Uranus is the seventh planet from the Sun, the third-largest planet in the Solar System, and has twenty-seven known moons. Though visible to the naked eye, it was dismissed as a star until March 13, 1781 when Sir William Herschel, using a telescope, noticed that this particular "star" seemed different from the others.
From Caltech, in conjunction with NASA and Cool Cosmos, Ask an Astronomer answers thirteen frequently asked questions about Uranus. How big is Uranus? Is Uranus really tilted on its side? Why is Uranus blue? You can explore the rest of the universe (planets, stars, galaxies, nebulas and black holes) by following the Ask an Astronomer link. Cool Cosmos is also a must see. "Learn about infrared light, and open a door into the fantastic world of Infrared and Multiwavelength Astronomy."
"Uranus is very cold, windy and, like most of the other planets, poisonous to humans. It is a gas planet like Jupiter, Saturn and Neptune. There is nothing to land on. The air -- atmosphere -- gets thicker and thicker until it is squished into liquid. That is called pressure." NASA presents a kid's eye view of Uranus with quick facts (11 Uranian rings, 84 Earth years in each Uranian year), a short article about the Voyager 2's 1986 Uranus flyby, and a Uranus calculator. How much would you weigh on Uranus? Because of the effects of gravity, you'd weight about eleven percent less there than you do here on Earth.
Originally published as a CD-ROM, this site is a photo gallery of images from NASA's planetary explorations. You can explore the Uranus photos by starting with any of the thumbnails and then following the next and previous links. The annotations are short and include hyperlinks to the site's glossary. "This image reveals many broad lanes of dust surrounding the 9 main rings of Uranus. It was taken by Voyager 2 looking back toward the sun through the ring system. The dust is especially bright in this view, for the same reason that we can see dust on a windshield better when we are driving toward the sun."
"John Flamsteed first recorded the planet in 1690, but believed it was a star. Almost 100 years later in 1781, Sir William Hershel made the formal discovery. Although originally mistaking it for a comet, Hershel quickly corrected his error and established Uranus as a planet. After much debate about what to call it, Uranus was named after the Greek god of the sky." Space.com's coverage of Uranus includes a data sheet, an archive of a dozen featured stories, a photo gallery, and a movie short "The Planet Hunter."
Windows to the Universe is my Uranus pick of the day because they publish their material at three different levels: beginner (for elementary students), intermediate (for middle school) and advanced (for high school and college students.) "The plain aquamarine face of Uranus confirms the fact that Uranus is covered with clouds. The sameness of the planet's appearance shows that the planet's atmosphere is mostly composed of one thing, methane."