Uranus' Moon Oberon
Uranus and its five major moons are depicted in this montage of images acquired by the Voyager 2 spacecraft. The moons, from largest to smallest as they appear here, are Ariel, Miranda, Titania, Oberon and Umbriel. Image Credit & Copyright: NASA/JPL
Uranus' Moon Titania
Titania has fault lines running across its surface, hinting at past or present seismic activity.
Titania's Profile:
Age: About 4.5 billion years old.
Distance from the sun: On average, Europa's distance from the sun is about 485 million miles (or 780 million kilometers).
Distance from Jupiter: Europa is Jupiter's sixth satellite. Its orbital distance from Jupiter is 414,000 miles (670,900 km).
Size: Europa is 1,900 miles (3,100 km) in diameter, making it smaller than Earth's moon, but larger than Pluto. It is the 15th largest body in the solarsystem, and the smallest of the Galilean moons.
Temperature: Europa's surface temperature at the equator never rises above minus 260 degrees Fahrenheit (minus 160 degrees Celsius).
The planet Uranus has 27 known moons, most of which were not discovered until the space age. The largest five are Oberon, Titania, Miranda, Ariel and Umbriel.
Miranda appears to be a jumble of disconnected features. It's unclear what made the mashed-up surface. Perhaps a huge meteorite blew the moon apart and it reassembled, or smaller meteorites melted the surface and caused slush to flow and freeze again.
Uranus' Moon Miranda
Miranda's Profile:
Age: About 4.5 billion years old.
Distance from the sun: On average, Europa's distance from the sun is about 485 million miles (or 780 million kilometers).
Distance from Jupiter: Europa is Jupiter's sixth satellite. Its orbital distance from Jupiter is 414,000 miles (670,900 km).
Size: Europa is 1,900 miles (3,100 km) in diameter, making it smaller than Earth's moon, but larger than Pluto. It is the 15th largest body in the solarsystem, and the smallest of the Galilean moons.
Temperature: Europa's surface temperature at the equator never rises above minus 260 degrees Fahrenheit (minus 160 degrees Celsius).
Europa is one of the so-called Galilean moons of Jupiter, along with Io, Ganymede and Callisto.
Uranus' Moon Ariel
Ariel's Profile:
Age: About 4.5 billion years old.
Distance from the sun: On average, Europa's distance from the sun is about 485 million miles (or 780 million kilometers).
Distance from Jupiter: Europa is Jupiter's sixth satellite. Its orbital distance from Jupiter is 414,000 miles (670,900 km).
Size: Europa is 1,900 miles (3,100 km) in diameter, making it smaller than Earth's moon, but larger than Pluto. It is the 15th largest body in the solarsystem, and the smallest of the Galilean moons.
Temperature: Europa's surface temperature at the equator never rises above minus 260 degrees Fahrenheit (minus 160 degrees Celsius).
Europa is one of the so-called Galilean moons of Jupiter, along with Io, Ganymede and Callisto. The surface of Europa is frozen, covered with a layer of ice, leading scientists to believe there is a very active ocean beneath the surface. The icy surface also makes the moon one of the most reflective in the solar system.
Uranus' Moon Umbriel
Umbriel's Profile:
Age: About 4.5 billion years old.
Distance from the sun: On average, Europa's distance from the sun is about 485 million miles (or 780 million kilometers).
Distance from Jupiter: Europa is Jupiter's sixth satellite. Its orbital distance from Jupiter is 414,000 miles (670,900 km).
Size: Europa is 1,900 miles (3,100 km) in diameter, making it smaller than Earth's moon, but larger than Pluto. It is the 15th largest body in the solarsystem, and the smallest of the Galilean moons.
Temperature: Europa's surface temperature at the equator never rises above minus 260 degrees Fahrenheit (minus 160 degrees Celsius).
This highest-resolution Voyager 2 view of Ariel's terminator shows a complex array of transecting valleys with super-imposed impact craters. Image Credit & Copyright: NASA/JPL
The Discovery of Phobos
English astronomer William Lassell located Ariel in 1851. This moon has the youngest and brightest known surface among the moons. This could be due to meteorite hits, as well as possible geologic activity — among its features are grabens, or valleys surrounded by faults. Voyager 2 detected a silicate rock and water ice composition on this moon, with hints of carbon dioxide.
Exploration of Phobos
In 1971, NASA's Mariner 9 spacecraft became the first manmade satellite to orbit another planet. Images from the craft revealed that both Phobos and Deimos have lumpy, potato-like shapes, rather than spherical like most moons. The Viking Orbiters flew by in the late 1970s. The Soviet Phobos 2 mission, NASA's Mars Global Surveyor, and the European Mars Express all provided more clues about the two curious moons. Rovers from the planet's surface even got in on the act, with Spirit, Opportunity, and Curiosity all providing images from the ground.
This color composite of the Uranian satellite Miranda was taken by Voyager 2 on Jan. 24, 1986, from a distance of 147,000 kilometers (91,000 miles). Image Credit & Copyright: NASA/JPL.
The Discovery of Phobos
Miranda was discovered in telescopic photos of the Uranian system by Gerard P. Kuiper on 16 February 1948 at the McDonald Observatory in western Texas. It was the last moon of Uranus to be discovered prior to Voyager 2's visit in 1986.
Exploration of Phobos
In 1971, NASA's Mariner 9 spacecraft became the first manmade satellite to orbit another planet. Images from the craft revealed that both Phobos and Deimos have lumpy, potato-like shapes, rather than spherical like most moons. The Viking Orbiters flew by in the late 1970s. The Soviet Phobos 2 mission, NASA's Mars Global Surveyor, and the European Mars Express all provided more clues about the two curious moons. Rovers from the planet's surface even got in on the act, with Spirit, Opportunity, and Curiosity all providing images from the ground.
This is the highest-resolution picture of Titania returned by Voyager 2. Image Credit & Copyright: NASA/JPL
The Discovery of Phobos
In the early 17th century, German astronomer Johannes Kepler proposed that Mars might host two moons. However, no evidence of such moons could be found. American astronomer Asaph Hall tried searching closer to the planet than previous surveys. After searching without success, a frustrated Hall was about to give up when his wife urged him to continue. The next night, August 12, 1877, he discovered the moon that would later be known as Deimos. Six days later, he found Phobos as well. The two moons lay so close to their primary that they were hidden by the planet's glare.
Exploration of Phobos
In 1971, NASA's Mariner 9 spacecraft became the first manmade satellite to orbit another planet. Images from the craft revealed that both Phobos and Deimos have lumpy, potato-like shapes, rather than spherical like most moons. The Viking Orbiters flew by in the late 1970s. The Soviet Phobos 2 mission, NASA's Mars Global Surveyor, and the European Mars Express all provided more clues about the two curious moons. Rovers from the planet's surface even got in on the act, with Spirit, Opportunity, and Curiosity all providing images from the ground.
Uranus' outermost and largest moon, Oberon, is seen in this Voyager 2 image, obtained Jan. 22, 1986. Image Credit & Copyright: NASA/JPL
The Discovery of Oberon
Oberon was discovered in January 1787 by William Herschel. There was not a lot of information known about this moon, however, until Voyager 2 passed it during a flyby of Uranus in 1986.
Exploration of Oberon
So far the only close-up images of Oberon have been from the Voyager 2 probe, which photographed the moon during its flyby of Uranus in January 1986. The images cover about 40% of the surface, but only 25% of the surface was imaged with a resolution that allows geological mapping. At the time of the flyby the southern hemisphere of Oberon was pointed towards the Sun, so the dark northern hemisphere could not be studied. No other spacecraft has ever visited the Uranian system, and no mission to this planet is planned in the foreseeable future.
Oberon is the second largest moon of Uranus. Oberon is heavily cratered, especially when compared to three other moons of Uranus: Ariel, Titania and Miranda. Like all of Uranus' large moons, Oberon is composed of roughly half ice and half rock. Oberon has at least one large mountain that rises about 6 km off the surface.
Oberon's Profile:
Age: About 4.5 billion years old.
Distance from the sun: On average, Europa's distance from the sun is about 485 million miles (or 780 million kilometers).
Distance from Jupiter: Europa is Jupiter's sixth satellite. Its orbital distance from Jupiter is 414,000 miles (670,900 km).
Size: Europa is 1,900 miles (3,100 km) in diameter, making it smaller than Earth's moon, but larger than Pluto. It is the 15th largest body in the solarsystem, and the smallest of the Galilean moons.
Temperature: Europa's surface temperature at the equator never rises above minus 260 degrees Fahrenheit (minus 160 degrees Celsius).
The Discovery of Phobos
English astronomer William Lassell spotted Umbriel, the darkest of Uranus' big moons, in 1851. In Voyager 2's quick fly-by, scientists were unable to figure out how the surface got so dark, or why there is a bright ring on Umbriel's surface that is 90 miles (140 kilometers) in diameter.
Exploration of Phobos
In 1971, NASA's Mariner 9 spacecraft became the first manmade satellite to orbit another planet. Images from the craft revealed that both Phobos and Deimos have lumpy, potato-like shapes, rather than spherical like most moons. The Viking Orbiters flew by in the late 1970s. The Soviet Phobos 2 mission, NASA's Mars Global Surveyor, and the European Mars Express all provided more clues about the two curious moons. Rovers from the planet's surface even got in on the act, with Spirit, Opportunity, and Curiosity all providing images from the ground.
Mosaic of high-resolution images of Miranda. One wide-angle and eight narrow-angle camera images of Miranda were combined in this view. Image Credit & Copyright: NASA/JPL
This Voyager 2 picture of Oberon is the best the spacecraft acquired of Uranus' outermost moon. Image Credit & Copyright: NASA/JPL
Voyager 2 obtained this full-disk view of Uranus' moon Titania in the early morning hours of Jan. 24, 1986. Image Credit & Copyright: NASA/JPL
The complex terrain of Ariel is viewed in this image, the best Voyager 2 color picture of the Uranian moon. Image Credit & Copyright: NASA/JPL
The southern hemisphere of Umbriel displays heavy cratering in this Voyager 2 image, taken Jan. 24, 1986. Image Credit & Copyright: NASA/JPL