A lovely crescent Moon hangs as if suspended between Jupiter (upper left) and Venus (lower right) in this February 2012 image; a similar grouping will occur in the sky this week. Credit: Steve Elliot (Flickr, CC BY-SA 2.0) Sky This Week is brought to you in part by Celestron. Friday, May 15 Are you familiar with the constellation Crater the Cup? If not, don’t worry — you’re about to spot it tonight.  This mid-sized constellation, measuring 53rd in size among the 88 official constellations, sits about 30° high in the south an hour after sunset. It is located to the right (west) of Corvus the Crow, and both appear to the lower right of larger Virgo. Crater also hangs directly beneath the hindquarters of Leo the Lion at this time of year and night.  Despite being of reasonable size, Crater is not bright — it ranks much lower, 82nd, in terms of brightness. Its alpha star is the only star in the constellation with a name: Alkes. It shines at magnitude 4.1.…