Why are planets round?

  • 2 Replies
  • 1061 Views

0 Members and 1 Guest are viewing this topic.

*

Offline thedoc

  • Forum Admin
  • Administrator
  • Sr. Member
  • *****
  • 513
    • View Profile
Why are planets round?
« on: 09/02/2014 13:30:01 »
Paul Anthony Weston <> asked the Naked Scientists:
   
Why are planets round, and not lumps of rock?

Paul Weston

What do you think?
« Last Edit: 09/02/2014 13:30:01 by _system »

*

Offline RD

  • Neilep Level Member
  • ******
  • 8185
    • View Profile
Re: Why are planets round?
« Reply #1 on: 09/02/2014 13:46:54 »
Why are planets round ...

A. by definition (#2) ...

Quote from: wikipedia.org
The definition of planet set in 2006 by the International Astronomical Union (IAU) states that, in the Solar System, a planet is a celestial body which:

1.   is in orbit around the Sun,
2.   has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
3.   has "cleared the neighbourhood" around its orbit.
https://en.wikipedia.org/wiki/2006_definition_of_planet


B. because they are/were largely fluid , fluid in space forms a sphere (or an oblate spheroid if it is spinning) ... http://www.youtube.com/watch?v=qTy9NpSLm0I
« Last Edit: 09/02/2014 14:07:48 by RD »

*

Offline Aashish Karia

  • First timers
  • *
  • 1
    • View Profile
Re: Why are planets round?
« Reply #2 on: 22/02/2014 22:04:45 »
I think it is because Gravity is the key, there is an equal amount of gravity pulling in mass on all sides which is why the atmosphere is a constant distance from ground even the surface is so unsmooth.