How long does it take for a day to pass on Neptune?

Answer 1

The length of a day, or sidereal period, on Neptune is 16 hours 6 min 13 seconds (0.6713 days)

Because Neptune is not a solid body, its atmosphere undergoes differential rotation. The wide equatorial zone rotates at a period of about 18 hours, at the polar regions the rotation period is about 12 hours.

Answer 2

Neptune's sidereal rotation period is 16 hours 6 minutes 36 seconds.

I can't find the precise length of a solar day there, but since Neptune's year is so long it would be only very slightly longer than that. (On Earth, the difference between the sidereal rotation period and the solar day is about 4 minutes; Neptune's year is 165 times longer, so the difference between the sidereal and solar days would be at most a couple of seconds.)

Answer 3

A day on Neptune, also known as its rotation period, is about 16.11 hours. This means that Neptune takes about 16.11 hours to complete one full rotation on its axis, compared to the Earth's 24-hour day.