The solar neighborhood is a fantastic place. The Solar
System is filled with moons, planets, comets, asteroids, minor planets and a
great many other exciting objects.
The solar system formed about 4.5 billion years back from a
massive swirling cloud of dust. We know this due to advances in technology,
including the Hubble telescope, have permitted us to look deep into space to
notice the birth of stars just like our Sun.
A Huge Cloud of Dust
Throughout the Milky Way along with other galaxies like it,
are massive swirling clouds of dust and gas called nebula. It is within nebula
that stars are created. Our star, the Sun, was produced in one such nebula.
Something, probably the shock wave from an exploding
supernova (dying star) triggered dust particles to be drawn together to make a
dense spherical cloud. The accumulation of dust set off a chain reaction. As
the central of the cloud attracted more dust, its gravitational pull improved.
More and more dust was sucked in and the cloud collapsed in on itself. As this
occurred, the rotation of the cloud improved in speed, as occurs when spinning
ice skaters pull in their arms. The rotational forces at the equator of the
cloud avoided dust along this plane being drawn in, causing the cloud to
flatten into a disc spinning around a dense core.
A Star is Born
As a growing number of mass accumulated at the core of the
disc, the temperature elevated dramatically. At some point there was sufficient
energy to set off nuclear reactions. Hydrogen atoms fused to make helium,
releasing massive amounts of energy in vigorous bursts. This marked the birth
of the Sun, even though it would take between one and 10 million more years for
it to settle into the primary sequence star recognizable today.
The Formation of the Planets
The planets and other extraterrestrial objects including
asteroids, shaped in the flat plane of the rotating disc of dust. Electrostatic
forces or sticky carbon coatings produced dust particles stick together to make
clusters, which in turn stuck together to create rocks. Mutual gravity caused
these rocks to get together, eventually to make planets. This 'coming together'
of material is a procedure referred to as accretion.
The Solar System Has Over 100 Worlds
It's true that you can find only eight planets. But, the
Solar System is composed of over 100 worlds that are every bit as fascinating.
A few of these minor planets and moons are actually bigger than the planet
Others, including Io, have active volcanoes. Europa has a
liquid water ocean, while Titan has rivers, lakes and oceans of liquid Methane.
Beyond The Oort Cloud
The Sun's solar winds carry on pushing outward till they
finally start to mix into the interstellar medium, becoming lost with the winds
through other stars. This produces a kind of bubble referred to as the
Heliosphere. Scientists define the limitations of the Solar System as being the
border of the Heliosphere or at the place where the solar winds from the Sun
combine with the winds from other stars.
The Heliosphere extends out through the Sun to a
distance around 15 billion miles, which is greater than 160 times further from
the Sun than is the Earth.