Today’s class assignment is about Asteroids
Asteroids are relatively small rocky metallic objects that orbit the sun.
In the Earth Solar System, you’ll find many asteroids between the planets called Mars and Jupiter in an area called the main asteroid belt. There is a popular hypothesis that this belt was created from leftover matter that never formed a planet since the formation of the solar system.
Gravity keeps the asteroids in orbit around the sun, but the asteroid belt that we see today is only a tiny fraction of what used to exist. It’s predominately empty space now. The gravitational fields of Mars and Jupiter, as well as collisions within the belt, also have an effect on the orbital paths of asteroids and can lead to their expulsion from the main belt.
Five key asteroid facts
- The only asteroid in the main belt visible to the naked eye is Vesta, which has a mean diameter of 530km and contains nine per cent of the entire asteroid belt’s mass.
- The way comets and asteroids are distinguished relies on visual appearance, with comets displaying a perceptible coma behind them while asteroids have none.
- Once an asteroid has been discovered it can only be named under the consultation of the International Astronomical Union, who will approve or disapprove the proposition.
- The first true asteroids to be photographed close up were Gaspra in 1991 and Ida in 1993. They were imaged by the Galileo space probe en route to Jupiter.
- One of the latest asteroids to be landed on is called ‘Itokawa’. It is a S-type asteroid that crosses the path of Mars. The Hayabusa space probe returned to Earth with a surface sample.
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