Our solar is estimated to be 4.6 billion years old according to the Big bang Theory. The Nebular hypothesis is concerning the origin of the solar system according to which a rotating nebula cooled and contracted, throwing off rings of matter that contracted into the planets and their moons, while the great mass of the condensing nebula became the sun. We have a heliocentric solar system which means everything revolved around the sun. At first it was thought to be geocentric, when everything revolves around Earth, but that was soon disproved. The inner planets include: Mercury, Venus, Earth, and Mars. They all have a solid surface, closely similar in size, and all close to the Sun. The outer planets include; Jupiter, Saturn, Uranus, and Neptune. They are much bigger the inner planets, they are made of mostly hydrogen and helium, have own system of moons. Asteroids are rocky bodies that orbit the sun. Some could be as small as a grain of sand. Most are between Mars and Jupiter. They orbit the sun every 3-6 years. Comets are also pieces of rock but they are held together by frozen gases. Some orbit the sun every 1000 years.When a comet gets close to the sun, gases vaporize and create a tail called a coma. Most of found in the Kuiper belt which is located after Neptune. Meteoroids are small solid particles that travel through space (could be size of sand grains or large.) They either come from interplanetary debris, asteroid belt, or the remains of a comet. When they enter the atmosphere they are called meteor, and when they hit the earth its called a meteorite. All these of part of our galaxy, the Milky Way. Our galaxy is a typical barred spiral. The Milky Way does not sit still, but is constantly rotating. As such, the arms are moving through space. The sun and the solar system travel with them. The Sun is made up of 99% hydrogen and helium. The temp ranges from 2000000C to 70000000C. Sun has solar flares that are a brief eruption of intense high-energy radiation from the sun's surface, associated with sunspots and causing electromagnetic disturbances on the earth, as with radio frequency communications and power line transmissions. An electromagnetic pulse (EMP) is an intense burst of electromagnetic (EM) energy caused by an abrupt, rapid acceleration of charged particles, usually electron s. An EMP can contain energy components over a large part of the EM spectrum , from very-low-frequency ( VLF) radio to ultraviolet ( UV ) wavelength s. Nuclear fusion fuels the sun which is a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.