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  2. Earth's rotation - Wikipedia

    en.wikipedia.org/wiki/Earth's_rotation

    Earth's rotation imaged by Deep Space Climate Observatory, showing tilt. Earth's rotation or Earth's spin is the rotation of planet Earth around its own axis, as well as changes in the orientation of the rotation axis in space. Earth rotates eastward, in prograde motion.

  3. Ecliptic - Wikipedia

    en.wikipedia.org/wiki/Ecliptic

    [1] [2] [a] From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic against the background of stars. [3] The ecliptic is an important reference plane and is the basis of the ecliptic coordinate system.

  4. Point groups in two dimensions - Wikipedia

    en.wikipedia.org/wiki/Point_groups_in_two_dimensions

    All of the cyclic groups are abelian or commutative, but only two of the dihedral groups are: D 1 ~ Z 2 and D 2 ~ Z 2 ×Z 2. In fact, D 3 is the smallest nonabelian group. For even n , the Hermann–Mauguin symbol n m is an abbreviation for the full symbol n mm, as explained below.

  5. Retrograde and prograde motion - Wikipedia

    en.wikipedia.org/wiki/Retrograde_and_prograde_motion

    A celestial object's axial tilt indicates whether the object's rotation is prograde or retrograde. Axial tilt is the angle between an object's rotation axis and a line perpendicular to its orbital plane passing through the object's centre. An object with an axial tilt up to 90 degrees is rotating in the same direction as its primary.

  6. Rotation formalisms in three dimensions - Wikipedia

    en.wikipedia.org/wiki/Rotation_formalisms_in...

    Rotation formalisms are focused on proper (orientation-preserving) motions of the Euclidean space with one fixed point, that a rotation refers to.Although physical motions with a fixed point are an important case (such as ones described in the center-of-mass frame, or motions of a joint), this approach creates a knowledge about all motions.

  7. Rotation - Wikipedia

    en.wikipedia.org/wiki/Rotation

    A sphere rotating (spinning) about an axis. Rotation or rotational motion is the circular movement of an object around a central line, known as an axis of rotation.A plane figure can rotate in either a clockwise or counterclockwise sense around a perpendicular axis intersecting anywhere inside or outside the figure at a center of rotation.

  8. Colatitude - Wikipedia

    en.wikipedia.org/wiki/Colatitude

    In a spherical coordinate system, a colatitude is the complementary angle of a given latitude, i.e. the difference between a right angle and the latitude. [1] In geography, Southern latitudes are defined to be negative, and as a result the colatitude is a non-negative quantity, ranging from zero at the North pole to 180° at the South pole.

  9. Glossary of geography terms (A–M) - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_geography_terms...

    A circle is divided into 360 degrees; subdivisions of the degree include the minute (1 ⁄ 60 of one degree) and the second (1 ⁄ 3600 of one degree). Degrees are commonly used to divide the roughly spherical shape of the Earth for geographic and cartographic purposes, e.g. when reporting latitudes and longitudes. [1] degree day