Do you ever look up at the night sky and wonder what are all those objects up there? Where do we on the earth fit in? We here on earth are part of the solar system, which is part of a larger entity, the Milky Way Galaxy.
A galaxy is a combination of gas, dust, and billions of stars that are held together by gravity. Galaxies can be spirals, barred-spirals, elliptical, and irregular shaped. Our Milky Way Galaxy is a spiral galaxy.
Our solar system is made up of eight (Or nine depending on how you count.) planets, asteroids, meteors, comets, and the sun. The sun is approximately 93,000,000 miles away from Earth and is the center of the solar system. The sun is a star that gives off energy from nuclear reactions in its core.
The planets in order from the sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto (If you count it.). The word “planet” has a Greek origin that means “the wanderer”. “Wanderer” because they seemed to “wander” across the sky. Mercury, Venus, Earth, Mars, and Pluto are considered “terrestrial” meaning they are like Earth in that they have rocky surfaces. The outer planets are considered gaseous because they are made out of a hydrogen and helium inner and outer mantle with a rocky core. Each planet takes a different amount of time to orbit the sun. Mercury has the shortest orbital period of only 88 Earth days. Pluto of course has the longest orbital period of 248.5 Earth years.
Some of the planets have moons that orbit them. Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto all have at least one or more moons. Some of the outer planets have rings around them. Saturn is the most famous for this. The rings are made of billions of ice-covered rock fragments and dust particles.
There are a number of other celestial bodies orbiting our sun. Asteroids, comets and meteors are scattered throughout our solar system. Asteroids are pieces of left over planet, which mostly exist in the Asteroid Belt between Mars and Jupiter. They can be as small as gravel or hundreds of miles across.
Comets are basically dirty snowballs that orbit the sun. We usually think of comets as having “tails” but the tail does not develop until the comet gets close to the sun. This is because they are burning off gases. The tail is made up of two parts the ionized gas, which is bluish in color, and dust partials, which are yellowish in color. A comet’s orbit is elliptical and planets can have a gravitational effect on their orbital path.
Meteors are pieces of comets that have broken off. The pieces continue to travel the same path as the comet was going when it broke up. If Earth crosses this path we experience a meteor shower, and if some of those meteors fall to Earth, they are called meteorites.
I hope you now have a better understanding of our small piece of the universe. It is really amazing when you stop to consider how small we are, or how small the earth is compared to the rest of the galaxy. I’ve only touched on a very small part of it!
3D Astronomer is an interesting way to explore the solar system. You can visit one of the nine planets in our solar system or why not call on another galaxy all together! For more information, please go check out the 3D Astronomer section on the “Space Shuttle Stuff” page of SpaceShuttleFacts.com And while your there, why not learn some interesting facts about space shuttles!
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