Shooting stars and meteor showers
Interplanetary space and the
solar wind |
Meteors are pieces of stray extraterrestrial rock, sometimes with
a high proportion of metals like iron, that enter the Earth's atmosphere.
Meteorites are the remnants of meteors that actually hit the Earth. Meteors
or meteorites come from a variety of sources and are best described as
bits of planetary debris as well as stray asteroids.
Mars is source of meteor material; in fact, a dog was killed by a meteor
in Alexandria, Egypt, in 1911, by what is now believed to be a piece of
Mars rock. It has been calculated that thousands of tonnes of Martian
rock and dust fall on Earth each year, this massive quantity of debris
floating in space is due to rock having been blasted from the surface
of Mars by asteroid impacts occurring over the past few million years.
A similar amount of material from Earth may also be colliding with Mars
each year, and some scientists have theorised that this may be a way that
life could "jump" from one planet to another in the form of
rock dwelling bacteria.
Shooting stars and meteor showers
Shooting stars are small dust particles entering the Earth's atmosphere
and burning up as they shoot across the sky. The material that forms shooting
stars is generally dust from passing comets which has spread out into
space, and gone into orbit around the Sun. When the Earth passes through
one of these comet dust orbits, a meteor shower occurs. For a short period
of time tens to hundreds of shooting stars may be seen in the night sky
each hour as the dust grains strike the upper atmosphere of the Earth.
Although random meteors can be observed nightly, they occur at a much
higher rate during a meteor shower. It has been calculated that the Earth
is showered with 400 tons of asteroid and cometary material daily!
Interplanetary space and the solar
wind
Besides the leftovers from comets, meteors, and asteroids, the space within
the Solar System contains protons, electrons, and ions all streaming outward
from the Sun in the form of the solar wind. Giant flares or sunspots on
the Sun's surface expel matter, along with light and other high-energy
radiation, that contribute to this interplanetary medium.
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The solar wind |
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