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  2. Star polygon - Wikipedia

    en.wikipedia.org/wiki/Star_polygon

    The parametric angle 𝛼 (in degrees or radians) can be chosen to match internal angles of neighboring polygons in a tessellation pattern. In his 1619 work Harmonices Mundi , among periodic tilings, Johannes Kepler includes nonperiodic tilings, like that with three regular pentagons and one regular star pentagon fitting around certain vertices ...

  3. Octagram - Wikipedia

    en.wikipedia.org/wiki/Octagram

    In Unicode, the "Eight Spoked Asterisk" symbol is U+2733.; The spikes are specially visible around Jupiter's moon Europa (on the left) in this NIRCam image.. The 8-pointed diffraction spikes of the star images from the James Webb Space Telescope are due to the diffraction caused by the hexagonal shape of the mirror sections and the struts holding the secondary mirror.

  4. Pentagram - Wikipedia

    en.wikipedia.org/wiki/Pentagram

    The Order of the Eastern Star, an organization (established 1850) associated with Freemasonry, uses a pentagram as its symbol, with the five isosceles triangles of the points colored blue, yellow, white, green, and red. In most Grand Chapters the pentagram is used pointing down, but in a few, it is pointing up.

  5. Proper motion - Wikipedia

    en.wikipedia.org/wiki/Proper_motion

    Barnard's Star's transverse speed is 90 km/s and its radial velocity is 111 km/s (perpendicular (at a right, 90° angle), which gives a true or "space" motion of 142 km/s. True or absolute motion is more difficult to measure than the proper motion, because the true transverse velocity involves the product of the proper motion times the distance.

  6. Astronomical coordinate systems - Wikipedia

    en.wikipedia.org/wiki/Astronomical_coordinate...

    Angles in the hours ( h), minutes ( m), and seconds ( s) of time measure must be converted to decimal degrees or radians before calculations are performed. 1 h = 15°; 1 m = 15′; 1 s = 15″ Angles greater than 360° (2 π ) or less than 0° may need to be reduced to the range 0°−360° (0–2 π ) depending upon the particular calculating ...

  7. Parallactic angle - Wikipedia

    en.wikipedia.org/wiki/Parallactic_angle

    In spherical astronomy, the parallactic angle is the angle between the great circle through a celestial object and the zenith, and the hour circle of the object. [1] It is usually denoted q . In the triangle zenith—object—celestial pole, the parallactic angle will be the position angle of the zenith at the celestial object.

  8. Cosmic distance ladder - Wikipedia

    en.wikipedia.org/wiki/Cosmic_distance_ladder

    This shift is the apex angle in an isosceles triangle, with 2 AU (the distance between the extreme positions of Earth's orbit around the Sun) making the base leg of the triangle and the distance to the star being the long equal-length legs (because of a very long distance from the Earth orbit to the observed star).

  9. Hexagram - Wikipedia

    en.wikipedia.org/wiki/Hexagram

    A six-pointed star, like a regular hexagon, can be created using a compass and a straight edge: . Make a circle of any size with the compass. Without changing the radius of the compass, set its pivot on the circle's circumference, and find one of the two points where a new circle would intersect the first circle.