English Deutsch Français Italiano Español Português 繁體中文 Bahasa Indonesia Tiếng Việt ภาษาไทย
All categories

since gravity pushes us down here of earth so how come the planets could stay afloat. curiousity

2007-05-07 05:14:32 · 7 answers · asked by Belee 2 in Science & Mathematics Astronomy & Space

7 answers

Fall where? There is no up or down in space.

Also, the planets are hold in their ellipse patterna by the gravity of the Sun. The gravity of the Sun is what holding them into place. Otherwise they would just float away somewhere just like you wondered.

Also if a planet comes too close to the Sun, the gravity of the Sun can grab it and cause it to "fall" into the Sun itself but that won't happen unless something unordinary and catastrophic happens.

Edit:
Since Joylin doesn't credit the source that he COPIED AND PASTED, I'll do it for him: http://curious.astro.cornell.edu/question.php?number=416

2007-05-07 05:23:23 · answer #1 · answered by Mattias 3 · 1 0

The planets are not floating.The planets are always falling. An orbit is just one continuous never ending fall that always misses the ground. A satellite in Earth orbit is always falling to Earth, but it is moving so fast sideways that the surface of the Earth curves out from under it as fast as the satellite falls. So with the planets, they are always falling into the Sun but missing to one side because of their sideways speed through space. Floating is a totally different thing, where some material like water supports something else, like a boat, against the pull of gravity. In an orbit, nothing supports anything.

2007-05-07 05:22:54 · answer #2 · answered by campbelp2002 7 · 1 0

ok, you need to expand your understanding of gravity. Gravity doesn't "push us down". It pulls us towards the center of mass (which is the center of the earth's mass). In space there is no such thing as up or down, but each planet has its own gravitational field. The bigger (more mass) the planet, the stronger the gravitational force. Each planet's gravitational force has an effect on other planets. In some cases it's a very small effect, in other cases it's quite noticeable like the tides which are caused mainly by the gravitational forces of the moon and I think the sun.
Imagine the planets as a bunch of magnets floating in space, and they're set up in such a way that the forces that cause them to attract each other and repel each other keep them in the positions where they are. This is oversimplified, but that's kinda how it works.

2007-05-07 05:29:21 · answer #3 · answered by Anonymous · 0 0

There is no force that causes the planets to rotate. Most of the rotation comes about from the conservation of angular momentum. Angular momentum is given by L=m*w*r2 where m is the mass, w is the angular velocity in radians per second, and r is the radius of the circular motion. Due to conservation of angular momentum, if the radius of the orbit decreases, then its angular velocity must increase (as the mass is constant).

All planetary and stellar systems are born from the collapse of dense interstellar clouds. The clouds may originally be very large (even thousands of light years across). Consider a portion of the cloud the collapses from a size of a light year or so to the size of the solar system. That is a huge change in the size of the system. So, the very slight rotation that the cloud has in the beginning is increased dramatically when the collapse takes place. In fact, this is one of the barriers in star formation: there is excess angular momentum and there has to be a way of losing angular momentum before you can form a star.

Anyway, the bottom line is that stars like the Sun spin from the original angular momentum that was there in the solar nebula from which it formed. Not only that, all orbital motion of the planets (including the spin) is due to this orginal angular momentum.

You are saying that original angular momentum of the cloud causes orbital motions and rotations of the planets(mostly). But in the case of orbital motions we have gravitational force that gives us some restrictions of movement(Kepler laws,for example).

What I am saying is that there will be no planets if there was no initial angular momentum in the primordial solar nebula. If a nebula with absolutely no rotation collapses, then there will only be a central non-rotating star and there will not be any planets. Planets form out of a protostellar disk, which itself forms only because of the initial angular momentum of the cloud. The dynamics of a rotating body is of course controlled by forces like gravity. Kepler's laws are a direct consequence of gravity.

Are there some laws also in the case of rotations?

The only thing that has to be kept in mind in rotation is that it results in a centrifugal acceleration that points radially from the center of motion. Hence, there has to be some force that conteracts this acceleration; otherwise the body will fly away (in case of orbital motion) or will disintegrate (in case of spinning). In the case of orbital motion, the counteracting force is gravity; gravity causes the body to continually fall towards the center, and this exactly conteracts the force resulting from the centripetal acceleration. In the case of a spinning object, it is the self-adhesion of the body itself that keeps it together. This results in a limit for how fast an object can rotate and still keep itself together. If it rotates too fast, the outward acceleration felt by the elements in the body may be more than the force that keeps them bonded together, and if this happens, the body breaks up. Other than this, there is no real law concerning rotations. (Note that rotational motion involves conservation of angular momentum just like linear motion conserves linear momentum).

2007-05-07 05:20:54 · answer #4 · answered by joysam 【ツ】 4 · 0 2

gravity pulls us towards the earth
there is no "down" in space
earth's gravity keeps the moon orbiting us
the sun's gravity keeps the earth orbiting around it
every large mass has a certain amount of gravity

2007-05-07 05:23:32 · answer #5 · answered by drizzle 2 · 0 0

The planets are falling. They have sufficient momentum that they are constantly going to the side and "missing" the Sun. That is an orbit.

There is no "floating".

2007-05-07 05:24:57 · answer #6 · answered by novangelis 7 · 1 0

This is the craziest question ive heard. Space doesnt have any gravity, things with mass make gravity.

2007-05-07 07:49:28 · answer #7 · answered by Anonymous · 0 0

fedest.com, questions and answers