Transcript The Terrestrial Planets

The Solar System Missions
The Missions
http://www.jpl.nasa.gov/solar_system/index.cfm
planets not shown to scale >>
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
Mean Distance from the Sun (AU)
0.3871
0.7233
1
1.524
5.203
9.539
19.19
30.06
39.48
Sidereal period of orbit (years)
0.24
0.62
1
1.88
11.86
29.46
84.01
164.79
248.54
Mean Orbital Velocity (km/sec)
47.89
35.04
29.79
24.14
13.06
9.64
6.81
5.43
4.74
Orbital Eccentricity
0.206
0.007
0.017
0.093
0.048
0.056
0.046
0.010
0.248
Inclination to ecliptic (degrees)
7.00
3.40
0
1.85
1.30
2.49
0.77
1.77
17.15
Equatorial Radius (km)
2439
6052
6378
3397
71490
60268
25559
25269
1160
Polar Radius (km)
same
same
6357
3380
66854
54360
24973
24340
same
Mass of planet (Earth=1)
0.06
0.82
1
0.11
317.89
95.18
14.53
17.14
0.002
Mean density (grams/centimeter³ )
5.43
5.25
5.52
3.95
1.33
0.69
1.29
1.64
2.03
Body rotation period (hours)
1408
5832
23.93
24.62
9.92
10.66
17.24
16.11
153.3
Tilt of equator to orbit (degrees)
2
177.3
23.45
25.19
3.12
26.73
97.86
29.6
122.46
Number of observed satellites
0
0
1
2
>28
30
24
8
1
Mercury
Mercury is the planet nearest to the sun. It is difficult to observe from the Earth
because it rises and sets within two hours from the sun. It is estimated that Mercury
was formed about 4 billion years ago. Scientist are still not exactly sure because
very little was know about it until about 1974. The estimate was based on the
craters on Mercury's surface. It is said that the older the planet is the more craters
the surface has. Mercury has a very dense and thin atmosphere of hydrogen,
helium, potassium and sulfur surrounds the planet. Mercury revolves around the
Sun of 87.97 Earth days.
Mercury
Messenger of gods
Mercury is the fastest traveling planet so in mythology,
he is referred to as the messenger of gods because of
his agility. His symbol represents a snake entwined on
a staff for protection. Mercury ís Greek name is
Hermes and is the son of Jupiter and Maia, the
goddess of the fields born in the cave of Arcadia.
Mercury was given a staff, winged sandals, etc. When
Mercury stole Apollo's cows, he was known as the god
of thieves, travelers, commerce, athletes, etc. Jupiter,
later gave him a place in the Olympian home. Mercury
was part of many myths; he saved Dionysus and had
four children, and he helped Pluto by guiding the spirits
of the dead into the underworld. In astrology, Mercury
symbolizes intelligence, communication and
transportation. The element mercury is named after the
god.
Mercury
Mercury Facts Sheet:
Type: Terrestrial
Mass of planet (Earth=1) =0.06
Mean density (grams/centimeter³ ) = 5.43
Interior: Metallic core about ¾ of the planet’s
radius, rocky mantle and crust
Surface: heavily cratered
Water: Frozen ice in permanently shadowed
portion of north and south poles
Atmosphere: No significant atmosphere
Moons: 0
Mercury’s Interior
Mercury is an important part of the Solar
System puzzle, yet we know less about it than
any other planet, except Pluto. Mercury is the
smallest of the inner, rocky planets (Mars,
Earth, and Venus) and the closest to the Sun.
Its relatively high density (5.4 grams per cubic
centimeter) indicates that it has a large
metallic core (about 3/4 of the planet's radius)
compared to its rocky mantle and crust. The
surface is heavily cratered like the highlands
of the Moon, but some areas are smooth and
less cratered, possibly like the lunar maria
(but not as dark). Radar data suggest that
Mercury, like the Moon (see PSRD article Ice
on a Bone Dry Moon), has deposits of water
ice in permanently shadowed areas at the
poles. Unlike the Moon, where water is only at
the south pole, Mercury has ice at both poles.
(The water composing the ice deposits
probably came from comets hitting the
surface.)
Mercury’s Atmosphere
So far, observations of Mercury from groundbased observers and the Mariner 10 spacecraft
have not shown evidence of a significant
atmosphere compared to other planets. Mariner
10 did observe a tiny amount of helium 1000 km
above the surface, but this is probably produced
by capturing particles from the solar wind and
radioactive decay of Mercury's crust. Other
elements observed in Mercury's extremely
tenuous atmosphere (which exerts a pressure
one million billionths that of Earth) include
sodium, potassium and oxygen. When these
gases are ionized by solar radiation, they are lost
to the atmosphere through the interaction of the
planet's magnetic field with the solar wind.
Temperatures at the surface range between -300
and 800oF (hot enough for lead to melt). This
large range in surface temperature is possible
because Mercury is so close to the Sun (a year
is only 88 Earth days long) and does not have
sufficient atmosphere present to moderate the
range in surface temperature.
Mercury’s Volcanoes (?)
The smooth areas inside the larger craters in this
photo of Mercury may be volcanic plains,
somewhat like the maria on the Moon. There are
many such smooth plains on Mercury. Some
scientists hbave suggested that the plains were
formed by rapidly-flowing material ejected from
immense impact craters (called basins).
However, the plains have smaller numbers of
craters on them than do the ejecta blankets of
impact basins, indicating a younger age. On
some smooth plains, such as those inside the
Caloris Basin, sinuous rilles occur, which are
thought to be either lava channels or collapsed
lava tubes, again suggesting a volcanic origin for
the smooth plains.
http://www.psrd.hawaii.edu/Jan97/MercuryUnveiled.html
Mercury’s Atmosphere
Most important, the blue area has fuzzy
boundaries that seem to grade into the
surroundings. This is what one would
expect for a pyroclastic deposit. It is
also similar to debris from an impact,
but there is no crater in the center that
would act as a source for the deposited
material. In fact, the dark blue materials
lie along a straight segment of a border
of Homer, similar to some volcanic
fissures on the Moon.
This 1959 pyroclastic eruption
at Kilauea volcano in Hawaii
sent lava up to 550 meters into
the air.
Venus
Venus is the closest planet to the Earth, it is also most similar to Earth in mass,
size and density. Venus rotates once every 243 days in a retrograde motionwhich means that it rotates in a direction opposite to the rotation of the other
planets. (Clockwise when viewed from above the Earth's North Pole). When
Earth and Venus meet in their orbit around the Sun, Venus is always facing Earth
with the same side. Venus atmosphere is mostly made up of carbon dioxide. The
surface temperature is about 450 C which is even hotter than Mercury's "noon"
temperature. Scientists believe that Venus is only about 400 million years old.
Venus
Goddess of Love and Beauty
Venus was a very special goddess in Greek and Roman
mythology. She is named after a woman, and her symbol
represents a hand mirror. Venus was named after the goddess
of love and beauty. In Greek, her name was Aphrodite. The
Chinese called Venus Tai-pe, which means "the beautiful white
one", the Babylonians called Venus Ishtar, which means "the
bright torch of heaven". Venus was born in the sea and was
carried to the Greek island of Cyprus. Venus was so beautiful
that the gods of Olympus each presented her with a gift to marry
him. Jupiter put Venus with the ugly and lame god, Vulcan, who
made a magic girdle for her that made her irresistible. Venus fell
in love with Mars instead. She had a child Cupid or Eros, who is
the god of love. Venus also had many lovers and children. Venus
loved the glamour of love. Her son, Cupid married Psyche, a
daughter of a king. Venus originally came from Western Asia into
Greek mythologies. Her planet has two names: Phosperous
"Morning Star" and Hesperus "Evening Star". Some symbols of
Venus are the myrtle tree, the swan, sparrow, dove, turquoise
and the emerald. Venus represents femininity, love, aesthetics,
grace and beauty in astrology.
Venus
Venus Facts Sheet:
Type: Terrestrial
Mass of planet (Earth=1) = 0.82
Mean density (grams/centimeter³ ) = 5.25
Interior: Iron core about 3000 km radius,
rocky mantle and crust
Surface: volcanic and cratered
Water: Probable in the past
Atmosphere: Primarily Carbon Dioxide,
clouds of sulfuric acid
Moons: 0
Venus
Venus is the second planet from the Sun, and is Earth's neighbor in the solar system. Venus is the
brightest object in the sky after the Sun and the Moon, and sometimes looks like a bright star in the
morning or evening sky. We can't see the surface of the planet because it has a very thick atmosphere
filled with clouds that strongly reflect sunlight. Observations of Venus in the ultraviolet show cloud features
that relate to characteristics of the planet's atmosphere. Venus is slightly smaller than Earth, and
considering its neighboring position in the solar system might be expected to be similar to Earth. We think
that the internal structure of Venus is similar to Earth, with a metallic core, rocky mantle, and crust. The
atmosphere of Venus produces hostile conditions at the planet's surface, where temperatures can reach
more than 460C (900F), atmospheric pressure is 90 times that at the Earth's surface, and clouds filled with
sulfuric acid surround the planet. Nonetheless, space missions sent to Venus have managed to land on
and photograph the surface while the Magellan spacecraft mapped the surface of the planet from above.
These maps reveal a surface covered with craters, over 1600 major volcanoes, mountains, large highland
terrains, and vast lava plains.
The interior of Venus is probably very similar to that of Earth: an iron core about 3000 km in radius, a
molten rocky mantle comprising the majority of the planet. Recent results from the Magellan gravity data
indicate that Venus' crust is stronger and thicker than had previously been assumed. Like Earth,
convection in the mantle produces stress on the surface which is relieved in many relatively small regions
instead of being concentrated at plate boundaries as is the case on Earth.
Venus has no magnetic field, perhaps because of its slow rotation.
Venus has no satellites, moons.
Venus is usually visible with the unaided eye. Sometimes (inaccurately) referred to as the "morning star"
or the "evening star", it is by far the brightest "star" in the sky. There are several Web sites that show the
current position of Venus (and the other planets) in the sky. More detailed and customized charts can be
created with a planetarium program such as Starry Night.
Venus
The atmosphere of Venus is very hot and thick. If you
were on the surface of the planet, the air above you would
be about 90 times heavier than the Earth's atmosphere.
This is like what a submarine experiences at 3000 ft below
the surface of the Earth's ocean. The atmosphere is
composed mainly of carbon dioxide (96%), 3.5% nitrogen,
and less than 1% is made up of carbon monoxide, argon,
sulfur dioxide, and water vapor.
All this carbon dioxide in the air has produced at strong
greenhouse effect, which traps heat in the atmosphere. A
small amount of sunlight can penetrate the planet's thick
cloud layer (about 2%) without being reflected by the
sulfuric acid clouds or absorbed by the atmosphere.
Whatever sunlight does make it through heats the surface,
and is reemitted in the infrared. But virtually all energy
emitted by the planet in the infrared (heat radiation) is
absorbed by the carbon dioxide rich air. The result is
unusually high surface temperatures of about 460C
(860F).
Why should Venus and not the Earth have a hot and thick
atmosphere? Some scientists call it the Goldilocks
phenomenon.
Measurements made by probes which travelled through
the atmosphere have shown that temperature varies no
more than a few degrees from the equator to the poles,
and that the atmospheric temperature remains nearly
constant through the long dark night. Thus there are no
significant daily, seasonal, or latitudinal temperature
gradients in the atmosphere.
Venus
The pressure of Venus' atmosphere at the surface is 90 atmospheres (about the same as
the pressure at a depth of 1 km in Earth's oceans). It is composed mostly of carbon dioxide.
There are several layers of clouds many kilometers thick composed of sulfuric acid. These
clouds completely obscure our view of the surface. This dense atmosphere produces a runaway greenhouse effect that raises Venus' surface temperature by about 400 degrees to
over 740 K (hot enough to melt lead). Venus' surface is actually hotter than Mercury's
despite being nearly twice as far from the Sun.
There are strong (350 kph) winds at the cloud tops but winds at the surface are very slow,
no more than a few kilometers per hour.
Venus probably once had large amounts of water like Earth but it all boiled away. It is now
quite dry. Earth would have suffered the same fate had it been just a little closer to the Sun.
We may learn a lot about Earth by learning why the basically similar Venus turned out so
differently.
Most of Venus' surface consists of gently rolling plains with little relief. There are also
several broad depressions: Atalanta Planitia, Guinevere Planitia, Lavinia Planitia.
There two large highland areas: Ishtar Terra in the northern hemisphere (about the size of
Australia) and Aphrodite Terra along the equator (about the size of South America). The
interior of Ishtar consists mainly of a high plateau, Lakshmi Planum, which is surrounded by
the highest mountains on Venus including the enormous Maxwell Montes.
Venus
The interior of Venus is probably very similar to that of Earth: an iron core about
3000 km in radius, a molten rocky mantle comprising the majority of the planet.
Recent results from the Magellan gravity data indicate that Venus' crust is
stronger and thicker than had previously been assumed. Like Earth, convection
in the mantle produces stress on the surface which is relieved in many
relatively small regions instead of being concentrated at plate boundaries as is
the case on Earth.
Venus has no magnetic field, perhaps because of its slow rotation.
Venus has no satellites, moons.
Venus is usually visible with the unaided eye. Sometimes (inaccurately)
referred to as the "morning star" or the "evening star", it is by far the brightest
"star" in the sky. There are several Web sites that show the current position of
Venus (and the other planets) in the sky. More detailed and customized charts
can be created with a planetarium program such as Starry Night.
Venus
Magellan's images
show a wide variety of
interesting and unique
features including
pancake volcanoes
which seem to be
eruptions of very thick
lava and coronae which
seem to be collapsed
domes over large
magma chambers.
Venera Lander (USSR)
Earth
Earth is the only planet known to have the right temperature and the right
atmosphere to support the kind of life humans know. Some scientists believe that
millions of planets in the Milky Way, (the galaxy that contains the Earth), maybe
able to support life, yet no one can predict anything. Many plants and animals have
developed on Earth.. Many people believe that Earth is the only planet in the solar
system that can support life. The Earth takes 365 days to orbit the Sun. Most of the
earth is composed of water. Only about 1% of that is good for human-kind to drink.
Earth
Goddess of Death
Earth is known as Terra Mater in Roman and Gaea in Greek. Her
symbol is a sphere or the earth. She was the first goddess on earth.
She gave birth to Uranus, whoís also known as ìfather skyî. Gaea
and Uranus had children, the hundred-headed, the Cyclops and then
the Titans who were very powerful. Since Uranus thought that his
children were ugly, he was very cruel to them. Gaea got angry and
told one of the Titans to overthrow their father with a scythe. He
created the giants, Erinnyes and the beautiful Venus with his blood.
Cronus, the Titan, ruled the universe. He had children with his sister,
and had children, which included Jupiter, Demeter, Pluto, Neptune,
Hera, etc. Jupiter and his sisters and brothers had a war with their
father for trying to eat them, but legend says that the one who
overthrows his father, their children will overthrow them. Gaea gave
birth to another monster called Typhon, which Jupiter easily defeated
with his lighting and bolt. Gaea is known as the Goddess of Death
because she is like the Earth which eventually brings the dead back
to life.
This photo was
taken in
December 1972
by the Apollo 17
crew. The
spacecraft was
traveling between
the Earth and the
Moon. The redish
landmass is
Africa and Saudi
Arabia which is
desert. The white
is both clouds
and the ice
covering
Antarctica.
(Courtesy
NASA/JPL)
This United States is a mosaic prepared by using 16 images from the Advanced Very High Resolution
Radiometer (AVHRR) sensors on the meteorological satellites NOAA-8 and NOAA-9. The images were
taken between May 24, 1984 and May 14, 1986. On false-color infrared mosaics, vegetation appears in
red instead of green. The "redness" indicates vegetation density, type and whether growing on dry land or
in a swamp. Grasslands appear light red, deciduous trees and croplands appear red, and coniferous
forests appear dark red or maroon. Desert areas appear white and urban areas appear bluish green.
Lakes, rivers and oceans appear in various shades of blue, dark blue for deep water and light blue for
shallow or turbid water. (Courtesy USGS)
Image of clouds taken by the STS-63.
This is an image of the sunrise from space over the South China Sea. An astronaut would see
something like this; clearly defined bands of color through the atmosphere as the sun rises. Highpeaking cumulus clouds, topping out in anvil-head cirrus can be seen as black shadows against the
sunlit horizon. The brightness of the colors in the atmosphere in this photograph is due to the amount
of dust in the atmosphere. More dust is found in near the equator. There are various sources for such
upper level
This is an image taken of cumulonimbus clouds in the
atmosphere.
Aris Multimedia Entertainment, Inc. 1994
This is an image of a Cyclonic Storm.
Aris Multimedia Entertainment, Inc. 1994
This is an image of a tropical storm.
(courtesy of Aris Multimedia
Entertainment, Inc. 1994)
This is a satellite image taken of
Mount St. Helens Volcano on
October 16, 1994 from STS-64.
This volcano erupted on May 18,
1980 in Washington.
Corel Photography
This is an image of the sun reflecting on the ocean
Aris Multimedia Entertainment, Inc. 1994
This is a picture of the Colorado River.
Aris Multimedia Entertainment, Inc. 1994
This image shows the topography of the ocean floor.
(the Clausthal Mineral Collection, Institute for Mineralogy and Mineral
Resources, Technical University of Clausthal; phbotograph by A.K. Schuster.)
Mars
Since ancient times Mars has been an interest to astronomers. Mars is about half
the size of Earth. Its atmosphere is composed mostly of carbon dioxide. Liquid
water does not exist on Mars because of low temperature and pressure. Water
exists only at ice form on the poles of Mars. Another thing about Mars is that it has
the largest volcano in our solar system, Olympus Mons. At a height of 27
kilometers, the volcano is 3 times higher than Mount Everest and it covers an area
the size of Arizona.
Mars
God of War
Mars is the god of war. His Greek name is Ares and
the son of Jupiter and Hera. Mars never married but
had three children with Venus. Mars loved war and
battle, so many people saw him as a violent god.
His animal is the vulture and the tree but it was said
to be a dog. Mars is the opposite of Venus and his
sign is the male symbol, which represents a shield
and a spear. In astrology, Mars shows your energy,
strength, courage and passion.
Mars
Mars Facts Sheet:
Type: Terrestrial
Mass of planet (Earth=1) = 0.11
Mean density (grams/centimeter³ ) = 3.95
Interior: rocky
Surface: volcanic, cratered, evidence of river
systems
Water: ????
Atmosphere: Primarily Carbon Dioxide,
clouds consist of water ice condensed on
dust
Moons: 2
Mars
Mars has an average diameter of 4,217 miles. This is about half
the size of Earth, and about twice the size of Earth's moon.
Despite its small size, Mars has approximately the same land
area as Earth, primarily due to an absence of liquid water on its
surface.
The mass of Mars is about 10 percent that of Earth, and its
gravity is about 38 percent as strong as our planet. The density
of martian land is 3.9 times greater than liquid water -- on
Earth, land density is 5.5 times greater. Mars has no detectable
magnetic field.
The martian atmosphere is composed of 95.3 percent carbon
dioxide, 2.7 percent nitrogen and 1.6 percent argon. This would be
sufficient to suffocate a human in a matter of minutes. The
atmospheric pressure there is about 1 percent that of Earth's.
Surface winds have been measured to a maximum of 80 m.p.h. -comparable to hurricane force on Earth.
Dust storms occur frequently on Mars. These can be local,
regional or can cover the entire planet. Dust can reach as high as
six miles above the surface and settles very slowly.
Surface temperatures average -64 degrees Fahrenheit, measured
from a minimum -199 degrees Fahrenheit during polar night to a
maximum +80 degrees Fahrenheit at the martian equator.
Mars
The uniquely red global surface of Mars
is marked by many interesting features some like those on the Earth and others
strangely different. The reddish color is
caused by rust (iron oxide) in the soil.
Some of these features are; volcanoes,
canyon systems, river beds, cratered
terrain, and dune fields.
Of these features, the most interesting
includes the apparently dead volcano
Olympus Mons, which rises 23 km
(~75,000 ft) above the surrounding plains
and is the highest known peak in the
Solar System. Valles Marineris is a giant
canyon system that runs about 2,500
miles across the surface of the planet
and reaches depths of 6 km or 4 miles
(for comparison, the Grand Canyon is
not more than 1 mile deep).
The atmosphere of Mars is much thinner
than that of Earth, with a surface
pressure averaging 1/100th that at the
surface of the Earth. Surface
temperatures range from -113oC at the
winter pole to 0oC on the dayside during
summer.
Although the length of the Martian day
(24 hours and 37 minutes) and the tilt of
its rotational axis (25 degrees) are similar
to the values for these parameters on
Earth (24 hours and 23.5 degrees), the
eccentric orbit of the planet about the
Sun impacts the lengths of the seasons
the most. The atmosphere is composed
mainly of carbon dioxide (95.3%),
nitrogen (2.7%), and argon (1.6%), with
trace amounts of other gases. Oxygen,
which is so important to us on earth,
makes up only 0.13% of the atmosphere
at Mars. There is only one-fourth as
much water vapor in the atmosphere.
Although small, this is thought to be
enough to allow water ice to be frozen
into the near subsurface at mid to high
latitudes. With so little water, clouds are
rarely seen in the Martian sky. The
possible role in the distant past of liquid
water in forming the dry river beds which
we can see is still unknown, particularly
because water ice is not plentiful on the
surface of the planet.
Mars
HST
Olympus Mons
Olympus Mons
Viking Landing Site
South Candor Chasm
Valles Marineris
Valles Marineris
South Polar Ice Cap
Viking Lander 1
Sand Dunes Near South Pole
Martian Clouds from Pathfinder
Sunset on Mars
Surface features and soils observed by pathfinder
Spirit and Opportunity
This stunning image features the heat shield impact site of NASA's Mars
Exploration Rover Opportunity. This is an approximately true-color mosaic of
panoramic camera images taken through the camera's 750-, 530-, and 430nanometer filters.
Spirit and Opportunity
Scientists working with NASA's Mars Exploration Rover Spirit decided to examine
this rock, dubbed "Wishstone," based on data from the miniature thermal emission
spectrometer.
Deimos (left) and Phobos (right)
Phobos
The Question of Water
Mars – Hot off the Presses
'Pack ice' suggests frozen sea on Mars
11:48 21 February 2005
NewScientist.com news service
Kelly Young
A frozen sea, surviving as blocks of pack ice, may lie just beneath
the surface of Mars, suggest observations from Europe's Mars
Express spacecraft. The sea is just 5° north of the Martian
equator and would be the first discovery of a large body of water
beyond the planet's polar ice caps.
Images from the High Resolution Stereo Camera on Mars
Express show raft-like ground structures - dubbed "plates" - that
look similar to ice formations near Earth's poles, according to an
international team of scientists.
But the site of the plates, near the equator, means that sunlight
should have melted any ice there. So the team suggests that a
layer of volcanic ash, perhaps a few centimetres thick, may
protect the structures.
"I think it's fairly plausible," says Michael Carr, an expert on
Martian water at the US Geological Survey in Menlo Park,
California, who was not part of the team. He says scientists had
previously suspected there was a past water source north of the
Elysium plates. "We know where the water came from," Carr told
New Scientist. "You can trace the valleys carved by water down
to this area."
He says the evidence is "compelling" for past flooding near the
plates. "Maybe the ice is still there in the ground, protected by a
volcanic cover, as they suggest," he says.
There is abundant evidence for the past presence of water on
Mars but today it appears relatively dry, with water ice confined to
the planet's polar caps. Remote observations of hydrogen atoms
by NASA's Odyssey spacecraft in 2002 hinted that ice might be
locked in the top metre of soil at lower latitudes. But the evidence
was inconclusive as the signal could have come from minerals
exposed to water in the past.
And, of course, the Faces on Mars