1The Great Icy Travelers
Comets are some of the oldest objects in our solar system, often called "dirty snowballs" because they are made of frozen gases, rocks, and dust. Most of these icy wanderers live in the freezing outer edges of the solar system, far beyond the planet Neptune in areas called the Kuiper Belt and the Oort Cloud. While the center of a comet, called the nucleus, might only be the size of a small town (around 10 to 15 kilometers wide), it carries enough ice to create a spectacle that can be seen across the night sky. As they orbit the Sun, they spend most of their time frozen solid, but everything changes when their path brings them into the inner solar system.
2Why Do Comets Have Tails?
As a comet gets closer to the Sun, it begins to warm up rapidly. This heat causes the ice to turn directly into gas through a process called sublimation. This gas and dust escape the comet, forming a giant glowing cloud called a coma that can be larger than the planet Jupiter! The Sun's light and a stream of particles called the solar wind then push this material away, creating two distinct tails. The dust tail is usually curved and white, made of tiny particles reflecting sunlight. The ion tail is straight and often glows blue because it is made of electrified gas molecules interacting with the Sun’s energy.
3Millions of Kilometers Long
Even though the solid part of a comet is small, its tail can stretch for over 100 million kilometers! That is long enough to reach from the Earth almost all the way to the Sun. Interestingly, because the Sun’s solar wind is always blowing outward, a comet’s tail always points away from the Sun, no matter which direction the comet is flying. This means that when a comet is traveling away from the Sun, it is actually following its own tail! These beautiful visitors remind us how much the Sun’s energy affects everything in our cosmic neighborhood.
