Uranus is the seventh planet from the Sun and has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. Though it is visible to the naked eye like the five classical planets, it was never recognized as a planet by ancient observers because of its dimness and slow orbit. It was the first planet to be discovered in modern history. It was discovered in 1781 by Sir William Herschel (Encyclopedia: Uranus (planet)) and expanded the known boundaries of the Solar System for the first time in modern history.
Uranus was also the first planet discovered with a telescope. Uranus had been observed many times before it was discovered as a planet, but it was generally mistaken for a star. On March 13, 1781, Sir William Herschel observed the planet from his home in Somerset, England using a reflecting telescope that he designed and built himself (Uranus (2), 2009). He initially reported it as a comet, but also compared it to a planet. He notified astronomers who also started observing the planet.
After observing it for a while, they noticed it did not have any coma or tail to it, and eventually noticed it’s nearly circular orbit that led them to the conclusion that it was a planet rather than a comet. Herschel originally named the planet Georgium Sidus, or George’s Star in honor of King George III (Encyclopedia: Uranus (planet)). However, this name was not very popular outside of Britain and soon people started volunteering alternative names. Some thought it should be called Herschel after the man who discovered it, and others thought Neptune was a good name for it.
Finally, the name Uranus was suggested. Uranus is the Latinized version of the Greek god of the sky, Ouranos. This name was fitting because just as Saturn was the father of Jupiter, the new planet should be named after the father of Saturn. Although Uranus is not the farthest planet from the Sun, it is the coldest planet in the Solar System. The surface temperature is about -224 degrees Celsius. The planet is so cold because it has a low internal temperate. The core of Uranus is only about 5000 degrees K, compared to Jupiter which is 30,000 degrees K at its core.
Uranus is an ice giant, meaning it does not have a solid surface and what is called its ‘surface’ is actually a layer of clouds that lies above what may be a layer of liquid water and a core of rock at the center of the planet. The atmosphere of Uranus is composed of 83% hydrogen, 15% helium and 2% methane plus trace amounts of other gases such as ethane. Uranus is almost 15 times bigger than Earth, making it the third largest planet in the Solar System after Jupiter and Saturn; Uranus’s core alone is as large as our planet (Fountain, Observatory, 1999).
The mass of Uranus is 8. 68103 ? 1025 kilograms. This is 14. 54 times Earth’s mass. However, even though Uranus is larger than Earth, it is less dense. The density of Uranus is 1. 27 g/cm? and the density of Earth is 5. 52 g/cm?. To leave the planet of Uranus, an escape velocity of 21. 2 km/s is required. Compared to Earth’s escape velocity of 11. 2 km/s, you need to be moving about double the speed to leave Uranus and get out of its gravitational pull (Encyclopedia: Uranus (planet)). The average distance from Uranus to the Sun is roughly 3 billion km, or about 20 AU. Uranus revolves around the Sun once every 84 Earth years and it takes about 17 hours, 14 minutes to complete a full rotation (Uranus (2), 2009). Uranus rotates about an axis that tilts 98° into its orbital plane. Because of this tilt, one pole of Uranus points almost directly toward the Sun during half of Uranus’s 84-year orbit, and the other pole points toward the Sun during the second half. This pattern creates 42-year-long seasons of lightness and darkness, alternately, on each end of Uranus.
Uranus has 10 known rings and at least 18 moons (Fountain, 2007), however there may be up to 27 per recent studies. Since the surface of Uranus is made up of gases, there is no volcanic activity on the planet. However, there may be ice spewing volcanoes on a few of Uranus’s moons (Fountain, 1999). Although it was previously believed that Uranus was climactically a bland planet, recent observations from the Hubble Space Telescope have shown that the planet actually has dynamic weather pattern (Colombo, 1998).
Uranus is swept by huge wind storms, with wind speeds reaching as much as 900 km/hr although it receives much less energy from the Sun than Earth. One storm, dubbed the Great Dark Spot, is as large as the diameter of Earth or approximately 13,000 km long. Uranus has a magnitude of about 5. 3 which means it is possible to see it with the naked eye. However, the sky would need to be very dark and other obstructions, like clouds could not be in the way. It is the most distant planet that can be seen with the naked eye. However, a chart is normally needed to find it in the sky.
In 1977, NASA launched the Voyager 2. The probe made its closest approach to Uranus on January 24, 1986, coming within 81,500 kilometers of the planet’s cloudtops, before continuing on to Neptune. Voyager 2 studied the structure and chemical composition of Uranus’s atmosphere and it made the first detailed investigations of its five largest moons, and discovered 10 new moons. It examined all nine of the system’s known rings and discovered two new ones. It also studied the magnetic field, its irregular structure, and its tilt (Encyclopedia: Uranus (planet)).
This flyby remains the only investigation of the planet carried out from a short distance, and no other visits are currently planned. Uranus is a very interesting planet. Although there is a lot we have learned about this planet, there is still much to be discovered. Hopefully more probes will be sent to explore Uranus and we will learn more about this magnificent planet. There is always something new to discover in the solar system and in cases like this where a planet was discovered on accident, who knows what else is out there waiting to be found.
Uranus (2). (2009, January 27). Retrieved October 8, 2012, from Encyclopedia Britannica: http://elibrary. bigchalk. com. bakerezproxy. palnet. info/elibweb/elib/do/document? set=search&dictionaryClick=&secondaryNav=advance&groupid=1&requestid=lib_standard&resultid=1&edition=&ts=19E5F880963FE79575C6C6DC7BF7B440_1349740525801&start=1&publicationId=&u Colombo, J. R. (1998, January 1). Science and Nature: Astronomy and Space. Retrieved October 8, 2012, from The 1998 Canadian Global Almanac: http://elibrary. bigchalk. com. bakerezproxy. palnet. info/elibweb/elib/do/document? set=search&dictionaryClick=&secondaryNav=advance&groupid=1&r