The sky this week for August 27 to September 2
Do you like planets? Well, you’re in luck, because planets abound in the sky this week.
By Richard Talcott
Tuesday, August 28
Although Jupiter reached opposition and peak visibility in early May, it remains a conspicuous object from evening twilight until it sets around 10:30 p.m. local daylight time. Jupiter shines at magnitude –1.9 and dominates the southwestern sky after Venus sets. The gas giant resides among the background stars of Libra the Scales; this evening, it lies 1.5° due east of Zubenelgenubi (Alpha [a] Librae). If you view the planet through a telescope, its disk spans 35″ and displays spectacular cloud-top detail.
Wednesday, August 29
The constellations Ursa Major the Great Bear and Cassiopeia the Queen lie on opposite sides of the North Celestial Pole, so they appear to pivot around the North Star (Polaris) throughout the course of the night and the year. In late August and early September, these two constellations appear equally high as darkness falls. You can find Ursa Major and its prominent asterism, the Big Dipper, about 30° above the northwestern horizon. Cassiopeia’s familiar W shape, which currently lies on its side, appears the same height above the northeastern horizon. As the night progresses, Cassiopeia climbs above Polaris while the Big Dipper swings below.
Thursday, August 30
Saturn reached its peak about two months ago, when it appeared opposite the Sun in the sky, but our view of the ringed planet remains magnificent. It appears against the backdrop of northwestern Sagittarius, a region that climbs highest in the south as darkness falls. Saturn continues to shine brightly, too, at magnitude 0.4. Center the planet in your binoculars and you’ll see the Trifid Nebula (M20) 1.7° to the west and the Lagoon Nebula (M8) 2.2° to the southwest. But the best views come through a telescope. Even the smallest instrument shows Saturn’s 17″-diameter disk surrounded by a dramatic ring system that spans 39″ and tilts 27° to our line of sight.
Friday, August 31
Distant Neptune reaches opposition and peak visibility a week from tonight, but the view now is essentially the same. The ice giant planet rises during evening twilight and climbs halfway to the zenith in the southern sky by 1:30 a.m. local daylight time. The magnitude 7.8 planet lies in Aquarius, 2.1° west-southwest of 4th-magnitude Phi (f) Aquarii. You’ll need binoculars to spy Neptune and a telescope to see its blue-gray disk, which spans 2.4″.
Saturday, September 1
The variable star Algol in Perseus reaches minimum brightness at 4:52 a.m. EDT tomorrow morning. If you start watching this evening (it rises in the northeast shortly after 8 p.m. local daylight time), you can see its brightness diminish by 70 percent over the course of about five hours as its magnitude drops from 2.1 to 3.4. This eclipsing binary star runs through a cycle from minimum to maximum and back every 2.87 days.
Mars’ brief excursion into Sagittarius comes to an end today, as it moves eastward across the border into Capricornus.
Sunday, September 2
Last Quarter Moon occurs at 10:37 p.m. EDT. It rises around midnight local daylight time and climbs high in the southeast by the time twilight starts to paint the sky. Earth’s only natural satellite lies just east of the Hyades star cluster and 1st-magnitude Aldebaran in the constellation Taurus the Bull.