i’m a yellow body
After taking five past PHYS 212 (Electricity & Magnetism) exams and scoring 10-20 points above average on each exam, you would think that you're ready for the real thing. Apparently not. Regardless, I do expect an above average score.
That aside, yesterday NASA released their first four infrared images taken by the Wide-field Infrared Survey Explorer (WISE). Needless to say, they're amazing. According to the news release, since it began its survey of the sky in infrared on January 14th, over a quarter-million images have been obtained. WISE has about eight more months before its ten month-long mission ends, but after the survey, an initial batch of data will be made public in the spring of 2011, while the complete catalog will be made public in 2012.
Siding Spring
While it's not the most brilliant or breath-taking of the four photos, I find the photo on the right the most interesting. It's a photo of a comet named Siding Spring, which was discovered in August 25, 2007 by D. M. Burton. It's not necessarily the picture itself that blows me away, but it's the fact that Siding Spring's tail is about a staggering sixteen-million miles long. Sure, this is only about a tenth of the distance from Earth to the sun, but consider the size of a comet. I couldn't find the diameter of Siding Spring, but most comets are about 16 kilometers or less in diameter. Assuming that Siding Spring is of that diameter, that means the trail it left behind is a million times longer than the actual diameter of the comet itself. I think that's insane.
The closest Siding Springs ever got to Earth was about 180 million kilometers away, which was about when this photo was taken. The image was artificially colored so that the light measured at 22 microns was colored red. The comet being red in the image means that according to Wien's displacement law, the comet is roughly 132 degrees Kelvin in temperature, which is -141 degrees Celsius. That may seem very cold, yet it's warm enough to vaporize volatile substances within the comet. As these vapors escape, dust is carried away as well, and coupling this with solar wind and radiation pressure, you get two tails: the dust tail like a vector marking the trajectory of the comet, and the gas tail pointing away from the sun.
Sorry for this random splurge of information, but I really do find astronomy to be one of the most fascinating sciences. Even so, I can't help but think that being hundreds of millions of kilometers away and now cruising away from Earth at a sickening speed... well, it has to be a bit lonely out there.