Asteroids are small, rocky objects that orbit the sun. Although asteroids orbit the sun like planets, they are much smaller than planets. There are lots of asteroids in our solar system. Most of them live in the main asteroid belt—a region between the orbits of Mars and Jupiter. Asteroids hang out in other places, too. For example, some asteroids are found in the orbital path of planets. This means that the asteroid and the planet follow the same path around the sun.
DISCOVERY OF ASTEROIDS.
In 1801, Giuseppe Piazzi discovered what he believed to be a new planet. He named the newfound object, after the Roman goddess of the harvest. Soon after Ceres’ discovery similar objects were found. It was soon realized that these new objects were not, in fact, planets, but some other type of celestial body. One characteristic these objects shared was their resemblance to distant stars as viewed through the telescopes of the time. As a result of their similar appearance to stars the objects were named asteroids, meaning “star shaped.”
Facts and Information About Asteroids
Asteroids are rocky worlds revolving around the sun that are too small to be called planets. They are also known as planetoids or minor planets. There are millions of asteroids, ranging in size from hundreds of miles to several feet across. In total, the mass of all the asteroids is less than that of Earth’s moon.
Despite their size, asteroids can be dangerous. Many have hit Earth in the past, and more will crash into our planet in the future. That’s one reason scientists study asteroids and are eager to learn more about their numbers, orbits and physical characteristics. If an asteroid is headed our way, we want to know that.
Asteroids are clues to the formation of the rocky planets of our solar system. The objects we see today are leftover from a time when the solar system formed 4.5 billion years ago. There are a LOT of these leftovers out there. Let’s learn some cool facts about them.
- Asteroids aren’t the only things that hit Earth. Each day, more than 100 tons of material from asteroids and comets falls toward Earth. Most of it is destroyed by friction as it passes through our atmosphere. If something DOES hit the ground, it is known as a meteorite.
- While asteroid impacts were more common in the past, they aren’t as frequent today.
- An asteroid impact some 65 million years ago contributed to the extinction of the dinosaurs. (It was one of several factors that affected all life on Earth at that time.)
- Earth suffers an impact from an object the size of a football field about once every 2,000 years.
- A car-sized meteoroid (a piece of asteroid) falls into Earth’s atmosphere about once a year. The result is a beautiful fireball, but the meteoroid usually burns up before reaching the ground.
- Asteroids are rich in precious metals and other metals, as well as water.
- Some asteroids are actually blown-out comets. The ices are gone, and all that’s left is the rocky material.
- Some asteroids have moons of their own!
- Most asteroids orbit the Sun in the Asteroid Belt, which lies between Mars and Jupiter.
Asteroids are also referred to as minor planets or planetoids.