Stargazer

• Summer sky takes shape

Star Calendar

• July


• August


• September

Summer sky takes shape

By Arnold Medalen

The Summer Triangle dominates the evening eastern sky during July and August and is easy to spot this year because brilliant magnitude -2.7 Jupiter has taken up residence nearby in the southeast. The three stars in the triangle include magnitude 0.9 Altair in the constellation Aquila, magnitude 0.1 Vega in Lyra and magnitude 1.3 Deneb in Cygnus.

Just after sunset, look 3 fist-widths to Jupiter’s upper left to find Altair. (If you have trouble spotting Jupiter, the moon will be alongside on 16 July and 12 Aug.) Continue another 4 fist-widths beyond Altair to find Deneb. Vega is 2½ fist-widths to Deneb’s upper right.

Another prominent feature of the summer sky, the Milky Way stretches from the southwest through the tail of Scorpius to the northeast through Cassiopeia. What looks like high, thin clouds is actually the edge of our galaxy. The word galaxy comes from the Greek word “galaxias,” meaning “milky.” The Milky Way stretches about 150,000 light-years across, 1,500 light-years thick and contains about 200 billion stars.

From our point of view on Earth, the center of the Milky Way is located in the direction of Sagittarius, which is low in the south just above the tail of Scorpius at this time of year. This is where we see the greatest concentration of stars. If you do nothing else in the next two months, pick a clear evening and spend a few minutes admiring the stars that make up our galaxy.

P/C Arnold Medalen, SN, of California’s Diablo Sail & Power Squadron, has been boating in the California Delta and San Francisco Bay since childhood. The stargazer first came to appreciate the night sky while boating in the Delta, far away from city lights. Today, he boats with his wife, Patricia, aboard Shelly C and serves on The Ensign Committee.

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July–September 2008

New moon

July

16 Jul
Jupiter and the nearly full moon rise together just before sunset.

27 Jul
High in the east before dawn, the Pleiades Cluster is less than 1 finger-width below the moon. The bright star 3 fist-widths to the moon’s lower left is Capella, while Aldebaran is 1½ fist-widths below the moon.

August

1 Aug
A total solar eclipse is visible across Greenland, Russia and China. A partial eclipse covers parts of Asia and Europe. In the United States, only the northern tip of New England can see a partial eclipse.

6 Aug
Magnitude 1.2 Spica is 2 finger-widths to the moon’s upper right at dusk.

9 Aug
The moon is in the head of Scorpius.

10 Aug
Antares, the red heart of the Scorpion, is 2 finger-widths to the moon’s upper right. The moon is at apogee, 63.43 Earth-radii away.

12 Aug
The Perseid meteor shower reaches its peak before dawn. The moon is in the dome of the Teapot constellation, Sagittarius, this evening. Jupiter is less than 3 finger-widths to the upper left.

13 Aug
Jupiter is to the upper right of the moon this evening.

16 Aug
There is a partial lunar eclipse today, but only easternmost parts of the central Atlantic coast can catch a glimpse of the final moments.

23 Aug
The Pleiades Cluster is 2 finger-widths to the moon’s left or lower left, high in the southeast, before dawn.

26 Aug
Betelgeuse is 2 fist-widths to the right of the moon this morning. The Gemini Twins are 1½ fist-widths to the lower left. The moon is at perigee, 57.81 Earth-radii away.

September

2 Sep
As the sky begins to darken this evening, try to spot Spica, 2 finger-widths to the moon’s upper left. Now look to the lower right. If you have an unobstructed view of the western horizon, Mercury, Mars and Venus should be visible.

6 Sep
Antares is one-half finger-width to the moon’s upper left.

9 Sep
Jupiter is 2 finger-widths to the moon’s upper right this evening.

14 Sep
Uranus is only two days past opposition, the brightest it will be this year. At magnitude 5.7, it is still difficult to see. Tonight is your best opportunity, however, as it is only 1 finger-width below the nearly full moon. Look just below the moon an hour or so after sunset. It should look like a faint blue-green star.

use binoculars

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