The inner four planets are called terrestrial planets. That means that they are like the earth in some ways. The terrestrial planets Mercury, Venus, Earth, Mars, and the earth's moon have similar compositions and densities. The term terrestrial can be misleading because each of the four has vastly different environments. They’re made up mostly of heavy metals such as iron and nickel and have either no moons or few moons.
These planets are close to the sun, rocky, and dense. They are fairly small and have few moons and no rings. Their environments are oxidized; that is, oxygen dominates the chemistry. Meteors, tectonic activity, and erosion have modified the surfaces of the terrestrial planets.
The atmospheres of the terrestrial planets have changed as a result of sunlight (which produces chemical reactions, such as those that break apart water molecules), escape of light gases, volcanic activity, and in the case of our planet, biological activity.
The main stages of evolution of the terrestrial planets are: -formation -impacts from space remains -volcanic activity and flooding of low areas with lava -the lessening of impacts, and, in some cases, the creation of an atmosphere -plate tectonics -slowing down of activity -cooling, inactive
One of the most interesting of the inner planets is Mars and will likely be the planet that humans first visit because of its friendlier environment. Mercury and Venus are simply too hot at this point for humans to consider given our current technology.
Questions: 1. What four planets make up the inner planets? A. Mercury, Venus, Earth, Mars B. Jupiter, Saturn, Uranus, Neptune C. Mercury, Venus, Earth, the moon D. Mercury, Venus, Earth, Jupiter
2. What does the term terrestrial mean? A. Made of water B. Mars-like C. Gas planet D. Earth-like
3. What characteristics of inner planets are correct? A. Terrestrial, Larger, few or no moons B. Gas, Smaller, few or no moons C. Gas, Larger, man moons D. Terrestrial, Smaller, few or no moons
4. Which is the correct order of how the inner planets were formed? A. Impact flooding, cooling, plate tectonics B. Impact, flooding, plate tectonics, cooling C. Plate tectonics, cooling, lower activity, impact D. Flooding, plate tectonics, cooling, lower activity
Watch It! Inner Planets Questions 1. List 3 facts about the planet Mercury. 2. List 3 facts about the planet Venus. 3. List 3 facts about the planet Earth. 4. List 3 facts about the planet Mars
Research It! Inner Planets questions 1. What do you notice about the shape of the orbits of the inner planets? 2. What do you notice about the speed of the orbits of the inner planets? 3. Rotate the image around until you can see all the orbits from the side. What do you notice? Are they all in the same plane or different planes?
1. Compare the distances between each of the inner planets to the distances between the outer planets.
2. What are some common characteristics of the inner planets?
3. Venus is often called the Earth’s sister planet. Why is unlikely that we can ever go there?
Assess It! Inner Planets
1. Which are the characteristics of inner planets? A. close together, rocky terrain, long orbits B. far apart, rocky terrain, shorter orbits C. far apart, made up of gas, shorter orbits D. close together, rocky terrain, shorter orbits
2. Inner planets have _______ orbits and outer planets have _________ orbits. A. Longer, shorter B. Shorter, longer C. Square, circular D. Elliptical, oval
3. __________ is the hottest planet in the solar system due to its thick atmosphere which traps greenhouse gases. A. Saturn B. Mercury C. Jupiter D. Venus
4. _________ is likely the first planet humans will colonize due to its proximity to Earth and favorable characteristics. A. Venus B. Saturn C. Jupiter D. Mars