OUR SOLAR SYSTEM

The Solar System is the name given to the planets, moons, and other material that circle our sun. Scientists think that the Solar System formed about 5 billion years ago. They think the universe was already 10 billion years old when the Solar System exploded into existence as a "Big Bang" of energy and matter. The most important part of the solar system is the sun. The next important part of our solar system is the nine planets that orbit the sun. Another major part of the solar system includes our moon. Several other planets in our solar system also have moons. Additionally, asteroids, meteorites and comets also form a part of our solar system. Asteriods are big chunks of rocks, some as big as a mountain, that circle the sun. Meteorites are smaller bits of rock and can even be as small as a grain of sand. Comets are a collection of ice, gas, and dust that are only a few miles wide but can have tails a million miles long.

The word "sol" means sun so the solar system could have been named the "sun system". Our sun is really an ordinary, middle sized yellow star. Our solar system is located in the Milky Way galaxy with 100 billion other stars. The sun may be an average star in the universe but in our solar system, it is considered a giant. More than a hundred Earths could fit, side by side, across the sun. The sun is a huge bubbling, flaming ball of gas. It is hotter than the hottest thing you can imagine. Deep inside the sun, the temperature is millions of degrees hot. The sun's gravity is the force that keeps the planets and other parts of our solar system orbiting the sun. Mercury, the closest planet to the sun, takes only 88 days to go around the sun once, while Pluto takes 248 years.

An easy way to remember the order of the planets is the mnemonic sentence "My Very Eager Mother Just Served Us Nine Pizzas."

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