Comparison of Solar Systems & Galaxies

There are many solar systems in existence, perhaps even more that have yet to be discovered. A solar system is a group of celestial bodies orbiting a central star. The most commonly discussed solar system is the one we inhabit. "Our" solar system consists of eight official planets, at least three dwarf planets, many satellites, comets, asteroids, and the interplanetary medium; all of which revolve around the Sun. The Sun, Mercury, Venus, Earth, and Mars comprise the inner solar system. The outer solar system includes Jupiter, Saturn, Uranus, and Neptune. Pluto was included in this region, but is now considered a dwarf planet.

The solar system is mostly comprised of empty space. The space between the planets is massive in comparison to the size of the planets. The planets orbit in ellipses. Mercury is the only planet with an elliptical path that is not nearly circular, but the rest are considered nearly circular. The "elliptical" is the plane in which all of the planets' orbits lie. the main asteroid belt of the solar system lies between the orbits of Mars and Jupiter. Solar systems are one of the main components in a galaxy, which explains why solar systems are so much smaller.

Galaxies are vast collections of solar systems, dust, gas, and countless stars. Galaxies rotate about a cluster of stars rather than a central star. There are more than 100 billion galaxies in the "observable universe" alone. The galaxy that is considered to be "our" galaxy is known as the Milky Way galaxy. "Small galaxies" are galaxies with less than a billion stars. There are three main galaxy classification, which are spiral, elliptical, and irregular galaxies. Spiral galaxies consist of "a flat disc with a bulging center and surrounding spiral arms". The galaxy's disc rotates around the "galactic center" in a regular pattern. One example of the spiral galaxy is the Milky Way. Elliptical galaxies are shaped as ellipses. Most stars in elliptical galaxies contain older star. Irregular galaxies are all the left-over galaxy variations that cannot be classified as an elliptical galaxies or spiral galaxies. It is theoretically stated that galaxies formed shortly after a cosmic "big bang".

While researching, I found it interesting that solar systems are mostly left without a name, but quite a few galaxies are given a name. I also found it intriguing that there are so many galaxies in existence that we do not even have a number large enough to say how many there are. It is also interesting that some scientists believe that galaxies start as globular clusters and transform into galaxies later. Solar systems and galaxies are a topic with a vast amount of information discovered, yet there may still be something left to find out.