Thursday, September 15, 2011

September 2011 guide to the five visible planets



Good chance that you’ll be able to see four of the five visible planets in September 2011: Saturn, Jupiter, Mercury and Mars.

With some diligence, you can catch four of the five visible planets in September 2011. By visible planet, we mean any planet that can be viewed without an optical aid and that was known to our ancestors since time immemorial. In their outward order from the sun, the visible planets are Mercury, Venus, Mars, Jupiter, and Saturn. All but Venus are visible in September 2011. Learn how to identify these worlds in Earth’s night sky.
Venus, the sky’s brightest planet, sets almost immediately after sunset throughout September 2011. Venus can’t be seen this month, especially from northerly latitudes, because it’s too close to the glare of the sun. From the southern hemisphere in late September, Venus appears low in the western sky but only for a brief while after sunset.
Evening planets: Saturn (dusk), Jupiter (evening until dawn)
At our northerly latitudes, Saturn is the only visible planet that pops out at dusk throughout September 2011. Saturn, the sixth planet outward from the sun, can be found low in the western sky after sunset. All month long, Saturn sinks closer into the glare of evening twilight, to disappear from view by late September.
Now and for the rest of 2011, Saturn resides in front of the constellation Virgo, fairly close to Virgo’s brightest star Spica. You can distinguish Saturn from Spica by color. Saturn exhibits a golden hue, while Spica sparkles blue-white. However, in September 2011, binoculars may be necessary to see the colors of Spica and Saturn in the glare of evening twilight.
You'll easily spot Jupiter near the moon in mid-September 2011. Here they are on September 15.
Dazzling Jupiter rises an hour or so after Saturn sets in early September. Jupiter is the brightest starlike object to light up the September 2011 night sky. You’ll find it rising in the east in mid-evening (roughly 10 p.m. Daylight Saving Time) in early September. By the month’s end – as Saturn is sinking into the western twilight glare – Jupiter will be rising over the eastern horizon around nightfall.
After rising, Jupiter blazes all night long. You cannot miss it, because it is so bright. As evening deepens into late night in September, watch for Jupiter to move westward and upward. This dazzling world transits – reaches its high point in the sky – at or near dawn in early September and around 3 a.m. (Daylight Saving Time) by the month’s end.
After soaring to its highest point for the night, Jupiter then descends into the western half of sky. At morning dawn, look for Jupiter to be a little farther west in the sky as September approaches October.
Jupiter and moon in east by mid evening on September 15
Jupiter and its moons as seen on August 15, 2009. From left to right, these moons are Europa, Ganymede, Io and Callisto.
Use the moon to find Jupiter in middle September, as the waning gibbous moon passes close to Jupiter on the nights of September 14, 15 and 16. Even on a moonlit night, it’s pretty easy to see Jupiter’s four largest moons with a backyard telescope. In their outward order from Jupiter, these moons are Io, Europa, Ganymede and Callisto. However, the position of Jupiter’s moons – as seen from Earth – varies from night to night. Sometimes, a moon may be “missing” because it’s in front of or behind Jupiter. If you want to know which moon is which at a certain date and time, check out this handy almanac.
Jupiter photo credit: Velo Steve
Morning planets: Jupiter, Mars and Mercury
After it rises at early to mid-evening, Jupiter is up all night. You’ll have to stay up late or wake up early to see Mars in the predawn sky or Mercury at dawn. Modestly-bright Mars rises over the eastern horizon in the wee hours after midnight. Mercury rises in the east as darkness gives way to dawn.
Moon, Mars and nearby bright stars as seen from North America before dawn on Thursday, September 22
Mars comes up around 2 to 3 a.m. (Daylight Saving Time) for most of September. If you have trouble locating the modestly-bright red planet Mars, let the moon assist you later this month. The waning crescent moon swings by Mars during the predawn hours on September 22 and 23.
Twin stars, Mars and the moon greet early morning risers
Mercury, the innermost planet of the solar system, presents a respectably good showing in the early morning sky (for the northern hemisphere) during the first two weeks of September. It won’t be this good again until mid-December 2011. Look for this world to shine low in the east around one hour before sunrise. On the mornings of September 8 and 9, Mercury pairs up with the first-magnitude star Regulus. Use binoculars or a low-powered telescope to zoom in on the early morning couple.
Mercury, Regulus pair up before sunrise September 9
Rising times of the morning planets into your sky
Bottom line: With some luck, you might see four of the five visible planets in September 2011. Saturn appears at evening dusk and Mercury at morning dawn, but the other two planets – Jupiter and Mars – more conspicuously stage themselves in the September nighttime sky.

Aquatic species decline at dams and weirs documented

Aquatic species decline at dams and weirs documented