As you know sidereal day is 4 min less than solar day,why?
2006-06-24 20:44:18 · 5 answers · asked by Andromeda 2 in Science & Mathematics ➔ Astronomy & Space
Solar day is the time to have the sun in the same meridian. Sidereal day is the time to have a star in the same meridian. While Earth is rotating around its axis it also is orbiting around the sun, so to see the sun in the same direction after a rotation the Earth need a further time because meanwhile it is in another position in its orbit.
Sorry for my English
It's difficult to explain it in a better way without a picture
2006-06-24 21:15:38 · answer #1 · answered by Vittorio 4 · 0⤊ 0⤋
The Earth is orbiting the Sun.
To spin the Earth 360 degrees is a sidereal day.
To spin the Earth (after orbiting) so that the SAME part faces the Sun at the SAME TIME is a solar day. For example, Noon is always when the sun is the highest in the sky. Noon from one day, to noon the next is a solar day. However, in that solar day, the Earth has spun a tiny bit more than 360 degrees.
Hope that helps!
EDIT:
I reread that wiki. Sorry, the 22s to 29s was a difference between a possible solar day and a mean solar day.
Thanks, NotEasilyFooled!
2006-06-25 05:23:15 · answer #2 · answered by nickworks 2 · 0⤊ 0⤋
Nickworks has it a bit wrong, the article he is referencing is describing a different effect. The difference between the solar day and the sidereal day is about 1/365th of a day, or 4 minutes. Our orbit around the sun cancels out one revolution of the earth each year, so when we use the sun to measure our days, we miss one.
2006-06-25 06:23:20 · answer #3 · answered by NotEasilyFooled 5 · 0⤊ 0⤋
a lot of good answers here. and mostly correct ones. In a nut shell - we have to spin once and as we do we move around the sun so the vector is different. 4 minutes for the stars to appear to catch up.
2006-06-25 07:39:26 · answer #4 · answered by orion_1812@yahoo.com 6 · 0⤊ 0⤋
Because the orbit is an arc.
2006-06-25 03:54:38 · answer #5 · answered by xtowgrunt 6 · 0⤊ 1⤋