noun
solar day
Astronomical term: the time it takes for the Sun to return to the same position in the sky, about 24 hours.
太陽日は恒星日より約4分長い。
A solar day is about 4 minutes longer than a sidereal day.
恒星日 (sidereal day) is measured relative to the fixed stars, about 23 hours 56 minutes, while 太陽日 is measured relative to the Sun.
Compound of 太陽 (taiyō, 'sun') and 日 (jitsu, 'day'), a straightforward calque from Western astronomical terminology.