Classification
Based on classification by size, Uranus is one of the giant planets or
gas giants. The other three giants planets are Jupiter, Saturn and Neptune. These gas giants all have diameters greater
than 48000 kilometers.
The other planets five planets are called the small planets. The small
planets all have diameters less than 13000 kilometers.
Where is It?
Uranus is the seventh planet in the solar system, located between Saturnand Neptune. Uranus
is very far away from the Sun. Its average distance from the Sun is about
3 billion kilometers., or about twenty times the distance from the Sun
to Earth. The path, or orbit, Uranus follows around
the Sun is an ellipse, or stretched out circle, which means that Uranus'
distance from the Sun varies from about 2.7 billion kilometers. at its
closest to about 3.1 billion kilometers. at its furthest away.
How Did It Get Its Name? At first Uranus was named "Georgium Sidus", after George III (the King
of England at the time). Other people called the planet Herschel, in honor
of the man who discovered it. Another astronomer suggested the name
Uranus, an ancient Greek god who was the father of Saturn, so that the new
planet would have a name from mythology like the rest of the planets. The
name Uranus was finally agreed on by everybody in the mid 1800's.
How long are its years and
days? Since Uranus is so far away from the Sun, it takes it a very
long to to go around the Sun once. A year on Uranus, the amount of time it
takes for this trip, is 84 Earth years. A day on Uranus, which is the
amount of time it takes for the plant to spin around, or rotate once, is
shorter than one day on Earth.
The blue-green planet spins around once in a little over seventeen hours.
How Big Is It?
Uranus is about four times the size of Earth, but it is still much smaller than either Saturn or Jupiter. Uranus is a about 51800 kilometers. in diameter,
compared to Earth's diameter of around 12800 kilometers. Even though Uranus
is much larger than the Earth, it is dwarfed when compared to mighty Jupiter,
which is over 142800 kilometers. in diameter.
Can It Be Seen From
Earth? Since it is so far away from Earth,
and so much smaller than the other giant planets Jupiter
and Saturn,
it is fairly hard to see. Away from cities where the skies are dark Uranus
might be seen with a pair of binoculars. The planet appears as a faint
blue-green light. But even through a telescope, Uranus will only be a
small blue-green disc.
What Is It Made Of? Uranus is another member of the family of gas planets of the solar
system, but it is quite a bit different from Jupiter
and Saturn.
First, it has methane mixed in with the hydrogen and helium that make up
most of the giant planets. Methane gives Uranus its unusual color. Second,
Uranus appears to have a core, or center, of melted rock, which changes
into a dirty ocean made up of water, ammonia and other elements. Finally,
the dirty ocean changes into the blue-green cover of clouds. Scientists
believe that the layers of the planet are not separate, like those of an
onion, but gradually blend with one another.
What Is It Like on The
Surface?
Since Uranus is a gas planet, it doesn't have a solid surface like Earth. The top layer of gas is far from quiet. By
studying the pictures sent back by the Voyager spacecraft, scientists
were able to see that there are winds blowing at over 645 kilometers.
an hour.
How Many Moons Does It
Have? Uranus has at least fifteen moons. There are probably more,
but this won't be known for sure until another spacecraft is sent to
investigate. The largest, and furthest away, of Uranus' moons are
Miranda, Ariel, Umbriel, Titania and Oberon. The moons are named after
characters in the stories of William Shakespeare and Alexander Pope.
The remaining ten moons are much smaller and a lot closer to the
planet. They were discovered by the Voyager 2 spacecraft as it sped past
the planet in 1986. Some of the smaller moons act as "shepherds", helping
to keep some order in some of the rings. The others may be comets or
asteroids that have been "captured" by the planet.
Does It Have Rings? All the gas planets have rings, but the rings of Uranus are a very
faint. The rings cannot be seen from Earth
but the Voyager spacecraft showed them. Astronomers get a hint of the
rings when they occasionally block the light of a star behind them. Even
the Hubble Space
Telescope cannot get a very good view of the rings. While the rings of
Saturn
are made up of fairly small pieces of bright white ices, the rings of
Uranus seem to be made of larger chunks of very dark, rocky material. The
darkness of the chunks may help explain why they cannot be seen from
Earth.
Who discovered it? Uranus
was the first planet to be discovered by an astronomer. It was discovered,
accidentally, by British astronomer William Herschel in 1781.
Does it have any special
features?
One of the many odd facts about Uranus is that it is "laying on its
side" as it faces the Sun. Earth
faces the sun standing almost straight up, with the north and south
poles at the top and bottom. Uranus, however, has its south pole is
facing the Sun. Scientists don't know why the planet is like this, but
it may be the result of a collision with some other body in space.
Also, the planet rotates, or spins, from east to west which is the
exact opposite of the way that Earth spins.
Resources Used Astronomy for Kids
www.dustbunny.com/afk/ Small Worlds David Drew: Nelson, 1989
The Gas Giants David Drew: Nelson, 1989
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