... The Round Earth . ... Aristarchus around 270 BC derived the Moon's distance from the duration of a lunar eclipse (Hipparchus later found an independent method). ... Let R be the radius of that circle and T the time it takes the Moon to go around once, about one month. ... Viewed from Earth, a "new Moon" (occuring between the time a thin crescent is last seen before sunrise and the time one is seen shortly after sunset) happens when the Moon in its apparent motion around the sky overtakes the Sun. ...

... Hubble Detects Faster-Than-Light Motion in Galaxy M87 . ... Click on image for larger version. (100kB GIF) Sequence of Hubble images showing apparent motion at six times the speed of light in the galaxy M87. ... The slanting lines track the moving features, and the speeds are given in units of the velocity of light ``c." The images were made between 1994 and 1998 with the Faint Object Camera on the Hubble Space Telescope. ... PHOTO CREDIT: John Biretta, Space Telescope Science Institute. ...

Compilation of distance measurements . HyperLeda home | Documentation | Search by name | Search near a position | ... SQL Search | Search an object in the distance catalogue . This catalog (table a007 in the database) presents the compilation of published distance mesurements using photometric distance indicators. Photometric modulus. Error of modulus measurement. The method used to determine the distance is coded for each measurement as follow: . HyperLeda . ...

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