Because we are spinning at the same time as orbiting the sun
The basic reason why the planets revolve around, or orbit the sun (rotate actually is used to describe their spin, for example, the Earth completes one rotation about its axis every 24 hours, but it completes one revolution around the Sun every 365 days), is that the gravity of the Sun keeps them in their orbits. Just as the Moon orbits the Earth because of the pull of Earth's gravity, the Earth orbits the Sun because of the pull of the Sun's gravity.
Because the sun has a different orbit just as the earth have a full year to orbit around the sun Technically, what is going on is that the Earth, Sun and all the planets are orbiting around the center of mass of the solar system. This is actually how planets orbiting other stars are often detected, by searching for the motion of the stars they orbit that is caused by the fact that the star is orbiting the center of mass of the system, causing it to wobble on the sky.
The center of mass of our solar system very close to the Sun itself, but not exactly at the Sun's center (it is actually a little bit outside the radius of the Sun). However, since almost all of the mass within the solar system is contained in the Sun, its motion is only a slight wobble in comparison to the motion of the planets. Therefore, assuming that the Sun is stationary and the planets revolve around its center is a good enough approximation for most purposes.
2007-01-21 18:48:03
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answer #1
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answered by QuiteNewHere 7
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It is because the Earth's rotational axis is inclined to the plane of its orbit. In plain language this means that the Earth is not straight up and down but tipped over a bit (about 23°). So as it travels around the Sun, a side that is tipped closer to the Sun in one season is tipped a bit farther away in the opposite season. That makes the position of the Sun wobble a bit to the north and south over the course of the year. The tropics of Cancer and Capricorn mark the boundaries of the region where the sun passes directly overhead.
2007-01-21 18:51:51
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answer #2
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answered by Scarlet Manuka 7
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The earth's axis is tilted in relation to earth's orbit around the sun. The varying angle of sunlight this produces gives us our seasons. Once the earth completes its orbit around the sun, which takes a year, it starts all over again.
A great explanation with clear pictures can be found at the link below.
2007-01-21 18:46:33
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answer #3
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answered by roxburger 3
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Tilt and slight shift of the axis in which earth spins. If you measure it it is 23 and 1/2 degrees, over the year.
This causes Equinoxes twice a year.
Seasons are caused by elliptical orbit around the sun. Tilt plays minimum role.
Tides are caused my moon and the rotation of the earth.
2007-01-22 04:09:21
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answer #4
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answered by minootoo 7
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The axis on the Earth is tilted 23.5 degrees off the plane of the orbit. The Sun rises at its extremes on the solstices, and due east on the equinoxes.
2007-01-21 18:48:03
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answer #5
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answered by novangelis 7
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the earth's rotational axis is tilted by about 22 degrees from the plane of earth-revolution around the sun.
this accounts for the seasons and also accounts for the different positions of rising which you (correctly) observe
2007-01-21 18:46:23
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answer #6
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answered by atheistforthebirthofjesus 6
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< Confusion is the wrongdoer...I stay interior the U. S., yet 10 yrs in the past, I traveled to Jamaica...the sunlight "looked" to upward push over a distinctive horizon as though it have been transforming into from the west and not the east...it replaced into puzzling to me even however I "knew" there replaced into no way it might desire to truthfully upward push from the west...unusual adventure, it replaced into :)
2016-12-16 10:25:32
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answer #7
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answered by ? 4
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earth's axis is tilted
2007-01-22 00:57:38
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answer #8
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answered by Earth to Mars 5
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