Scorpions in the Sky
By Calvin L. Chrisman
Many constellations require some imagination to visualize what they represent, but Scorpius, the scorpion is not one of them. If you look low in the southern sky and hour or two after sunset, you will see the scorpion raising its head and you will certainly note the bright red star Antares. Antares is Greek for the rival of Mars. The Chinese called it the Great Fire in the heart of the Dragon of the East and the French called it Le Coeur de Scorpion, the heart of the scorpion. You may think our Sun is large; and at 109 times the diameter of the Earth, it is the largest thing in our celestial neighborhood. Antares is 700 times the diameter of the Sun. That is over 76,000 Earth diameters. No wonder they call it a red supergiant. If by some magic, Antares and the Sun were swapped in space, Earth would be inside the star – a bit toasty.
According to Greek mythology, Scorpius is the scorpion that killed Orion. To avoid further trouble, they were put on opposite sides of the sky. Look south in six months to see Orion. Scorpius offers many interesting sights for binocular observers. Using a tripod or steadying your binoculars on a post, start by focusing on Antares. The view through binoculars will really emphasize its beautiful red-orange color. Now, if you move your view slowly about three degrees to the north-northwest, you will see a triple star combination – Rho Ophiuchi. The brightest of the three is fifth magnitude and the other two are seventh magnitude, so binoculars will make them easily visible. It is a pretty trio. Finally, slightly to the west of Antares is the open cluster of stars known as M4. You will see many small stars clustered together. If you are careful with your aim, you should be able to get M4, Antares and Rho Ophiuchi in the same field of vision.
If you watched Jupiter, Venus and Mercury as they maneuvered past one another last month, you know that Jupiter has moved too far toward the western horizon to be seen in the Sun’s glow. Venus and Mercury, however, continue to entertain. Venus moves lower as the month progresses while Mercury initially rises higher and then begins to lower. By June 12th, it will be at its greatest elongation from the Sun with only 40% of its surface illuminated making a thick crescent in telescopic views. On the 18th, it will appear directly to the left of Venus and will continue to sink toward the horizon. Saturn will be at its highest in the south near sunset. If you observe it through binoculars, you can perceive a slowing of its retrograde motion (toward the west) against the background stars as it slowly returns to its normal eastward movement.