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Other Objects in the Solar System
Comets
Most comets originate in the Kuiper belt (disc shaped group of millions
of objects orbiting the sun. These small objects are left over from the
formation of the solar system), and the Oort cloud (at the farthest
reach of the sun’s gravitational influence). Every so often a comet gets
too close to Jupiter. Jupiter’s gravitational force will either capture the
comet or nudge the comet to change orbit and enter the inner solar
system. When a comet comes close to the sun, the radiation from the
sun releases the gases and particles in the comet (like a giant fart!). the
wind from the sun pushes the gases and particles away forming a tail.
Asteroids
Are small, non-spherical objects that are debris left over from the
formation of the solar system. Most asteroids orbit the sun in a band,
called the asteroid belt between mars and Jupiter. Asteroids range in
size from a tiny speck (picture a grain of sand) to about 500 km wide!!!
An object called Ceres (Which is 1000 km wide) is in the asteroid belt.
Ceres has recently been promoted to the status of dwarf planet (like
Pluto). Some asteroids even have their own moon.
Meteoroids, Meteors, Meteorites
Meteoroids are pieces of rock moving through space. Astronomers
think that meteoroids are rocky chunks that have broken off asteroids
and planets. When they collide with the Earth’s atmosphere, they burn
up due to the friction they encounter, forming meteos. Meteor showers
result from the earth passing through an area where there is a lot of
excess material, such as debris left over from a comet, a meteor shower
results. The most famous meteor shower is the Perseid meteor shower,
which occurs on August 12 each year.
Some people call meteors ‘shooting stars’. But they are not stars at all.
They are meteoroids colliding with the earth’s atmosphere. Meteoroids
that survive the impact and reach the ground are called meteorites.
Scientists estimate that 100 000 tonnes of material reach the earth’s
surface each year.
Impacts
An asteroid about the size of a mountain struck earth 65 million years
ago. As a result, there were catastrophic changes to the Earth’s
atmosphere. Some scientists think these changes were responsible for
global mass extinction of thousands of species, including the dinssaurs.
There are many impact craters on earth, and a lot of them are in North
America. About 39 million years ago, an object about 2 km hit Devon
Island, Nunavut. It left the crater known as Haughton Crater. More
recently, about 40000-50000 years ago, a huge impact produced the
Barringer Meteorite Crater in Arizona. This impact produced an
explosion with energy that was equivalent to 1000 atomic bombs. It
destroyed everything within a 10 km radius. In 1908 Tunguska, Siberia
an object impacted as destroyed an area of 2000 km2 (about the size of
Kingston Ontario). The object flattened nearly 100 million trees and
killed 10’s of thousands of forest animals including several large herds
of reindeer (poor Santa).