why is the earth round?

Answer 1

It's the gravity, of course.

Imagine Earth were liquid--consisting, say, only of water. Gravity
would of course pull that water towards the center, and if any could
flow closer to the center, it would do so.

Therefore, if such an Earth were not a sphere--if some points were
higher than the average--their water would quickly flow down. Water
would also flow into any valley deeper than the average and fill it up.
The final shape MUST be a sphere. Only then does every point on the
surface have the same distance from the center.

Answer 2

Why is the Earth round?
Author: bragee
Text: Why is the earth round?

Response #: 1 of 1
Author: Robert Topper
Text: An interesting question. Now, the first question that comes to
my suspicious mind is "IS the earth round?" And the answer is no, at least
not perfectly round. But it is round compared to your average cube, that is
for sure! Now, my understanding of how solar systems form is pretty
inadequate; all I can tell you is what I see on "Nova." But basically, I
guess it has to do with gravity, which is a CENTRAL FORCE. What that means is
that gravity pulls things together along a straight line, and the more massive
one of the things is, the stronger it pulls. When the earth was forming, it
was basically a big ball of dust left over from an exploded sun (a supernova).
Gravity caused a lot of the matter to condense into a big fiery ball (our
sun), but some of the dust was far enough away from the Sun so that the
stronger forces were between planetary dust particles and not the sun. SO,
they swirled together into a ball. You can see something similar when you
make a painting with one of those "spin-art" machines; you put a card on the
spinner, which whirls around real fast, and then you squirt paint on the card.
The whirling causes the paint to go out away from the center (this is like the
explosion of the supernova) and droplets go out along an interesting path
until they stop, which happens when the spinning force is equal and opposite
to the force which attaches paint to the card (this is like gravity). Now, if
the force attaching paint to the card were not so strong,eventually the drops
would get bigger - "planets."

Answer 3

Gravity pulls everything toward the center of mass. And it turns out the way the most stuff can get closest to the center is to become a sphere. So the earth is roughly round. Not precisely because it is a bit flattened at the poles because the spin of the earth adds a little force against gravity. Sort of pushes out a bit at the equator.

Answer 4

Yes; I think gravity would certainly be a prime contributor, but surely that would be boosted by the fact that it's spinning ... because you've also got to take into the mental picture that at the same time, it is moving through space at 70,000 mph - that action would tend to yield it more into the shape of a comet!

I would tend to believe the spinning motion would assist greatly in ofsetting that outcome ... because it ensures that no particular aspect of it has time to take on a permanent position and therefore particular 'role', as it hurtles through space!
If it wasn't hurtling through space, gravity alone may be sufficient to retain the spherical shape.

Answer 5

Because it has sufficient mass for it's own gravity to overcome rigid body forces and attain hydrostatic equilibrium.

Or god made the earth round so that he could stand his archangels at the four corners. Oh, hang on.....

Answer 6

'cuz when it was being formed and was all molten and stuff, gravity pulled it into a ball. But it's not a perfect ball because it was spinning on an axis, so centrifugal force pulled it out at the equator, which is why the earth has a fat waistline.

Answer 7

Because of the Europeans. If they would not have carried out sea voyages in the middle ages the earth would still remain flat today!

Answer 8

Earth is not round. It is a spheroid; almost flat at the poles and bulging at the equator.

Answer 9

Its round. Since when?

Answer 10

It's mass, creates a gravitational pull, and the sphere is the most sensible outcome. We're not absolutely round though, we're slightly ellipsoidal.