Is called a sunset
Both cross the horizon.
The sun rises in the east.
The altitude of the highest point of the rainbow that you see is (42 degrees) minus (the altitude of the sun above the horizon behind you). If the sun is sitting right on the horizon ... just risen or just about to set ... then the highest point of the rainbow is about 42 degrees above the horizon opposite the sun. If the sun is higher, then the rainbow is lower, by the same amount. If the sun is more than about 42 degrees above the horizon, then any rainbow you might otherwise see is entirely below the opposite horizon, and you don't see one.
Depending on your location, the Sun is probably low above the northeastern horizon in the northern hemisphere, or above the southeastern horizon in the southern hemisphere.
Just over the horizon.
The western horizon.
Eastern Horizon
The sun is below the northern horizon at midnight in the Northern Hemisphere.
Sunset occurs when the top edge of the sun disappears below the horizon. The moment when the bottom of the sun touches the horizon is known as "solar immersion."
The sun and ocean met on the horizon.
The sun sets over the horizon.
Ten bellow is about 450 degrees warmer than absolute zero. All the heat keeping us that warm is coming from the sun.
It is when the sun or moon breaks the horizon. And sunset and moonset happen when the last bit (trailing limb) goes below the horizon.
The sun sets behind the horizon.
at sunset you can see the sun sink below the horizon
I looked toward the horizon as the sun was setting.
Both cross the horizon.