why is the earth on its axis?
363001
Some people think its because of the moon. The theory is that a huge asteroid hit the earth and then bounced of into orbit around the earth. This supposedly caused the earth to have a tilt to its axis.
759412
Even if the earth wasn't tilted at all, it would still be colder at the poles and hotter at the equator.  Imagine that you want to find a place to lay down solar power panels on the ground.  You'll get more solar energy if you picked a spot at the equator than at the poles, because one gets the maximum solar energy influx when the sun is directly overhead, and minimum when it's at the horizon.  Having the earth tilted merely exaggerates this effect, and causes seasonal changes in solar influx for different parts of the world, but is not the primary cause of "too cold" and "too hot" being in some places.  The primary cause is that the earth is round, so that some places just get more solar energy than others.
479647
the tilt of the earth and when it revolves around the sun
224113
The same reason toilets flush in counterclockwise rotation in the southern hemisphere, the rotation of the earth.
419209
the Earth (Inclination of the Earth's Axis)\nThe axis of the earth's rotation is inclined 66.5 degrees from the plain of the ecliptic or 23.5 degrees from an imaginary line vertical to it.\n\nWithout the inclination of the earth there would be no seasons.\n\nDaylength would be exactly 12 hr light and 12 hr dark except at 0º when the sun would always be at the horizon
879838
Well this might be a bad explanation 'cause I'm from Minnesota. Things are a lot different up here.\n\nBut here's something I learned in 8th grade.\n\nWell the Earth makes one revolution around the sun in one Earth year. We'll just say that its plane is horizontal to the Sun. at some point the earth is closer to the sun and then farther from it.\n\nNot really important but here's the major thing.\n\nThe earth rotates on its axis. This axis to us common humans is depicted as VERTICAL although it is not. It is at a slight slant and if I can remember... that slant is about... 23.7 degrees or 27.3 degrees. But anyways, the earth is slant that much so part of the year, the earth's northern hemisphere is pointed towards the sun, thus Minnesota's late spring/early summer climate. As the year goes on, the top part of the axis points away from the sun so the bottom of the axis is point to the sun. Now the southern hemisphere gets its summer. Right now, the northern hemisphere is pointed away from the sun so we are almost in complete darkness (but the sun's light is reflected into our earth's atmosphere, so we still have light in the morning, just at a different time). Therefore, in the southern hemisphere it is their brightest time of the year.\n\nHope that helps.\n\n~Ninth grader (tee hee)
356220
Depends on your point of view. If you're hovering above the North pole, the earth rotates counter-clockwise. If you're hovering above the South pole, it rotates clockwise.
884879
Because the earth is round, and if you made your flat map a oval(circle), the oceans would connect and become one!
1125779
The earth rotates around the sun on an elliptical course at an axis of 23 degrees.  As the northern or southern hemisphere gets closer or further from the sun the amount of light hitting it changes making the seasons.\n\nCombine the axial tilt and the ellipitical path and you create periods of warmth (spring and summer) and periods of cold (fall and winter).\n\nThe primary property is the earth’s 23 degree tilt.  The axial tilt remains fixed as the earth rotates.  When the earth’s axis is turned away from the sun less light falls on that side of the earth and it gets colder.  When the axial tilt is closer to the sun then more light falls upon the earth making it warmer.  This also explains the length of the days.  The earth’s rotational speed doesn’t change, but one hemisphere is tilted closer to the sun so their day is longer.\n\nThen there is the orbital path.  When part of the earth is farther from the sun it gets colder, as it gets closer it gets warmer.  As the earth rotates around the sun it gets closer and further from the sun so the temperature varies.  This is because of the orbital path the earth takes around the sun.  It is not a circular path because to orbit in a true circular path you need to be in a perfectly balanced orbital position with the speed of travel just matching and canceling the attraction of the object.  Satellites in Geo-stationary orbits around the earth are on such a path (since this point matches the speed of the earth’s rotation the satellite is in a fixed position relative to the earth), no planet is in such a position around the sun.  As the earth rotates it gets closer to the sun (and its speed increases, because the sun’s gravity is tugging on it), as the earth goes around the sun it reaches a point where it is closer than at any other point (perihelion), so the earth’s surface gets warmer.  As the earth continues around the sun it slows down, because the sun’s gravity is still tugging on it.  But, since it has accelerated it has a higher velocity so it can travel farther from the sun.  When it reaches its maximum distance (aphelion) the earth is colder.  At this distance it’s speed (velocity) is zero.  The sun is still tugging on the earth so it falls in toward the sun and accelerates, continuing on its orbital path.\n\nSounds real tricky doesn’t it, but counting all the asteriods, planets, and comets over a billion objects rotate around the sun on similar paths and they all have season.
991215
Because the sun has a gravitational pull on all objects that rotate around it. The earth, like all the other planets revolving around the sun, is pulled toward it to a certain extent, which keeps the earth from floating away into outer space.
505384
We can see the sun rise and set, and it would be impossible for the sun to revolve around the earth because of the huge difference in math, so the only explanation is that the earth is spinning.\n\nIn reply to the first two replys, the sun is not the center of the universe, it is the center of the solar system. Also, because of the sun's gravity, we REVOLVE, but that has nothing to do with rotation. MOMENTUM is what causes us to not feel the spin/movement, not inertia.
996336
If you mean on it's axis...no.  We're pretty small. Like ants building ant hills on an Island. BUT.......  We are digging and delving and pulling from the earth many elements and resources that will eventually cause some degree of irreplaceable loss. Whether this will totally upset the planet's inner workings or not can only be told over time. But aren't we seeing some very strange things happening these days?  Maybe it's all cyclical or maybe we are partially to blame.  Why chance it.  Best example is obvious.....stop using fossil fuels.
12606
Our world, Earth, is a planet, and planets are round because their gravitational field acts as though it originates from the center of the body and pulls everything toward it. With its large body and internal heating from radioactive elements, a planet behaves like a fluid, and over long periods of time succumbs to the gravitational pull from its center of gravity. The only way to get all the mass as close to planet's center of gravity as possible is to form a sphere. The technical name for this process is "isostatic adjustment."\n\nIf the shape of the Earth were due solely to gravity it would be a perfect sphere (round in 3 dimensions) but it's not, the Earth is shaped like what is called an oblate spheroid. As the Earth spins on it's axis, it produces a centrifugal force that pulls away from the Earth (in opposition to gravity)  at 90 degrees from the spin axis, this corresponds to the equatorial regions. So the Earth bulges out a little around it's middle.
515806
The earth rotates on its axis (spins) the same way as the sun does on its axis, since the planets all formed out of the proto-solar disc when the sun was forming.  All of the planets spin the same way, EXCEPT for Venus, which rotates (very slowly, once every 243 days) in the opposite direction.  Some planetary scientists consider this evidence that Venus at one time collided with another large body early in its lifetime, which caused the retrograde rotation.
1009840
1. Earth's rotation is the reason we have days and nights. Without Earth rotating the sun would shine on one place only and the other side of the planet would be in the dark. Rotation is also the possible reason for its magnetic field.\n\n2. Earth's revolution is the reason for seasons and gravity.
1015345
The Earth rotates on its access and revolves around the Sun.
773087
None of the answers given so far can be right.  The Earth doesn't spin bolt-upright, the rotational axis wobbles over time (precession).  Both poles alternately spend 6 months of the year in continuous sunlight with little or no darkness, and then 6 months in almost perpetual darkness, so it cannot be just due to the amount of sunlight available.  \nI seem to remember reading an explanation for this that relates to the Earth's magnetic field channelling solar radiation away from the polar regions toward the equator.  Presumably then the poles are colder because the magnetic poles happen to be relatively close to the rotational poles and the radiation is being channelled away from these areas ?