Why are all planets spherical and why asteroids are not?

Why are all planets spherical and why asteroids are not?

i mean what makes them spherical?? asteroids may look like rock pieces etc, bt in any case they r nt spherical, so r d meteors, comets etc.......

Answer1:

There is limit for the mass which decides wheather the object becomes spherical or not.. During the formation when the nebula is condensing the matter comes close and there will formation of dense globules .. They attract each other and come closer colliding with each other .. During colision the kinetic energy is converted to heat energy.. The heat energy produced in this process must be large enough to melt that material, If it is not sufficiently massive then the object does not assume spherical shape. Approximately calculating this mass it comes out to be of the order of 10^21 . The mass of the asteroids we have is far below this mass and that of planets is above this.. Hence the planets ae spherical but asteroids are not..

Answer2:

spherical shape is due 2 bound gravity................
asteroids are crushed fragment-like remains of any celestial body.............
they donot posses gravity................but are influenced by gravity.

Answer3:

according to me!!
as planets also revolve around their axis, this has two effects!!
> they have stronger gravitational pull.
> they maintain their spherical shape.

while asteroids dont revolve around their own axis!!
any comments?

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