Share an Eclipse Online!



October 26, 2004 at 12:45 pm | Leave a Comment

I thought I’d lend my “space” here to my friend Kelly Beatty from Sky & Telescope Magazine. For the past 20 years or so a bunch of us have been meeting on Sunday afternoon/evenings on Compuserve’s Astronomy Forum to chat about astronomy and other such topics. On Wednesday October 27 there will be a lunar eclipse, and we’re inviting everybody who’s got a good view of the eclipse to log in to the forum (it’s open to those with CIS, AOL, and AIM accounts) and share their observations with others! Here’s Kelly’s invite:

I invite everyone to join us in the Chat Room of Compuserve’s
Astronomy Forum on Wednesday night, Oct. 27th, to talk about the total
lunar eclipse as it’s happening (it’s a real-time exchange — no time
lag!!). This’ll be a great chance to describe what you’re seeing and
to learn how it looks to others. These kinds of visual observations
can actually be valuable for post-eclipse analyses.

Tentatively, the chat will start at 10 p.m. EDT (7 p.m. PDT) — I
might be there a few minutes earlier or later, depending on how the
weather is here in Boston and on how the Red Sox are doing in Game 4.

To get to the Astronomy Forum, go to
http://community.compuserve.com/astronomy. To join the chat you’ll
need to login with an AOL, CompuServe, or AIM account. Use the login
button at upper right on the Forum’s home page. (I’m told that AIM
accounts are free.)

I hope to “see” you there on Wednesday!

clear skies,
Kelly

P.S. For times and other background info on the eclipse, see the
messages posted in the Astronomy Forum or go to the observing section
of SkyandTelescope.com





Recipe for a Planet



October 19, 2004 at 22:27 pm | Leave a Comment

Did you ever stand outside looking up at the stars, and then down at the ground, and then wonder to yourself, “How did this planet come into being?”

Of course we all know the standard “theory” about how planets are formed—a star begins to coalesce out of a cloud of gas and dust. Over millions of years this action goes on until things get hot enough in the center to turn on the nuclear furnace that stokes the burning “machine” we call a star. The leftovers are where planets come into being. There’s LOTS of stuff left over after a star forms— grains of dust and chunks of ice and clouds of gases and so on. The ice and clouds nearest the star are pretty much “burned off” by the heat from the newborn stellar creation, but the rocks and dust grains stick around. In fact, they start to stick together. IF this goes on for long enough you get bigger and bigger “hunks” of stuff out there trundling around the stars. Eventually these hunks form worlds.

Courtesy The Spitzer Space Telescope

Courtesy the Spitzer Space Telescope

That’s the “potted” history of planetary formation. But, how do we observe this going on in other stellar systems today? The Spitzer Space Telescope has just released some observations that reveal large dust clouds around several stars. They likely formed when rocky, embryonic planet “seeds” crashed together, sending debris flying out through space.

It’s a chaotic scenario, but a plausible one. And, the scientists using Spitzer are looking for such dusty disks around many nearby stars to see just where collisions are affecting planetary formation in the neighborhood. Before Spitzer, only a few dozen planet-forming discs had been observed around stars older than a few million years. Spitzer’s uniquely sensitive infrared vision allows it to sense the dim heat from thousands of discs of various ages.

So, the next time you find yourself out there gazing at the stars and marveling at their seeming serenity, remember this: it’s not all as serene as you think. Somewhere around a newborn star is a scene of remarkable chaos. And born out of that chaos in a few million or billion years might be another Earth, and maybe another being to gaze skyward and wonder what’s happening “out there.”





Remote Sensing the Earth’s Surface



October 14, 2004 at 21:13 pm | Leave a Comment
A satellite view of Mount St. Helens volcano sending out a steam and ash plume. Taken at 1 p.m. EDT on Oct. 5, 2004, about an hour after being released by the volcano. Courtesy NOAA.

A satellite view of Mount St. Helens volcano sending out a steam and ash plume. Taken at 1 p.m. EDT on Oct. 5, 2004, about an hour after being released by the volcano. Courtesy NOAA.

We don’t always think of our home planet as a target for space exploration, but of course it is. Satellites lofted into orbit by the National Oceanic and Atmospheric Administration give us near-constant views of the Earth’s surface and its weather. Most of us are familiar with the weather sats that give us our daily, weekly, and monthly forecasts, so it’s not a big stretch to think of those types of instruments sensing things like volcanic eruptions or other changes on the Earth’s surface.

Mt. St. Helens, the volcano in Washington state, is putting on quite a show. You can, if you want to watch it all day long, open up a webcam view of the mountain, taken from an observation post about 5 miles way from the summit of the mountain. If you’re really into it, open up NOAA’s eye in the sky and follow the action from geosynchronous orbit.

It’s kind of cool to think that while we monitor Mars using the rovers and orbiters, we can do the same at Earth, using near-real-time satellite imagery and in-situ cameras on the ground.





Viewing A Supernova Using Celestial Eyes



October 7, 2004 at 11:28 am | Leave a Comment
Courtesy Space Telescope Science Institute, Chandra X-Ray Center,Spitzer Space Telescope

Courtesy Space Telescope Science Institute, Chandra X-Ray Center,Spitzer Space Telescope

A somewhat drab-looking object in optical telescopes is all that’s left of a supernova that flared in 1604 and dubbed “Kepler’s Supernova.” However, the optical view of the universe only shows us a tiny part of this object’s story. The Chandra X-Ray Observatory, the Spitzer Space Telescope, and the Hubble Space Telescope show how the catastrophic death of a star looks in visible, x-ray, and infrared wavelengths of light. Here the story the three observatories are telling:

The combined image unveils a bubble-shaped shroud of gas and dust that is 14 light-years wide and is expanding at 4 million miles per hour (2,000 kilometers per second). Observations from each telescope highlight distinct features of the supernova remnant, a fast-moving shell of iron-rich material from the exploded star, surrounded by an expanding shock wave that is sweeping up interstellar gas and dust.

Each color in this image represents a different region of the electromagnetic spectrum, from X-rays to infrared light. These diverse colors are shown in the panel of photographs below the composite image. The X-ray and infrared data cannot be seen with the human eye. By color-coding those data and combining them with Hubble’s visible-light view, astronomers are presenting a more complete picture of the supernova remnant.

Visible-light images from the Hubble telescope’s Advanced Camera for Surveys [colored yellow] reveal where the supernova shock wave is slamming into the densest regions of surrounding gas.

The bright glowing knots are dense clumps from instabilities that form behind the shock wave. The Hubble data also show thin filaments of gas that look like rippled sheets seen edge-on. These filaments reveal where the shock wave is encountering lower-density, more uniform interstellar material.

The Spitzer telescope shows microscopic dust particles [colored red] that have been heated by the supernova shock wave. The dust re-radiates the shock wave’s energy as infrared light. The Spitzer data are brightest in the regions surrounding those seen in detail by the Hubble telescope.

The Chandra X-ray data show regions of very hot gas, and extremely high-energy particles. The hottest gas (higher-energy X-rays, colored blue) is located primarily in the regions directly behind the shock front. These regions also show up in the Hubble observations, and also align with the faint rim of glowing material seen in the Spitzer data. The X-rays from the region on the lower left (colored blue) may be dominated by extremely high-energy electrons that were produced by the shock wave and are radiating at radio through X-ray wavelengths as they spiral in the intensified magnetic field behind the shock front. Cooler X-ray gas (lower-energy X-rays, colored green) resides in a thick interior shell and marks the location of heated material expelled from the exploded star.

Kepler’s supernova, the last such object seen to explode in our Milky Way galaxy, resides about 13,000 light-years away in the constellation Ophiuchus.





Will You Ever See This?



October 5, 2004 at 12:42 pm | Leave a Comment

A view from a height

Many of us dream of the day we can see this sight for ourselves—the curve of Earth’s surface falling away from us as we ride a rocket ship into space. Spaceship One did it yesterday, and here’s the view. Heady isn’t it?





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Image of Horsehead Nebula: T.A.Rector (NOAO/AURA/NSF) and Hubble Heritage Team (STScI/AURA/NASA)

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