Let's Get Together
If the blob of stuff gets big
it forms a sphere or ball. The center of gravity of the sphere is in
middle. Everything is being pulled towards the very center of the
If enough material is pulled toward the center, the weight of the outer
crush the inner parts and cause the atoms to fuse, or join together to
newer, more complex atoms. This process is called fusion.
What About the Leftovers?
Whatever parts are not used to
make the new atom are released as heat and light energy. Whenever atoms
fused or split, they release a lot of energy. That is how atom bombs
That is also how stars works. Stars are not on fire in space, they are
having nuclear explosions. This is what makes them shine.
Here Comes the Sun
Sun formed from a nebula in this region of space, it gobbled up
nearly all of the material for itself. The key word here is “nearly”,
means that some material was left over after the Sun was created.
if the mass of the solar system was converted into one dollar, the Sun
be worth more than 99 cents, and all the planets, moons, asteroids and
put together would total less than one penny!
As the Sun shines, it generates what
is called a solar wind. It is not wind as we know it where air moves
– because there is no air in space. It is a flow of energy outward from
Sun that acts like a wind and pushs things outward.
When the Sun grew large enough and started shining through nuclear
the solar wind it created blew the remaining nebular material outward.
planets, moons asteroids and comets condensed from this leftover
in much the same way that the Sun formed – from gravitational
pulling nearby available material together. Heavier elements remained
to the Sun and lighter elements were blown further out.
Density of the Planets
This explains why the inner planets of Mercury, Venus,
Earth and Mars are
dense, rocky planets and the outer planets of Jupiter, Saturn, Uranus
by the way, is properly pronounced ’YUR-uh-nis’) and Neptune are gas
Pluto, while still called a planet, resembles more closely the body of
being classified as Kuiper Belt Objects. These distant objects are more
giant comets and are apparently made of materials light enough to be
out past Neptune’s orbit.
This image shows the newly
discovered planet-like object, "Sedna," in relation to other bodies in
solar system, including Earth and its Moon; Pluto; and Quaoar, a
beyond Pluto that was until now the largest known object beyond Pluto.
is bigger than an asteriod, but smaller than a planet. It is three
farther away from Earth than Pluto and is the reddest object in the
System, after Mars.
picture is the more recently discovered "tenth planet", 2003ub313, that
estimated to be larger than Pluto, perhaps around the size of the Moon.
the "Big Bang Theory" page for more about this discovery.
on the image for a closer look.)
Image Credit: NASA/JPL-Caltech