On July and August evenings, try finding two stars in the constellation Libra with the coolest of all star names: Zubenelgenubi and Zubeneschamali. In any year, they’re located in between two of the sky’s brightest stars, Antares in the constellation Scorpius and Spica in the constellation Virgo.
For the next several months, you’ll see the golden planet Saturn shining in front of the constellation Libra. In fact, an imaginary line from the ruddy star Antares through the golden planet Saturn points right to the star Zubeneschamali. (See the sky chart below.) Try it tonight, noting that the only other modesty-bright star to light up Libra is Zubenelgenubi.
If you live at mid-northern latitudes – North America, Europe or Asia – you’ll see these Libra stars rather low in your south to southwestern sky at nightfall and early evening. As seen from middle latitudes in the Southern Hemisphere – for example, in Australia – Libra’s stars shine close to overhead as darkness falls at this time of year.
Antares, Zubenelgenubi and Spica are stars of the Zodiac, or legendary Pathway of Animals that resides in our sky. This band around our sky marks the sun’s annual pathway in front of the backdrop stars. Nowadays, astronomers are more likely to speak of the ecliptic, which is more or less the same thing; the ecliptic is defined differently, as the plane of Earth’s orbit around the sun. Zodiac and ecliptic both mean a band around the sky, in front of which the sun travels throughout the year. If you could see stars during the daytime, you’d see the stars of the Zodiac. The sun sweeps near these stars, pairing up with Spica in middle October, Zubenelgenubi on or near November 7 and Antares on or near December 1.
Zubenelgenubi and Zubeneschamali were once seen in western culture as being part of the constellation Scorpius the Scorpion. They represented the Scorpion’s Claws. Zubenelgenubi and Zubeneschamali have been seen as a celestial Gateway in some cultures, because the moon and planets travel in between these Libra stars whenever they north of the ecliptic. Note that Saturn is north of the ecliptic, and in 2015, so is the moon when it makes its monthly rounds through the constellation Libra the Scales.
Bottom line: Look for two stars in the constellation Libra the Scales: Zubenelgenubi and Zubeneschamali. They’re located in between two of the sky’s brightest stars, Antares in the constellation Scorpius and Spica in the constellation Virgo.