# Naked Science Forum

## Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Geezer on 30/03/2010 19:41:12

Title: How long for a 360?
Post by: Geezer on 30/03/2010 19:41:12
How long does it take the Earth to rotate through 360 degrees?
Title: How long for a 360?
Post by: syhprum on 30/03/2010 20:12:37
The time of one rotation of the Earth known as the sidereal day day is approximately 23 hrs, 56 minutes, 4.091 seconds.
It varies a little year on year by a few milliseconds due to tectonic and ocean movements.
Title: How long for a 360?
Post by: Geezer on 30/03/2010 20:22:32
The time of one rotation of the Earth known as the sidereal day day is approximately 23 hrs, 56 minutes, 4.091 seconds.
It varies a little year on year by a few milliseconds due to tectonic and ocean movements.

Well, that topic didn't last too long!  [;D]

Presumably, the Earth rotates 366.25 (approximately) revolutions in one year rather than 365.25 (approx) as I had always imagined, until I actually started to think about it.
Title: How long for a 360?
Post by: Geezer on 30/03/2010 20:39:33
We might tend to think the Moon does not rotate, but I suppose it really does rotate once per orbit of the Earth.
Title: How long for a 360?
Post by: syhprum on 30/03/2010 21:51:01
It is very pleasent to get a simple factual question to answer, I get cheesed off by all the stuff about General relativity, blackholes etc.

I could not find anyone that quoted the length of the sidereal day on the Moon so I had to do the laborious Babylonian arithmetic and I make it 27 days, 5 Hrs, 55 Minutes and 46.7 sec

Title: How long for a 360?
Post by: Geezer on 31/03/2010 23:55:43

I could not find anyone that quoted the length of the sidereal day on the Moon so I had to do the laborious Babylonian arithmetic and I make it 27 days, 5 Hrs, 55 Minutes and 46.7 sec

How does Babylonian arithmetic work? That might be an interesting topic.

BTW, Is there any connection between the number of degrees in one revolution (360) and the number of days in a year, or is it just a coincidence that they are not very far apart?
Title: How long for a 360?
Post by: Soul Surfer on 01/04/2010 00:21:20
Yes there is a relationship the Babylonians thought there was about 360 days in a year and one degree in the sky is the distance travelled by the sun against the stars in a day.  they liked round numbers and a system based on 60