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  2. 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.

  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. Decagram (geometry) - Wikipedia

    en.wikipedia.org/wiki/Decagram_(geometry)

    There are isotoxal decagram forms, which alternates vertices at two radii. Each form has a freedom of one angle. The first is a variation of a double-wound of a pentagon {5}, and last is a variation of a double-wound of a pentagram {5/2}. The middle is a variation of a regular decagram, {10/3}.

  5. Aberration (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Aberration_(astronomy)

    The change in angle is of the order of v/c where c is the speed of light and v the velocity of the observer. In the case of "stellar" or "annual" aberration, the apparent position of a star to an observer on Earth varies periodically over the course of a year as the Earth's velocity changes as it revolves around the Sun, by a maximum angle of ...

  6. Hendecagram - Wikipedia

    en.wikipedia.org/wiki/Hendecagram

    The star in this scroll is not one of the regular forms of the hendecagram, but instead uses lines that connect the vertices of a hendecagon to nearly-opposite midpoints of the hendecagon's edges. [ 8 ] 11-pointed star Girih patterns are also used on the exterior of the Momine Khatun Mausoleum ; Eric Broug writes that its pattern "can be ...

  7. Position angle - Wikipedia

    en.wikipedia.org/wiki/Position_angle

    The concept of the position angle is inherited from nautical navigation on the oceans, where the optimum compass course is the course from a known position s to a target position t with minimum effort. Setting aside the influence of winds and ocean currents, the optimum course is the course of smallest distance between the two positions on the ...

  8. AOL Mail

    mail.aol.com

    Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!

  9. Orbital speed - Wikipedia

    en.wikipedia.org/wiki/Orbital_speed

    In gravitationally bound systems, the orbital speed of an astronomical body or object (e.g. planet, moon, artificial satellite, spacecraft, or star) is the speed at which it orbits around either the barycenter (the combined center of mass) or, if one body is much more massive than the other bodies of the system combined, its speed relative to the center of mass of the most massive body.