Nadir crater
A nadir crater is a hole or pit on the surface of a planet or moon that is located directly beneath an orbiting spacecraft. It's kind of like a dent that you might see in the ground when you're looking straight down at it from above.
When a spacecraft is in orbit around a planet or moon, it's always moving forward in its orbit. But it's also constantly falling down towards the surface because of gravity. So, as the spacecraft moves over the surface, the ground appears to move underneath it in the opposite direction.
If the spacecraft is directly over a crater when it's moving forward, the crater will appear to move backwards underneath the spacecraft. But when the spacecraft moves past the crater, the crater will suddenly appear directly beneath it.
This point when the crater appears directly beneath the spacecraft is called the nadir point. It's kind of like the "bottom" of the spacecraft's orbit, where it's closest to the planet or moon's surface.
Scientists like to study nadir craters because they can give us a lot of information about the history and geology of a planet or moon. By looking at the size, shape, and location of these craters, we can learn about things like the age of the surface, the types of rocks that are present, and even whether there might be any water or ice hidden beneath the surface.
When a spacecraft is in orbit around a planet or moon, it's always moving forward in its orbit. But it's also constantly falling down towards the surface because of gravity. So, as the spacecraft moves over the surface, the ground appears to move underneath it in the opposite direction.
If the spacecraft is directly over a crater when it's moving forward, the crater will appear to move backwards underneath the spacecraft. But when the spacecraft moves past the crater, the crater will suddenly appear directly beneath it.
This point when the crater appears directly beneath the spacecraft is called the nadir point. It's kind of like the "bottom" of the spacecraft's orbit, where it's closest to the planet or moon's surface.
Scientists like to study nadir craters because they can give us a lot of information about the history and geology of a planet or moon. By looking at the size, shape, and location of these craters, we can learn about things like the age of the surface, the types of rocks that are present, and even whether there might be any water or ice hidden beneath the surface.