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.
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.
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 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.
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 Mercury.
Others, including Io, have active volcanoes. Europa has a liquid water ocean, while Titan has rivers, lakes and oceans of liquid Methane.
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.