> Some people think that a day is one revolution of Earth's axis, and not exactly 86400 seconds
One day is more than one revolution of the planet. The sidereal day is exactly one rotation of the planet, but that's about four minutes shorter than a civil day.
The reason is that the planet also moves around the sun, so in order to get the sun to the same position in the sky for noon the planet needs to turn a little bit more than 360 degrees, about 360/365 extra.
One day is more than one revolution of the planet. The sidereal day is exactly one rotation of the planet, but that's about four minutes shorter than a civil day.
The reason is that the planet also moves around the sun, so in order to get the sun to the same position in the sky for noon the planet needs to turn a little bit more than 360 degrees, about 360/365 extra.