The Inner Planets

1. The Inner Planets Mercury, Venus, Earth and Mars Click here to move to the next slide!

2. Vocabulary Click on each word to find the definition and record it on your paper. Click on the orange arrow button to return to the vocabulary screen. When done click on the pink arrow key to move on to the next step! Click here to begin the vocabulary section.

3. Vocabulary Rotation Revolution Orbit Diameter Satellite Atmospheric Geological

4. 0 Gathering information about the INNER PLANETS! 1.Click on the picture of the planet to learn about the planet, fill in your chart as you go. 2. To return to the planets page click the home button. 3. To return to the previous page click on the arrow button. Click here to move to the next slide!

5. The Inner Planets!

6. Mercury • The planet closest to the sun is Mercury. Mercury is not much larger than Earth’s moon and has no moons of its own. Mercury is made up mainly of the dense metals iron and nickel. • Mercury has many flat plains and craters on its surface. The craters on Mercury have been named for artists, writers, and musicians including the composers Bach and Mozart. Mercury Continued

7. Mercury Continued • Mercury has an extremely thin atmosphere. Astronomers have detected small amounts of sodium and helium. Mercury is a planet of extremes. It is so close to the sun that during the day, the side facing the sun reaches temperatures of 450˚C. Because Mercury has almost no atmosphere, at night all the heat escapes into space. The temperature drops to -170˚C. Mercury thus has a greater range of temperatures than any other planet in the solar system. Take away fact: Mercury resembles the moon!

8. Venus • Venus is so similar in size to Earth that it is sometimes called Earth’s twin. Astronomers think that the density and internal structure of Venus are similar to Earths; however, Venus differs in many other ways. • Venus is the second planet from the sun; therefore, it receives a great deal of light. Ordinary light from the sun causes Venus’s surface to heat up. In turn, carbon dioxide traps this heat in the atmosphere causing Venus’s surface to become hotter and hotter, until it is about 460˚C—hot enough to melt lead. This trapping of heat by the atmosphere is called the greenhouse effect. • Venus takes about 7.5 Earth months (225 days) to revolve around the sun. It takes about 8 months (243 days) for Venus to rotate on its axis. Venus rotates so slowly that its “day” is longer than its “year.” Oddly, Venus rotates from east to west, the opposite direction from most other planets and moons. This type of rotation is called retrograde rotation, from the Latin words for “moving backward.” One hypothesis proposed by astronomers to explain this unusual rotation is that Venus was struck by a very large object billions of years ago. This collision caused the direction of its rotation to change. Venus Continued

9. Venus Continued • Venus is covered with rock, similar to many rocky areas on Earth. Venus has volcanoes with lava flow, many craters and strange domes not found on other planets. • Venus is also known as the "morning star" or the "evening star" since it is visible and quite bright at either dawn or dusk. It is only visible at dawn or dusk since it is closer to the sun than we are. Take away fact: Venus has retrograde rotation!

10. Earth • The Earth is the third planet from the Sun in our Solar System. It is the planet we evolved on and the only planet in our Solar System that is known to support life. Earth is 12,756 km in diameter, the fifth largest! • Our planet’s atmosphere extends more than 100 kilometers above Earth’s surface. The oxygen you need to live makes up about 20 percent of the gases in Earth’s atmosphere. Almost all the rest is nitrogen gas, with a small amount of carbon dioxide. Earth’s atmosphere also contains water vapor and clouds of water droplets. • Most of Earth, about 70 percent, is covered with water. Perhaps the planet should be named “Water” instead of “Earth”! No other planet in our solar system has oceans like Earth’s. • Earth has three main layers—a crust, a mantle, and a core. The crust includes the solid rocky surface. Under the crust is the mantle, a layer of hot molten rock. When volcanoes erupt, this hot material rises to the surface. Earth has a dense inner core made up mainly of iron and nickel Earth Continued

11. Earth Continued • Our Earth has one satellite or moon which is about ¼ of the diameter of Earth. Some scientists hypothesize that the moon may have once been a part of the Earth: it may have been broken off during a catastrophic collision of a huge body with the Earth billions of years ago. Take away fact: Earth is 70% water!

12. Mars • Mars is the farthest inner planet from the sun, approximately 228,000,000 kilometers away. Mars is called the “red planet” because it has a slightly reddish color when you see it in the sky. The atmosphere of Mars is mostly carbon dioxide. In the early 1900’s, two Italian astronomers convinced many people that there were canals on Mars that had been built by intelligent Martians to carry water. Astronomers now know that this was a mistake. There are no canals on Mars; however, we have found that some water remains in the form of ice at its north pole. Unlike Earth’s ice caps, during the winter this polar cap is covered by a layer of frozen carbon dioxide. • For the most part, Mars is deserted and covered with craters like the moon. Some regions of Mars have giant volcanoes that show signs of lava flow. The rocks on Mars look red because they are covered with a rusty dust. There are also deep canyons possibly formed by fault zones. Mars Continued

13. Mars Continued • Mars has two very small moons. Phobos, the larger moon, is only 27 kilometers in diameter, about the distance a car can travel on the highway in 15 minutes. Deimos, is even smaller, only 15 kilometers in diameter. Close-up views from space show that, like Earth’s moon, Phobos and Deimos are covered with craters. Take away fact: Mars has the largest volcanoes in our Solar System!

14. Revolution The movement of an object around another object!

15. Geological The physical characteristics, especially the surface features of an area (mountains, craters, etc)!

16. Satellite Any object that revolves around another object in space (moon)!

17. Diameter A straight line connecting two points of a circle (size).

18. Orbit The path of an object as it revolves around another object in space!

19. Rotation The spinning motion of a planet about its axis!

20. Atmospheric The air or climate in a specific place!

21. QUIZ TIME!!!!! Click here to start the quiz! Time to test out what you have learned!

22. 1. Which planet is green and blue, and has an average diameter of 12,756 kilometers? • Mercury • Venus • Earth • Mars

23. 2. Which planet orbits the sun once every 687 days, and has the largest volcanoes in our solar system? • Mercury • Venus • Earth • Mars

24. 3. Which planet is about the same size as Earth, shows evidence of volcanic activity, but is so hot you wouldn’t be able to live? • Mercury • Venus • Earth • Mars

25. Correct!!! Excellent Job! Make sure you record your answer in Chart 1.

26. Incorrect Sorry, Try Again! Look at your chart 1: Terrestrial Planets!

27. Good Job! You have learned all about the inner planets! Start Over End Show