Why Mars Isn't Round |
This
diagram shows Mars doesn't look round sometimes. The diagram is looking
down on the top of the orbits.
Notice the orange line running between the Sun and Mars. This is the direction sunlight comes from. The side of the planet away from the Sun is dark. As you look at Mars from the Earth, you mostly see the sunlit side, but your line of sight also includes part of the edge that is in darkness. You can't see this edge because it is too dark. So Mars doesn't look round because you are not seeing all of the planet. The line between the dark and sunlit side is called the terminator. If you were standing on this line on Mars, the Sun would have just set and it would be twilight. |