tilt of earths axis [Archive]

jjjsarnis

Jan21-05, 06:04 PM

The Bob

Jan21-05, 06:15 PM

i was thinking that it might be from einsteins theory of gravity, in which a large object, such as the sun, causes a bend in space time forming gravity and causing earth to rotate around it.
I would disagree because Mercury is smaller and its tilt is about 2° if not less. Same with Jupiter.

The Bob (2004 ©)

check

Jan21-05, 06:26 PM

I think the theory goes that Earth got its tilt from a huge collision that happened to it very early in it's history. This collision with a Mars-sized object lead to the formation of the moon also.

Chronos

Jan21-05, 08:17 PM

All the planets have axial tilts: http://nssdc.gsfc.nasa.gov/planetary/factsheet/planet_table_british.html:
Mercury 0.01
Venus 177.4
Earth 23.5
Mars 25.2
Jupiter 3.1
Saturn 26.7
Uranus 97.8
Neptune 28.3
Pluto 122.5
It is believed this occured due to collisions in their formative phase. As you can see they are quite random as would be expected from a random cause like collisions.

Garth

Jan22-05, 02:21 AM

i was wondering what causes the earths tilt on its axis.
i was thinking that it might be from einsteins theory of gravity, in which a large object, such as the sun, causes a bend in space time forming gravity and causing earth to rotate around it.

Hi jjjsarnis!
No, the curvature of space-time does not cause the tilt of the Earth's axis; however it does cause a very tiny 'tilting over', or precession, called geodetic precession. This is being measured at the moment by the Gravity Probe B (http://einstein.stanford.edu/) satellite. GR predicts a geodetic precession of 6.6 milliarcsecs/year and there are some other gravitational theories, such as Self Creation Cosmology (http://arxiv.org/abs/gr-qc/0405094) that predict a different amount, it is a genuine 'head-to-head' contest; we shall find out in about a year!

Garth