The History Of Uranus

As one of the Gas Planets with a diameter of 32,190 miles, the planet Uranus gets its name from the god “Ouranos”.  This name comes from Greek mythology meaning  “god of the sky.” In Greek mythology, “Uranus” was the son of “Mother Earth” or “Gaia”. He became Gaia’s husband, and went on to produce many children, including “Cronus.”

This seventh planet from the Sun was discovered by William Herschel in 1781, and is the furthest planet seen from Earth without a telescope. However, the German astronomer Johann Bode is credited with naming the planet.

The Orbit Of Uranus

The orbit of Uranus is elliptical. The planet spins in a clockwise or retrograde direction. The perihelion, or point at which the planet is closest to the sun, is 1.7 billion miles (2.7 billion km), whereas its aphelion, or the point at which the planet is farthest from the sun, is 1.9 billion miles (3.0 billion km). The orbit of Uranus lasts for 84 Earth years or 30,685 Earth days. Uranus completes one day in 17 hours and 14 minutes.

Uranus is substantially tilted on its axis at 98 degrees. This is in comparison to the axis tilt of the Earth at only 23.5 degrees.

Expeditions To Uranus

There has been only one expedition to Uranus in January 1986, by the Voyager 2 spacecraft.

While it flew by Uranus, Voyager 2 collected data on new rings in the ring system that Uranus possesses. It was also able to discover 10 new satellites during this expedition, while sending information about the diameter of the major satellites, and their surface typography.

The weather patterns on Uranus, and its magnetic field were also detected during this expedition. Lastly, Voyager 2 was able to use instruments on board the spacecraft to determine the mass and diameter of Uranus.

Even though only one expedition was completed to Uranus, the Voyager 2 spacecraft was able to collect “a wealth” of information.

Exploring A Day On Uranus

As a gas planet, a day on Uranus is a little more than 17 hours, however one year on Uranus would be equal to 84 years on Earth.

Uranus’ atmosphere is composed of hydrogen (83 percent), helium (15 percent), and methane (2 percent), compared to the larger amount of nitrogen (78 percent) in the Earth’s atmosphere. Trace amounts of acetylene and ethane can also be found in the atmosphere.

One of the most notable characteristics of Uranus is the color of the planet. With the interaction of methane gas with light from the Sun, Uranus’ atmosphere has a blue-green color. This is seen as blue-green clouds surrounding the planet.

As a result of more than 90 degrees tilt of Uranus’ axis, the temperature at the poles are warmer than the temperature at the Equator. The temperature of Uranus varies depending on the altitude. At the outer edge of the atmosphere, the temperature is – 355 degrees Fahrenheit, while closer to the “core” of Uranus, the temperature is around 4,200 degrees Fahrenheit.

Uranus does have small “spots” of swirling winds, but not like the size of the Great Red Spot like Jupiter, or the Great White Spot like Saturn. Yet, its wind system is quite intensive, with wind speeds of 100-360 miles per hour in latitudes between the Equator and the poles. The wind system here moves in the direction the planet is rotating. However at the Equator, the wind speeds are moving in the opposite direction of the planet’s rotation.

The first rings of Uranus were discovered in 1977. They are composed mostly composed of dust particles. The rings are also thinner than the rings found surrounding Saturn. There are thirteen rings within the ring system. The widths of the rings vary from 3-60 miles with a thickness of more than 33 feet. The brightest ring is called the Epsilon ring, and it is the outermost ring in the system.

Based on the fact it is a gas planet, scientists feel it is unlikely that Uranus possesses any life forms.

Table 1: The Ring System Of Uranus. (David Darling 2006).

The Satellites Of Uranus

There are 27 satellites associated with Uranus, and the majority of them are very small. The satellites of Uranus are named after characters in the literary works of Pope and Shakespeare. Herschel first discovered Oberon and Titania in 1787. William Lassell discovered the two other main satellites – Umbriel and Ariel. The last of the main satellites, Miranda, was discovered in 1948 by Gerard Kuiper.

Since there has only been one expedition to study Uranus, not much is known about its satellites. They vary in diameter between 25 – 1,000 miles, and orbit Uranus between 8 hours to 14 days. Almost all of the observations have revealed the satellites of Uranus are composed mostly of water ice and rock. Many of them are cratered with impact basins, or possess rift valleys or smooth plains. A few of them have mountains, such as the satellite Oberon, with a mountain 4 miles high. This is the typical description of the satellites of Uranus, except Miranda.

Miranda

With a diameter of 290 miles, many scientists believe that Miranda has the most interesting typography of any other satellite discovered. The satellite consists mostly of rock and water ice with a variety of ridges and valleys. Miranda’s surface also contains large canyons at least 6 miles deeps, and round grooves called Coronae.

The most interesting characteristic of the surface of Miranda is the way in which these features are arranged. Its surface seems haphazardly constructed, suggesting this satellite has been continuously remodeled in the past. There are new areas of light and dark patches showing young and old areas of the typography. Miranda lacks the neat and tidy surface features commonly seen in other satellites.

Scientists believe the tectonic features of Miranda are due to previously active tectonic activity on the satellite. It orbits Uranus every 1.4 days, and is located 129,872 km from Uranus.

Table 2: The Common Satellites Of Uranus. (Space Today 2004)

Statistics About Uranus

Discovered By	William Herschel
Date of Discovery	1781
Average Distance from the Sun	Metric: 2,870,972,200 km English: 1,783,939,400 miles Scientific Notation: 2.8709722 x 109 km (19.191 A.U.) By Comparison: 19.191 x Earth
Perihelion (closest)	Metric: 2,735,560,000 km English: 1,699,800,000 miles Scientific Notation: 2.73556 x 109 km (18.286 A.U.) By Comparison: 18.60 x Earth
Aphelion (farthest)	Metric: 3,006,390,000 km English: 1,868,080,000 miles Scientific Notation: 3.00639 x 109 km (20.096 A.U.) By Comparison: 19.76 x Earth
Equatorial Radius	Metric: 25,559 km English: 15,882 miles Scientific Notation: 2.5559 x 104 km By Comparison: 4.007 x Earth
Equatorial Circumference	Metric: 160,592 km English: 99,787 miles Scientific Notation: 1.60592 x 105 km
Volume	Metric: 69,142,000,000,000 km3 Scientific Notation: 5.9142 x 1013 km3 By Comparison: 63.1 x Earth
Mass	Metric: 86,849,000,000,000,000,000,000,000 kg Scientific Notation: 8.6849 x 1025 kg By Comparison: 14.371 x Earth's
Density	Metric: 1.30 g/cm3 By Comparison: 0.236 x Earth
Surface Area	Metric: 8,115,600,000 km2 English: 3,133,400,000 square miles Scientific Notation: 8.1156 x 109 km2 By Comparison: 15.91 x Earth
Equatorial Surface Gravity	Metric: 8.43 m/s2 English: 27.7 ft/s2 By Comparison: If you weigh 100 pounds on Earth, you would weigh 86 pounds on Uranus.
Escape Velocity	Metric: 76,640 km/h English: 47,620 mph Scientific Notation: 21,290 m/s By Comparison: 1.904 x Earth
Sidereal Rotation Period (Length of Day)	-0.7196 Earth days (retrograde) -17.24 hours (retrograde) By Comparison: 0.722 x Earth
Sidereal Orbit Period (Length of Year)	84.02 Earth years 30,687.2 Earth days
Mean Orbit Velocity	Metric: 24,607 km/h English: 15,290 mph Scientific Notation: 6,835.2 m/s By Comparison: 0.229 x Earth
Orbital Eccentricity	.047168 By Comparison: 2.823 x Earth
Orbital Inclination to Ecliptic	0.770 degrees
Equatorial Inclination to Orbit	97.86 degrees By Comparison: 4.173 x Earth
Orbital Circumference	Metric: 17,620,000,000 km Scientific Notation: 1.762 x 1010 km By Comparison: 19.06 x Earth
Effective Temperature	Metric: -216 °C English: -357 °F Scientific Notation: 57 K
Atmospheric Constituents	Hydrogen, Helium, Methane Scientific Notation: H2, He, CH4 By Comparison: Earth's atmosphere consists mostly of N2 and O2.
Table 3: Concise statistics on the planet Uranus (N.A.S.A. 2006)

References

Col, Jeananda. 1996. “Uranus.” Enchanted Learning. http://www.enchantedlearning.com/subjects/astronomy/planets
/uranus/uranusrings.html

Darling, David. 2006. “Uranus’ Rings.” http://www.daviddarling.info/encyclopedia/U/Uranus_rings.html

Encyclopedia Britannica. 2006. "Uranus.” Encyclopedia Britannica Premium Service. 2006 http://www.britannica.com/eb/article-54289

Gierasch, Peter J., and Philip D. Nicholson. 2004. "Uranus." World Book Online Reference Center. World Book, Inc. http://www.nasa.gov/worldbook/uranus_worldbook.html

National Aeronautics and Space Administration (N.A.S.A). 2006. “Uranus: Facts & Figures.” http://solarsystem.nasa.gov/planets/profile.cfm?
Object=Uranus&Display=Facts

Space Today Online. “The Moons Of Uranus.” 2004. http://www.spacetoday.org/SolSys/Uranus/UranusMoons.html

Uranus Images