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LITTLE VAGABONDS FLYING THROUGH SPACE 
When you think about comets and asteroids it's almost like looking at
little planets and suns, except that they are flying through space. Comets
are small balls of ice and dirt that fly through solar systems in long,
wild orbits. Comets are created when a solar system is developing. You
may know that planets move in elliptical orbits around their sun. Comets
move in narrow and stretched out ellipses, sometimes crossing the orbits
of several planets in their trip around the sun. Comets also have tails.
Those tails are streams of gas and dust that follow the comets for thousands
of miles. Comets aren't really on fire. The light you see is reflected
light from the Sun. The light is reflected off of the gases, ice, dirt
and dust that travel with the comet.COLD AND SPINNING Asteroids are different from comets. They are like small pieces of planets. Some asteroids that orbit planets are even considered moons. One of the moons of Mars (Deimos) is only 4 miles across. In our solar system you will find asteroids orbiting the Sun in a regular orbit (unlike comets that long stretched orbits). There is an Asteroid Belt between the orbits of Mars and Jupiter. They are just small pieces of rock that spin around the sun in a specific orbit, almost like a planet that never formed. Pieces spinning through space. IS ONE COMING FOR US? Chances are the Earth doesn't have to worry about a collision with a comet. Asteroids are another matter. Scientists already think that an asteroid/comet hit the Earth when the dinosaurs were alive. That collision changed our atmosphere and probably led to the extinction of the dinosaurs. We just told you about that asteroid belt just outside Mars' orbit. There may come a day when one of those asteroids drops out of orbit (maybe from a collision with another asteroid) and heads toward Earth. ABOUT THE PICTURE This is a photograph of an asteroid found near Jupiter. |