The area south of the Antarctic Circle is known as the Antarctic, and the zone immediately to the north is called the Southern Temperate Zone. The equivalent line of latitude in the northern hemispher ...
A topographical map is the main type of map used to depict elevation, often through use of contour lines. In a Geographic Information System (GIS), digital elevation models (DEM) are commonly used to ...
Further information: Biomolecule, cell (biology) and biochemistryStructure of a triacylglycerol lipidMost of the structures that make up animals, plants and microbes are made from three basic classes ...
A supplement to the factors that support life's emergence is the notion that life itself, once formed, becomes a habitability factor in its own right. An important Earth example was the production of ...
An understanding of planetary habitability begins with stars. While bodies that are generally Earth-like may be plentiful, it is just as important that their larger system be agreeable to life. Under ...
As the Earth spins around its axis and orbits around the Sun, several quasi-periodic variations occur due to gravitational interactions. Although the curves have a large number of sinusoidal component ...
These formulae characterize the periapsis and apoapsis of an orbit:Periapsis: maximum speed v_\mathrm{per} = \sqrt{ \tfrac{(1+e)\mu}{(1-e)a} } \, at minimum (periapsis) distance r_\mathrm{per}=(1-e)a\ ...
The existence of Earth's free nutation was predicted by Isaac Newton in Corollaries 20 to 22 of Proposition 66, Book 1 of the Philosophi? Naturalis Principia Mathematica, and by Leonhard Euler in 175 ...
In mathematics and theoretical physics, quasiperiodic motion is in rough terms the type of motion executed by a dynamical system containing a finite number (two or more) of incommensurable frequencies ...
It consists of two quasi-periodic components and a gradual drift, mostly in the direction of the 80th meridian west, of the Earth's instantaneous rotational axis or North pole, from a conventionally d ...
In torque-free precession, the angular momentum remains fixed, but the angular velocity vector changes. What makes this possible is a time-varying moment of inertia, or more precisely, a time-varying ...
If a top is set at a tilt on a horizontal surface and spun rapidly, its rotational axis starts precessing about the vertical. After a short interval, the top settles into a motion in which each point ...
An equinox occurs twice a year, around 20 March and 22 September. The word itself has several related definitions. The oldest meaning is the day when daytime and night are of approximately equal durat ...
When Julius Caesar established his calendar in 45 BC he set 25 March as the spring equinox. Because a Julian year (365.25 days) is slightly longer than an actual year the calendar drifted with respect ...
The summer solstice occurs when the tilt of a planet's semi-axis, in either the northern or the southern hemisphere, is most inclined toward the star (sun) that it orbits. Earth's maximum axial tilt t ...
