Earths seasons

[yanira2011]

Do any of you know what causes the earth to spin or what keeps it spining?

or simply anything about earth and its seasons.

if u do just tell me

[Clanad]

Large question for a short answer... but let me try.. the earth is tilted 23.5 degrees from the vertical compared to it's rotational plane around the sun.  This causes, in the course of a year, (which is the time required for the earth to complete one circuit of the sun) the sunlight to strike the earth either more directly or less directly.  The time spent with the sun striking the earth directly (in the northern hemisphere, for example) warms the earth and causes spring and summer, as the earth continues the journey, the sunlight begins to strike the earth less directly causing fall and winter.  This is greatly simplified, but accurate for a description of your request.  The same warming cooling causes weather patterns throughout the earth...

The earth was set spinning during the intial formation out of cosmic dust, about 4.5 billion years ago...it continues to spin, basically because there is nothing to stop it.  BTW, it spins counter-clockwise as viewed from space and compared to the north pole. It spins about 1,000 miles per hour and travels around the sun at nearly 67,000 miles per hour.  The total speed of the earth in all modes of motion is over 1 million miles per hour.

[Space]

there are 2 different things:

Earth spins ( around its axis ) , at 1 spin per day, that is what we have night and day

Earth rotates around the sun, 1 rotation per year, that gives us seasons.

[jake-the-peg]

Check this out for a visual demonstration

http://www.astro.uiuc.edu/projects/data/Seasons/seasons.html

[JudgeJ]

Just to add a little more. There is something slowing the earth down and that is the “tidal” effect that the moon has upon the Earth’s rotation. The tidal effect caused by the moon’s gravitational “pull” causes the earth to “bulge” towards the moon. This happens to all celestial bodies but can be seen quite clearly on Earth by the twice daily movement of the sea known as the “tides”.

This daily distortion of the Earth’s shape is causing a gradual loss of its angular momentum (i.e. the energy it has by virtue of its spinning) and it is slowly, but very surely, slowing down. Some scientists suggest that the earth’s day was as short as ten hours when it was first formed.

Eventually the Earth will become “tidally locked” with the moon and the same point on earth will always face the moon. This is because the Earth will take the same time to rotate once on its axis as the moon takes to revolve around the Earth.

This has already happened to the moon. The tidal effect of the earth upon the moon was far greater because the Earth is about 100 times more massive than the moon, so Tidal Locking of the moon occurred much sooner. The moon takes 28 days to revolve around the Earth and the same time to rotate once on its axis. As a result we always see the same face of the moon facing the Earth and it was not until the 1960’s when a spacecraft first revolved around the moon that photographs of the far side were taken.