Lighting Up the Night Sky
While you’re waiting for fireworks in the gathering darkness, impress your friends and family with a quick orientation of the celestial lights popping into view.
First to emerge in twilight’s glare is Venus, low in the west, so bright you might confuse its twinkling with a jet high overhead. With a little more darkness, Jupiter pops into view a little to the right of Venus. To the upper left of the two planets is Regulus, the heart of Leo the lion. The three provide a good contrast in brightness, with Venus blazing at –4.6 magnitude, Jupiter outshining any star at –1.8 magnitude, and Regulus still quite prominent at 1.6 magnitude.
The month began with Venus and Jupiter less than one degree apart, and on July 4th they are still within two degrees of one another. But they are parting ways, with Venus moving closer to Regulus and Jupiter inching to the northwest and the wake of the setting sun.
By 9pm, Arcturus, the brightest star of summer is directly overhead. Shining at magnitude –0.1, it is the lead star in the constellation Boötes the herdsman, who tends the bears Ursa Major and Ursa Minor, which contain the Big and Little Dipper respectively.
To the east of Boötes is the Hercules, most notable for its trapezoid-shaped keystone. Look for the minor constellation Corona Borealis, the Northern Crown, between Boötes and Hercules.
To the east of Hercules are the three constellations that host the Summer Triangle. The smallest constellation, Lyra, hosts the brightest star, zero-magnitude Vega. From there look for first-magnitude Deneb at the head of the Northern Cross, Cygnus the swan. The final point in the triangle is Altair, the eye of the eagle Aquilla, shining at magnitude 0.8.
Low in the south-southeast at sunset is golden Saturn at the head of Scorpius. The heart of the scorpion, Antares, shines a dozen degrees to Saturn’s lower left of Saturn twinkles fiery orange Antares, not quite as bright.
Early risers can spot Mercury above the east-northeast horizon about 40 minutes before sunrise. Binoculars will help pick it out of the growing glow of dawn. Don’t confuse it for Aldebaran, the eye of Taurus the bull, much higher overhead.