This is the Skywatch Line for Monday and Tuesday July 6th and 7th.
The Sun sets at 8:36 PM; night falls at 10:49. Dawn breaks at 3:12 AM and ends with the Sun rising at 5:25.
The Moon occupies Capricornus on both nights. Monday’s Moon, one day after Full Moon, appears 96% lit, rises at 10:07 PM and sets at 7:41 AM, Tuesday. Tuesday’s Moon appears only a little thinner and slimmer, rising at 10:47 and setting at 8:07 AM.
Jupiter shares Sagittarius with Pluto and Saturn. Jupiter rises at 9 PM and appears about 16° high in the south eastern sky. This month, Jupiter is at its largest and full of telescopic detail. Observers now describe the Great Red Spot as closer to pink-red. The Great Red Spot will appear centered on Jupiter’s face at 2:50 AM on Tuesday. Tuesday night also affords views of the Jovian moon Io casting its shadow on Jupiter at 1:36 AM, beginning its transit at 1:47 AM and ending its trek at 3:53 AM. At 1:14 AM on Wednesday, Io reappears from behind the giant planet. Pluto rises 6 minutes after Jupiter, is preparing for a June 30th conjunction with Jupiter; it glows dimly with 14th magnitude, appears less than an arc-second in size and lies within 1 arc-second from Jupiter. Pluto hunters need at least an 8-inch telescope, dark skies and detailed star charts.
Saturn rises about 20 minutes after Jupiter. It shines with zero magnitude, is 18 arc-seconds in size; it will remain the same for a couple of weeks. Its rings span 42 arc-seconds, providing dramatic telescopic views. The Moon accompanies Saturn on both nights, about 10° below Saturn on Monday and 23° aside on Tuesday.
Both Jupiter and Saturn appear to follow each other, but actually they are slowly separating from 6° to 7° at month’s end. They are also retrograding – traveling westward.
Mars rises in Pisces at 12:23 AM, shines with minus 0.6 magnitude, larger with 11.2 arc-seconds in size. This month it grows brighter and larger in our instruments in preparation for its October close approach to Earth; Mars begins this month 76 million miles from Earth and ends only 60 million miles away.
Neptune rises in Aquarius at 11:38 PM glows with 8th magnitude and appears 2 arc-seconds. Uranus rises in Aries at 1:32 AM, brighter at 6th magnitude and about 4 arc-seconds in size.
Venus is the last to rise in Taurus at 3:15 AM, blazes with minus 4th magnitude, 39 arc-seconds, but only about 7° high in the East. Note that Venus appears close to Aldebaran, the brightest star in the constellation; this month Venus climbs higher in the pre-dawn sky.
As appropriate for the upcoming racing season, two horses appear by midnight. The largest horse is, of course, Pegasus. The smallest is Equuleus. This dim constellation is easy to find. Pegasus flies upside down and is easily identified as a Great Square. Two thin chains sweep northward from the upper left. If one sweeps across the chain, binoculars reveal a large hazy oval; this is revealed, in telescopes, to be the Andromeda Galaxy – about two and a half million light years distant. You can see it with the naked eye under rural skies. Pegasus’ neck flows from the lower right corner and angles up. Equuleus is the small angular line of stars West of the Pegasus’ nose. A globular star cluster, M 15, lies exactly halfway between Pegasus’ nose and Equuleus. This too is easily seen in binoculars.