The Inner Planets

20.320.3

Mercury

Closest planet to the sun.Closest planet to the sun. 22ndnd smallest planet smallest planet Only spacecraft ever sent to Mercury was Only spacecraft ever sent to Mercury was

Mariner 10 in 1974-1975. It flew around Mariner 10 in 1974-1975. It flew around the planet and sent back pictures of 45% the planet and sent back pictures of 45% of Mercury’s surface. of Mercury’s surface.

Mercury looks like our moon- many Mercury looks like our moon- many craters and cliffs.craters and cliffs.

Mercury Facts

Rev around the Sun-87 daysRev around the Sun-87 days Rotation 58 days, 15 hoursRotation 58 days, 15 hours Diameter- 4878 Kilometers, 3048 milesDiameter- 4878 Kilometers, 3048 miles No moonsNo moons No ringsNo rings Orbital Speed 47.89 km/sOrbital Speed 47.89 km/s .387AU from sun.387AU from sun

Atmosphere of Mercury

Most gases on Mercury escaped, because of its Most gases on Mercury escaped, because of its low gravitational pull.low gravitational pull.

However, the gases that remain form a very However, the gases that remain form a very thin atmosphere composed of: thin atmosphere composed of: Hydrogen and Helium, which we probably Hydrogen and Helium, which we probably

captured by Mercury from the sun’s solar captured by Mercury from the sun’s solar windswinds

Sodium and Potassium, which came up from Sodium and Potassium, which came up from the crust.the crust.

Temperature of Mercury

Because Mercury is so close to the Because Mercury is so close to the sun and has hardly any atmosphere, sun and has hardly any atmosphere, its temperatures are extreme.its temperatures are extreme.

Surface temperature during the day Surface temperature during the day reaches 450 C, 842 F and –170 C, -reaches 450 C, 842 F and –170 C, -274 F at night.274 F at night.

Venus

Second Planet from the SunSecond Planet from the Sun

Venus Facts

Revolution- 224.7 daysRevolution- 224.7 days Rotation- 243 daysRotation- 243 days Diameter- 12,104 Km, or 7565milesDiameter- 12,104 Km, or 7565miles Orbital Speed- 35.03 km/sOrbital Speed- 35.03 km/s No moonsNo moons No ringsNo rings .723 AU from sun.723 AU from sun

Earth’s Twin

Venus is called the Earth’s twin because it is Venus is called the Earth’s twin because it is very similar in mass and size.very similar in mass and size.

The major difference is the atmosphere- Venus The major difference is the atmosphere- Venus is covered by a thick, dense cloud of mostly is covered by a thick, dense cloud of mostly carbon dioxide. carbon dioxide.

This atmosphere is 90 times heavier than the This atmosphere is 90 times heavier than the Earth’s atmosphere which makes the Earth’s atmosphere which makes the atmospheric pressure at sea level on Venus 90 atmospheric pressure at sea level on Venus 90 times that of Earth’s.times that of Earth’s.

Atmosphere

Since the atmosphere is mostly carbon dioxide, Since the atmosphere is mostly carbon dioxide, its atmosphere is highly toxic. its atmosphere is highly toxic.

This is because the carbon dioxide mixes with This is because the carbon dioxide mixes with sulfur to create sulfur dioxide, which is acid sulfur to create sulfur dioxide, which is acid rain. This make the atmosphere appear yellow.rain. This make the atmosphere appear yellow.

Clouds on Venus are so thick that they only let Clouds on Venus are so thick that they only let in 2% of the sunlight that strikes Venus. in 2% of the sunlight that strikes Venus. However, the atmosphere is so thick that all However, the atmosphere is so thick that all that heat is trapped creating a greenhouse that heat is trapped creating a greenhouse effect.effect.

Temperature on Venus

Temperatures on Temperatures on Venus normally Venus normally remain around remain around 470 C which is 878 470 C which is 878 F.F.

Explorers of Venus

In 1970 the first In 1970 the first exploration on exploration on Venus occurred by Venus occurred by the Russians. Their the Russians. Their spacecraft called spacecraft called the Venera probe the Venera probe began to photo and began to photo and mapped Venus’s mapped Venus’s surfacesurface

Magellan

The US followed by sending the The US followed by sending the Magellan in 1990 which mapped the Magellan in 1990 which mapped the surface of Venus with intense radar. surface of Venus with intense radar. This showed the surface to have This showed the surface to have huge craters, faults, volcanoes with huge craters, faults, volcanoes with visible lava.visible lava.

Mars

44thth Planet from the sun Planet from the sun

The Red Planet

Revolution: 686.98 daysRevolution: 686.98 days Rotation: 24 hours, 37 minutesRotation: 24 hours, 37 minutes Diameter: 6794 km, or 4246.25 milesDiameter: 6794 km, or 4246.25 miles Orbital Speed: 24 .13 km/sOrbital Speed: 24 .13 km/s 2 moons2 moons No ringsNo rings 1.525 AU from sun1.525 AU from sun

Why is it called the red planet?

Iron oxide in the weathered rocks on its surface Iron oxide in the weathered rocks on its surface give it’s a reddish appearance.give it’s a reddish appearance.

Mars also has polar ice caps that are visible Mars also has polar ice caps that are visible and get larger during the Martian winter and and get larger during the Martian winter and shrink during the summer. shrink during the summer.

Is it water? Is it water? Yes and No- the southern polar ice cap is Yes and No- the southern polar ice cap is

made of frozen carbon dioxide, the northern made of frozen carbon dioxide, the northern polar ice cap is made of water frozen into ice.polar ice cap is made of water frozen into ice.

Mariner 9

Orbited Mars in Orbited Mars in 1971-19721971-1972

Revealed long Revealed long channels that could channels that could have contained have contained flowing waterflowing water

Found largest Found largest volcano in the solar volcano in the solar system, Olympus system, Olympus MonsMons

Viking 1

1976 landed on Mars 1976 landed on Mars with 2 probes, and 2 with 2 probes, and 2 orbitersorbiters

The 2 orbiters The 2 orbiters Photographed the entire Photographed the entire surface of Marssurface of Mars

The 2 probes landed and The 2 probes landed and conducted experiments. conducted experiments. Found No Evidence of Found No Evidence of LIFE.LIFE.

                                                 

Atmosphere of Mars

Much thinner than Earth’sMuch thinner than Earth’s Composed of mostly carbon dioxide, Composed of mostly carbon dioxide,

some nitrogen, and argon.some nitrogen, and argon. This leads to temperature on the surface This leads to temperature on the surface

ranging from 35 C, 95 F to –170 C, -274 ranging from 35 C, 95 F to –170 C, -274 F.F.

There are also strong winds storms that There are also strong winds storms that can cover the entire planet at one time.can cover the entire planet at one time.

Moons of Mars The moons of Mars The moons of Mars

are heavily cratered are heavily cratered and very smalland very small

Phobos is 25 km in Phobos is 25 km in diameter. It’s orbit diameter. It’s orbit is expected to have it is expected to have it impact Mars in 50 impact Mars in 50 million years.million years.

Deimos is 13 km in Deimos is 13 km in diameter.diameter.

Phobos and Deimos

Named for the Greek war god AresNamed for the Greek war god Ares Phobos means “fear”Phobos means “fear” Deimos means “panic”Deimos means “panic”

Olympus Mons

Polar Ice Caps of Mars