| dtewi said:
1) If the moon is constantly orbiting the Earth, why is it that we only see it regularly during nighttime? 2) If there were a planet oribiting the sun and was equidistant from the sun as Earth, how would we know if that planet existed? |
1) You can see the moon as much in the day as you can at night. You may not notice it as much during the day because it is reflects less light and everything else is much brighter, but it spends as much time in the day sky and it does in the night sky.
2) We could spot this planet in the same way that we spot every other planet. However, another planet in Earth's orbit could not exist, physics has a tendency to concentrate masses in the same orbit and if it was possible for such a phenomenom to form, it would have to have the same exact mass and speed as Earth to stay in the same orbit without colliding.
