Rare Uranian eclipse.The Hubble Space Telescope Hubble Space Telescope (HST), the first large optical orbiting observatory. Built from 1978 to 1990 at a cost of $1.5 billion, the HST (named for astronomer E. P. Hubble) was expected to provide the clearest view yet obtained of the universe. has for the first time recorded an eclipse on Uranus. The white dot is Uranus' moon Ariel, which is 1,120 kilometers wide. By blocking the sun, it casts a shadow (black dot to right) on the planet's cloud tops. Although eclipses frequently occur on Jupiter and Saturn, Uranus rotates tipped on its side, so the sun alternately shines on one pole or the other during the planet's 84-year orbit. Because the moons of Uranus Uranus has twenty-seven known moons. The first two moons (Titania and Oberon) were discovered by William Herschel on March 13, 1787. Two more moons (Ariel and Umbriel) were discovered by William Lassell in 1851. orbit at the planet's equator, the sun seldom illuminates them directly. During the last equinox equinox (ē`kwĭnŏks), either of two points on the celestial sphere where the ecliptic and the celestial equator intersect. The vernal equinox, also known as "the first point of Aries," is the point at which the sun appears to cross the on Uranus, in 1965, no telescope was sharp enough to record an eclipse. As uranus approaches its 2007 equinox, astronomers Famous astronomers and astrophysicists include: Directory: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A
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