Earth is not alone in the universe! Even though the objects out
there are a long ways away, they still affect us. The Sun is 93
million miles away, but it still provides the light plants need
in order to grow. The Sun also provides the heat that keep the surface
of Earth warm. If we didn't have heat and light from the Sun, we
would all quickly become part of the cryosphere.
Yuk! Not a pleasant thought!
Sometimes we get visitors
from the exosphere such as comet dust (which makes the meteors we
see at night) and meteorites (which we see in museums). Very occasionally
we get unwelcome visitors such as asteroids and comet heads that
explode in the atmosphere or hit the ground and explode to make
huge craters and change Earth's climate. Many people think that
65 million years ago one of these giant impacts caused
the dinosaurs to become extinct.