Stars and stripes in space
Posted: Thursday, July 03, 2008 3:22 PM by Alan Boyle
NASA / ESA / STScI / JHU
A twisting ribbon of glowing gas marks the point where the expanding blast wave
from a stellar explosion known as SN 1006 is sweeping through.
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Two of NASA's Great Observatories present a red-white-and-blue example of cosmic stars and stripes, just in time for the Fourth of July.
The focus of all this patriotic fervor is a stellar explosion whose first flash was seen centuries before the United States was a twinkle in the Founding Fathers' eyes: The supernova remnant SN 1006 represents what's left over from a blast witnessed by observers from Africa to Europe to the Far East in the year 1006.
The star that blew up was 7,000 light-years away in the constellation Lupus. Scientists speculate that it was the brightest observed supernova in recorded history, blazing with a light that could be seen in the daytime sky for weeks afterward. (Other supernovae may have been intrinsically brighter, but we're talking about how they were seen on Earth.)
The supernova sent out a shock wave that expanded at an average rate of nearly 20 million mph. In the 1960s, radio astronomers first detected the ring of material that was pushed out by that wave. Since then, telescopes have done even better, charting the edge of the shock wave in multiple wavelengths.
As the wave moves out, it lights up the thin hydrogen gas surrounding the star - and that rippling glow is what's chronicled in the latest imagery released by the Hubble Space Telescope's science team. A close-up view of the wave front looks like a gossamer red stripe with starlight shining through it.
If you compare the stripe's position with a picture taken a decade ago from the Cerro Tololo Inter-American Observatory, you'll see that the wave is continuing to move outward at about 6 million mph. For an extra treat, check out the zoomable version of the Hubble view.
NRAO / NASA / CXC / Rutgers / Middlebury / NOAO |
This composite image combines visible-light, radio and X-ray data for the full shell of the supernova remnant from SN 1006. The small green box along the bright filament at the top of the image corresponds to the dimensions of the Hubble release image. Click on the image for a larger version.
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The full picture of the supernova remnant has been filled out with data from NASA's Chandra X-Ray Observatory (another one of NASA's Great Observatories), Cerro Tololo, the Digitized Sky Survey and the National Radio Astronomy Observatory. The colors may evoke flags and fireworks, but they don't reflect how the supernova would look to the naked eye. In this case, they're just being used to distinguish the different wavelengths that went into the picture.
Speaking of the naked eye, there's plenty to see in the sky on the Fourth of July - and we're not just talking about fireworks: Science @ NASA shows you how to spot a great grouping of Saturn, Mars and the moon in western skies this weekend, with the bright star Regulus in a supporting role. Consider it a warmup act for the Saturn-Mars close encounter on July 10.
If you're a morning person (as in, um, 4 a.m. or so), you can watch for the international space station passing overhead this weekend: NASA's real-time satellite tracking site can tell you exactly when the orbital outpost will be visible.
If you're really lucky (and early), you'll catch a glimpse of Comet Boattini. Tony Flanders sizes up the comet for Sky & Telescope. "Few people are likely to see the comet without optical aid, but it should be pretty easy to spot through binoculars as long as your light pollution isn't too bad," he writes. Check out the detailed viewing chart.
Looking ahead, we're starting to get into the summer season for meteor observing. After this weekend's fireworks, keep an eye on the skies for stray shooting stars. A couple of meteor-watchers have noticed stronger-than-expected activity over the past couple of nights. The Delta Aquarids are due to heat up later this month, and the Perseids will hit their peak on Aug. 12. Now there's a fireworks show worth waiting for.
For more online fireworks, check out the Spitzer Space Telescope's view of the Fireworks Galaxy, Hubble's view of the Coma Cluster, and our "Month in Space" roundup of cosmic imagery.
