aphelion

/æ'fi:ljən/

Thân thiện

Earth reaches its aphelion in early July.

Definition

1. Noun:
   • The point in the orbit of a planet, comet, or other celestial body where it is farthest from the Sun. This is a specific astronomical term used to describe a position in an elliptical orbit around the Sun.

Usage

• The term "aphelion" is used exclusively in astronomy and astrophysics to describe orbital mechanics. It is the opposite of "perihelion," which is the point of closest approach to the Sun.
• It is typically used with the preposition "at" (e.g., ) or "reaches" (e.g., ).

Examples

• Noun:
  • Earth reaches its aphelion in early July each year.
  • The comet's speed is slowest when it is at aphelion.
  • Calculating the aphelion distance is crucial for understanding an object's orbital period.

Advanced Usage

• "Aphelion distance": The specific measurement of the distance from the Sun at the aphelion point.
  • The aphelion distance of Mars is significantly greater than that of Earth.

Variants and Related Words

• Aphelia (n): The plural form of "aphelion."
  • The aphelia of the outer planets occur at vast distances from the Sun.
• Perihelion (n): The point in an orbit nearest to the Sun. This is the direct antonym of aphelion.
  • The comet is most visible from Earth when it is near perihelion.

Synonyms

• Apoapsis (n): The general term for the point in any orbit where the orbiting body is farthest from the center of mass. "Aphelion" is the specific term for orbits around the Sun.
• Farthest point (from the Sun).

Antonyms

• Perihelion (n): The point in an orbit closest to the Sun.

Học thuật

Noun

1. apoapsis in solar orbit; the point in the orbit of a planet or comet that is at the greatest distance from the sun