Current Events Lesson Plan January 21-27, 2016
Current Event: Planet Nine From Outer Space
Astronomers recently released a study suggesting that there may be a ninth planet in the solar system. But it isn’t Pluto or some other dwarf planet. Instead, astronomers believe that the ninth planet might be about 10 times the mass of Earth. Although the evidence is strong, scientists will have to see Planet Nine to believe it. The planet will be extremely difficult to locate by telescope, despite its apparently large size. It is incredibly far away, from 600 to 1,200 times farther than is the sun from the Earth. Planet Nine completes an orbit every 15,000 years. For comparison, Pluto, the former ninth planet, is only about 40 times farther from the sun than Earth is and it completes an orbit every 248 years. It might take as long as five years of scientists combing the night sky with powerful telescopes to find Planet Nine.
Objective:
A planet is a large, round heavenly body that orbits a star and shines with light reflected from the star. Traditionally, the term planet has had no formal definition in astronomy. Millions of objects orbit the sun—the most basic characteristic of a planet. But scholars have struggled to devise a simple classification system that distinguishes the smallest worlds from the largest comets, asteroids, and other bodies. Our solar system includes eight known planets and five dwarf planets, including Pluto, which used to be classified as a planet. Since the 1990′s, astronomers have discovered many planetary systems around distant stars. The distant planets, called extrasolar planets or exoplanets, cannot be seen directly. But they can be studied indirectly, through small changes they cause in light coming from the parent star. The Behind the Headlines news story and related World Book articles explore planets and other astronomical topics.
Words to know:
Discussion Topics:
1. Ask your students if they can name the eight planets in the solar system. (The eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.) See if your students can come up with a mnemonic for remembering the names of the planets.
2. Have your students debate the topic, “It is important to study planets and other parts of the universe.”
3. Private companies have begun launching people into space. Ask your students if they would want to visit another planet or any other celestial body. Assuming they could safely travel anywhere in space, where would they go? Would they go if they knew they could never return to Earth?
4. Ask your students to use World Book’s Timelines feature to view or add to the Advances in Astronomy timeline. (Students may wish to use World Book’s “Astronomy” article for help.)