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For thousands of years man has looked up into the night sky and wondered about his place in the cosmos. While we still do not have many of the answers, we are more aware at least of our place in the closest of celestial vicinities. This “vicinity” is of course the solar system and its family of objects.

The solar system, in the simplest terms, is our cosmic “family”. At the center of this “family” is the Sun – a medium-sized star. Revolving around this center are objects generally categorized into four types - the planets with their accompanying moons, asteroids, comets and the interplanetary medium.

The planets are by far the most visible “children” of the solar system. Numbering nine altogether, they hobble into two groups. The group closest to the Sun (sometimes called the “inner planets”) is made of Mercury, Venus, our very own Earth and Mars. The planets on the outer rim are Jupiter, Saturn, Uranus, Neptune and Pluto. All planets revolve around the Sun in elliptical paths called orbits. Except for Uranus and Pluto, the orbits of the planets never cross each other’s trail. Jupiter is by far the largest of the planets (about 125 times the size of the Earth) with Pluto being the smallest. Pluto is also the furthest planet from the Sun while Mercury is the closet. Venus is usually regarded as the third brightest object visible in the sky (after the Sun and moon, of course) as viewed from the Earth, although comets and meteorites when past Earth’s atmosphere far outshine Venus. Venus (normally called the “morning star” although it is not a star at all) is sometimes regarded as Earth’s twin planet because its size and density closely matches the Earth’s. Mars is the only other planet that has liquid water – which give rise to theories of possible Martian life.

Comets have been seen since ancient times. Although only a few are famous there are actually more then 800 comets revolving around the Sun, but because of their large orbits they remain invisible most of the time. It has been difficult tracking them and determining their orbital periods (time taken to complete a full path around the Sun), which can be up to a thousand years or more. Comets are a mixture of ices (both water and frozen gases) and dust. They are remnants from the creation of the Solar System and are often studied for that reason. When Earth passes through the orbit of a comet, a meteor shower is seen. Some of these occur at great regularity. For example, the Perseid meteor shower that occurs every year between August 9 and 13 is the result of the Earth passing through the orbit of Comet Swift-Tuttle. Since comets are brightest when near the Sun, they are usually visible only at sunrise or sunset.

Asteroids are most “populous” residents of the Solar System. Numbering in their hundred of thousands (new ones are discovered by the hundreds each year), they orbit the Sun mostly between the planets of Mars and Jupiter. These rocky bodies come in all shape and sizes – from those as small as a football to quite a few larger than New York City! The largest asteroid is believe to be 1 Ceres – a whooping 933 km giant that is estimated to have a quarter the mass of all the asteroids combined! Now one knows for sure why asteroids exist in such numbers or why they sometimes get pushed from their orbits and come hurtling down to the planets – including Earth - as meteorites. It is widely believed a meteorite that left an 180km crater in the Yucatan Peninsula was responsible for the extinction of the dinosaurs 65 million years ago. And what are the chances of one fairly large asteroid like that hitting the Earth? Now that is a thought to shudder at!

Also, if you think that the space between the planets, comets and asteroids is empty, you’re wrong! It full of electromagnetic radiation, hot plasma, cosmic rays, microscopic dust particles and the Sun’s magnetic fields. These are sometimes called the solar wind and its interaction with the Earth’s own magnetic field and atmosphere generate the auroras lights in the northern hemisphere.

Our knowledge of the solar system is far from complete. As we observe the skies either from the Earth or from satellites floating in space, we are learning new things about our solar system and the universe. Our understanding of the world and ourselves is in more ways than can be explained tied closely to what is out there.