Question

As M1 orbits around M2, the point where the distance is the shortest between them is called the...
Responses

Perihelion
Perihelion - no response given

Retrograde
Retrograde - no response given

Aphelion
Aphelion - no response given

Parallax

Answer 1

The point where the distance is the shortest between two orbiting bodies, such as M1 and M2, is called the **perihelion** when referring to an orbit around the sun; however, in a more general context regarding any two celestial bodies, it is often referred to as the **closest approach** or **periapsis**.

In your options, **perihelion** is the correct term if the context specifically involves an orbit around the sun. If you are looking for a more general term, **periapsis** would be appropriate.

The other terms listed are not relevant to the concept of closest approach:
- **Aphelion** refers to the point in an orbit where the object is farthest from the sun.
- **Retrograde** describes the motion of an object moving in the opposite direction to the rotation of its primary.
- **Parallax** is related to the apparent displacement of an object due to a change in the observer's point of view.

So, the answer you're looking for is **perihelion** if specifically about orbits around the sun.