Sunday, August 18 The Moon reaches perigee, the closest point in its orbit around Earth, at 9:26 p.m. EDT. It then lies 225,100 miles (362,264 kilometers) away from us. Monday, August 19 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 passes 6° south of the constellation’s luminary, Pollux, this morning. Mars’ eastward motion relative to the background stars will carry it into a straight-line configuration with Pollux and its “twin,” Castor, next weekend. At magnitude 1.6, Mars appears as bright as Castor but slightly fainter than Pollux. Mountains and lava plains, rays, and a hint of color invite exploring a bright Full Moon. // John Chumack Tuesday, August 20 Full Moon arrives at 9:45 p.m. EDT. It rises in the eastern sky just before the Sun sets and reaches its peak in the south around 1 a.m. local daylight time. The Moon lies among the background stars of Aquarius the Water-bearer, just off the northeastern corner of Capricornus the Sea Goat. Wednesday, August 21 The variable star Algol in Perseus reaches minimum brightness at 6:17 a.m. EDT. If you start watching it late yesterday evening (it rises in the northeast around 9 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. Thursday, August 22 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. The observing season for Jupiter is getting underway in August, and views of the planet through a telescope should be exquisite. // Don Parker Friday, August 23 Shining at magnitude –2.0, Jupiter stands out in the eastern sky from the time it rises (shortly before 2:30 a.m. local daylight time) until twilight is well underway. This week, the giant planet lies some 25° above the horizon as morning twilight commences. A telescope reveals Jupiter’s 34"-diameter disk and at least two parallel dark belts in its atmosphere. Saturday, August 24 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. 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. From Astronomy - The Sky this Week - astronomy/
Posted on: Sun, 18 Aug 2013 17:25:47 +0000
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