In Their Wake Hitching a ride on a comet may be like latching onto a bus's tailpipe, a recent Arizona State University study found. The heart of a comet is its nucleus, a dirty snowball a few kilometers in size that sheds gas and dust when heated by the Sun.
Comets generally have two tails, a dust and a gas tail.
Surprisingly, according to the ASU study, they're not. The ASU team, including Wyckoff, computer specialist Rodney Heyd and undergraduate student Rebecca Fox, explain that the lack of water ions in comet tails is due largely to the relatively fragile nature of water molecules compared with carbon monoxide molecules when exposed to sunlight. According to Wyckoff, survivability is the key factor that can explain the observations. Ultraviolet sunlight is very energetic and can break chemical bonds. Because the bond strength of carbon monoxide is much greater than that of water, carbon monoxide can survive this trip much better than water can.