Long considered to be the smallest, coldest,
and most distant planet from the Sun, Pluto may also be the largest of
a group of objects that orbit in a disk-like zone of beyond the orbit of
Neptune called the Kuiper Belt. This distant region consists of thousands
of miniature icy worlds with diameters of at least 1,000 km and is also
believed to be the source of some comets.
Pluto is a very long way from the Sun.
Its average distance from the Sun is over 3.5 billion (3,500,000,000) miles.
The closest Pluto gets to the Sun is over 2.7 billion (2,700,000,000)
miles, and the furthest away it gets is over 4.5 billion (4,500,000,000)
miles From Pluto, the Sun is not much brighter than any other star. Not
only is Pluto a very long way from the Sun, but its orbit is tilted. If
you could look at our solar system from an "edge", most of the planets
would be on a line like a table top, with the Sun being in the
middle. This line, also called
a plane, is the ecliptic, and the rest of the planets' orbits stay on this
line. Pluto's orbit, though is tilted at an angle to the rest of the solar
system. Since Pluto is so far away from the Sun, one of its years, which
is the time it takes for the planet to go around the Sun once, is a very
long time. A year on Pluto lasts
for 248 Earth years! A day on Pluto, which is the length of time it takes
for the planet to spin around once, is also longer than a day here on Earth.
It takes Pluto over six Earth days to spin around once. Pluto is also one
of the planets that spins around in the opposite direction from Earth.
This means that the dim Sun would rise in the West and set in the East.
Can I See It?
Probably
not, even if you have a telescope. Pluto is so tiny, and so far away, that
you will need a telescope that is at least ten inches in diameter. You
will also need to know exactly where to look for it. If there is an observatory
close to where you live, you might be able to see it through their telescope.
Even if you can find the planet, it will be nothing more than a pinpoint
of light among the stars.
How Big Is
It?
Pluto is
the smallest planet in our solar system at a little over 1,300 miles in
diameter, or about one-sixth the diameter of Earth. Put another way, if
Earth was the size of a basketball, Pluto would be the size of a ping-pong
ball. Many of the moons of other planets, including our very own
Moon, are larger than Pluto.
How Many Moons
Does It Have?
Pluto has
one tiny moon, named Charon, that wasn't discovered until 1978. Charon
is half the size of Pluto. No other moon in the solar system is as large,
when compared to its mother planet, as Charon. Pluto and Charon are so
similar in size that some astronomers think of them as a double planet.
How Did It
Get Its Name?
Pluto was
discovered in 1930 by astronomer Clyde Tombaugh. After Neptune was discovered,
astronomers noticed that something was changing the orbits of Uranus
and Neptune and decided that there must be another undiscovered planet
that was causing these changes. Mr. Tombaugh spent a long time taking
photographs of the area of the sky where the unknown planet should be and
finally discovered Pluto in one of the photographs. Pluto is the Roman
god of darkness and the underworld. Perhaps Pluto got its name because
it is always in darkness. It may have also gotten its name from the fact
that its symbol "PL" are the initials of Percival Lowell, who founded
the observatory where Mr. Tombaugh worked.
What Is It
Made Of?
Pluto is
the only planet in our solar system that we have not explored with a spacecraft.
What we know about the dark, frozen world is the result of many years of
work by dedicated scientists here on Earth. The current studies tell us
that Pluto is made up of a mixture of rocks and several kinds of
"ices". Scientists believe that most of the ices that make up Pluto are
frozen methane and ammonia.
What's It Like
On The Surface?
The surface
of Pluto is very dark and extremely cold. Since the planet is so far away
from the Sun, it gets almost no light or heat. Scientists believe that
the temperature on the surface of the ninth planet over over four hundred
degrees Fahrenheit below zero. At this low temperature, almost everything
freezes solid. Scientists here on Earth have determined that Pluto does
have a very thin atmosphere, but it is far too thin to support any kind
of life. is the ninth, or last, planet in the solar system. The orbit,
or path the planet takes around our Sun is an ellipse, or stretched out
circle. For this reason there are times when Pluto is the furthest away
from the Sun. There are also times when it is closer to the Sun than Neptune.
Right now, Pluto is the furthest planet.
