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We are riding on the edge of a huge void in space, hurtling along at 600,000 miles per hour. Yes, it's true. We're moving along with the expansion of the universe AND with the coalescence of galaxies along filaments, in clusters at places where the filaments intersect. Yet, as we go about our daily lives, we're largely (if not completely) unaware of the ride we're taking through space and time as part of the Milky Way Galaxy. Yet, our motion tracks with the continuing evolution of the universe.
Did that get your attention? It's a compelling story, and one that astronomer Brent Tully is telling in his latest research into the motions of galaxies in our neighborhood of the universe. In the past, our distance measurements to other galaxies could give us some very broad information about our galaxy's motion through space. In addition, other measurements of the Cosmic Microwave Background Radiation tell about some aspects of our galaxy's motion. But, there's always been a part of our motion that was unexplained—until now. Tully and a team of colleagues have done extremely precise measurements of distances to galaxies around us. Those measurements tell a great story of motion and action of galaxies through time and helped them finger a largely unexplored component of space as the culprit: the Local Void. This is a gap in space that is 50 megaparsecs across. (A megaparsec is about 3,260,000 light-years, and a light-year is the distance that light travels in a year.)
The distribution of galaxies in the region around the Milky Way (in galactic coordinates). Each little dot represents a galaxy of typically 100 billion stars. The colors indicate the relative motions of galaxies with accurately measured distances, with shades of gree and blue indicating motions toward us, and shades of yellow to red indicating motions away from us. (For more information, see the IFA press release.
Concentrations of matter (like the filaments and clusters) are aggregates of matter that is pulled together. Concentrations of matter have gravity; they PULL on things. The Local Void, on the other hand, is empty. It seems to PUSH on things, including our galaxy. Tully explains it as the absence of a pull. If an object is surrounded by matter in all directions, except for one empty sector, then the absence of a pull from that sector is actually the same as a push. And, it can have a large effect on our region of space, in effect turning us into void riders moving along the edge of the Local Void.
It's quite fascinating that we (all of us in the Milky Way Galaxy) should live on the edge of such a huge gap of nothingness; and, we ride along not really feeling our motion across the depths of space and time.
The astronomy profession is a small community of kindred souls all focusing on dozens of different ways to understand the science of the cosmos. I go to astronomy meetings pretty frequently (well, at least once or twice a year), to catch up on the latest and greatest in astronomy research. Mr. Spacewriter has accompanied me to a couple of meetings because I wanted him to experience the science being presented, and so he could meet some of the same folks. At the opening reception of the meetings, we've run into many, many people I've worked with or went to school with "back in the day." And, marvelled at the fresh infusion of new blood into the profession. Of course there are folks from NASA and many research institutions at the meetings, but also people like Pamela Gay and Fraser Cain, who are the main drive behind Astronomy Cast. Pamela (who is also a university professor) is doing a lot more than research and teaching in astronomy. Like me, she loves to share astronomy with the public, in any way she can.
There are also a good many very talented science writers who attend AAS meetings, reporting on the science "hot off the presses." It's been an honor to meet some of them, too. Where else could I have met New York Times science writer John Noble Wilford? He attended a great many AAS meetings, always asking the astute questions and subtly drawing out an education in astrophysics through his questions. Or Dutch writer Govert Schilling? Or many others who have attended these sessions over the years.
As a writer, I've found many outlets for the material I learn at astronomy meetings. Of course, I use the science in my documentary shows. But, for the past few years, in addition to my fulldome show production work through Loch Ness Productions, I've been contracted by various observatories to work as an editor and outreach person. The work runs the gamut from writing and/or editing press releases to creating exhibits. Lots of fun, and I'd love to do more of it.
And, so I shall. To wit: in a very short time, Mr. Spacewriter and I will be starting production on some vodcasts under a NASA grant with MIT Haystack Observatory. And, much of the material we're going to talk about is from papers I've heard and read about at AAS meetings, as well as from direct contact with astronomers in their research settings. Through all my "productions," I hope to excite the downloading public about the science these guys are doing. I want to show their enthusiasm and love of subject to the rest of the world, because astronomers really are as much the stars of my work as the stars they research and explore.
I'm a member of the International Dark-Sky Association. These guys are the light pollution authorities of the world. If you visit their website, you can find all kinds of information about the importance of dark skies (and not just to astronomers), as well as how to make your block, your community, your city, your state, a dark-sky site. They have a link to lighting practices and equipment that will help preserve dark skies while maintaining safety in your community. And, many of their suggestions help preserve energy expenses (an important factor).
The community I live in has some energy- and light-pollution-cutting lighting practices, although some neighbors still think it's great to throw light up to the sky indiscriminately. In our neighborhood we managed to get our local utility to put up "screens" around the nearest streetlight so that the light shines down on the street, like it's supposed to, and not in our bedroom window, or bathing our yard.
One of the more illustrative pages on their site is a series of links to various places on Earth, showing the light pollution from satellite's-eye views. Check it out, and do your part to reduce light pollution, save energy, and preserve the beauty of the night skies for everyone to appreciate.
I was browsing around at Borders Books last night, checking out the latest science books. One thing I've been noticing over the past few years is that the science sections in bookstores are getting smaller at about the same rate that pseudoscience, religion, and mystery book sections are growing. I don't know that there's a strict correlation (and I'm not saying that those three sections are related, so don't go there), but I note the trend.
Anyway, I ran across this great little book at the counter called the Ultimate Book of Useless Information. I'm a sucker for factoids and little-known data points. So, I bought it and started browsing through it while waiting to pick someone up at the airport.
Since I'm interested in astronomy and space science, and since I've been doing a lot of reading on global warming and our atmosphere, a few nuggets caught my eye. First, as it says on page 61, the surface temperature on planet Earth would be 176 Fahrenheit by day and fall to 220 F by night if we didn't have this atmosphere that sustains us. Also, as it says on page 61, Earth's atmosphere is proportionally thinner than the skin of an apple.
Interesting facts, these. But useless? I don't think so. They tell us a lot about our planet in just a few words. Stuff worth knowing. So, I'm not sure why the compiler of these "useless" facts dubs them so, because every fact is a teachable moment, a chance to learn something about the universe. Still, the book makes us think about these facts. It raises questions like "How do they know that?" and "Is that still true?" So, perhaps that's the authors' intention. Still, I don't like seeing facts dismissed as "useless."
Here's another one: hot water is heavier than cold water. How do they know that? Can you prove this to yourself? How? A nice little lesson in science and fluid physics, don't you think?
Here's another: the human tooth has about 55 miles of canals in it. Ask your dentist about THAT the next time you're in for a checkup (or, a root canal)!
Here's a not-so-useless fact: a third of all cancers are Sun-related. That's news you can use, and proof that much science data IS useful. And I think most people agree with that, once they stop to think about it.
Yet, there are those who reject science for a variety of reasons: ignorance, fear, religious misinterpretation or misunderstanding of the role of science. They may have spurred a bit of head-banging among those of us who see science as a system of knowledge and not the evil, godless practice that a few misguided souls make it out to be. In that case, I offer this last bit that I'll mention from the book: banging your head against a wall burns 150 calories an hour.
Update: if you get this book, don't take every "fact" in it that you read as correct. I've found a few "facts" that are somewhat sloppily stated, and at least one that's flat-out wrong and could have been corrected with very simple research. With that caveat, this is still an interesting read, and now can be used as a jumping-off point to sharpen your critical thinking skills by fact-checking the "fact" mongers.
Today Fraser Crane over at Universe Today is hosting the third Carnival of Space. Included among the blogged articles is my previous entry (below) about the Dark Matter Ring. Head on over and enjoy Fraser's commentary and links to other great articles!
It's out there. Dark matter. You've probably read about it in the papers, or heard scientists talk about it. Nobody's quite sure exactly what it is, yet. But, we do know it's out there, distributed in clumps throughout the galaxies in the universe.
Tracking down dark matter, which is one of the great "Holy Grails" of astronomy and astrophysics these days, is no easy matter (so to speak). Dark matter doesn't give off light, it doesn't reflect light. It just sits there, making its presence known by the gravitational effect its mass has on light. To find it, astronomers study how the light from more distant galaxies (beyond or "behind" the dark matter clumps) is distorted and smeared into arcs and streaks by the gravity of the dark matter. The smears are produced by a phenomenon called "gravitational lensing."
One Ring to Rule Them All... and in the Dark Matter Bind Them
Today a team of astronomers announced that they found a RING of dark matter at the heart of a galaxy cluster. An ordinary "visible light" image of the cluster shows galaxies and some smears of light that are distorted images of galaxies behind the cluster. The smears indicate that there's something in the cluster causing the light from the distant galaxies to bend or distort. That "something" turns out to be a ring of dark matter. Now, if much of the dark matter we've "seen" so far in the universe is clumpy, how does a ring of it end up at the heart of a galaxy cluster?
According to one of the astronomers, Dr. M. James Jee of Johns Hopkins University in Baltimore, MD, the collision between two galaxy clusters created a much larger cluster, but it also formed a ripple of dark matter separate from the gas and dust components of the cluster that left distinct footprints in the shapes of the background galaxies. "It's like looking at the pebbles on the bottom of a pond with ripples on the surface," he said. "The pebbles' shapes appear to change as the ripples pass over them. So, too, the background galaxies behind the ring show coherent changes in their shapes due to the presence of the dense ring."
This is the first time such a distinct ring of dark matter has been seen, and at first Jee did not want to believe the ring-like structure was anything but a statistical fluke in the data analysis. But, like any good scientist does, he systematically went through the data, and eventually was convinced it was real.
"I was annoyed when I saw the ring because I thought it was an artifact, which would have implied a flaw in our data reduction," Jee explained. "I couldn't believe my result. But the more I tried to remove the ring, the more it showed up. It took more than a year to convince myself that the ring was real. I've looked at a number of clusters and I haven't seen anything like this."
It's really quite a cosmic detective story. Dark matter is sort of like the "last frontier" of matter studies in some ways. We know it's ubiquitous in the universe, and we're now starting to trace out its distribution, its "shapes" (if you will). There's more dark matter than "regular" (so-called "baryonic" matter in the universe) and it serves as a sort of gravitational glue to bind galaxies and clusters together.
If you want to read more about this story, and see some very cool animations, go to the Space Telescope Institute website and visit their news center. And stay tuned. I think there's going to be more news about this "binding force" of dark matter as scientists do more cosmic mapping!
A Jupiter-sized planet (artist's impression) passing in front of its parent star. The planet was discovered by the NASA/ESA COROT satellite. (Read here for more COROT information.)
Exoplanets are grabbing the headlines these days. There are something around 220 or so planets around other stars that we about, and the number keeps growing as astronomers refine their planet-searching techniques and upgrade specialized telescopes to do the searches. There have been several discoveries announced in recent weeks, and at least one more that I know of will be announced soon. So, there's a bonanza in planet discoveries going on.
One of these days we'll find an Earth-like planet and know it's an Earth-like planet (we think we've found one, but the "Earth-like" part is still unconfirmed). That'll set off a huge firestorm of discussion about what life might be like on such a world. Of course, for science fiction readers, such discussion topics are old hat, but as an SF reader myself, I suspect that the reality of an Earth-like planet and its life will probably be nothing at all like what we've imagined in SF magazines and books for the better part of a century now.
When I was a kid, I used to imagine going to Mars and finding life there. I didn't know about the Edgar Rice Burroughs "life" on Mars until I was much older, so my childish imaginings were not limited to fighting men and princesses. Most of the time I was finding strange red plants, weird talking worms, rabbits, etc. I guess the life I imagined was what was familiar to me as a child. Although, since I lived part of my life on a farm, I don't recall imagining Martian sheep and cows and chickens.
Life on other planets around other stars didn't even enter into my world view until I was somewhat older and had read my first science fiction. And, of course, that life was humanoid, water-based, and still somehow weird. Science fiction tales are made up by humans, so it's pretty obvious that our stories of alien life will have some attributes of humanity, no matter how that life looks. I suspect that's because if somebody came up with a truly weird life form, the story would founder along until one of the characters found a way to communicate with it. (Shades of Star Trek, and the many ways Hollywood tried to imagine the truly weird and talk to it.)
So, SF fan that I am, I can't wait til the first life-bearing planet outside our solar system is found. The debates and discussions are going to be amazing to witness and take part in!
We celebrated my birthday on Friday by taking the day off and wandering up the coast of Maine. It's a pretty state and when the weather's nice but the tourists haven't arrived yet, it's sublime.
I noticed the skies were pretty dark there, even with the glow of a few distant city nebulae on the horizons.
As we were driving back home, we kept watching Venus off in the west. Even though I knew Venus was setting, the planet still looked a little different from what I'm used to. It seemed more "reddish," probably because we were looking at it through the lower part of Earth's atmosphere—the "muck" as we call it in stargazing circles. But it was shining like a bright beacon as it set.
Venus and the Pleiades, 2007 April 13 by Geoff Chester, and posted on the US Naval Observatoryweb page.
Venus is still bright in the western sky, and sets late in the evening for the next few weeks. It'll be the bright light in the western sky that isn't point-like, doesn't move like a plane, and isn't a flying saucer. Look for it if you're out wandering around enjoying the onset of northern hemisphere summer or early winter in the southern hemisphere.
We live in a pretty amazing age, although I suppose people in every age think their own times are amazing. But, I have to count an age where we (humans) can reach out and explore other planets and distant stars and galaxies seemingly as readily as we turn on the computer as amazing.
Going over some recent press releases that have landed in my mailbox, I see a story about water ice on Mars—not a big surprise, we know there's water on Mars, but now we are getting a better feel for how much and how it is distributed (paricularly as underground ice) on the Red Planet. That one broke earlier today, and you can see the full story and pictures here. Now, you might wonder why this is a Big Deal. I mean, we detect ice on our planet all the time. But, again—astronomers reached out with a specialized camera across from Earth to Mars, and were able to tease out data about underground ice on a planet we haven't even personally set foot on yet. THAT is amazing.
Also released today from the European office of the Hubble Space Telescope is a great image of the globular cluster NGC 2808. It's a great picture, very pretty! And, it reveals that (for this globular cluster anyway) star birth is NOT a thing of the past.
Globulars are typically the oldest members of our galaxy's system, born when the Milky Way was, and astronomers thought all the stars in a globular were the same age. For THIS globular, however, there are three generations of stars, implying that instead of one big burst of stars, it had three baby booms. This upsets the conventional theories about globular cluster formation, and we get another great pic of a globular in the process, using a telescope that reaches out across thousands of light-years to tell us a story about stars as they formed some 12 billion years ago!
Speaking of stellar ages, the folks at Lowell Observatory in Flagstaff, Arizona, announced a new method for determining very accurate ages of stars based on how fast they rotate. Why would you want to know how old a star is? If it has planets, knowing its age helps you put a timetable on the planets' ages and how their evolution is proceeding. That's a large and very important part in the study of any planets actually—how they change over time. The rotation rate of a star, as it turns out, is a function of its age and color. If you measure the rotation period and the color, for example, you can calculate the age of the star.
Finally, although it's not entirely new news, the recent announcement that astronomers using the European Southern Observatory have discovered the most Earth-like planet around another star is a new benchmark in planet searches. Stars are large and bright, and their light can hide planets that orbit close by. We usually have to use indirect methods (like taking a spectral measurement of the star's light and then measuring any "wobbles" in the spectrum that indicate the gravitational tug of a planet on its star) to find exoplanets. Most of the exoplanets you've heard about are Jupiter-like (ie. big and gassy) planets. This new one is more Earth-like, and astronomers think that it may have water in its atmosphere. That doesn't mean it has life, but water is an important factor for the creation of life as we know it. Stay tuned on that one.
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