上弦(じょうげん)

じょうげん
noun
first quarter moon
nature
1. first quarter moon
The moon phase when the right half is illuminated, occurring about a week after the new moon.
今夜(こんや)は上弦(じょうげん)の月(つき)だ。
Tonight is a first quarter moon.
上弦(じょうげん)の月(つき)は右半分(みぎはんぶん)が光(ひか)っている。
A first quarter moon has the right half illuminated.
上弦(じょうげん)から満月(まんげつ)まで約(やく)一週間(いっしゅうかん)かかる。
It takes about one week from first quarter to full moon.

上弦(じょうげん) refers to the first quarter moon phase. The name compares the half moon to a drawn bow (弦(げん) 'bowstring'): the first-quarter moon sets around midnight with its straight edge, the 'string', facing up. Seen from Japan, its right half is lit.

Related words

Note: These terms are used in astronomy, traditional calendars, and sometimes weather forecasts.

Related Words

Antonym: 下弦(かげん) (last quarter moon)
Related: 新月(しんげつ) (new moon)
Related: 満月(まんげつ) (full moon)
general
Added 2026.1.29 8:58 · Revised 2026.10.13 16:13
08500/08869_jougen