Download The Inner Planets

The Inner Planets
20.3
Mercury
Closest planet to the sun.
 2nd smallest planet
 Only spacecraft ever sent to Mercury was
Mariner 10 in 1974-1975. It flew around
the planet and sent back pictures of 45%
of Mercury’s surface. Next Mission 2009
 Mercury looks like our moon- many
craters and cliffs.

Mercury Facts
Rev around the Sun-87 days
 Rotation 58 days, 15 hours
 Diameter- 4878 Kilometers, 3048 miles
 No moons
 No rings
 Orbital Speed 47.89 km/s
 .387AU from sun

Atmosphere of Mercury




Most gases on Mercury escaped, because of its
low gravitational pull.
However, the gases that remain form a very
thin atmosphere composed of:
hydrogen and helium, which we probably
captured by Mercury from the sun’s solar
winds
two others: sodium and potassium, which
came up from the crust.
Temperature of Mercury
 Because
Mercury is so close to the
sun and has hardly any atmosphere,
its temperatures are extreme.
 Surface temperature during the day
reaches 450 C, 842 F and –170 C, 274 F at night.
Venus
Second Planet from the Sun
Venus Facts
Revolution- 224.7 days
 Rotation- 243 days
 Diameter- 12,104 Km, or 7565miles
 Orbital Speed- 35.03 km/s
 No moons
 No rings
 .723 AU from sun

Earth’s Twin


Venus is called the Earth’s twin because it is
very similar in mass and size.
The major difference is the atmosphere- Venus
is covered by a thick, dense cloud of mostly
carbon dioxide. This atmosphere is 90 times
heavier than the Earth’s atmosphere which
make the atmospheric pressure at sea level on
Venus 90 times that of Earth’s.
Atmosphere


Since the atmosphere is mostly carbon dioxide,
its atmosphere is highly toxic. This is because
the carbon dioxide mixes with sulfur to create
sulfur dioxide which is acid rain. This make
the atmosphere appear yellow.
Clouds on Venus are so thick that they only let
in 2% of the sunlight that strikes Venus top
clouds to reach its surface. However, the
atmosphere is so thick that all that heat is
trapped which leads to the planet having the
greenhouse effect.
Temperature on Venus

Temperatures on
Venus normally
remain around
470 C which is 878
F.
Explorers of Venus

In 1970 the first
exploration on
Venus occurred by
the Russians.
Their spacecraft
called the Venera
probe began to
photo and mapped
Venus’s surface
Magellan
 The
US followed by sending the
Magellan in 1990 which mapped the
surface of Venus with intense radar.
This showed the surface to have
huge craters, faults, volcanoes with
visible lava.
Earth
The third planet from the sun is 150 million
km away from the star. That is
approximately 1 astronomical unit or AU.
 Temperatures allow for solids, liquids, and
gases on the Home Planet.
 Most Meteors burn up in the atmosphere
before reaching the surface.

Earth Facts
Diameter 12756 km or 7952 miles
 Revolution 365.25 days
 Rotation- 23 hours 56 minutes
 Orbital speed- 29.79 km/s
 1 moon
 No rings

Mars
4th Planet from the sun
The Red Planet
Revolution: 686.98 days
 Rotation: 24 hours, 37 minutes
 Diameter: 6794 km, or 4246.25 miles
 Orbital Speed: 24 .13 km/s
 2 moons
 No rings
 1.525 AU from sun

Why is it called the red planet?


Iron oxide in the weathered rocks on its surface
give it’s a reddish appearance.
Mars also has polar ice caps that are visible
from other and get larger during the Martian
winter and shrink during the summer. Is it
water? Yes and No- the southern polar ice cap
is made of frozen carbon dioxide, the northern
polar ice cap is made of water frozen into ice.
Mariner 9



Orbited Mars in
1971-1972
Revealed long
channels that could
have contained
flowing water
Found largest
volcano in the solar
system, Olympus
Mons
Viking 1



1976 landed on Mars
with 2 probes, and 2
orbiters
The 2 orbiters
Photographed the entire
surface of Mars
The 2 probes landed and
conducted experiments.
Found No Evidence of
LIFE.
Atmosphere of Mars
Much thinner than Earth’s
 Composed of mostly carbon dioxide,
some nitrogen, and argon.
 This leads to temperature on the surface
ranging from 35 C, 95 F to –170 C, -274
F.
 There are also strong winds storms that
can cover the entire planet at one time.

Moons of Mars



The moons of Mars
are heavily cratered
and very small
Phobos is 25 km in
diameter. It’s orbit is
expected to have it
impact Mars in 50
million years.
Deimos is 13 km in
diameter.
Phobos and Deimos
Named for the Greek war god Ares
 Phobos means “fear”
 Deimos means “panic”

Olympus Mons
Polar Ice Caps of Mars
Exploring Mars
In 2004 2 new probes landed on Mars.
Spirit and Opportunity
 Looked at rocks and found evidence of past
water.
