This is an image of Neptune and its famous Great Dark Spot. Click on image for full size (32K JPG) Courtesy of NASA

If you had a quiz question in school that asked what year Neptune was discovered, you'd probably choose 1846. But Neptune wasn't discovered the way all the other planets in our solar system were. Astronomers didn't scan the sky with their powerful telescopes to find Neptune. They used math instead!

After the discovery of Uranus, astronomers were having trouble figuring out the planet's orbit. They realized that there must be another planet farther out than Uranus. They were right! Independently, French astronomer Leverrier and English astronomer John Couch Adams made the mathematical calculations of where Neptune should be and German astronomer Johann Galle observed it.

Neptune is the eighth planet in our solar sytem (most of the time, anyway). It's gravitational pull slightly changes Uranus' orbit, and that's how scientists found it!

All the planets were named after ancient gods. So when it came time to name this one, astronomers chose Neptune. Neptune was the Roman god of the deep seas.

Neptune's largest moon, Triton, was discovered at the same time as the planet. Another satellite, Nereid, wasn't found until 1949. The other six were spotted by Voyager II during its flyby in 1989. A lot of research has been done on Triton, and there is evidence that life may have existed there at one time. Of course, the moon must be studied a lot more before we will know for sure.