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Typically, the stated rotation period for a giant planet (such as Jupiter, Saturn, Uranus, Neptune) is its internal rotation period, as determined from the rotation of the planet's magnetic field. For objects that are not spherically symmetrical, the rotation period is, in general, not fixed, even in the absence of gravitational or tidal forces.
This can be roughly taken as 3 × 10 10 N/m 2 for rocky objects and 4 × 10 9 N/m 2 for icy ones. Even knowing the size and density of the satellite leaves many parameters that must be estimated (especially ω , Q , and μ ), so that any calculated locking times obtained are expected to be inaccurate, even to factors of ten.
For instance, a small body in circular orbit 10.5 cm above the surface of a sphere of tungsten half a metre in radius would travel at slightly more than 1 mm/s, completing an orbit every hour. If the same sphere were made of lead the small body would need to orbit just 6.7 mm above the surface for sustaining the same orbital period.
Average distance of Earth's orbit from the Sun (sunlight travels for 8 minutes and 19 seconds before reaching Earth) — Mars: 1.52 — Average distance from the Sun — Jupiter: 5.2 — Average distance from the Sun — Light-hour: 7.2 — Distance light travels in one hour — Saturn: 9.5 — Average distance from the Sun — Uranus: 19.2 ...
The orbits are ellipses, with foci F 1 and F 2 for Planet 1, and F 1 and F 3 for Planet 2. The Sun is at F 1.; The shaded areas A 1 and A 2 are equal, and are swept out in equal times by Planet 1's orbit.
G is the universal gravitational constant (G ≈ 6.67 × 10 −11 m 3 ⋅kg −1 ⋅s −2 [4]) g = GM / d 2 is the local gravitational acceleration (or the surface gravity , when d = r ). The value GM is called the standard gravitational parameter , or μ , and is often known more accurately than either G or M separately.
The asteroid and comet belts orbit the Sun from the inner rocky planets into outer parts of the Solar System, interstellar space. [16] [17] [18] An astronomical unit, or AU, is the distance from Earth to the Sun, which is approximately 150 billion meters (93 million miles). [19] Small Solar System objects are classified by their orbits: [20] [21]
To help compare different orders of magnitude, this section lists lengths between 10 −15 meters and 10 −14 meters (1 femtometer and 10 fm). 1 fm – diameter of a neutron, approximate range-limit of the color force carried between quarks by gluons [6] [7] 1.5 fm – diameter of the scattering cross section of an 11 MeV proton with a target ...