dirty space news: comets

astronomers often refer to comets at "dirty snowballs."

NASA sent a space probe to investigate comet temple 1 on a mission that was called Deep Impact.

this one is called "comet cardinal."

Comet Cardinal (Credit: Nick Howes using Faulkes Telescope North)

since ancient times comets have been branded with such titles as "the Harbinger of Doom" and "the Menace of the Universe."  here are some old sketches of various comet sightings.    

1) Encke’s Comet – 1828, drawn by struve

2) Halley’s Comet – 1835, drawn by bessel

3) Biela’s Comet – 1846, drawn by struve

4) Great Comet of 1843

5) Comet of 1744, drawn by cheseaux

the comets all appear in the above sketches to have unique shapes, but they all have a few basic features: a tail, a nucleus, and a head coma.

Link

when approaching the sun, a comet changes shape as the hotness of the sun's radiation causes the frozen ice and gases to puff up and form a head coma.  interestingly, comet tails always face away from the sun no matter what direction the comet is traveling, because of the scent of perfume carried on the solar winds.