SCIENCE Everything you wanted to know about comets Add to ...


CP Video |
Show Description
Stargazers have been eagerly observing comet ISON as it travels near earth. But what is a comet? York University physics and astronomy professor Paul Delaney says comets can be compared to a "dirty snowball."

More from this section

Most Popular

Editor's Picks

Globe Shows »

Put your best foot forward with our expert advice