YOU TRY IT! A Guide to Earth’s Orbit, for Aliens (and Earthlings)

There are two times in a day when you can watch the Earth turn: at sunrise and sunset. While it appears that the sun is sinking into the horizon at sunset and rising from it at dawn, the fact is that the Earth is turning, not the sun, and it’s carrying you with it.

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WHAT YOU NEED

  1. A lamp (a desk lamp, or one with a shade that shines light in one direction, is best)
  2. A swivel chair, or a stool
  3. A dark room

WHAT TO DO

  1. Place the lamp in the middle of the room with the chair a short distance from it. Aim the lamp at the chair. Then sit in the chair and face the light.
  2. Think of your head as the Earth and the lamp as the sun. When you face the lamp, it’s daytime.
  3. 3. Slowly turn your body and your head in a counterclockwise direction and notice how the “sun” seems to be moving to the right. This is the direction the sun moves across the sky during the day when you’re facing south. It rises in the east and moves to the right across the sky until it sets in the west.
  4. Keep turning around until the sun is on the edge of your vision on your right. That is sunset.
  5. Turn more and you’ll not see the sun at all. Now you are in night, or on the dark side of the Earth. Continue all the way around and the sun will reappear on your left side, which is sunrise. Welcome to a new day.

If you want to give the experiment a twist, try repeating it from the opposite side of the lamp. You should be looking back at where you were sitting before. Notice how now, when it’s “night” and your back is toward the light, you’re facing a different direction than you were before? That is why the summer constellations are different from those in winter. Stars completely surround the Earth, just as the walls of your room are all around the lamp. We face opposite directions in the sky (or different “walls”) in summer compared to winter, which is why we see different stars in each season.