Features: Calendar | Lunar Almanac | Monthly Topic
This Month's Night Sky - NOTE: The next paragraph describes the sky as it
appears at 10 pm EST (11 pm EDT) near mid- month. The sky also looks
this way at 11 pm EST (midnight EDT) during the beginning of the month and
at 9 pm EST (10 pm EDT) by month's end.
Angular Measurement Review: It is interesting to note that the relationship between the angle subtended by combinations of fingers on your fully outstretched arm are the same for all viewers. This is due to the fact that the hand's size is proportional to the arm's length. A shorter arm is attached to a smaller hand while a longer arm is attached to a larger hand, thus the angle measured remains the same. If you hold your arm fully outstretched, your little finger, when sighted down your arm, is one degree wide. Your three middle fingers is five degrees, your fist, 10 degrees, and the distance between your little finger and your pointer finger is 15 degrees no matter what your age or size.
This month the Summer Triangle asterism is high as the sky darkens. The reddish glow of Arcturus (Bootes) sinks towards the W horizon while the stars of another asterism, the Big Dipper (Ursa Major), dip low in the NW. You may see Antares, also reddish,(Scorpius)in the SW. Very low in the SE, Formalhaut [FO-mel-hote](Piscis Austrinus)[PIE-sees OS-tra-nis], rises all alone. In the E, the Great Square of Pegasus rises and is followed by the stars of Andromeda. You may also see Capella (Auriga), high in the NE.
MERCURY reaches its greatest elongation about 26 degrees from the Sun on the 6th. Usually this is the best time to view an inferior (between the Earth and the Sun) planet but, due to the fact the ecliptic make a very shallow angle to the W horizon at this time of the year, it will be very low on the horizon. It will be only about 6 degrees above the horizon at a half hour after Sunset. It dips below the horizon about a half hour later. VENUS, on the other hand dominates the night sky. It will lie about 15 degrees above the W horizon about a half hour after Sunset. It will brighten all month and by the 31st. it will be about 10 degrees above the horizon. MARS joins Venus, about 7 degrees above, glowing dimly red-orange. Brilliant JUPITER rises at about 10 PM early in the month. By month's end, it will rise some two hours earlier. It will remain in the sky all night and is a wonderful object to study even in a small telescope or "big" binoculars. SATURN joins Venus and Mars and glows a creamy yellow. All three planets do a delightful dance all month. One of the year's best meteor showers, the PERSEIDS, peaks during the night of August 12th./13th. It will be moonless so don't miss it!
Calendar of Events
NOTE: For those observers not in the ET zone, convert the calendar times to your zone's time by subtracting one hour for CT, two for MT and three for PT. Don't forget to adjust for Daylight Savings Time when necessary by subtracting one hour from your planisphere's time.; Dawn and dusk times must also be corrected. See your local newspaper, TV news, or cable TV's Weather Channel for sunrise and sunset times. Unfortunately some of these events may occur during daylight hours in your area.
| DATE | EVENT |
01 |
At dusk, Mars is 2 degrees below brighter Saturn and both are 7 degrees above and to the left of bright Venus. |
03 |
Look for a pseudo-conjunction (3 to 4 degrees) of the Moon and the stars of the Pleiades (M45) of Constellation Taurus before dawn. |
06-08 |
At dusk, Mars, Saturn and Venus are within 5 degrees of one another. This dance will continue throughout the night until well after mid-month. |
09 |
Look for a close (3 degrees) conjunction of Venus and Saturn at 10 PM. |
12/13 |
The Perseid meteor shower peaks. They appear to radiate from the Constellation
Perseus. Although Perseus will be low at nightfall, it will be high after
midnight. Best viewing will occur between then and dawn when its radiant is
highest. If observed from a dark site you can expect to see between 60 to 100
events/hour! Almost half that amount will be visible the evening before and the
evening after the peak.
The Perseid meteors are the result of dust ejected as Comet 109/Swift-Tuttle has crossed Earth's orbit over many thousands of years. Our atmosphere then rams the particles at about 37 miles/second causing the streaks of light we enjoy every August. |
13 |
Look for a conjunction (8 degrees) of the Moon and Saturn at 3 AM.
Look for a conjunction (5 degrees) of the Moon and Venus at 8 AM. (It might still be visible from your location since these objects are so bright.) |
17 |
Look for a pseudo-conjunction (1 to 2 degrees) of the Moon and the bright star Antares (Scorpius). |
26-27 |
During the late evening of the 26th., the Moon is about 6 degrees above Jupiter but at the same time on the 27th., the Moon is now about 12 degrees to the left of Jupiter. |
31 |
Look for another pseudo-conjunction (+/- 1 degree) of dim Spica (Virgo) and the much brighter Venus. |
| Phases of the Moon | Phase and Date(s) | Best viewed before local midnight |
 |
New |
Deep Space Objects |
 |
1st. Qtr |
Planets & Moon |
 |
Full |
Moon |
 |
Last |
Deep Space & Planets |
Topic of the month:
Scorpius, the eighth Constellation of the Zodiac
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Scorpius is an ancient zodiacal constellation which is best observed in summer for those of us located in the Northern Hemisphere. Its many bright stars outline an asterism that looks very like its namesake animal. It was a double constellation in pre-Roman times known as Scorpio cum Chelae (scorpion with claws). Its "claws" now reside in the constellation Libra.
--See
you next month!
The star chart above was generated by Stellarium, a free open source planetarium program. The above image was created by Dawn Jenkins, using Stellarium and a graphic editing program to format the image for this web page. Editing was done for educational purposes only. Stellarium offers much more to amatuer astronomers and is being used in planetariums and to guide telescopes in the field. Simple charts like the one above can be used on the internet for non-profit, illustration purposes. Proper credit is due of course! Thank you to the makers of this fine program from Astra's Star Gate.
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This installment of "Whats Up?" is ©2010 Ronald A. Leeseberg, encoded by Dawn Jenkins for Astra's Stargate.
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