light year

IPA/ˈlaɪt jɪə(r)/
IPA/ˈlaɪt jɪr/

light year — noun

1. a unit used by astronomers for measuring the enormous gaps between stars and gal

1.名詞B2
釋義

a unit used by astronomers for measuring the enormous gaps between stars and galaxies, defined by how far light moves in a single Earth year — roughly 9.5 trillion kilometres

例句

Bao learned the Andromeda Galaxy is 2.5 million light years from Earth.

light years from [celestial body] — distance to a nearby galaxy

Astronomers use the light year to describe distances that are too large for kilometres.

同義詞
  • parsec

    a professional astronomy unit equal to about 3.26 light years; less common in everyday science news

文法句型

[number] light years from [place]

[number] light years away

用法筆記

This sense refers to distance, not time — a light year is a unit of length like a kilometre, not a period like a year. Frequently used with a number followed by from or away (e.g., 4.2 light years from Earth).

常見錯誤

❌The movie felt like a light year long.
✅The movie felt like it would never end.
💡A light year measures distance; use 'forever' for a long period of time.
❌The star is one light year from Earth.
✅The closest star is about 4.2 light years from Earth.
💡No known star is exactly one light year from us; Proxima Centauri is about 4.2 light years away.