This is Dudley Observatory’s Skywatch Line for Friday, May 6, through Sunday, May 8, written by Sam Salem.
On Friday, the Sun rises at 5:43am and sets at 8:02pm. The New Moon occurs at 3:30pm, this afternoon, and sets a few minutes before sunset, around 7:58pm. On Saturday, the New Moon sets at 9:10pm, try to catch the hairline crescent Moon twenty or thirty minutes after sunset, just a few degrees above the west-northwest horizon, Aldebaran is a few degrees above or upper left. Binoculars will help finding the 28 hours young Moon.
Jupiter reaches its transit altitude around 8:55pm on Friday and sets around 3:30am the next day. Tonight is the last chance to see a double shadow transit on Jupiter this apparition. Watch the two shadows on Jupiter as both Callisto and Io cast their tiny black shadows onto Jupiter’s sunlit face from 12:38 to 1:42 am tonight. Io’s shadow joins Callisto’s on the Jovian disk around 12:38am. Callisto’s shadow leaves the planet around 1:42am.
On Friday, Mars rises around 9:36pm, reaches its transit altitude around 2:17am and sets shortly after sunrise. Mars is entering its closest two-month charm in a decade. Blazing upper in constellation Scorpius, as it climbs higher, you’ll find Antares below it and Saturn to its lower left. Mars continues to grow in diameter as Earth continues to approach it. Mars will come to opposition on the night of May 21–22. For several days around its closest approach to Earth on May 30th, it will reach its largest since 2005.
The return of bright globular clusters to the evening sky is a signal that summer is just around the corner. This moonless weekend provides a good opportunity to search out for one of the globular star clusters that has gone on to become one of the best-studied objects in the night sky. Messier Object 3 (M3 or NGC 5272) is considered by amateur astronomers to be one of the finest clusters. As darkness arrives, M3 is in prime position nearly overhead. M3 is located in the northern starless space of constellation of Canes Venatici on the border with Boötes. The easiest way to pin down M3 is to draw an imaginary line connecting the stars Arcturus and Cor Corali. M3 is situated a little less than half way from Arcturus. The cluster is an easy catch in binoculars, which show it as a slightly bloated, fuzzy “star.” With a small telescopes used at moderate magnification you will start to resolve individual cluster members, and the view in an 8- or 10-inch scope can be spectacular. In 1764, Charles Messier logged M3 as a “Nebula without star”. With his small telescope, rather like the finder scope of a modern amateur telescope, Messier could not resolve M3 into stars.
Mercury will make its daytime transit across the Sun’s face on Monday. You can join the Dudley Observatory at miSci for this special event on Monday from 9am—3pm. See the link below. Special telescopes will be set up for safe solar viewing, hands-on sun-themed activities throughout the gallery, and a live stream of the transit. The entire transit is visible in Eastern North America. Don’t miss it as the next transit of Mercury won’t occur until 2019.