Comet ISON surprises skywatchers as NASA tries to photograph it from Mars
By Marshall Connolly, Catholic Online (NEWS CONSORTIUM)
Comet appears to glow green with poisonous gas.
Well, are you ready? After a year of breathless anticipation, skywatchers are prepared to receive the potential comet of the century next month as Comet ISON sails by Earth one it's first and last trip around the Sun.
Comet ISON has a yellow-green tint in this image.
LOS ANGELES, CA (Catholic Online) - Astronomers have been watching Comet ISON closely as it approaches Mars this week, then continues in the general direction of Earth. When it was detected, now just over a year ago, astronomers originally predicted that its close brush with the Sun might cause it to brighten enough to rival the full moon. That prediction has been downgraded as the comet's brightness develops, but there are a number of other surprises that makes ISON worth paying attention to, including its color.
Backyard astronomers still have a couple weeks to wait before they can spot the icy comet, but professional and semi-professional astronomers with telescopes over 10 inches in diameter say they can already spot the fuzzy object near the planet Mars in the sky.
As of today, ISON is making its closest approach to the planet Mars and NASA astronomers are attempting to photograph the comet from the planet's surface and from orbit. If photographed, it would become the first comet ever imaged from the surface of another world.
The photos might also shed light on another curious phenomenon. As astronomers get their first look at the brightening comet with high-resolution equipment, they are observing a surprising development. Comet ISON isn't white, it's green.
Green comets are rarer than the usual white ones, but they appear with some regularity. The green color observed in the comet's coma, or head, is the result of cyanogen gas and diatomic carbon. Cyanogen gas smells like almonds, but despite the pleasing scent you won't be using it in your air freshener anytime soon because it's also poisonous. Diatomic carbon also has the dubious distinction of being a very strong acid.
Luckily, the gasses given off by the comet are far from Earth, nor are they concentrated. In fact, the gas is so diffuse that if you were to stand on the comet's nucleus and somehow breathe, you probably would not be poisoned.
However, the diffusion of this out-gassing is giving ISON a beautiful green tint, and is the reason why it is so bright. A handful of comet dust would appear black to us on Earth, but against the absolute blackness of space, it reflects enough sunlight to appear a bright greenish-white to us on Earth.
The brightness of Comet ISON has long been a subject of excitement with early estimates saying it could be as bright as the full moon around magnitude -17. Negative numbers indicate brighter objects. Now estimates say the comet will probably be closer to -3 or -5, about as bright as the planet Venus in the evening sky.
That means it will be easy to spot with the naked eye and will put on a spectacular show for billions to see.
ISON will become visible to the naked eye around November 6, and will remain visible for about two months, dimming out of view as it recedes into the depths of space around January 6. Still, a two-month display is amazing and exceptionally rare.
However, we may not get two months with the comet. Comet ISON is expected to pass less than a million miles above the surface of the Sun, and it is relatively small as comets go. This means there is a good chance that it will break up as it buzzes by. While this breakup could cause the comet to brighten suddenly, it may also fizzle out very quickly as it dissipates into space.
Alternatively, and what most skywatchers hope, is that ISON will survive the extreme tidal forces of its close approach to the Sun and remain intact and bright for all to watch into January.
ISON rounds the Sun on 28th November, and this is when it should be at its brightest. It will also be close to the Sun in the sky, so it won't be as easy to spot next to the Sun's glare. If it survives, it will pass closest to Earth on December 26. It will pass almost 40 million miles above the north pole, way too far away to be any threat to Earth.
After January, the comet should remain visible to most telescopes into March. After that, it will fade from view until it becomes invisible, sailing far beyond the power of our most capable instruments. ISON will silently sail into deep space on an path that will never ever bring it back to the Sun. ISON will continue traveling for eons, until another star or gravitational body acts upon it, likely billions of years from now.
Follow this link to have a look at ISON's path around the Sun!
For now, if you want to view Comet ISON, find Mars in the sky. You will need a large telescope with an aperture of more than 10 inches. Under good conditions, you should be able to pick out a faint, fuzzy patch to the upper left of the planet Mars on the morning of October 1. In fact the moon will align diagonally with Mars, and ISON should be just above the to the left of the two objects in the predawn sky. Again, you will need a powerful telescope.
If you miss it on Oct. 1, keep looking near Mars to see the comet.
For the rest of us, it will be a wait of four more weeks, possibly five at the most. Then one of the greatest spectacles in nature will present itself in the skies above.
Backyard astronomers still have a couple weeks to wait before they can spot the icy comet, but professional and semi-professional astronomers with telescopes over 10 inches in diameter say they can already spot the fuzzy object near the planet Mars in the sky.
As of today, ISON is making its closest approach to the planet Mars and NASA astronomers are attempting to photograph the comet from the planet's surface and from orbit. If photographed, it would become the first comet ever imaged from the surface of another world.
The photos might also shed light on another curious phenomenon. As astronomers get their first look at the brightening comet with high-resolution equipment, they are observing a surprising development. Comet ISON isn't white, it's green.
Green comets are rarer than the usual white ones, but they appear with some regularity. The green color observed in the comet's coma, or head, is the result of cyanogen gas and diatomic carbon. Cyanogen gas smells like almonds, but despite the pleasing scent you won't be using it in your air freshener anytime soon because it's also poisonous. Diatomic carbon also has the dubious distinction of being a very strong acid.
Luckily, the gasses given off by the comet are far from Earth, nor are they concentrated. In fact, the gas is so diffuse that if you were to stand on the comet's nucleus and somehow breathe, you probably would not be poisoned.
However, the diffusion of this out-gassing is giving ISON a beautiful green tint, and is the reason why it is so bright. A handful of comet dust would appear black to us on Earth, but against the absolute blackness of space, it reflects enough sunlight to appear a bright greenish-white to us on Earth.
The brightness of Comet ISON has long been a subject of excitement with early estimates saying it could be as bright as the full moon around magnitude -17. Negative numbers indicate brighter objects. Now estimates say the comet will probably be closer to -3 or -5, about as bright as the planet Venus in the evening sky.
That means it will be easy to spot with the naked eye and will put on a spectacular show for billions to see.
ISON will become visible to the naked eye around November 6, and will remain visible for about two months, dimming out of view as it recedes into the depths of space around January 6. Still, a two-month display is amazing and exceptionally rare.
However, we may not get two months with the comet. Comet ISON is expected to pass less than a million miles above the surface of the Sun, and it is relatively small as comets go. This means there is a good chance that it will break up as it buzzes by. While this breakup could cause the comet to brighten suddenly, it may also fizzle out very quickly as it dissipates into space.
Alternatively, and what most skywatchers hope, is that ISON will survive the extreme tidal forces of its close approach to the Sun and remain intact and bright for all to watch into January.
ISON rounds the Sun on 28th November, and this is when it should be at its brightest. It will also be close to the Sun in the sky, so it won't be as easy to spot next to the Sun's glare. If it survives, it will pass closest to Earth on December 26. It will pass almost 40 million miles above the north pole, way too far away to be any threat to Earth.
After January, the comet should remain visible to most telescopes into March. After that, it will fade from view until it becomes invisible, sailing far beyond the power of our most capable instruments. ISON will silently sail into deep space on an path that will never ever bring it back to the Sun. ISON will continue traveling for eons, until another star or gravitational body acts upon it, likely billions of years from now.
Follow this link to have a look at ISON's path around the Sun!
For now, if you want to view Comet ISON, find Mars in the sky. You will need a large telescope with an aperture of more than 10 inches. Under good conditions, you should be able to pick out a faint, fuzzy patch to the upper left of the planet Mars on the morning of October 1. In fact the moon will align diagonally with Mars, and ISON should be just above the to the left of the two objects in the predawn sky. Again, you will need a powerful telescope.
If you miss it on Oct. 1, keep looking near Mars to see the comet.
Comet ISON will be near Mars for the next couple weeks.
For the rest of us, it will be a wait of four more weeks, possibly five at the most. Then one of the greatest spectacles in nature will present itself in the skies above.
Where and when can I see Comet ISON?
There it goes! Look! It’s right behind you! Driving the tan Kia! Never mind, you missed it. It was spectacular.
Shouldn't have been playing with your smartphone. Credit: Soerfm, Wikimedia Commons
So, we can’t tell you for sure yet. Despite everyone’s hopes, it’s entirely possible that Comet ISON will disintegrate when it approaches the Sun, or that it won’t be visible to the naked eye. For ISON to become a spectacle, it would have to survive its approach to the Sun and develop a long tail as it becomes exposed to the Sun’s heat. And there are a lot of factors that go into that, including the size and composition of the comet’s nucleus.
So your view of ISON, if it survives “perihelion,” or its approach to the Sun, will depend on how bright it is and where it is located in the sky. It will have to be far enough from the Sun to be visible, because the glare of the Sun washes out dimmer objects.
Late October is your first possible, maybe, sort-of chance for a glimpse of the comet. It may become visible, depending on how bright it is, in the morning before sunrise if you use binoculars or a telescope. Take a look then, because in late November it’ll become invisible again as it reaches perihelion — it’ll be too physically close to the Sun for you to view it.
The last days of November and early December will be best for viewing if the comet survives its closest approach to the Sun on Nov. 28. The comet will appear in both the early morning and early evening in the Northern Hemisphere, but it will rise with the Sun in the southern hemisphere. After that, it’ll start fading fast. January still presents a possibility for viewing, but that’s very iffy.
Look, we made you a picture!
Need more info? Stuart Atkinson’s Waiting for ISON has lots of great information, and he’s made a series of images on where and when the comet will be in the sky.
Where are all the pictures of Comet ISON?
There actually aren’t a lot of images of ISON right now. Basically, ISON was discovered when it was extremely far away — so far away that you need a large telescope to see it.
Then, ISON passed behind the Sun from our vantage point, and no one could see it. It re-emerged in late August, its reappearance captured by an amateur astronomer.
It may seem strange that the professional astronomical community isn’t tracking ISON’s every move, but there really isn’t much point right now. ISON is too far away for scientists to glean much from observations. Hubble took pictures to try to determine the size of the nucleus. Spitzer studied its carbon dioxide emissions. But ISON’s most interesting behavior takes place when it nears the Sun. Not while it’s plowing onward through the vast emptiness of the solar system.
Not actually the most interesting part of going someplace. Credit: TheFriendlyFiend, Wikimedia Commons
Observing it frequently during this period doesn’t reveal much new information. It continues to be a blob of ice moving through space. We’ll only get new info when it draws close enough for us to get a better look, or it begins reacting to the Sun.
In the meantime, professional observatories have other things to do — a LOT of other things. Using a space telescope like Hubble, or a professional ground observatory, doesn’t mean glancing through a lens. There are so many astronomers who want to use these telescopes for research that they have to submit proposals on why then need to use the telescope. The proposals are reviewed by committees of scientists to decide who deserves to win time on the telescopes. On average, there are six times more proposals to use Hubble than there are proposals selected. There’s just not enough time for everyone to get a shot. Your scientific reason for receiving access needs to be compelling and convincing.
So the short answer is, don’t expect a lot of images of ISON until it starts getting closer and doing something other than putter along.
Why do amateur astronomers keep finding ISON? Huh? NASA? Huh?? HUH??
OK, meet Bruce Gary.
Mr. Gary, an amateur astronomer, was the first to see ISON re-emerge from behind the Sun. It was quite the feat — he found the comet earlier than many people suspected would be possible.
Now meet Mr. Gary’s telescopes.
Some people have flower beds next to the driveway. Credit: Bruce Gary
He has a control room dedicated to them.
He has a control room dedicated to them.
Your blog author has always wanted a control room. Preferrably in a hollowed-out mountain. Credit: Bruce Gary
Now let’s look at his resume. Before Mr. Gary retired, he led the Radio Astronomy Group at the Jet Propulsion Laboratory. He helped develop instruments flown on NASA aircraft. He constructed radiometric maps of the Moon. He holds four patents. He pioneered “calibration techniques (including "tip curves") for water vapor radiometers as well as in the optimum use of combined multi-frequency/multi-angle temperature profilers,” which is apparently a thing.
Now that he’s retired, he studies exoplanets for fun.
The question, to put it another way, is based on something of a misunderstanding of what an amateur astronomer is and the difference between amateur and professional astronomers.
Professional astronomers perform astronomy as a career. That means they have to write grant proposals, research, get hired on as faculty, publish results in refereed journals, present results at professional meetings, and get paid for doing it. A lot of professional astronomers have no idea how to use the kind of telescope you would see in a normal setting, or even find objects they’ve been studying their entire careers in the night sky. It’s not part of the job. The job is poring over data and putting the pieces together.
Amateur astronomers can be just as dedicated, but because they aren’t living off their work, they have the freedom to observe whatever they desire, whenever they desire. They don’t have the constraints that go with professional astronomy. They can specialize, and many do. They often work on teams with professional astronomers, belong to astronomy organizations, and win recognition for their efforts. Their reward is the challenge of the task and being able to contribute to the collection of knowledge about a cosmic object.
Amateur and professional astronomy work complement each other. So a professional astronomer using Hubble will investigate the size of ISON’s nucleus, and an amateur astronomer working diligently and carefully in a private observatory in his yard will find ISON reappearing from behind the Sun. Not everyone has to be on the same task. Different telescopes, different priorities, different discoveries. Everyone wins.
Or, as Bruce Gary puts it, “You ask, ‘What keeps you doing this kind of work into retirement …?’ That’s like asking a writer why they keep writing: ‘Because I can’t not write!’ I suspect that all astronomers are driven by a childhood inspiration that can never be extinguished. Mine was born at age 7, and I can’t imagine ignoring the heavens!”
Oh, did we mention he has an asteroid named after him?
This is the part where the amateur astronomy community, as a whole, drops the mic and walks away.
Bruce Gary writes about finding Comet ISON here. We had an earlier story about the amateur astronomers who discovered ISON in the first place. NASA has a good list of amateur astronomy organizations.
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