★ SKYFORECASTS Saturday, August 24 The variable star Algol in Perseus reaches minimum brightness at 3:05 a.m. EDT. If you start watching it around mid-evening (it rises in the northeast shortly before 9 p.m. local daylight time), you can see its brightness diminish by 70 percent over the course of about 5 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. Algol passes nearly overhead about the time morning twilight commences. Mercury reaches superior conjunction at 5 p.m. EDT. This means the innermost planet lies on the opposite side of the Sun from Earth and remains hidden in our star’s glare. It will return to view in the evening sky, though just barely, in late September. Sunday, August 25 As darkness falls in late August, Saturn lies about 15° above the west-southwestern horizon. The ringed planet shines at magnitude 0.7 among the background stars of eastern Virgo. Although a naked-eye view of the planet is nice, seeing it through a telescope is breathtaking. Even a small instrument shows the distant world’s 16"-diameter disk and the spectacular rings, which span 37" and tilt 18° to our line of sight. Monday, August 26 Neptune reaches opposition tonight, which means the planet lies opposite the Sun in our sky. This marks the peak of Neptune’s observing season because it then shines brightest (magnitude 7.8), appears largest through a telescope (2.4" across), and remains on view all night. The most distant planet currently resides among the background stars of Aquarius between magnitude 4.8 Sigma (σ) Aquarii and magnitude 5.4 38 Aqr. Brilliant Venus lies low in the west shortly after sunset all week. Shining at magnitude –4.0, the planet appears conspicuous as darkness falls to anyone with a clear sky and an unobstructed horizon. It stands approximately 10° above the horizon 30 minutes after the Sun sets. If you turn a telescope on Venus, you’ll see a disk that spans 14" and appears about three-quarters lit. Tuesday, August 27 By 4 a.m. local daylight time, Mars appears low in the east-northeast. The Red Planet resides among the background stars of Gemini the Twins, where it forms a straight-line configuration with the constellation’s two brightest stars, Castor and Pollux, both today and yesterday. At magnitude 1.6, Mars appears as bright as Castor but slightly fainter than Pollux. Wednesday, August 28 Last Quarter Moon arrives at 5:35 a.m. EDT. It rose in the east-northeast late yesterday evening (shortly before midnight) and climbs high in the east before dawn. During this period, our half-lit satellite lies among the background stars of Taurus the Bull, between the Pleiades and Hyades star clusters. Thursday, August 29 Any clear evening this week is a great time to explore the constellation Sagittarius the Archer. This star group lies due south and at peak altitude between 9 and 10 p.m. local daylight time, around the time twilight ends. The brightest stars within the constellation form the shape of a teapot — a distinctive asterism once you’ve found it. The central regions of the Milky Way pass through Sagittarius, so it’s always worth exploring the area through binoculars or a telescope. Friday, August 30 The Moon reaches apogee, the farthest point in its orbit around Earth, at 7:46 p.m. EDT. It then lies 251,581 miles (404,881 kilometers) from Earth’s center. Saturday, August 31 Shining at magnitude –2.0, Jupiter stands out in the eastern sky from the time it rises (around 2 a.m. local daylight time) until twilight is well underway. This week, the giant planet lies about 30° above the horizon (one-third of the way to the zenith) as morning twilight commences. A telescope shows Jupiter’s 35"-diameter disk and at least two parallel dark belts in its atmosphere. Sunday, September 1 The Aurigid meteor shower peaks this morning. Although this minor shower typically produces only six meteors per hour under optimal conditions, it occasionally performs much better. Rates six times higher than normal occurred in 1935, 1986, and 1994, and viewers recorded up to 130 meteors per hour in 2007. No one knows when the shower will burst out again, but this year’s waning crescent Moon provides minimal interference to check it out. The meteors will appear to emanate from the constellation Auriga the Charioteer.
Posted on: Sat, 24 Aug 2013 10:31:14 +0000
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