Yearly Archives: 2012

astronomy, astronomy research, Helix Nebula, Infrared astronomy, planetary nebulae, star death, stars, stellar evolution

Staring into the Eye of Star Death

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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.

ESO’s VISTA telescope, at the Paranal Observatory in Chile, has captured a striking new image of the Helix Nebula. This picture, taken in infrared light, reveals strands of cold nebular gas that are invisible in images taken in visible light, as well as bringing to light a rich background of stars and galaxies.

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.

International Dark-Sky Association, light pollution

Occupy the Milky Way!

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But First, Try to Find It

Empire State Building at night. Picture taken in October 2004 by Charliebrown7034

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.

The Milky Way as it should be seen. Courtesy European Southern Observatory.

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!