Aphelion refers to the point in an object's orbit where it is farthest from which body?

Aphelion refers to the point in an object's orbit where it is farthest from which body?

• A. The Sun
• B. The Earth
• C. The Moon
• D. The center of the galaxy

Answer: (A)

Aphelion is the point in an object's Sun-centered orbit where it is farthest from the Sun. Orbits are ellipses, so distance to the central body changes as the object moves; the Sun sits at one focus of that ellipse, and the farthest point in the orbit is called aphelion, with the closest point named perihelion. The other bodies listed aren’t described by aphelion: for motion around the Earth you’d use apogee and perigee, and the center of the galaxy isn’t involved in this solar-system terminology. So the farthest distance in a Sun-centered orbit is from the Sun.

Aphelion is the point in an object's Sun-centered orbit where it is farthest from the Sun. Orbits are ellipses, so distance to the central body changes as the object moves; the Sun sits at one focus of that ellipse, and the farthest point in the orbit is called aphelion, with the closest point named perihelion. The other bodies listed aren’t described by aphelion: for motion around the Earth you’d use apogee and perigee, and the center of the galaxy isn’t involved in this solar-system terminology. So the farthest distance in a Sun-centered orbit is from the Sun.