Chapter 27.3 The Inner Planets

Std. 1a- Students know how the sun, the terrestrial planets, and the gas planets may have been established during the formation of the solar system

Std. 4d- Students know the differing greenhouse conditions on Earth, Mars and Venus

Objective 1: Identify the characteristics of the inner planets

Objective 2: Summarize the features that allow Earth to sustain life

The Inner Planets

• Planets closest to the sun are:1. Mercury 3. Earth

2. Venus 4. Mars

•All similar to Earth • Metallic cores and consist mostly of rock•# of moons vary from 0-2

1) Mercury

• Planet closest to the sun (no moons)• Orbits (day) the sun every 88 days• Rotates (year) every 59 days• Heavily cratered • Slow rotation and no atmosphere causes a

large temperature range (Day: 427°C and Night: -173°C)

2) Venus

• 2nd planet from the sun (no moons)• Orbits the sun every 225 days• Rotates every 243 days• Same size, mass and density as Earth

Venus’s Atmosphere

• 96% carbon dioxide causing a greenhouse effect that heats the surface to 464 degrees C

• Hottest planet in the solar system • Sulfur dioxide droplets in the upper

atmosphere creates clouds which reflect sunlight– It is the brightest object in the night sky (aside

from the moon and sun)

Venus’s Surface Factors

• Has mountains, volcanoes, lava plains and sand dunes

• Lots of volcanic activity

Objective 1: Identify the characteristics of the inner planets

• How many moons do the inner planets have?– 0-2 moons

• Which planet has the same mass and density as Earth?– Venus

• What % of Venus’ s atmosphere is carbon dioxide?– 96%

Earth

• 3rd planet from the sun (1 moon)• Rotation 365 ¼ days• Weathering and erosion continues to change

Earth’s surface

• Water on Earth– Atmosphere and distance from the sun allows

water to exist in solid, liquid and gas states

• Life on Earth – Earth maintained a moderate temperature during

formation = it can support life

Mars

• 4th planet from the sun• Orbital period 687 days • Rotates every 24 hours• 2 moons – Deimos and Phobos• Same tilt as Earth – has similar seasons to Earth

• Martian Volcanoes – Olympus Mons - Largest volcano is 3 times as tall

as Mt. Everest• The base is the size of Nebraska

– Reasons for large volcanoes - no moving tectonic plates

• Active volcanoes = unknown• Seismic activity has been detected

• Water on Mars– Pressure and temperature on Mars are too low for

water to exist in liquid form – Features caused by erosion indicate that water did

exist in the past –Water on Mars is trapped by polar icecaps

Mars Earth

Objective 2: Summarize the features that allow Earth to sustain life

• Why can Earth support life?– Earth maintained a moderate temperature during

formation

• What is Mars’s largest volcano?– Olympus Mons

• Why does Mars have large volcanoes?– No moving tectonic plates

• Why can’t water on Mars exist in liquid form?– Pressure and temperature is too low