Debris left over from the formation of the Solar System
Aside from the LARGE bodies that are known to reside in the Solar system
(the nine planets and the MANY moons), there is a large amount of junk
out there. Most of it is material that is left over from the formation
of the other larger bodies, and comes in the form of meteoroids, asteroids,
and comets.
Meteoroids
Note: Meteoroids and asteroids are
Some Terminology
What do we learn from meteorites?
Are they dangerous?
What is a Meteor Shower and what causes one?
Asteroids
Asteroids are also rocky objects, but are larger than meteroids, they tend
to be found in two places in the solar system: (Why?)
However, some asteroids can be found just about everywhere in the solar
system - some are NEAr.
Comets
A few times every decade an object appears in our sky that is bright and
might have a long tail. For a few weeks it will slowly move against the
background of "fixed stars" and then disappear. These are comets.
Major misconception:
What is a Comet? Quite simply, it is
What happens when this chunk of rock and ice gets close to the Sun?
Where do all of these dirty snowballs come from?
It is believed that during the formation of the Solar System that there
were billions and billions (don't you dare call me Carl!) of these
bodies in the solar nebula. Those that were not accreted into planets or
moons would sooner or later be perturbed by close encounters with the Jovian
planets into long period orbits or ejected from the Solar System altogether.
The bodies with long period orbits would slowly have their orbital perihelion
raised, so today we think that there is a cloud of comets known as the
Oort Cloud
In addition to the Oort Cloud, it is also believed that material in the
solar nebula beyond the orbit of Neptune did not form into planets. These
objects are still there, and have become known as the Kuiper belt. Several
of these have been directly observed.
Where do Short Period comets that we see on Earth (like Halley's, Hyakutake,
and Hale-Bopp) originate?
What will eventually happen to all short period comets?
Impacts
Could an asteroid or a comet ever hit the Earth or another planet?
We know from the cratering on the Moon and other worlds that impacts were
quite common in the past; does it still happen?
A necessary condition for an object to collide with the Earth is:
In a collision, how much energy is released?
Consequences of an impact with the Earth:
Does this really happen to planets . . . or is it just the wild imagination
of astronomers?
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