In addition to the nucleus and the tail, what's the third main part of a comet?
And the answer: the coma.
When passing close to the sun, a comet warms up and begins to release gases. This produces a visible dusty cloud, known as the "coma," which surrounds the nucleus. The comet's tail extends from the comet and points away from the sun.
Comets have lit up night sky for thousands of years, but it has only been in the past few centuries that they have begun to be studied as astronomical phenomena. Up until the 16th century, comets were considered bad omens and harbingers of hard times. Often they were seen as divine forces or intervention. The oldest image of a comet ever recorded is that of Halley's Comet in 1483.
Currently, there are over 3,000 known comets in our solar system. Scientists believe that the actual number runs much higher– around one billion in our solar system alone!
Comets are sometimes referred to as "dirty snowballs" or "cosmic snowballs" because they're made up of mainly ice, rock, gas and dust. In other words, they're set to form the world's most intense snowball fight.