Planets · Comets and asteroids
Aphelion
Say it: ap-HEE-lee-un IPA: /æpˈhiːliən/ noun
Aphelion: The point in a body's orbit where it is farthest from the Sun.
An elongated solar orbit has a near end and a far end. Aphelion names the farthest point specifically for an orbit around the Sun.
- Example
- The comet moved more slowly near aphelion than near its closest approach to the Sun.
- Why astronomers use it
- It describes orbital geometry and helps explain changes in solar heating along an orbit.
- Tiny cosmic connection
- Earth's seasons mainly come from axial tilt, not from which end of its orbit it occupies.
Observatory Planets Comets and asteroids
Where to check it
Written for Cool Moon Facts in its own words; the sources cover the same idea in more depth.