Constellation Hopping and The Planets this month — September 2010

Highlights:

* Venus, Mars and Spica together in evening sky at start of month
* The above 3 joined by the Moon on the 11th
* Jupiter at opposition (21st) with Full Moon (23rd) and Uranus nearby
* Mercury bright in the morning sky

Western sky view a few minutes after sunset on September 11 – the thin crescent moon joins the celestial trio of Venus, Mars and Spica (brightest star of Virgo)

Philippine nights will be longer as the Sun approaches the celestial equator. Autumnal equinox will occur on September 23 when day and night will have approximately equal length on Earth.This point is also called as First point of Libra.

The rich band of constellations and stars along the Milky Way from the constellations Cygnus, the Swan, in the north to Sagittarius and Scorpius in the south, begin to give way this month to fainter constellations, many of them with watery associations such as the constellations of Capricornus, the Sea Goat, Aquarius, the Water Bearer and Pisces the Fish. The famous asterism Teapot in the sky in the constellation of Sagittarius can be observed at about 40 to 47 degrees above the southern horizon, an hour after sunset as shown below.

View of the eastern sky on September 7 at 4:00 AM (PST)

Betelgeuse, the super giant red star and the prominent star of the famous constellation Orion, the Mighty Hunter, will be located at about 25 degrees to the upper right of Mars. Sirius, the brightest star in the sky of the constellation Canis Major, the Big Dog, will be an easy target as it glows below the constellation of Orion. Procyon, the brightest star of the constellation Canis Minor, the Little Dog, can be located at the lower left of Canis Major. By drawing an imaginary line among the bright stars of these constellations, an equilateral triangle will be formed called the Winter Triangle as shown here:

Southern sky at 7:25 PM (PST)

Also, flying high in this month’s sky is the mythical winged horse Pegasus. Although one of the largest constellations in area, it boasts no bright stars. Its most noticeable star pattern is the Great Square of Pegasus: four second magnitude stars marking the body of the horse. Ironically, the brightest of those stars, Alpheratz, isn’t even an official member of the Pegasus constellation, being part of the neighboring constellation Andromeda. The brightest star in Pegasus isn’t part of the Square: it is Enif, the Arabic word for “nose.” It marks the head of Pegasus, off to the west.

As you look further south, you can see Piscis Austrinus, the southern fish, with the only bright star in the region: Fomalhaut. Fomalhaut, which is 25 light-years from Earth, made headlines in 2008 as one of the first stars to observed to have a planet that was directly imaged with telescopes.

To the east of Fomalhaut is another huge dim constellation, Cetus the Whale, with the only other brightest star in the area, Deneb Kaitos, which means the tail of the whale. Cetus also contains the variable star Mira. Currently this star is too faint to be visible with the naked eye, but over the next few months it will start climbing in brightness until it becomes one of the brightest stars in this constellation.

Normally this sea world is a dim and mysterious place, with only one bright star, Fomalhaut. But this year it is enlivened by a visit from the giant planet Jupiter, right on the border between Pisces and Aquarius.

The Planets

The tight grouping of Venus, Mars, Saturn, and Spica ends its spectacular run this month. All four are low in the western sky at nightfall as September begins, but Saturn drops from sight early in the month. Mars and Venus are still in the sky by month’s end, but they shine for only a little while before dropping below the horizon. By that time, however, the night sky’s next-brightest object, the planet Jupiter, is climbing skyward in the east, and will shine brilliantly throughout the night.

Mercury will shine brightly at magnitude -1 as it reaches its greatest elongation west on September 20 (18°  from the Sun). For early risers, Mercury makes its best morning appearance of the year on the second week of September. Look in the constellation of Leo the Lion near his lower foot star, Rho Leonis. The two objects are 20 arcminutes apart on September 16 and 17.

Venus continues to be prominent in the evening sky, though also low for northern hemisphere observers, at around magnitude -4. The crescent Moon, less than 3° away on September 11 will make an attractive pairing. On the 24th, Venus will reach its peak magnitude of -4.6.

Mars is now shining very low in the evening twilight sky. This month +1.5 magnitude Mars starts a few degrees to the upper right of brilliant Venus. Though the planets will slowly move apart they will stay within 7° of each other all month long.On September 11, the Moon will pass with 5° of the planet.

Giant planet Jupiter is now top target for planetary observers, dominating the night sky and rising in the east as it is getting dark at a bright magnitude of -2.9 in Pisces. The planet is putting on a show for those with reasonable sized telescopes, having lost one of its prominent dark belts and with its two red spots in close proximity. On the 21st,  Jupiter will be at opposition,means it will be visible all night long, rising in the evening, reaching its highest elevation around midnight and setting during dawn.

Saturn is located low in the west during evening twilight. By month’s end the +1.0 magnitude planet will be too close to the Sun to be seen easily by most observers. On September 9,the Moon will be within 7° of Saturn.

Uranus will lie within one degree of Jupiter in Pisces between September 12 and 25, making the giant planet a good signpost to finding its more distant cousin. On the 22nd, it will also be at opposition. If given a clear dark sky and no moonlight, it can be spotted with the unaided eye at magnitude of 5.7.

Neptune will be found among the background stars of the constellation Capricornus, the Sea-Goat and will be standing 42 degrees above the east southeastern horizon at around 7:00 PM (PST) on the 19th of the month. A modest size telescope will be needed to observe the bluish planet.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During September, 10-16 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Information on most of the minor showers will be provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook this month.

Additional information on these showers and other minor showers not included here can be found at the following sites: Wayne Hally’s and Mark Davis’s NAMN Notes, and the International Meteor Organization’s 2010 Meteor Shower Calendar.

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sources: PAGASA, SPACE.com, Skymania.com, TheTransientSky

September 6, 2010 | Categories: Amateur Astronomy, Observation, Philippine Astronomy, Planets, Sky Viewing Tips | Tags: bright stars, celestial trio, constellations, equinox, Jupiter, mercury, night sky observation, planets, september 2010, september highlights, skygazing, star-hopping, summer triangle, venus | 1 Comment