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Uranus, Neptune and Pluto "The Far 3"

Check out: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Nepture, Pluto

Uranus

Click Image to EnlargeDiscovered in 1781 by amateur astronomer William Hershel using a home-made telescope.

Uranus is composed mostly of rock and ice, but with a thick hydrogen and helium atmosphere. It also has a methane component which causes the planet to look greenish-blue in colour from our point of view on Earth.

Uranus has 15 orbiting satellites. The five major ones are Miranda, Ariel, Umbriel, Titania and Oberon.

Uranus is the third largest planet in our Solar System afterJupiter and Saturn. It has a rotation axis that is greatly tilted (like Venus) and sometimes points near the Sun. It remains an astronomical mystery why is so tilted.

Above image was snapped by theVoyager 2 Spacecraft in 1986. Coutesy of NASA.

Neptune

Discovered in 1843 Neptune can not be seen with the naked eye. With a telescope it looks to have a faint green-blue tinge. It is very similar to Uranus in its size and it is surrounded by rings. Also similar, is the temperature -200 degrees Celsius.

Neptune is composed mostly of liquid water, methane and ammonia, is surrounded by a thick gas atmosphere of mostly hydrogen and helium, and has many moons and rings.

Neptune has 8 satellites that we know of. The two main ones are Triton and Nereid. Triton has a very unusual orbit. It travels in the opposite direction of the planet's own spin. It's cycle takes 680 years. It also has active volcanoes.

 

 

 

 

 

 

 


Above: This picture was taken by the Voyager 2 spacecraft.

 

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Pluto

In 2006 astronomers declared Pluto was no longer an official planet. Its now considered a "dwarf planet."

Pluto was discovered in 1930 and it is very difficult to see even with a telescope. It's surface is covered with methane ice and its only moon is called Charon. Due to its unusual orbit, Pluto sometimes is inside Neptune's orbit. Most recently, this happened from 1979 to 1999.

Pluto has mottled surface and a tenuous, transient atmosphere visible as blue haze beyond the bright limb.

Left: Artist's renditoin of Pluto. Click the image to see Pluto's moon, Charon looming in the distance. Image credit: NASA, JPL, Michael W. Carroll.

Sedna

NASA announced in 2004, the discovery of a dark red object dubbed Sedna. Although over twice the distance to Pluto, Sedna is currently near its closest approach to the Sun.

Sedna's highly elliptical orbit will further displace it by 10 times, making it a candidate for the long-hypothesized Oort cloud of icy objects thought to extend to the Solar System's edge.

Sedna is estimated to be about three-quarters the size of Pluto and therefore the largest Solar System object found since Pluto in 1930.

Right: drawing depicts how Sedna might look facing the distant Sun. The unexpectedly red color, the unusual orbit, and the origin of Sedna will surely be topic of much future research. Illustration Credit: R. Hurt ( SSC-Caltech ), JPL-Caltech , NASA

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