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Mercury |
Mercury means:
Mercury was the Roman version of
the god Hermes. He was the messenger for the other gods, and for this
reason Mercury is often depicted in pictures with winged sandals. In
addition to delivering messages, he was also the protector of
travelers and merchants.
How much would you weigh on Mercury?
If you moved to Mercury you would not weigh as
much as you do on Earth. Not because you would lose weight on the
space ship, but because Mercury is smaller, and so has less gravity.
If you weigh 70 pounds (32 kg) on Earth, you would weigh only about 27 pounds (12 kg)
on Mercury.
The Planet:
Mercury is a world of
extremes. Because it is so close to the Sun a visitor could
easily cook to death. However, because mercury spins so slowly
it gets very cold in the night time, which means a visitor could also
freeze to death.
We are just starting to
understand this world. It looks a lot like our moon, because it
has craters and basins. Scientists used to think it
acted like the Moon, but we are now learning that Mercury is in
fact very different. In March of 2011, NASAs Messenger probe entered Mercury's orbit. It will soon give scientists a lot of new information about Mercury.
Moons:
Mercury has no moons.
Mercury
is so close to the Sun and so small that it has only a very small
atmosphere. It has been blown away by the Sun's solar winds. That
means that there is almost no air on Mercury. |
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Mercury |
|
1 Orbit of Sun |
87.969 Days |
|
1 Rotation |
58.6461 Days |
|
Mass |
5% of Earth |
|
Volume |
5% of Earth |
|
Escape Velocity |
15,450 km/h
(9,600 mph) |
|
Distance From Sun |
57 million kilometers
(36 million miles) |
|
Maximum Temperature |
465°C
(870° F) |
|
Minimum Temperature |
-184°C
-300° F |
|
Atmosphere |
Hydrogen, Helium |
|
Diameter |
4876 kilometers
(3030 Miles) |
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Venus |
Venus means:
Venus was the Roman goddess of
love and beauty. In Greek her name was Aphrodite.
How much would you weigh
on Venus?
Because Venus and the Earth are
almost the exact same size, you would weigh almost exactly the same
on either planet. If you weighed 70 pounds (32 kg) on Earth, you would weigh
63 pounds (29 kg) on Venus.
The Planet:
Venus is a hostile planet.
Its thick cloud cover makes it impossible to see the surface, and
traps much of the Sun's heat. This extra heat gives Venus
the hottest average temperature of all the planets.
In many ways Venus is similar
to the Earth. It has active volcanoes, venusquakes, mountains
and valleys. The major difference is that Venus' atmosphere
makes the planet far too hot for life.
Moons:
Venus has no moons.
Because
Venus and the Earth are the same size, scientists call Venus Earth's
sister planet. For a long time most scientists thought that Venus had
plants, animals, and possibly even people. However, because Venus is
so hot, we now know that it is impossible for anything to live there. |
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Venus |
|
1 Orbit of Sun |
224.701 Days |
|
1 Rotation |
243.16 Days |
|
Mass |
81% of Earth |
|
Volume |
86% of Earth |
|
Escape Velocity |
37,498 km/h
(23,300 mph) |
|
Distance From Sun |
107 million kilometers
(67 million miles) |
|
Average Temperature |
449°C
(850° F) |
|
Atmosphere |
carbon dioxide, nitrogen, |
|
Diameter |
12,107 kilometers
(7,523 Miles) |
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Earth |
Earth means:
Her name in Greek was Gaea. Earth
was the mother of the mountains, valleys, streams and all other land
formations. She was married to Uranus.
How big is the Earth?
The Earth is the biggest of all
the terrestrial planets. A terrestrial planet is a dense planet found
in the inner Solar System.
The Planet:
Our planet is an oasis of
life in an otherwise desolate universe. The Earth's
temperature, weather, atmosphere and many other factors are just
right to keep us alive.
Moons:
The Earth has one moon.
Its name is Luna.
Scientists
use the Earth to study all the other planets. Since no human has
ever visited another planet, we have to use what we know about the
Earth and try to guess what the other planets must be like. This is
called Comparative Planetology. |
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Earth |
|
1 Orbit of Sun |
365.3 Days |
|
1 Rotation |
23hour 56min |
|
Mass |
|
13,200,000,000,000, |
|
000,000,000,000 |
|
Pounds |
|
|
Volume |
- |
|
Escape Velocity |
67,578 km/h
(25,000 mph) |
|
Distance From Sun |
150 million kilometers
(93 million miles) |
|
Average Temperature |
7.2°C
(45° F) |
|
Atmosphere |
nitrogen, oxygen, argon |
|
Diameter |
12,755 kilometers (7,926
Miles) |
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Mars |
Mars means:
Mars was the Roman god of war and
agriculture. It may not seem like these two things go together, but
they do. Mars protected those who fought for their communities and
stayed home to raise crops for food.
How much would you weigh on Mars?
If you weighed 70 pounds (32 kg) on the
Earth, you would weigh about 27 pounds (12 kg) on Mars.
The Planet:
Mars excites scientists because
its mild temperament is more like the Earth's than any of the other
planets. Evidence suggests that Mars once had rivers,
streams, lakes, and even an ocean. As Mars' atmosphere slowly
depleted into outer space, the surface water began to permanently
evaporate. Today the only water on Mars is either frozen
in the polar caps or underground.
Moons:
Mars has two moons, their names
are Deimos and Phobos.
Mars
has much higher mountains and far deeper canyons than the Earth.
Mars' biggest canyon would stretch from New York City to Los Angeles
on the Earth. That makes the Grand Canyon look tiny. It also has the
Solar System's biggest volcano called Olympus Mons. |
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Mars |
|
1 Orbit of Sun |
686.98 Days |
|
1 Rotation |
24hour 37min |
|
Mass |
10% of Earth |
|
Volume |
15% of Earth |
|
Escape Velocity |
18,024 km/h
(11,200 mph) |
|
Distance From Sun |
229 million kilometers
(142 million miles) |
|
Maximum Temperature |
36°C
(98° F) |
|
Minimum Temperature |
-123°C
(-190° F) |
|
Atmosphere |
carbon dioxide, nitrogen, argon |
|
Diameter |
6794 kilometers
(4222 Miles) |
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Jupiter |
Jupiter means:
Jupiter, known as Zeus in Greece,
over threw his father Saturn to become king of the gods. He then
split the Universe with his brothers Neptune and Pluto.
How much would you weigh on Jupiter?
If you traveled to Jupiter on
vacation you would be very heavy. If you weigh 70 pounds (32 kg) on the
Earth, on Jupiter you would weigh 185 pounds (84 kg).
The Planet:
Jupiter's great red spot
is where a giant storm has been
raging for at least 300 years. Its super hurricane winds blow
across an area larger than the Earth.
This giant planet has no solid
surface. Under its atmosphere is a large liquid ocean of
hydrogen and water. What lies in between that ocean and the
atmosphere? Actually there is no in between. The
atmosphere slowly gets thicker and thicker until it becomes part of
the ocean. In other words, Jupiter's ocean has no surface on
which you could float a boat. The sky slowly becomes the ocean.
Moons:
Jupiter has 62 moons, 50 official and 12 unofficial. The four largest and most well-known were discovered by Galileo in the year 1610. Their names are Io, Europa, Ganymede and Callisto. Some of the other moons are Adrastea, Ananke, Carme, Elara, Himalia, Leda, Lysithea, Metis, Pasiphae, Sinope, and Thebe.
You
can see the four Galilean moons of Jupiter with a pair of binoculars at night.
Also, Jupiter spins really fast. It only takes 10 hours to go from
night to day on Jupiter. For that reason, its middle has been
stretched out. Rather than round it is short and fat. Kind of like
when someone spins pizza dough really fast to stretch it out. |
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Jupiter |
|
1 Orbit of Sun |
4332.59 Days |
|
1 Rotation |
9 hour 55 min |
|
Mass |
317 times more than Earth |
|
Volume |
1318 times more than Earth |
|
Escape Velocity |
214,203 km/h
(133,100 mph) |
|
Distance From Sun |
777 million kilometers
(483 million miles) |
|
Average Temperature |
-153°C
(-244° F) |
|
Atmosphere |
hydrogen, helium, methane |
|
Diameter |
142,983 kilometers
(88,846 Miles) |
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Saturn |
Saturn means:
Saturn was the god of agriculture,
he was called Cronus by the Greeks. He is the son of Uranus, and
father of Jupiter. Saturn over threw his father to become king of the
gods, but was then over thrown himself by his son Jupiter.
How much would you weigh on Saturn?
Because Saturn is bigger than the
Earth, you would weigh more on Saturn than you do here. If you weigh
70 pounds (32 kg) on Earth you would weigh 74.5 pounds (34 kg) on Saturn.
The Planet:
Saturn is a favorite object for
many observers. Its beautiful rings are 169,800 miles wide (approx 273,266 km). But the rings are amazingly thin. If you turned the rings on their side, they would be able to fit between the goal posts on a football field. In many ways Saturn is
similar to Jupiter, but it is much smaller. Under the clouds of
methane and helium, the sky gradually turns into liquid until it
becomes a giant ocean of liquid chemicals.
Moons:
Saturn has 53 official moons and 9 provisional (unofficial) moons. The most well-known of Saturn's moons is probably Titan. It is the second largest moon in the Solar System next to Jupiter's Ganymede. Titan is larger than the planet Mercury. Some of the other moons are Atlas, Calypso, Dione, Enceladus, Hyperion, Iapetus, Janus, Mimas, Phoebe, and Tethys.
Saturn
has several hundred rings. However, it is not the only planet with
rings. Jupiter, Uranus and Neptune also have rings. |
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Saturn |
|
1 Orbit of Sun |
10,759.2 Days |
|
1 Rotation |
10 Hours 13 Min |
|
Mass |
95 times more than Earth |
|
Volume |
744 times more than Earth |
|
Escape Velocity |
127,782 km/h
(79,400 mph) |
|
Distance From Sun |
1,429 million kilometers
(888 million miles) |
|
Average Temperature |
-184°C
(-300° F) |
|
Atmosphere |
hydrogen, helium, methane |
|
Diameter |
120,536 kilometers
(74,898 miles) |
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Uranus |
Uranus means:
Uranus was the lord of the skies
and husband of Earth. He was also the king of the gods until his son
Saturn overthrew him.
How much would you weigh on Uranus?
It would take you many years to
fly a rocket to Uranus. When you arrived you would weigh more because
Uranus is bigger than the Earth . If you weigh 70 pounds (32 kg) on the Earth,
you would weigh 62 pounds (28 kg) on Uranus.
The Planet:
Uranus is very odd.
Unlike all the other planets and most of the moons in our Solar
System, Uranus spins on its side. It is believed that long ago
a very large object smashed into this planet. The crash was so
powerful that it completely changed the direction of Uranus' spin.
Uranus may have an ocean of
water beneath its clouds. It has a large rocky core, and
because of the tremendous pressure could possibly contain trillions
of large diamonds.
Uranus is almost identical to
the planet Neptune.
Moons:
Uranus has 21 moons. Five of these moons are large and the rest are smaller. The largest moon is Titania, followed by Oberon, Umbriel, Ariel and Miranda. Some of the smaller moons are named: Belinda, Bianca, Caliban, Cordelia, Cressida, Desdemona, Juliet, Ophelia, Portia, Puck, and Rosalind.
Scientists
think Uranus has a huge water ocean underneath its clouds. |
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Uranus |
|
1 Orbit of Sun |
30,684 Days |
|
1 Rotation |
17.2 Hours |
|
Mass |
14.6 Times more than Earth |
|
Volume |
67 times more than Earth |
|
Escape Velocity |
76,605 km/h
(47,600 mph) |
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Distance From Sun |
2,871 million kilometers
(1,784 million miles) |
|
Maximum Temperature |
-184°C
(-300° F) |
|
Atmosphere |
hydrogen, helium, methane |
|
Diameter |
51,117 kilometers
(31,763 miles) |
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Neptune |
Neptune means:
Neptune was originally only the
god of water, but was later extended to the ocean when he became
associated with the Greek god Poseidon.
How much would you weigh on Neptune?
If you weigh 70 pounds (32 kg) on the
Earth, you would weigh 78.5 pounds (36 kg) on Neptune.
The Planet:
Neptune has a giant storm much
like the storm on Jupiter. This storm is often called The
Great Dark Spot. We do not know how long this storm has been
active, because it is so far away that we could not get a good view
of Neptune until modern times when we began to send robot explorers.
For many centuries people did
not know that this planet even existed. It was discovered by
Johann Galle and Heinrich D'Arrest in 1846.
Neptune has six rings which
circle the planet.
Moons:
Neptune has 13 moons that we know of. Because Neptune is so far away, it is difficult to see any of these worlds. There are probably many more moons orbiting this blue planet which we have not yet discovered. Perhaps you will be the astronomer who discovers some of these worlds. The first moon to be discovered was Triton. Triton was discovered by an amateur astronomer in England named William Lassell only 17 days after Neptune was discovered in 1846. The names of the other moons are: Despina, Galatea, Halimede, Laomedeia, Larissa, Naiad, Nereid, Neso, Proteus, Psamathe, Sao, and Thalassa.
Like
Uranus, scientists think there is a very large water ocean under
Neptune's clouds. |
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Neptune |
|
1 Orbit of Sun |
60,190 Days |
|
1 Rotation |
16 Hour 17min |
|
Mass |
17 times more than Earth |
|
Volume |
57 times more than Earth |
|
Escape Velocity |
84,651 km/h
(52,600 mph) |
|
Distance From Sun |
4,496 million kilometers
(2,794 million miles) |
|
Average Temperature |
-223°C
(-370° F) |
|
Atmosphere |
hydrogen, helium, methane |
|
Diameter |
49,527 kilometers
(30,775 Miles) |
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Pluto |
Pluto means:
To the Romans, Pluto was thought to
be the god to whom all men must eventually go. They believed him to
be the god of the underworld. His name in Greece was Hades.
How much would you weigh on Pluto?
Because Pluto is so small you
would be very light if you visited. If you weigh 70 pounds (32 kg) on Earth,
you would only weigh 4 pounds (2.5 kg) on Pluto.
The Planet:
Pluto is smaller than 7 of the moons in the Solar System. It is about two-thirds smaller than Earth's moon. Because it is so small, many scientists don't consider it a planet at all. In 1999, a group of scientists attempted to re-classify Pluto as a comet. On August 24, 2006, Pluto's status was officially changed from planet to dwarf planet. For decades, children have been taught in school that there are nine planets in our Solar System. However, with this change, there are now only eight planets. Also because of this change, there is a new category of small planets known as plutoids.
The only spacecraft to get somewhat close to Pluto was the Hubble Space Telescope. Hubble was able to take pictures of Pluto and its moons for scientists to study. Little is known about Pluto and its moons because it is so far away.
Moons:
Pluto has 3 moons. The largest is named Charon. Charon is only slightly smaller than its parent Pluto. For this reason, Pluto and Charon are often called a double system. The Earth and its moon, Luna, are sometimes considered double planets. Pluto's two other moons are called Hydra and Nix.
To learn more about Charon Click
Here.
Pluto
is so far away that no satellites have ever been sent there. This
means that we have no good pictures of it. All we can do is guess
what is must look like. The picture above was taken by the Hubble
Space Telescope. It is the most detailed picture we have. |
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Pluto |
|
1 Orbit of Sun |
90,465 Days |
|
1 Rotation |
6 Days 9 Hours |
|
Mass |
.02% of Earth |
|
Volume |
1% of Earth |
|
Escape Velocity |
15,449 km/h
(9,600 mph) |
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Distance From Sun |
5,869 million kilometers
(3,647 million miles) |
|
Average Temperature |
-234° C
(-390° F) |
|
Atmosphere |
methane, nitrogen |
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Diameter |
2,390 kilometers
(1,485 miles) |
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