Earth & Space Science
Students use models to explore solar and lunar eclipses.
After completing this tutorial, you will be able to complete the following:
In a lunar eclipse, the moon passes into the shadow of the Earth. This can only occur during the full moon, because that is when the moon is directly behind the Earth and can cross into its shadow. But it does not happen every full moon. While the moon does pass "behind" the Earth every full moon, it is not always in the same plane as the Earth and sun. In our solar system, most of the planets orbit the sun in the ecliptic plane, which you can think of like the rings of Saturn. All of the material in Saturn's rings swirls around in an organized, flat disk that spins in the same direction as Saturn's orbit. The solar system is organized in a similar fashion, just on a much larger scale. The ecliptic plane can be imagined as the rings of the sun.
Most of the planets and asteroids (located in the asteroid belt) within our solar system orbit the sun in a tidy imaginary ring. However, moons are not constrained by the ecliptic plane. Our moon's orbital plane is tilted about 5º compared to the Earth's.
If the moon happens to cross the ecliptic plane during a full moon, then we have a lunar eclipse. The moon passes into the shadow of the Earth, and as it does, we slowly lose sight of the moon. Eventually, it passes back out of the Earth's shadow, and we see the moon reappear. This can take three or four hours, and it happens (on average) twice each year.
In a solar eclipse, the shadow of the moon falls on the Earth, blocking out the sun. This can only occur during the new moon phase. During a lunar eclipse, the Earth's shadow is big enough to block out the whole sun compared to the moon, but that will not happen in a solar eclipse. The moon's shadow is very small compared to the sun and the Earth, so when that shadow falls on the Earth, only a relatively small area will experience the eclipse.
|Approximate Time||40 Minutes|
|Pre-requisite Concepts||Students should be familiar with orbits and rotation.|
|Course||Earth & Space Science|
|Type of Tutorial||Concept Development|
|Key Vocabulary||Earth, eclipse, lunar eclipse|