N - O Rocky object which passes close to the Earth. Most, if not
all, seem to have originated in the main asteroid belt. Their
Earth-approaching orbits are the result of collisions with other
asteroids or the gravitational influence of Jupiter. Many
thousands of asteroids inhabit the inner Solar System. The main
groups are the Amors, which travel between the Earth and Mars;
the Apollos, which cross Earth's orbit; and the Atens, which
stay mainly inside Earth's orbit. Occasionally, one of these
objects will collide with the Earth, creating a large impact
crater and possibly causing mass extinction of life forms. Cloud
of dust and gas in space. At more than 30 AU from the Sun,
Neptune is the eighth planet away from our star. It is one of
the gas giants and has a dense atmosphere consisting mainly of
hydrogen. Average surface temperature is 58 K. A fundamental
particle which has no electric charge and hardly interacts with
matter. Thus it is very elusive and difficult to detect.
Neutrinos only have a small mass