This is an illustration of the Chicxulub impact.
Click on image for full size
The Collisional Ejection Theory
Currently, the theory that best explains all the evidence
collisional ejection theory. This theory holds that the Moon formed
from debris ejected from the Earth when a large object (possibly as
large as Mars) crashed into the Earth. Simulations of this scenario
show that energy from such a collision produces a stream of vaporized
rock from the impact. The Moon forms from this cooled material.
This theory explains many of the known properties of the Moon's orbit
and composition. The ejected material would have coalesced in or near
the ecliptic plane, putting the Moon into an orbit much like the one
it has. The Moon, which is believed to have a small iron core, could
have retained this core through the collision. Volatile elements
would have been vaporized during the impact. Also, this collision
could have tipped the Earth's axis, causing the seasons we now know.
The problem with this theory is that it does not seem very likely, although objections to the theory based on considerations of the angular momentum between the two objects have been resolved in recent computer models.
Shop Windows to the Universe Science Store!
Our online store
includes issues of NESTA's quarterly journal, The Earth Scientist
, full of classroom activities on different topics in Earth and space science, as well as books
on science education!
You might also be interested in:
An element (also called a "chemical element") is a substance made up entirely of atoms having the same atomic number; that is, all of the atoms have the same number of protons. Hydrogen, helium, oxygen,...more
Charon is by far the largest of Pluto's // Call the moon count function defined in the document head print_moon_count('pluto'); known moons. Charon was discovered by the American astronomer James Christy...more
The co-formation theory explains the origin of the moon as an object which formed out of the primitive solar nebula at the same time and roughly the same place as the Earth. As shown in this picture, while...more
In decades past it was accepted that moons such as the Earth's moon or the moons of Jupiter were airless bodies with no atmosphere whatsoever. Now, however, measurements have shown that most of these moons...more
Unlike the Earth, which has a protective shield around it called the magnetosphere, the surface of the moon is not protected from the solar wind. This picture shows the magnetosphere surrounding the Earth,...more
You may have heard people refer to a Full Moon in the autumn as the "Harvest Moon" or the "Hunter's Moon". Native Americans in the eastern and northern parts of North America had special names for the...more
Altocumulus clouds (weather symbol - Ac), are made primarily of liquid water and have a thickness of 1 km. They are part of the Middle Cloud group (2000-7000m up). They are grayish-white with one part...more