Once considered one of the blander-looking
planets, Uranus (pronounced YOOR un nus) has been revealed as a dynamic
world with some of the brightest clouds in the outer solar system and 11
rings. Uranus gets its blue-green color from methane gas above the deeper
cloud layers (methane absorbs red light and reflects blue light).Uranus
is the seventh planet in our solar system, located in between Saturn and
Neptune. Uranus is very far away from the Sun. Its average distance
from the Sun is about one and three-quarters billion miles, 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 1.7 billion
(1,700,000,000) miles at its closest to about 1.87 billion (1,870,000,00)
miles at its furthest away.
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 a day here
on Earth. The blue-green planet spins around once in a little over seventeen
hours. One of the many odd facts about Uranus is that it is "lying
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 as it
looks at the Sun. For some reason, Uranus has
over, so what we would think of as the south pole is facing the Sun. Scientists
don't know why the planet does 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
Can I See
it is so far away from Earth, and so much smaller than the giant planets
Jupiter and Saturn, it is fairly hard to see. If you live in a place
where the skies are dark and you can see to the southern horizon, you might
be able to pick out Uranus with a pair of binoculars. The planet
will appear as a faint blue-green light. Even through a telescope, Uranus
will only be a small blue-green disc.
How Big Is
is about four times the size of Earth, but it is still much smaller than
either Saturn or Jupiter. Uranus is a little over 30 thousand miles
in diameter, compared to Earth's diameter of around 7,600 miles. Even though
Uranus is much larger than our Earth, it is dwarfed when compared to mighty
Jupiter, which is over 85 thousand miles in diameter.
Does It Have
it does, as all the gas planets do, but the rings of Uranus are a very
faint imitation of the spectacular rings that surround Saturn. The Voyager
spacecraft showed us the rings, which we cannot see at all from Earth.
The only way that Earthbound astronomers can even get a hint of the rings
is 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, as
the picture at right shows. While the rings of Saturn are made up
of fairly small pieces of bright white ices, the rings of Uranus for the
most part are made of larger chunks of very dark, rocky material.
The darkness of the chunks that make up the rings help explain why we
cannot see them from Earth.
How Many Moons
Does It Have?
plain as Uranus appears, it has an interesting collection of at least fifteen
moons. There are probably more, but we don't have any way of finding
out for sure until, and if, we send another spacecraft to investigate.
The five moons in the picture at right are the largest, and furthest away,
of Uranus' family of moons. From top to bottom, they are Miranda, Ariel,
Umbriel, Titania and Oberon. In case you are wondering where such unusual
names came from, they are named after characters in the stories of
William Shakespeare and Alexander Pope. We have known about these moons
for many years.
remaining ten moons in the collection 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 as they attempted
to fly by. This is another of many mysteries about Uranus that scientists
are trying to explain.
How Did It
Get Its Name?
was the first planet to be discovered by an astronomer. It was discovered,
accidentally, by British astronomer William Herschel in 1781. This
meant that someone had to come up with a name for the new planet. Herschel
named it "Georgium Sidus", after the King of England at that time,
George III (the King that Americans rebelled against). This seemed
fair to Herschel, since the King was paying for his research. Grownups
being what they are, others called the planet Herschel, in honor
of the discoverer. Another astronomer suggested the name Uranus, an ancient
Greek god who was the father of Saturn, so the new planet would have a
name from mythology like the rest of the planets at that time, and that
agreed on by everybody in the mid 1800's.
What Is It
is another member of the family of gas planets that live in our solar system,
but it is quite a bit different from Jupiter and Saturn. First, it has
methane gas mixed in with the hydrogen and helium that make up most of
the giant planets. Methane is what gives Uranus its unusual color. Second,
Uranus appears to have a core, or center, of melted rock, which changes
into a dirty ocean made of of water, ammonia and other elements the further
from the center you go. Finally, the dirty ocean changes into the blue-green
cover of clouds that we see in the pictures. Scientists believe that the
layer of the planet are not separate, like those of an onion, but
gradually blend with one another.
Like On The Surface?
Uranus is a gas planet, it doesn't have a solid surface like we have here
on Earth. The top layer of gas that we see is far from quiet, though.
By carefully studying the pictures sent back by the Voyager spacecraft,
scientists were able to see that there are winds blowing at over
four hundred miles an hour!