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■ Now the Moon shines upper left of Antares, as shown below (for North America). Long presumed to be stable, Delta unexpectedly doubled in brightness in the summer of 2000 and has remained nearly that bright, with fluctuations, for many of the years since.Īstronomers are waiting to see whether it will display another flareup soon, when the companion makes its third pass by the primary star since the instability started in 2000. It has a smaller orbiting companion that seems to trigger more such activity at 10.5-year intervals. It's an irregular variable star: a fast-rotating blue subgiant throwing off luminous gas from its equator. Delta's proper name, Dschubba, is from the Arabic for "Forehead" of the scorpion.ĭelta is the brightest of the three. Look left of the Moon for the roughly vertical row of Beta, Delta, and fainter Pi Scorpii, between the Moon and Antares. This evening the Moon shines near the head of Scorpius. ■ First-quarter Moon (exact at 11:20 a.m. ■ The brightest star high in the southeast these evenings is Altair, with little orange Tarazed above it by a finger-width at arm's length. Much higher to their upper right shines brighter Arcturus. ■ Much easier: Look for 1st-magnitude Spica lower right of the Moon, by a little less than a fist at arm's length. At visual magnitude 3.6, Beta Vir is 1,000 times fainter than Venus. You may notice a tiny spark barely 0.1° from it (below it as seen from mid- North America). ■ A twilight challenge: as twilight fades, examine Venus with binoculars or a small telescope. Cas too is excellently placed in the evening sky. As of August 12th it was down to about 8.5. Among its bumps were brightenings to magnitude 5.5 in early May and 6.0 around July 27th. Nova Cassiopeiae 2021 has bounced around in brightness ever since it erupted from 15th magnitude to 7.7 in March. Ophiuchus is ideally placed high in the evening sky. See Bob King's Recurrent Nova RS Ophiuchi Just Blew its Top! with finder charts and comparison stars. In the first week after its past outbursts RS Oph has faded smoothly by about two magnitudes, then it declines more slowly down to normal. For the first time since 2006, on August 8th the famous recurrent nova RS Ophiuchi lept from its normal magnitude 11.2 to 4.8, dim naked-eye magnitude.