perihelia
Definition
Noun (plural form of perihelion): - Astronomy: "Perihelia" refers to the points in the orbits of planets, comets, or other celestial bodies that are nearest to the Sun. For a single body, this point is called a perihelion; "perihelia" is used when referring to multiple such points.
Usage Examples
- (The nearest points to the Sun in the comets' orbits.)
- (The points of closest approach to the Sun for multiple planets.)
Advanced Usage
"At perihelia": occurring at the point of closest approach to the Sun.
- The comet becomes brightest at perihelia. (The comet shines most when it is nearest the Sun.)
"Perihelia shift": a gradual change in the orientation of the point of closest approach over time.
- Mercury's perihelia shift was explained by Einstein's theory of relativity. (The slow rotation of Mercury's closest point to the Sun.)
Variants and Related Words
Perihelion (n, singular): the point in an orbit closest to the Sun.
- Earth reaches its perihelion in early January. (The point where Earth is nearest the Sun.)
Aphelion (n): the point in an orbit farthest from the Sun (opposite of perihelion).
- The aphelion of a comet is often far beyond the orbit of Neptune. (The farthest point from the Sun.)
Synonyms
- Closest approach: the point of minimum distance in an orbit (general term, not specific to the Sun).
- Periastron: the point of closest approach to a star in general (used in binary star systems).
Related Idioms
- No common idioms: "Perihelia" is a technical astronomical term and does not appear in everyday idioms.