For beginning astronomers, young students, and amateurs, there are a few main facts everyone should know. First, knowing the language - vocabulary - of key aspects of the solar system is important. Next, know the basic way the solar system is organized, and finally, be aware of the basic online resources helpful for a modern study of astronomy and the solar system.
Astronomy Vocabulary
Commonly encountered words in astronomy include:
- Stars: a hot ball of gas producing heat and light from nuclear reactions in the core. Stars are rated for size and brightness.
- Messier Objects: objects which appear to be comets, but are not. A list of 110 Messier Objects is still used today. The objects include star clusters and nebulae.
- Asteroids: large chunks of rock, and sometimes metal also orbiting in the Solar System; the majority lie in the Asteroid Belt between Mars and Jupiter
- Comets: small, fragile, irregularly shaped bodies composed of a mixture of non-volatile grains and frozen gases. They orbit the Sun, and are visible when they get near the Sun.
- Planets: according to the International Astronomical Union (IAU) 2006 definition, a planet is now defined as a large body orbiting the Sun, with enough gravitational force to clear all other bodies out of its orbit, and with sufficient mass for its gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (meaning it is spherical).
- Galaxy: stars grouped together in huge collections
Facts About the Solar System
The solar system includes our sun and all the planets orbiting the sun. This includes the eight planets, all their moons, and everything else in orbit around the sun. The solar system is located in the Milky Way Galaxy.
A galaxy is the name for a huge collection of stars. The Milky Way Galaxy is about 100,000 light years across. A light year is calculated as the distance light travels in one year, which is approximately 9.46 million million kilometers (km).
To put this in perspective, the Sun is 150 million kilometers away from Earth, and light requires 8 minutes to travel from the Sun to Earth. The second closest star to planet Earth is Proxima Centauri, which is 4 1/4 light years away (40 million million km).
Planets in the Solar System
There were nine planets, until Pluto was downgraded to dwarf planet status in 2006. The eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. However, there are over 100 total worlds including all the minor planets and moons in the Solar System.
Tenth Planet in the Solar System
One of the most exciting finds in the new millenium (in 2005) is what is commonly described as "the 10th Planet:" Eris. It was called the 10th planet because it was found when Pluto was still known as the 9th planet. Since 2006, there have only been 8 planets, so calling the newly discovered planet Eris "the 10th planet" is incorrect. Furthermore, according to the scientists at the Planetary at Caltech website (Planetary.caltech.edu), at the annual IAU in 2006, it was decided that Pluto, Eris, and two other objects found in the Kuiper Belt are to be known as dwarf planets.
The Solar System continues to be exciting to study, even for amateurs simply because the technology continues to evolve and improve and show new objects never seen before in the history of humanity.
References
- International Astronomical Union (IAU), "Pluto and the Developing Landscape of Our Solar System," Iau.org Accessed 6/18/10
- Kids Astronomy "Solar System." Kidsastronomy.com Accessed 6/16/10
- Miles, Lisa, and Alastair Smith. The Usborne Complete Book of Astronomy and Science. EDC Publishing, Tulsa, OK. 1998.
- NASA, "10th Planet Discovered" Nasa.org Accessed 6/16/10
- Solar Views, "What is a Comet?" Solarviews.com Accessed 6/18/10
Rachel Schaus - Rachel Schaus, contributing writer,Minnesota-based freelance writer who has written hundreds of articles relating to classical education, ...
