Comet McNaught from STEREO
Author: Tom
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Comments(3)
A few days ago on January 11, 2007, one of the STEREO spacecraft took this image of Comet McNaught. It was the first of the pictures to come from the Hemispheric Imagers just turned on that day.
The tail is to the left, and the vertical bright line was caused by the nucleus being so bright it saturated the detector.
I did manage to see the comet, then our weather turned normal and clouded over. Ok sort of normal, we are getting the same freezing rain that many people endured over the weekend.
Credit: NASA
[...] I mentioned a bit about comet tails both in my Comet McNaught update, and even more in the post immediately prior to this one. Basically, there are two types of tails, the Type I ion, or gas, tail, and the Type II dust tail. The ion tail is typically bluish, and it is carried almost straight outward away from the Sun by the solar wind. But, the dust tail is a bit more complicated. It is pushed outward by light pressure. When the dust shed by outgassing of the nucleus of the comet, it forms a cloud around the nucleus. Most people don’t realize it, but light can actually push on things. So, the light from the Sun is able to push the tiny dust grains outward. But, these dust grains are still orbiting the Sun. So, a push outward causes them to be pushed into farther orbits. The farther an orbit is from the Sun, the slower it moves. So, these dust grains lag ever so slightly behind the nucleus of the comet. The farther they are pushed, the more they lag, so the tail gently sweeps backward, though still largely pointing away from the Sun. The result is a bifurcated tail, one bluish Type I and one yellowish Type II. Tom has posted an image on his site taken from the STEREO spacecraft showing the two tails. I’ve included a (not particularly well drawn) diagram to show this. [...]
[...] “Comet McNaught from STEREO“, no Tom’s Astronomy Blog. O cometa do momento visto pelo STEREO, um dos mais recentes satélites de observação solar. Ainda sobre este tema, “Comet McNaught now very brightly“, no Astroprof’s Page. [...]
Will Comet McNaught happen in 2008/