come in a wide variety of sizes. Some are smaller than Earth, and others are more massive than Jupiter. Some are found around solitary stars, while others are located in multiple star systems. In those systems, there can be individual or even multiple planets in orbit. In fact, recent surveys suggest there are planets orbiting every single star in the Milky Way.
So, what methods do astronomers use to find these “extrasolar planets”?
The first extrasolar planet was discovered in 1991.
It was found orbiting a pulsar, a dead star that rotates rapidly, firing out bursts of radiation on an eerily precise interval. As the planets orbit the pulsar, they pull it back and forth with their gravity. This slightly changes the wavelength of the radiation bursts streaming from the exotic star. Astronomers were able to measure these changes, and calculate the orbits of multiple planets.
Radial Velocity Method Extrasolar Planets Far Across GalaxyThe golden age of extrasolar planet discovery began in 1995 when a team from the University of Geneva discovered a planet orbiting the nearby star 51 Pegasi. Astronomers used spectroscopy to break up the light to reveal the elements in its stellar atmosphere. They carefully measured how the wavelengths of light were Doppler shifted over time, and used a technique known as the radial velocity method. They calculated the star’s average motion, and discovered slight variations, as if something was yanking the star towards and away from us.
That something, was a planet.
In fact, this planet was unlike anything we have in the Solar System. 51 Pegasi B has about half the mass of Jupiter and it orbits much closer to its parent star. Closer even, than Mercury to the Sun.
Until this discovery, astronomers didn’t think it was possible for planets to orbit this close, and have had to revise their theories on planetary formation. Many Hot Jupiter planets have been discovered since, some in even more extreme environments.
Gravitational Microlensing Gravitational microlensing method requires that you have two stars that lie on a straight line in relation to us here on Earth. Then the light from the background star is amplified by the gravity of the foreground star, which thus acts as a magnifying glass.Another method astronomers use to find planets is called gravitational microlensing. It works by carefully measuring the brightness of one star as it passes in front of another. The foreground star acts like a lens, focusing the light with its gravity and causing the star to brighten for a few hours. If the foreground star has planets, these will create a telltale spike in the light signature coming from the event.
Amateur astronomers around the world participate in microlensing studies, imaging stars quickly when an event is announced.
Transit Method Of course clouds are no issue if you’re watching the Transit of Venus from the ISS or the Hinode spacecraft. Compare this Hinode Transit image published on APOD on June 9 and enhanced by Marco Di Lorenzo,
The most successful way of finding planets is the transit method.
This is where telescopes measure the total amount of light coming from a star, and detect a slight variation in brightness as a planet passes in front.
Using this technique, NASA’s Kepler Mission has turned up thousands of candidate planets. Including some less massive than Earth, and others in the star’s habitable zone.
From the Kepler data, It’s just a matter of time before the holy grail of planets is uncovered… an Earth-sized world, orbiting a Sun-like star within the habitable zone.
All of these techniques are limited as they require the planets to be orbiting directly between us and their star. If the planets orbit above or below this plane, we just can’t detect them.
Coronographs New Worlds ImagerThere is another method in the works that would unleash the discovery of extrasolar planets, coronographs.
Imagine if you could block all the light from the star, and only see the planets in orbit. This technique has been used for observing the Sun’s atmosphere, but it requires much more precision to see distant stars.
One idea is to position a sunflower-shaped starshade in space, 125,000 km away from the observing telescope. This shade would just cover the star, dimming it by a factor of 10-billion. Light from the planets would leak around the edges.
A sophisticated instrument could even study the atmospheres of these planets, and possibly provide us with evidence of life.
We’re at an exciting time in the field of extrasolar planet research, and trust me, these clever astronomers are just getting started.
There are services which will let you name a star in the sky after a loved one. You can commemorate a special day, or the life of an amazing person. But can you really name a star?
The answer is yes, and no.
Names of astronomical objects are agreed upon by the International Astronomical Union. If this name sounds familiar, it’s the same people who voted that Pluto is not a planet.
Them.
There are a few stars with traditional names which have been passed down through history. Names like Betelgeuse, Sirius, or Rigel. Others were named in the last few hundred years for highly influential astronomers.
These are the common names, agreed upon by the astronomical community.
Most stars, especially dim ones, are only given coordinates and a designation in a catalog. There are millions and millions of stars out there with a long string of numbers and letters for a name. There’s the Gliese catalog of nearby stars, or the Guide Star Catalog which contains 945 million stars.
The IAU hasn’t taken on any new names for stars, and probably won’t ever. The bottom line is that numbers are much more useful for astronomers searching and studying stars.
But what about the companies that will offer to let you name a star? Each of these companies maintains their own private database containing stars from the catalog and associated star names. They’ll provide you with a nice certificate and instructions for finding it in the sky, but these names are not recognized by the international astronomical community.
You won’t see your name appearing in a scientific research journal. In fact, it’s possible that the star you’ve named with one organization will be given a different name by another group.
So can you really name a star after yourself or a loved one?
The Fraser Cain Tower of Awesomeness.Yes, you can, in the same way that you can name an already-named skyscraper after yourself. Everyone else might keep calling it the Empire State Building, but you’ll have a certificate that says otherwise.
There are a few objects that can be named, and recognized by the IAU.
Fragments of Shoemaker-Levy 9 on approach to Jupiter (NASA/HST)If you’re the first person to spot a comet, you’ll have it named after you, or your organization. For example, Comet Shoemaker-Levy was discovered simultaneously by Eugene Shoemaker and David Levy.
If you discover asteroids and Kuiper Belt Objects, you can suggest names which may be ratified by the IAU. Asteroids, as well as comets, get their official numerical designation, and then a common name.
The amateur astronomer Jeff Medkeff, who tragically died of liver cancer at age 40, named asteroids after a handful of people in the astronomy, space and skeptic community.
Artist’s impression of ErisKuiper Belt Objects are traditionally given names from mythology. And so, Pluto Killer Mike Brown’s Caltech team suggested the names for Eris, Haumea and Makemake.
So what about extrasolar planets? Right now, these planets are attached to the name of the star. For example, if a planet is discovered around one of the closer stars in the Gliese catalog, it’s given a letter designation.
An organization called Uwingu is hoping to raise funds to help discover new extrasolar planets, and then reward those funders with naming rights, but so far, this policy hasn’t been adopted by the IAU.
Personally, I think that officially allowing the public to name astronomical objects would be a good idea. It would spur the imagination of the public, connecting them directly to the amazing discoveries happening in space, and it would help drive funds to underfunded research projects.
I love it when scientists discover something unusual in nature. They have no idea what it is, and then over decades of research, evidence builds, and scientists grow to understand what’s going on.
My favorite example? Quasars.
Astronomers first knew they had a mystery on their hands in the 1960s when they turned the first radio telescopes to the sky.
They detected the radio waves streaming off the Sun, the Milky Way and a few stars, but they also turned up bizarre objects they couldn’t explain. These objects were small and incredibly bright.
They named them quasi-stellar-objects or “quasars”, and then began to argue about what might be causing them. The first was found to be moving away at more than a third the speed of light.
But was it really?
An artist’s conception of jets protruding from an AGN.Maybe we were seeing the distortion of gravity from a black hole, or could it be the white hole end of a wormhole. And If it was that fast, then it was really, really far… 4 billion light years away. And it generating as much energy as an entire galaxy with a hundred billion stars.
What could do this?
Here’s where Astronomers got creative. Maybe quasars weren’t really that bright, and it was our understanding of the size and expansion of the Universe that was wrong. Or maybe we were seeing the results of a civilization, who had harnessed all stars in their galaxy into some kind of energy source.
Then in the 1980s, astronomers started to agree on the active galaxy theory as the source of quasars. That, in fact, several different kinds of objects: quasars, blazars and radio galaxies were all the same thing, just seen from different angles. And that some mechanism was causing galaxies to blast out jets of radiation from their cores.
But what was that mechanism?
This artist’s concept illustrates a quasar, or feeding black hole, similar to APM 08279+5255, where astronomers discovered huge amounts of water vapor. Gas and dust likely form a torus around the central black hole, with clouds of charged gas above and below. Image credit: NASA/ESAWe now know that all galaxies have supermassive black holes at their centers; some billions of times the mass of the Sun. When material gets too close, it forms an accretion disk around the black hole. It heats up to millions of degrees, blasting out an enormous amount of radiation.
The magnetic environment around the black hole forms twin jets of material which flow out into space for millions of light-years. This is an AGN, an active galactic nucleus.
When the jets are perpendicular to our view, we see a radio galaxy. If they’re at an angle, we see a quasar. And when we’re staring right down the barrel of the jet, that’s a blazar. It’s the same object, seen from three different perspectives.
Supermassive black holes aren’t always feeding. If a black hole runs out of food, the jets run out of power and shut down. Right up until something else gets too close, and the whole system starts up again.
The Milky Way has a supermassive black hole at its center, and it’s all out of food. It doesn’t have an active galactic nucleus, and so, we don’t appear as a quasar to some distant galaxy.
We may have in the past, and may again in the future. In 10 billion years or so, when the Milky way collides with Andromeda, our supermassive black hole may roar to life as a quasar, consuming all this new material.
Did you know you can distinguish between stars and planets in the sky?
Stars twinkle, planets don’t.
Okay, that’s not actually correct. The stars, planets, even the Sun and Moon twinkle, all in varying amounts. Anything outside the atmosphere is going to twinkle.
If you’re feeling a little silly using the word twinkle over and over again, we can also use the scientific term: astronomical scintillation.
You can’t feel it, but you’re carrying the entire weight of the atmosphere on your shoulders. Every single square inch of your skin is getting pushed by 15 pounds of pressure. And even though astronomers need our atmosphere to survive, it still drives them crazy. As it makes objects in space so much harder to see.
Stars twinkle, I mean scintillate, because as light passes down through a volume of air, turbulence in the Earth’s atmosphere refracts light differently from moment to moment. From our perspective, the light from a star will appear in one location, then milliseconds later, it’ll be distorted to a different spot.
We see this as twinkling.
So why do stars appear to twinkle, while planets don’t?
Stars appear as a single point in the sky, because of the great distance between us and them. This single point can be highly affected by atmospheric turbulence. Planets, being much closer, appear as disks.
We can’t resolve them as disks with our eyes, but it still averages out as a more stable light in the sky.
Astronomers battle atmospheric turbulence in two ways:
First, they try to get above it. The Hubble Space Telescope is powerful because it’s outside the atmosphere. The mirror is actually a quarter the size of a large ground-based observatory, but without atmospheric distortion, Hubble can resolve galaxies billions of light-years away. The longer it looks, the more light it gathers.
Second, they try to compensate for it.
Some of the most sophisticated telescopes on Earth use adaptive optics, which distorts the mirror of the telescope many times a second to compensate for the turbulence in the atmosphere.
A beam from the Laser Star Guide on one of the VLT’s four Unit Telescopes helps to correct the blurring effect of Earth’s atmosphere before making observations (ESO/Y. Beletsky)Astronomers project a powerful laser into the sky, creating an artificial star within their viewing area. Since they know what the artificial star should look like, they distort the telescope’s mirror with pistons cancelling out the atmospheric distortion. While it’s not as good as actually launching a telescope into space, it’s much, much cheaper.
Now you know why stars twinkle, why planets don’t seem to twinkle as much, and how you can make all of them stop.
We have written many articles about stars here on Universe Today. Here’s an article that talks about a technique astronomers use to minimize the twinkle of the Earth’s atmosphere.
When tiny grains of dust impact our atmosphere, they leave a trail of glowing material, like a streak of light across the sky.
This is a meteor, or a shooting star.
On any night, you can go outside, watch the sky, and be guaranteed to see one. Individual meteors start as meteoroids – pieces of rock smaller than a pebble flying around the Solar System.
Even though they’re tiny, these objects can be moving at tens of thousands of kilometers per hour. When they hit Earth’s atmosphere, they release tremendous amounts of energy, burning up above an altitude of 50 kilometers.
As they disintegrate, they leave a trail of superheated gas and rocky sparks which last for a moment in the sky, and then cool down and disappear from view.
Throughout the year there are several meteor showers, when the number of meteors streaking through the sky increases dramatically. This happens when the Earth passes through the trail of dust left by a comet or asteroid.
Meteor showers are when night sky puts on a special show, and it’s a time to gather your friends and family together and enjoy the spectacle.
Some showers produce only a trickle of objects, while others, like the famous Perseid meteor shower, can dependably bring dozens of meteors each hour.
Meteor Burst – Credit: NASAIf the trail is dense enough, we can get what is called a meteor storm. The most powerful meteor storms in history truly made it look like the sky was falling. The Leonids in 1833 produced hundreds of thousands per hour.
Meteor showers take their name from the constellation from where they appear to originate. For example, the Perseids trace a trail back to the constellation Perseus; although you can see them anywhere across the sky.
You can see meteors any time of the year, and you don’t need any special equipment to enjoy an average meteor shower. But here are some ways you can improve your experience.
You’ll want to find a location with as clear a view to the horizon in as many directions as possible. An open field is great. Lie on your back, or on a reclining chair, look up to the sky
… and be patient.
A bright fireball meteor in twilight. The Lyrids, like all meteor showers, offer up the occasional fireball among a mix of fainter meteors. Credit: John ChumackYou probably won’t see a meteor right away, but after a few minutes, you should see your first one.
The longer you look, the more you’ll see, and the better chance you’ll have of seeing a bolide or fireball; a very bright meteor that streaks across the sky, leaving a trail that can last for a long time.
You can see meteors any time that it’s dark, but the most impressive ones happen in the early morning, when your location on Earth is ploughing directly into the space dust.
You also want the darkest skies you can get, far away from city light pollution, and many hours after the Sun has gone down.
Enjoy the early evening meteors, but then set your alarm and get up around 4 in the morning to see the real sky show.
The radiant for the Persieds, looking to the NE from latitide ~30N at around 2AM local. Created by the Author in Starry Night).If I could only see one meteor shower every year, it would have to be the Perseids. These come when the Earth passes through the tail of Comet Swift-Tuttle, and peak around August 12th every year. It’s not always the most active shower, but it’s warm outside in the Northern hemisphere, and this is a fun activity to do with your friends and family.
Astronaut Charles Duke collecting samples during Apollo 16. Credit: NASA.
Ask someone if they know the names of the astronauts who have walked on the Moon, and most people would be able to list Neil Armstrong, and maybe even Buzz Aldrin. But can you name the rest of the Apollo astronauts who made it down to the lunar surface? How many people have walked on the Moon?
In total twelve people have walked on the Moon. Besides Neil Armstrong and Buzz Aldrin – who were the first two astronauts to leave their bootprints on the Moon — there were also Pete Conrad, Alan Bean, Alan Shepard, Edgar Mitchell, David Scott, James Irwin, John Young, Charles Duke, Eugene Cernan, and Harrison Schmitt.
Interestingly, out of the dozen people who walked on the Moon, no one ever did it more than once.
An idea that really captures my imagination is what kinds of future civilizations there might be. And I’m not the only one. In 1964, the Soviet astronomer Nikolai Kardashev defined the future of civilizations based on the amount of energy they might consume.
A Type I civilization would use the power of their entire planet. Type II, a star system, and a Type III would harness the energy of an entire galaxy. It boggles the mind to think about the engineering required to rearrange the stars of an entire galaxy.
Is it possible to move a star? Could we move the Sun?
This idea was first proposed by physicist Dr. Leonid Shkadov in his 1987 paper, “Possibility of controlling solar system motion in the galaxy”.
Here’s how it works.
A future alien civilization would construct a gigantic reflective structure on one side of their star. Light from the star would strike this structure and bounce off, pushing it away.
If this reflective structure had enough mass, it would also attract the star with its gravity.
The star would be trying to push the structure away, but the structure would be pulling the star along with it.
If a future civilization could get this in perfect balance, it would be able to “pull” the star around in the galaxy, using its own starlight as thrust. At first, you wouldn’t get a lot of speed. But by directing half the energy of a star, you could get it moving through the galaxy.
Over the course of a million years, you would have changed its velocity by about 20 meters/second. The star would have traveled about 0.3 light years, less than 10% of the way to Alpha Centauri. Keep it up for a billion years and you would be moving a thousand times faster. Allowing you to travel 34,000 light years, a significant portion of the galaxy.
Imagine a future civilization using this technique to move their stars to better locations, or even rearranging huge portions of a galaxy for their own energy purposes.
This may sound theoretical, but Duncan Forgan, from the University of Edinburgh suggests a practical way to search for aliens moving their stars. According to him, you could use planet-hunting telescopes like Kepler to detect the bizarre light signatures we’d see from a Shkadov Thruster. There’s nothing in the laws of physics that says it can’t happen.
It’s fun to think about, and gives us another way that we could search for alien civilizations out there across the galaxy.
The idea that there is life on other worlds is humbling and exciting, and finding life on another world would change everything. This has been a driving force for scientists for decades. We find life wherever we find water on Earth, in pools of boiling water, inside glaciers, even in nuclear reactors.
Because of this, our best candidate for life is probably Mars.
The planet is hostile to life now, but evidence is mounting that it was once a warm and habitable world, with rivers, lakes and oceans. Mars could have vast reserves of subsurface water, where life could thrive even now.
If we did discover life there, it’s possible that it’s completely unrelated to Earth life. This would demonstrate that life can originate on almost any world, with the right conditions.
It’s also possible that life on Mars is related to Earth, and our two planets share a common ancestor billions of years in the past.
This is a theory called panspermia.
It suggests that life on Earth and Mars are connected. That life has been traveling from Mars to Earth and vice-versa for billions of years. “How is this possible?” you might ask.
Meteorites.
Mars Meteorite. Credit: NASAWe know that both Earth and Mars have been hammered by countless asteroids in their history long. Some of these impacts are so powerful, rock debris is ejected into escape orbits. This blasted rock could orbit the Sun for eons and then re-enter the atmosphere of another planet.
We know this is true, because we have meteorites on Earth which originated on Mars. Tiny gaps in the rock contained gases which match the atmosphere of Mars. You would think that an asteroid strike would sterilize life in the rocks, but amazingly, bacterial life can survive this process.
Microbial life can even withstand the harsh temperature, radiation and vacuum of space for thousands – possibly millions of years – riding inside their rocky spacecraft.
Some bacteria could even survive when their “space rock” enters the atmosphere of another world.
So a natural space exploration program has been in place for billions of years, with asteroid strikes hurling life-filled rocks into space, which then smash into other worlds.
Life on Mars has been elusive so far, but there are missions in the works which will have the scientific instruments on board to hunt for life on the Red Planet.
Artist illustration of a Europa probe. Image credit: NASA/JPLIf we do find it, will we discover that it’s actually related to us? If we find life under the ice on Europa, or in the cloud tops of Venus, will we discover the same thing?
It gets even stranger.
The Solar System is leaving a trail of debris behind as it orbits around the Milky Way, which could be colliding with other star systems. Which means, it’s possible that life around other stars is related to us too.
So maybe there’s no life on Mars, or if there is, maybe it originated on its own, or maybe it’s all related, as a result of trading life back and forth across giant spans of time and space.
Whatever the case, the search sure is going to be exciting.
