July 2001

By Steve Stefanik

You know its summer when the constellation Scorpio is on the meridian (an imaginary line running due North and South directly overhead) by the time it gets totally dark and Sagittarius is right behind it to the east. July of course is the first full month of summer and as the temperature heats up so does the celestial action.

The planet Mars is putting on a spectacular show thusfar. It is the large bright red-orange "star" in the constellation Ophiuchus just northeast of Scorpio. Having reached opposition on June 13^th and perihelion on the 21^st, we are now beginning to speed away from it in our shorter faster orbit but this month it will be well placed in the south by mid-evening and as high in altitude as it will get during this apparition. In the beginning of the month it will still be the biggest and brightest object in the night sky (with the exception of the moon of course) at magnitude –2.1, and 20 arc seconds in angular size. By the end of July however, it will diminish in size and brightness to 17 arc seconds and –1.5 magnitude respectively, so grab a telescope or some binoculars and get out there and have a look! Its still big enough and bright enough to make out some of its surface features. You should be able to spot one or both of its polar ice caps and some of the dark mountainous regions.

Mars is not the only show in town this month. If you are a "night owl" the planets Uranus and Neptune are rising in the constellation Capricorn to the east of Sagittarius. You’ll need at least binoculars to spot these +5.7 and +8.5 magnitude orbs until they reach opposition next month.

If you are an early riser or you just can’t sleep and you need to step out of the house for a breath of cool night air around 4 or 5 in the morning, look toward the northeastern horizon. There you will see the brightest "morning star" you’ll ever see, only it’s not a star, it’s the –4.1 magnitude planet Venus. It’s now in the constellation Taurus, the bull. It will be to the left of its brightest star Aldebaran and below the Pleiades miniature star cluster. Just below Venus and considerably dimmer at +0.2 magnitude, the planet Saturn will be rising in Taurus.

About an hour later Jupiter rises in the constellation Gemini. You shouldn’t have difficulty spotting this giant –1.9 magnitude planet even in a brightening dawn sky.

Finally, the planet Mercury (also in Gemini) joins the group on he 13^th making it a foursome for a few days. The speedy little planet makes up in brightness at 0 magnitude what it lacks in size.

If the reappearance of all these planets is not enough in itself, a waning moon joins the group passing each one in succession from the 17^th –19^th. The group of planets spend the remainder of the month "playing tag" in the cool morning hours before the hot summer sun rises.