If you noticed a planet wobbling around the sun, wouldn't you start to wonder if there weren't many more? Astronomersstarted looking for another planet because Uranus's orbit wasn't a perfect ellipse. They decided only another unknown planet could pull its orbit so out of shape! Knowingit should be there and finding it were two different things. To find Neptune, they used the orbits of the planetsthey knew and calculated where it should be. This may sound simple, but it took over fifty years to find it. Even its unusual blue color didn't help, as Neptune can only be seen through a telescope. Have you ever seen pictures of a hurricane or a tornado? The winds in these storms seldomreach 300 miles per hour, yet they destroy almost everything in their paths. Now imagine living on Neptune where the wind is constantly moving over 1,000 miles an hour, everywhere. Great hurricane-like storms as big as the planet Earth are spotted frequentlyon Neptune's surface, but they quickly disappear. What causes all this stormy weather? Although Neptune does get a little heat from the sun and has seasons just like Earth, it is not enough to drive a weather system. Neptune's great storms come from the internal heat found deep inside the planet that clashes with the icy cold space surrounding it.

Going Back

How worried would you be if you thought the earth's moon was getting closer, instead of moving out into space? Neptune's moon, Triton, with its retrograde orbit, is steadily moving closer to the planet. If it keeps moving in the same direction it will probably be pulled apart millions of years from now. Over the years this has people wondering if other planets have captured or destroyed moons? After examiningsome of Neptune's moons, they certainly do look like they have been through some rough battles and many seem to appear as though they may come from other parts of the solar system. Just imagine if all the planets and moons could talk, what stories they would tell.

Long Journey

Neptune is located at the outer edge of our solar system, so it takes a long time to travel all the way around the sun. In fact, even though Neptune was discovered in 1846, it still has not made one completeorbit! Use the following rules to cross numbers out of the grid. The remaining number will tell you how many Earth-years equal one Neptune-year!

Cross out numbers…

…with two zeroes

…with three digits that add up to 8

…that are divisible by 2

The Big Four Planets!

If someone asked you to describe a jovian or gas planet, where would you start? Most people would say, “They're long way from the sun, so they should be really cold.” Other things that are true:

• Surprisingly, they all have some rock in their cores.

• It's hard to tell where their moving bands of atmosphere stop and each planet starts.

• Some of their atmospheres turn faster than the planet does.

• Although some of the planets' areas near their poles move faster than their equators, they all rotate faster than their terrestrial neighbors do.

• All four make a complete rotation on their axis in hours, even though it takes them years to complete an orbit around the sun. This may be due to a lack of friction.

You may have also said you thought the gas planetsare big, which is very true. It would take you four times as long to circle around the smallest one, Neptune, as it would to go around Earth. One thing most people don't know is that the gas planets have magneticqualities. The hardest thing to believe is astronomersthink one of the planet's magnets might be made out of ammonia and water! Another difference is that gas planets have no craters. Of course, how could there be? About the only thing they have in common with the first four planets is that they have moons and they orbit the sun.