SkyWatch

July 2003

By Steve Stefanik

A sure sign of summer is the constellation Scorpius, which can be located due south after the sun sets. Look for a giant "J" pattern of stars just above the southern horizon in July. This is the asterism that represents the serpentine body of a scorpion, which is "marked" by the brilliant red first magnitude star Antares (rival of Mars) that represents the head of the arthropod.

Speaking of Mars, the ruddy red planet rises about 11:00 p.m. EDT low in the southeast along with the constellation Aquarius the water bearer. Currently it is about –1.4 magnitude and 16.7 arc seconds in angular diameter but it is getting bigger and brighter with each passing day on its way toward opposition in late August. By the end of the month it will rise by 10:00 p.m., brighten to –2.3 magnitude and become more than 22 arc seconds in apparent size, bigger and brighter than it has been in the past 15 years. By the time it reaches opposition in late August it will be appear bigger and brighter than it has in the past 50,000 years!

As Mars is rising in the southeast the giant planet Jupiter is setting in the west. Although it is only a fraction of its former mid-winter brightness at –1.8 magnitude, it is still formidable in this region of sky. Look for the Jovian planet below the "sickle" shaped asterism in the constellation Leo the lion. There is still plenty of action going on from its four Gallilean moons Io, Europa, Ganymeade, and Callisto.

The planets Pluto, Uranus, and Neptune are also in the evening sky but require a moderate sized telescope to spot them among the dim stars of the constellations Ophiuchus, Aquarius, and Capricornus respectively.

The planet Mercury makes a brief appearance late in the month and may be spotted about a third of a degree to the upper right of Jupiter on the night of the 25^th.

The remaining two planets, Venus and Saturn, don’t rise until about 50 minutes before sunrise in the east. During the month Venus keeps rising closer to sunup until it becomes "lost" in the sun’s glare by the end of the month while Saturn keeps rising earlier and earlier each day. By the end of July, Saturn comes up about 2 ½ hours before the sun rises.

On the night of July 16-17 a waning gibbous moon lies spectacularly close to Mars.