November 27, 2013 at 9:15 am | Leave a Comment
It’s a Heritage Science
A few weeks ago I went to Poland for a meeting called “Communicating Astronomy with the Public.” It was a gathering of about 200 people who work daily in bringing astronomy to public audiences. I presented a video called Losing the Dark about light pollution, and was part of a discussion about dark skies heritage for our children. All of us attending know that astronomy is one of the oldest, and most-approachable of all sciences. It’s also a gateway science; if you study astronomy, you can’t help but end up studying physics, chemistry, life sciences, astrobiology, and geology.
Astronomy began when the first people had a chance to go outside, look up, and marvel at the sky. It wasn’t long before they figured out how to use the sky as a calendar, a timekeeper. Why would they do that? To predict the seasons, which for hunter-gatherers as well as farmers is an important thing to do. If you know what season is coming up and when it begins, you know when to plant, to harvest, to hunt certain animals. Using the sky became a matter of survival. Later on, the use of the sky became more ritualized and incorporated into religious aspects of life, but the calendar and time-keeping functions remained as part of the observational practice of astronomy.
It really wasn’t until the Renaissance that astronomy came into its own as a science. And, from there, it evolved with each astronomer who put his or her telescope to work. Today, we stand on the shoulders of many giants in astronomy, beginning with the ancient Greeks, to Copernicus, Kepler, Galileo, Herschel, Hubble, and many others too numerous to name here. We get our star names from Arabic astronomers, our massive catalogs of galaxies and other deep sky objects from Herschel, Messier and others. Our perception of the universe was changed by Hubble, using Henrietta Leavitt’s discovery of the period-luminosity relationship of variable stars and their changing brightnesses. And, today, there are perhaps 10,000 trained astronomers using the world’s telescopes to learn more about the cosmos.
But, there are hundreds of thousands of amateur astronomers, too. Some are quite expert at observing and own very good equipment. Others are backyard-type astronomers using binoculars or small telescopes to explore the cosmos. And many people are content to go out each night, look at some constellations and planets and stars and take in the beauty of the night sky.
Astronomy IS for everybody. We should be encouraging more astronomy in our schools because it’s such an easy entry to other sciences. And science-literate children grow up to be savvier adults participating in society. It’s not a stretch; it’s true. And astronomy is a heritage we need to keep sharing.
November 25, 2013 at 9:30 am | Leave a Comment
Preparing for the Red Planet
Some years ago I wrote a popular fulldome show about Mars called MarsQuest. In it, we discuss future missions to Mars, and ask the question, “Where on Earth can we go to learn about Mars?”
As it turns out, there are several good Mars-analog regions here on Earth where scientists have trained rovers and practiced for crewed missions to the Red Planet. One is called the Haughton-Mars Project, run by the Mars Institute, in cooperation with the SETI Institute, NASA, and the Canadian Space Agency in northern Canada for several years. One look at this desolate landscape, and you’d swear it’s Mars.
Several robotic explorers have been tested at the site, and a number of researchers have studied the surface conditions at the site to understand how they might be similar to those found on Mars, particularly at the polar regions.
Mars-like conditions can also be found in Antarctica, particularly in dry valleys that might not be too different from similar terrain on the Red Planet. In addition, the deserts in Utah also provide useable regions to understand conditions on Mars.
Some years ago, when I was in graduate school, groups of us went to Hawai’i to study volcanic features similar to those found on Mars, as well as other terrain called sapping valleys. Tramping around the slopes of Mauna Loa and Kileaua gave us a good feeling for the volcanic terrains on Mars.
You might ask, why go through all this work if people won’t be going to Mars for some time yet? It may well be decades before we send people to Mars, but that doesn’t mean we can’t at least prepare and train in areas that are similar to the planet. Things will be alien enough there, and any kind of training will give future Mars explorers a leg up once they get to the planet. It’s also a great way to learn more about the alien landscapes that our own planet sometimes hands us.
Such studies are a legacy that we can hand down to the folks who WILL be going to Mars someday. They aren’t us, at least not unless we get a human-to-Mars program going in the next few years. No, they’ll be our kids, or maybe even our grandkids. And, all the work we do today will not be wasted on them.
November 23, 2013 at 9:00 am | Leave a Comment
But All they Are is Chunks of Ice and Rock
Does it ever seem to you that every time there’s a comet about to appear in our skies, a certain element of what I think of as the Whack Job Brigade (WJB) gets all lathered up and claims (yet again) that whatever it is, it’s NOT a comet! It’s a space ship. Or a rogue planet. Or something else they accuse NASA or the U.S. Government or the Trilateral Commission of creating and/or hiding from the rest of us.
The WJB really had a field day with Comet Hale-Bopp back in the 1990s, and the end result was a group of people committing suicide because somebody told them the comet was a “mother ship” coming to save them. From what, is not clear.
Even before that, however, comets were getting a bad rap. In fact, it goes back to early history, when comets were considered bad omens by ancient skygazers. Most of them didn’t go and kill themselves. They just kind of hunkered down until the comet passed and then got back to their daily business of using the stars to foretell the future.
In the 20th century, particularly in the latter couple of decades, we started to see people showing up on Usenet and the early World Wide Web, telling tales of how NASA was hiding the “truth” about comets being spacecraft bearing aliens to help humanity “progress”. There was (and probably still is) a woman named Nancy, who claimed she was in communication with aliens from the Pleiades or someplace, and they were telling her to tell the rest of us that the upcoming comet, or Planet X, or whatever it was she thought was coming our way, was really here to rescue us. Or something. I could never figure out what her deal was. Other than she honestly claimed that alien voices were in her head. I don’t doubt for one bit that she was hearing voices. I tangled with her once on Usenet, and she responded by claiming that I was a secret operative.
So, these days, Comet ISON is getting closer to the Sun, and is starting to do what all comets do: sublimate material off as its ices get heated by the warmth of the Sun. The last image I saw showed two tails—one’s a dust tail and the other is a plasma tail. Plasma tails are what I tracked as part of my graduate school work, and so I’m always interested to see how they interact with the solar wind.
And there are several other comets showing up, too. I would imagine the WJB is probably beside itself with frenzied speculation about what all these comets mean. Well, I’m here to tell you. They mean that chunks of ice and rock that formed some 4.5 billion years ago in the outer reaches of the solar system, are on orbits that will take them around the Sun. That’s what comets do when they’re not floating around out in the frozen reaches of the solar system beyond the planet Neptune. And when they get nudged out of their orbits (sometimes by collisions with each other, or gravitational perturbations from nearby planets, or maybe a passing star), they enter into an orbit that will eventually take them by the Sun. And when they get close enough, they do what icy objects always do in the presence of heat: they melt and/or sublimate. Sublimate is a fancy word that describes what dry ice does…and comets have CO2, and many other ices in them, which … ta da… sublimate when they get close to the Sun.
So, while it may be tempting, and perhaps even amusing, to read what the WJB says about comets, I would—if I were you— take what they imagine with a block of salt. Most of them don’t really know what comets are. And they’re missing the boat on how exciting comets can be to observe. There’s really NO need to make comets more exciting by adding aliens, hidden agendas, rogue planets, and all this other nonsense that the members of the WJB want you to believe. The universe, including comets, is far more exciting in its natural state than anything a whack job can dream up.
The big news about Comet ISON right now is that it is due to have its closest approach to the Sun on November 28th. It might break apart under the gravitational pull of the Sun. Cometary ices are quite brittle, and all other things being equal, they can break apart under the influence of gravity. So, most of the world will wait breathlessly to see if Comet ISON survives. If it does (or even if it doesn’t), there could be quite a show when it (or what’s left of it) appears in the predawn skies in the early part of December. So, check it out for yourself. Sky & Telescope and Astronomy magazines are sharing great viewing charts, so check it out! And, participate in a great natural event—the viewing of a comet!
I found a really cool NASA video about sungrazing comets. Check it out.
November 21, 2013 at 14:30 pm | Leave a Comment
Cosmic Neighborhood, That Is
What’s the most powerful event you can think of in the universe? An asteroid crash onto the surface of a planet? A supernova explosion? Two black holes colliding? The Big Bang? Each of those events is powerful, and changes the objects involved. Take a gamma-ray burst, for example. It’s the catastrophic “monstrous” explosion of a hugely massive star as it dies. The stars that obliterate themselves in these monster events are dozens or perhaps even hundreds of times the mass of the Sun. They explode quickly, sending out huge amounts of radiation, including gamma-rays (the most deadly radiation we know of).
Most explosions of this type are extremely far away, but are so bright they can be seen across the universe. The initial flash tells astronomers that something happened, and they start to track its afterglow immediately. They’ve had some help in tracking these fantastic explosions from the SWIFT satellite, which has been studying the gamma-ray universe since 2004. It finds about 100 gamma-ray bursts a year.
Last April, the spacecraft spotted a GRB that was extremely bright and, in a departure from GRBs that are usually very far away, this one was actually in a relatively nearby galaxy. It exploded almost 4 billion years ago. The progenitor star (the star that blew up) was about 2o-30 times the mass of the Sun, and rotating extremely fast. That means it was a very compact star, of a type known to astronomers as a Wolf-Rayet star.
The work to identify and characterize this explosion was done at the Niels Bohr Institute in Copenhagen, Denmark. They’ve created a cool video about exploding stars that you can watch here.
November 19, 2013 at 8:45 am | Leave a Comment
C2012 S1 ISON is Putting on a Show
Judging by this great image of Comet ISON just released from the European Southern Observatory, it’s safe to say that ISON is becoming the Comet of the Year for 2013. I know that naysayers have been muttering about what a fizzle it was, and it was kind of quiet. But, in the last couple of weeks, ISON has awakened and is putting doubts to rest. This image shows activity in the plasma tail, which forms when gas molecules are ionized by the solar wind as the comet passes through.
I look at this image and see that perhaps the comet is about to experience what’s called a plasma tail disconnection event. That’s a “break off” of the plasma tail as it encounters a change of polarity in the solar wind. A new plasma tail will start to form immediately, and the old one will float off to interplanetary space.
Now, you’re probably wondering about seeing Comet ISON for yourself. You only have a few days left to really get a good look. To do it, you have to get up before dawn, and look to the east (which makes sense —the comet is on a headlong rush toward the Sun) after 5 a.m. Look for the Big Dipper. Once you find that, locate the curved handle, and follow that curve until you find the star Arcturus. (You arc to Arcturus—one of my favorite stargazing commands). After that, curve down to Spica, and the comet shouldn’t be too far away from that star. After that, it will appear to head toward Scorpius before angling back up toward Bootes and Corona Borealis in December. For good viewing charts, check out Astronomy.com and SkyandTelescope.com. Also, keep checking places like Spaceweather.com and Astronomy Picture of the Day for comet images as they come in.
The comet will slip out of view for a few days around November 28th, its closest approach to the Sun. There’s a school of thought among astronomers that it could break up due to the intense gravitational pull of the Sun (and the heat). If it does that, it’s anybody’s guess about how it will look after that. If it doesn’t break up, then look for the comet (again in the early morning) after about the 3rd or 4th of December. I also read that the Solar Dynamics Observatory (focused on the Sun) will be able to follow the comet through perihelion, so keep an eye on their Web page for a video release after perihelion. There’s still a lot of comet-gazing coming up, so check it out! (And, while you’re at it, get ready for Comet Lovejoy!) Enjoy watching these incredibly cool bits of solar system history!
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Copyright 2013, Carolyn Collins Petersen
Image of Horsehead Nebula: T.A.Rector (NOAO/AURA/NSF) and Hubble Heritage Team (STScI/AURA/NASA)
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