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Planets
TERRESTRIALS VS JOVIAN
Terrestrial : having Earth like features; composed
of primarily silicates and rock
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Mercury: closet to the Sun. Because it is so close to the Sun, the
daytime temp can reach 45degrees C ( 840 degrees F) and then
plummet at night to -170C ( -275F). This is due to having no
atmosphere to hold in the temp.
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Mercury is the smallest planet, only slightly larger than our moon.

The Messenger probe has sent back data showing that a huge
meteor impact crater at its North pole contains some ice which may
be water ice, the crater permanently is shades the ice.

Mercury has many craters and cracks which are believed to have
been caused by impacts and volcanic activity during its forming
stages.
More about Mercury

Mercury is the second densest planet after Earth, with a huge metallic
core roughly 2,200 to 2,400 miles (3,600 to 3,800 km) wide, or about 75
percent of the planet's diameter. In comparison, Mercury's outer shell is
only 300 to 400 miles (500 to 600 km) thick. The combination of its
massive core and abundance of volatile elements has left
scientists puzzled for years.

A completely unexpected discovery Mariner 10 made was that
Mercury possessed a magnetic field. Planets theoretically generate
magnetic fields only if they spin quickly and possess a molten core. But
Mercury takes 59 days to rotate and is so small — just roughly one-third
Earth's size — that its core should have cooled off long ago. The
discovery in 2007 by Earth-based radar observations that Mercury's core
may still be molten could help explain its magnetism, though the solar
wind may play a role in dampening the planet’s magnetic field
Orbit and rotation of Mercury

Average distance from the sun: 35,983,095 miles (57,909,175 km). By
comparison: 0.38 Earth's distance from the Sun.

Perihelion (closest approach to sun): 28,580,000 miles (46,000,000
km). By comparison: 0.313 times that of Earth

Aphelion (farthest distance from sun): 43,380,000 miles (69,820,000
km). By comparison: 0.459 times that of Earth

Length of Day: 58.646 Earth-days

Revolution around Sun: 88 Earth days, traveling through space at
nearly 112,000 mph (180,000 kph)
Venus: Our Twin

Venus, the second planet from the sun, is named for the Roman
goddess of love and beauty. The planet — the only planet named
after a female — may have been named for the most beautiful
deity of her pantheon because it shone the brightest of the five
planets known to ancient astronomers.
Venus and Earth are often called twins because they are similar in size,
mass, density, composition and gravity.

Venus is the hottest world in the solar system. Although Venus is not
the planet closest to the sun, its dense atmosphere traps heat in a
runaway version of the greenhouse effect that warms Earth. As a
result, temperatures on Venus reach 870 degrees Fahrenheit (465
degrees Celsius)

Atmosphere: carbon dioxide with clouds of sulfuric acid, and
scientists have only detected trace amounts of water in the
atmosphere, very dense about 90 times that of Earth

There is no water on the surface due to the thick, ozone-filled
atmosphere which would boil it away

There are flat plain areas that a marked by thousands of volcanoes,
there are also 6 mountainous regions
Orbit, rotation, and composition

Average distance from the sun: 67,237,910 miles (108,208,930 km). By
comparison: 0.723 times that of Earth

Perihelion (closest approach to sun): 66,782,000 miles (107,476,000
km). By comparison: 0.730 times that of Earth

Aphelion (farthest distance from sun): 67,693,000 miles (108,942,000
km). By comparison: 0.716 times that of Earth

Magnetic field: 0.000015 times that of Earth's field.

Internal structure: Venus' metallic iron core is roughly 2,400 miles
(6,000 km) wide. Venus' molten rocky mantle is roughly 1,200 miles
(3,000 km) thick. Venus' crust is mostly basalt, and is estimated to be
six to 12 miles (10 to 20 km) thick on average.

Venus takes 243 Earth days to rotate on its axis, by far the slowest of
any of the major planets, and because of this sluggish spin, its metal
core cannot generate a magnetic field similar to Earth's
A different spin:

If viewed from above, Venus rotates on its axis the opposite way
that most planets rotate. That means on Venus, the sun would
appear to rise in the west and set in the east. On Earth, the sun
appears to rise in the east and set in the west.

The Venusian year — the time it takes to orbit the sun — is about 225
Earth days long. Normally, that would mean that days on Venus
would be longer than years. However, because of Venus' curious
retrograde rotation, the time from one sunrise to the next is only
about 117 Earth days long.
Mars: The Red Planet

Average Distance from Sun : 142 million miles

Average Speed in Orbiting Sun:14.5 miles per second

Diameter 4,220 miles about half of Earth

Tilt of Axis: 25 degrees which causes longer seasons on
each hemisphere.
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Length of Year 687 Earth Days

Length of Day 24 hours 37 minutes
Temps and Gravity

Gravity is 62.5 % less on Mars, so if you weighed
about 100 lbs. on Earth you would only weigh
about 38 lbs. on Mars

Scientists are not yet sure if the core is solid,
liquid, or in 2 sublayers like Earth. They are also
trying to confirm the presence of water.

Mars has ice caps at its poles. The atmosphere is
extremely thin and consists mainly of carbon
dioxide.
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Temperature on Mars varies from -287 F to 81 F
Features on Mars
Mars has some of the most highly varied and interesting
terrain of any of the terrestrial planets, some of it quite
spectacular:
• Olympus Mons: the largest mountain/ volcano in the
Solar System rising 24 km (78,000 ft.) above the surrounding
plain. Its base is more than 500 km in diameter and is
rimmed by a cliff 6 km (20,000 ft) high.
• Valles Marineris: a system of canyons 4000 km long and
from 2 to 7 km deep (top of page);
• Hellas Planitia: an impact crater in the southern
hemisphere over 6 km deep and 2000 km in diameter.
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Jovians: gas giants of the outer
solar system, Jupiter-like

Jupiter is the most massive planet in our solar system,
more than twice as massive as all the other planets
combined, and had it been about 80 times more
massive, it would have actually become a star instead of
a planet.

Its atmosphere resembles that of the sun, made up
mostly of hydrogen and helium, and with four large
moons and many smaller moons in orbit around it,
Jupiter by itself forms a kind of miniature solar system. All
told, the immense volume of Jupiter could hold more
than 1,300 Earths.
Jupiter: features

Great Red Spot, a giant hurricane-like storm seen for
more than 300 years

Jupiter's gargantuan magnetic field is the strongest of all
the planets in the solar system at nearly 20,000 times the
strength of Earth's

Jupiter's three rings came as a surprise when NASA's
Voyager 1 spacecraft discovered them around the
planet's equator in 1979. Each are much fainter than
Saturn's rings.

As the most massive body in the solar system after the
sun, the pull of Jupiter's gravity has helped shape the
fate of our system
Orbit and more Facts:
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Average distance from the sun: 483,682,810 miles

Perihelion (closest approach to the sun): 460,276,100
miles

Aphelion (farthest distance from the sun): 507,089,500
miles
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Atmosphere consists of: hydrogen, helium, methane,
sulfur, some trace water

Jupiter appears to have a dense core of unknown
material

The core is less that of Earth and is surrounded by liquid
hydrogen

Jupiter currently has 69 recognized moons and others on
a list
Saturn:
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Saturn is the second largest planet. Saturn has seven thin, flat rings
around it. Saturn's diameter at its equator is 74,600 miles which is
almost ten times that of Earth. The planet can be seen from Earth
with the unaided eye, but its rings cannot. Saturn was the farthest
planet from the earth that the ancient astronomers knew about.
They named Saturn after the Roman God of agriculture.
Saturn Facts

A 100 pound object on Earth would weight 116 pounds on Saturn.
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Saturn has the lowest density of all the planets in the solar system. It is
so light that it could actually float on water if there was an ocean
big enough to hold it.
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It takes about 29.46 Earth years for Saturn to orbit around our sun.
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Saturn has no solid surface. It is a giant ball of gas, but it does have
a solid inner core.
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The temperature difference between the poles and the equator is
very small on Saturn.
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The atmosphere of Saturn comprises mostly of Hydrogen and
Helium.
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Titan is the only Saturn Moon with an atmosphere.
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Titan is also larger than the planet Mercury
More about Saturn
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A day on Saturn is equal to 10 hours and 14 minutes in Earth days.
Saturn’s maximum distance from the Sun is 1.5 billion km (938 million
miles).
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Pioneer 11 did the first flyby of the planet in 1979. Since then,
Voyager 1 was sent closer to Saturn and it took much higher quality
photographs.
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In 2004 the Cassini-Huygens space probe entered into orbit around
Saturn and also took vivid photos of some of the planet's moons.
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The day of the week, Saturday, is named after Saturn.
Uranus
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Uranus is the seventh planet from the Sun and the third largest (by
diameter). Uranus is larger in diameter but smaller in mass than
Neptune
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Uranus has been visited by only one spacecraft, Voyager 2 on Jan
24 1986.
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Most of the planets spin on an axis nearly perpendicular to the
plane of the ecliptic but Uranus' axis is almost parallel to the ecliptic.
At the time of Voyager 2's passage, Uranus' south pole was pointed
almost directly at the Sun. This results in the odd fact that Uranus'
polar regions receive more energy input from the Sun than do its
equatorial regions. Uranus is nevertheless hotter at its equator than
at its poles. The mechanism underlying this is unknown.

Uranus' atmosphere is about 83% hydrogen, 15% helium and 2%
methane.
Uranus facts
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blue color is the result of absorption of red light by methane in the
upper atmosphere. There may be colored bands like Jupiter's but
they are hidden from view by the overlaying methane layer.
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Like the other gas planets, Uranus has rings. Like Jupiter's, they are
very dark but like Saturn's they are composed of fairly large particles
ranging up to 10 meters in diameter in addition to fine dust. There
are 13 known rings, all very faint; the brightest is known as the Epsilon
ring
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It has 27 known and named moons
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Even though Uranus is tipped on its side and experiences seasons
that last over 20 years, the temperature differences on the summer
and winter sides do not differ greatly because the planet is so far
from the sun. Near the cloud tops, the temperature of Uranus is -357
degrees Fahrenheit (-216 degrees Celsius).