precession period
41Month — For the Egyptian hawk god, see Monthu. A month is a unit of time, used with calendars, which was first used and invented in Mesopotamia, as a natural period related to the motion of the Moon; month and Moon are cognates. The traditional concept… …
42Earth — This article is about the planet. For other uses, see Earth (disambiguation). Earth   …
43Orbital perturbation analysis (spacecraft) — Isaac Newton in his Philosophiæ Naturalis Principia Mathematica demonstrated that the gravitational force between two mass points is inversely proportional to the square of the distance between the points and fully solved corresponding two body… …
44Newton's theorem of revolving orbits — Figure 1: An attractive force F(r) causes the blue planet to move on the cyan circle. The green planet moves three times faster and thus requires a stronger centripetal force, which is supplied by adding an attractive inverse cube force. The …
45Orbit of the Moon — Not to be confused with Lunar orbit in the sense of a selenocentric orbit, that is, an orbit around the Moon The Moon completes its orbit around the Earth in approximately 27.3 days (a sidereal month). The Earth and Moon orbit about their… …
46geomagnetic field — Magnetic field associated with the Earth. It is essentially dipolar (i.e., it has two poles, the northern and southern magnetic poles) on the Earth s surface. Away from the surface, the field becomes distorted. Most geomagnetists explain the… …
47Cyclostratigraphie — Sommaire 1 Les cyclicités recherchées 1.1 Cycles climatiques 1.1.1 Excentricité 1.1.2 Obliquité …
48Earth's rotation — is the rotation of the solid Earth around its own axis. The Earth rotates towards the east, which can be observed by orientation with a magnetic compass at sunrise. As viewed from the star Polaris, the Earth turns counter clockwise. Rotation… …
49Equinox — This article is about the astronomical event when the sun is at zenith over the Equator. For other uses, see Equinox (disambiguation). For the same event happening on other planets and setting up a celestial coordinate system, see Equinox… …
50Astronomy on Mars — Mosaic of two different Mars Global Surveyor Mars Orbiter Camera (MOC) exposures of Earth, the Moon, and Jupiter from 2003 …
