January 25, 2012 at 12:14 pm | Leave a Comment
The Blue Marble, 2012
There it is folks, our home in space. The Blue Marble. Mother Earth. Whatever you want to call it, it’s home to all the life we actually KNOW about in the cosmos.
This image was taken using an instrument called VIIRS (short for Visible Infrared Imaging Radiometer, sensitive to both visible and infrared wavelengths of light) on NASA’s Earth-observing satellite named Suomi NPP. This composite image uses a number of swaths of the Earth’s surface taken on January 4, 2012. Suomi is the first of a new generation of satellites that will observe many facets of our changing Earth — everything from climate to surface variations over time. This is the kind of work that helps us understand the planet we inhabit, and what we’re doing to it. Read more about this image (and get higher resolution versions) at NASA Goddard’s Flickr Site.
January 23, 2012 at 11:16 am | Leave a Comment
Visiting the Helix
One of the often-asked questions astronomers get is “What will happen when the Sun dies?” It’s an obvious concern, since whatever happens to the Sun will affect Earth, but it’s not an immediate concern. The death of the Sun isn’t going to happen for another few billion years yet, so we don’t have to worry about facing it grow larger during its red giant stage and then shrink down to become a tiny ghost of its former brilliance. Many, many generations of humans will live and die on our planet before future astronomers will start to detect the first instabilities that indicate the Sun’s upcoming demise.
There are stars like the Sun out there in space that have already gone through the death process, and so astronomers study them to understand what our star will look like when it finally gets down to the serious business of stardeath. One of the objects they have studied quite a bit is called the Helix Nebula.
The Helix was created as a Sun-like star reached the final stages of its life. It began to lose its outer layers of gas, which you can see in the image above as they expand into space. What’s left of the star appears as a tiny blue dot at the center of shell of material surrounding it. That ring spreads out over an area about four light-years across (almost the distance between the Sun and the nearest star in the Alpha Centauri system. This infrared view shows the extent of the gas cloud.
The nebula is made up of of dust, ionized material and molecular gas. it’s all being heated up by ultraviolet light streaming out from the central star (which is very hot). Notice the details in the cloud—there are clumpy, comet-shaped objects called cometary knots. They aren’t really comets, but they look similar to comets with their tails blowing out in the solar wind. In this case, the knots are strands of molecular hydrogen being shaped by the flow of high-energy radiation streaming out from the dying star. Even though they look small, each is about the size of our solar system.
This, in a nutshell (or a gas shell) is about how our Sun will look billions of years from now. Perhaps our descendants will watch it all unfold from a planet around neighboring star, and take similar pictures with their orbiting space telescopes.
Want to know more about this image. Check out the European Southern Observatory site for more details and an array of downloadable images.
January 20, 2012 at 12:15 pm | 2 Comments
But First, Try to Find It
Did you know that a great many people, particularly in cities, have NEVER seen the Milky Way in the night sky? I suppose you could shrug your shoulders and say, “eh… so what?” Yeah, I suppose it’s not much of a loss if you’re not into stepping outside on a clear, dark night and seeing stars. If you spend your nights indoors, hunched over a computer or parked in front of the TV. If so, you don’t know what you’re missing. And, for the people who haven’t seen the stars much, their loss, too.
Light pollution really sweeps away the view of the sky at night. When I’m in New York City I’m lucky to spot maybe a dozen stars. I know they’re there. But, darned if I can find ‘em. But, lucky for me, I live in a rural area and the stars are a constant reminder of the universe from which we all came.
Seeing the stars at night, particularly the glow of the Milky Way, shouldn’t be a matter of “luck”. It should be an every night (when it isn’t cloudy) occurrence for all of us. But, light pollution has done away with that chance. That’s too bad, because it’s such an easy thing to fix. We don’t need to be shining lights UP into the sky for security. We need to learn to use lights wisely. That means, shining them exactly where we need them, and UP ain’t it. Painting the sky orange doesn’t enhance safety and security. But, using the proper fixtures, using them wisely, and turning off the ones we don’t need: those are HUGE steps toward keeping the night skies dark AND keeping the security we need. Oh, and saving money, too. Lighting up the sky costs money. Light pollution also has health effects, on humans, plants, and animals. In light of all this, it’s about time all of us took responsibility for cleaning up our view of the Milky Way. Occupy it. Make it yours. And make it your neighbor’s. Make it the responsibility of all who light up the sky for no good reason (homes, cities, businesses, anyone who shines lights UP without thinking of the effect it has on wiping out the view of the stars, its role in people’s health, its effect on wildlife, and on our wallets as we pay more money to waste light.
Want to know more? Check out the International Dark Sky Association’s Web page. It is FULL of information about good lighting practices, the effects of light on life, and the costs associated with overlighting our environment. While you’re there, join up and make a contribution to a worthy cause. It’s tax-deductible, if that’s what floats your boat, too. Light pollution isn’t just the concern of astronomers; it’s everyone’s problem and should be treated as such. Occupy the Milky Way!
January 16, 2012 at 21:10 pm | Leave a Comment
The Ever-changing Lights in the Sky
When you go out and look up at the night sky, you see stars. If it’s out, you can see the Moon, and if you know where to look you can also spot planets. Sometimes asteroids flare across the field of view, and occasionally there’s a comet out there. If you’re a frequent skygazer, you already know that the view changes over time. Really avid stargazers also know that stars can vary in their brightness–and those that do are called variable stars. Other stars explode. They flare up into brilliance very quickly, and then fade away. Some time later, if you look at the area of space where the star was, using a good-sized telescope and special instruments, you can spot the remains of the star blasting out into space. Those are called supernovae.
The brightening and dimming of stars actually holds clues to activities and processes in the cosmos that help us understand such things as star birth, star death, the distances to galaxies, and even the expansion rate of the universe. So, it’s no surprise that astronomers want to pay attention to the flickering universe of stars. In particular, astronomers at the California Institute of Technology have been paying attention to the varying levels of light from stars and other celestial objects; in fact, they’ve released data on 200 million of them! One of the scientists is S. George Djorgovski, a professor of astronomy at Caltech and principal investigator on survey of variable objects called the Catalina Real-time Transient Survey. He’s a fellow whose work I’ve admired since I worked on the Griffith Observatory exhibits and his “Big Picture” was a focus of my writing for several weeks. He explained why astronomers survey objects that flicker in the dark. ”Exploring variable objects and transient phenomena like stellar explosions is one of the most vibrant and growing research areas in astrophysics,” he said. ”In many cases, this yields unique information needed to understand these objects.”
The data set includes more than a thousand supernovae, as well as hundreds of so-called cataclysmic variables. These are stars that periodically brighten up in what looks like a catastrophic outburst, only to quiet down after a period of time. The survey also shows pairs of stars in which one spills matter onto another. Such a star is called a white dwarf. There are also tens of thousands of other variable stars; and dwarf novae, which are binary stars that dramatically change in brightness.
The survey takes repeated images of large areas of the sky. By comparing them to previous images, the survey can monitor the brightness of about half-billion objects. This process helps astronomers search out objects that dramatically brighten. Our galaxy–and others–are filled with the flickerings of star life, star death, and everything in between, giving astronomers a treasure trove of data that will help them understand what’s out there.
The CRTS is part of a larger umbrella project called the Catalina Sky Survey, which also searches out near-Earth objects (asteroids that could pose a threat to our planet). They, too, have changing brightnesses, which are clues to their surface features and makeup.
If you want to know more about how astronomers are chasing down the dimmings and brightenings of the sky, check out the Catalina Sky Survey and the news released today about the Transient survey. There are discoveries in those distant flickerings!
January 12, 2012 at 9:25 am | Leave a Comment
The Cosmos in Short Bursts
I just spent most of this week at the American Astronomical Society meeting in Austin, Texas, what I think of as a “tsunami of astronomy”. There were more than 2,500 astronomers in attendance, all talking about everything from solar physics to the physics of the earliest cosmic objects. Many astronomers who gave talks at this conference had only five minutes to tell of their latest and greatest discoveries, plus a few minutes for questions. If they’re smart, they give “poster” papers, where they print out their talks in huge posters and then stand in front of them to talk with anybody who wants to know more about the research. I find the poster approach much more satisfying, especially when it’s been ME who’s been doing the paper. But, then, I like to stand around and talk to people, so that’s probably why I like it.
I was thinking yesterday of what a future AAS meeting would look like if it was held in the virtual world (instead of this meatspace environment) — something like Second Life, but for astronomers. It’s not a new idea, and I’m sure we’re pretty close to it today what with our tweeting and blogging and virtual conference rooms.
Would astronomers talk ab0ut their work by short bursts, much as we do with Tweets today? Or put up virtual posters? Would we have virtual newsrooms where you could virtually walk around and read astronomy papers in bloggy goodness? I suppose if we were all online, we could figure out some way to just directly transfer the news, brain to brain, without the virtual walls of an online astronomy cave. It sure would make the evening’s afterparty an interesting event!
I suppose, even at a virtual event, there’d still be info overload after awhile. And, you would miss the chance to stand around with your colleagues in a noisy ballroom on opening night, eating hors d’oeuvres not to be construed as dinner, getting caught up on the latest, a social event as important as all the science being shared.
I’m still reading through all the materials I picked up and will post a “here’s what I saw and learned” entry later today or tomorrow. I just gotta tell you about the color of the Milky Way and the cute little baby planets, and some of the other things I learned about this week. Stay tuned!
This blog a wholly pwnd subsidiary of Carolyn Collins Petersen, a.k.a. TheSpacewriter.
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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