What's Up in the Night Sky

August 2013 - Vol. 17, No. 8

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.

Bright blue-white Vega (Lyra) shines high overhead as it "leads" the Summer Triangle across the night sky. The "Triangle" is the summer’s most prominent asterism and is made up of three stars: Vega, the brightest, Denab (Cygnus) and Altair (Aquila). Scorpius and the bright star Antares occupy the southern sky. Look for another famous asterism, "the teapot" (Sagittarius). The stars of constellations Scorpius and Sagittarius, embedded in the "Milky Way" (part of one of the spiral "arm"” of our galaxy), are at their best this month.

August 2013 opens with MERCURY at 0 magnitude low in the morning sky, until mid-month, reaching superior conjunction on the 24th. VENUS visible in the evening sky, brightening to -4.0 by the last weeks of the month. JUPITER, low in the morning sky and may be seen just before sunrise. MARS is visible in the morning sky this month, look for it near Jupiter in Gemini. SATURN is still visible, setting late in the evening this month. Deep sky observers will enjoy some of those treasures in the Milky Way without bright planets nearby. Don't forget the Perseid shower on the 12th.

Review how to determine Angular Measurement.

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	The crescent Moon meets the Hyades and Pleiades in the morning sky.
03	Moon at apogee. Jupiter 4 deg. N of Moon. (What a morning lineup the Moon, Jupiter, Mars and Mercury!)
04	Mars 5 deg N. of the Moon. The asteroid Juno will be at opposition. This is a faint object around magnitude 9. Sky Online offers a finder chart this week, look for ot on thr border of Aquila and Aquarius..
05	Mercury 4 deg N of the Moon
07	Another fascinating morning lineup. Set the alarm clock!.
10	Venus 5 deg N. of the Moon. Jupiter, Mars and Mercury near Castor and Pollux at sunrise.
12	Perseid Meteor Shower peaks at 18 UT, up to 100 per hour at peak. Spica 6 deg S of the Moon, occultation visible from Asia, India, China, Japan, and Phillipines.
13	Saturn 3 deg N. of Moon. Watch the distance between Saturn, the Moon and Spica mid-month.
19	Moon at perigee. Watch the dance between Mars and Jupiter around this date, they pass within 1 deg of each other.
27	Neptune at opposition.
24	Mecury at superior conjunction .
28	The last quarter Moon joins the Hyades and Pleiades in the constellation of Taurus.
31	Jupiter 4 deg N. of Moon.

Lunar Almanac for August 2013

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 06	Deep Space Objects
	1st. Qtr 14	Planets & Moon
	Full 21	Moon
	Last Qtr 28	Deep Space & Planets

Perseus, a Hero and a Fantastic Meteor Shower

The month of August brings us a fabulous meteor shower, the Perseid shower. Meteor showers are caused when the Earth encounters particles of dusts that are ejected by comets that travel from the outer solar system to swing around the Sun in their orbit. The particles burn up in Earth's atmosphere, causing a bright flash. Sometimes they leave trails (especially the Perseids) or crumble into bright pieces. The brightest meteors are called fireballs. In the case of the Perseids, the parent body that causes the shower of particles is the periodic comet Swift-Tuttle. Because the particles are also orbiting the Sun in a stream following their parent body, all of the meteors in the stream appear to come from the same area of the sky. This is called the radiant. Meteor showers are named after the area of the sky that they appear to originate from. Although they will streak across the entire sky, the Perseid meteors will seem to emerge from the constellation of Perseus.

Meteors are always best after local midnight because of the angle of the Earth and Sun. This is especially true of the Perseids because the constellation is not fully above the horizon until about 1 am local time for observers in North America. The constellation is deep in the bright star fields of the Milky Way and will appear as a bright group of stars at on the eastern horizon at midnight. Perseus is followed into the night sky by the ecliptic constellation of Taurus and the bright star Aldebaran. The chart below shows the eastern horizon at 1 pm on August 12.

Stellarium screenshot of Perseus over the Eastern horizon on August 12, 2013 at 1 am

There is really no equipment necessary to view the Perseid shower. Many people like to pull out a lawan chair or heavy blank and lie under the stars. Your blanket or chair may become very wet from dew, so make sure to prepare. A plastic tarp under the blanket works wonders. Also, you may want to set up your telescope or bring binoculars to observe the bright star clouds of the Milky Way especially if you drive to a dark site or are planning to stay late into the night. If you do plan to spend a few hours, a beverage and a snack will be a welcome treat. It may cool off after midnight, so dress warmly. Open country fields are subject to deer ticks and mosquitos, so bring what you need to protect yourself.

Last year, What's Up featured the constellation of Perseus, for more information on the myth and the stars, check out the September 2012 issue. The night of the Perseid shower was recently rated by NASA as the most magical of all nights. This year the moon is new on August 6, so it will set before the real show starts after midnight.

--See You Under the Stars!
Astra for Astra's Almanac

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