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 PISGAH ASTRONOMICAL RESEARCH INSTITUTE Text by Dr. Bob Hayward Astronomer/Educator Graphics by TheSky Software Bisque Mountain Skies July 18, 2016 ALL FIVE VISIBLE PLANETS APPEAR AFTER SUNSET The planets: They’re back! All five of the visible or naked-­eye planets are now in the evening skies although Venus and Mercury are still very low in the evening twilight and, thus, a bit difficult to spot. The other three, from east to west, are Saturn, Mars and Jupiter and each of these is easy to spot as the sky darkens. Jupiter, which has been our “Evening Star” since about mid-­March has now moved farther to the west and shines brightly about a third of the way up in the southwest as the sky darkens. It is quickly sinking into the west and will be lost to us by early September. The red planet Mars is well up in the south these evenings. It is quickly dimming as the earth moves away from it but still outshines any of the stars in the sky. The observer with a good telescope can still make out some of the markings on the surface. (With the exception of Mercury, Mars is the only planet whose surface marking can be observed from the earth and even they are sometimes obscured by the monster dusk storms that have been observed on this fascinating planet.) The third of the trio of bright planets is the beautiful ringed planet Saturn. If you have not viewed Saturn through a telescope recently, make an effort to do so. Its rings are fully “open” as we say meaning they are tilted the maximum towards the earth and present a beautiful picture through a telescope. They also contribute to Saturn’s brightness making this planet, while not as bright as Jupiter, Venus or Mars, easily spotted above Antares, the heart of the scorpion. So, there you have it…three bright planets easily visible after sunset all month long plus two making appearances very low in the evening twilight late in the month. All five of these will remain visible throughout the month of August. The stars: Now that summer is upon us, it’s not too early to look high in the east in the early evening for the so-­called “Summer Triangle.” This pattern of three bright stars is not one of the classical constellations but rather what astronomers refer to as an asterism. In fact, the corners of the triangle lie in different constellations each associated with a bird in classical sky lore. Highest and brightest is Vega in the constellation of Lyra the lyre or harp. This is the musical instrument with which Orpheus charmed so many of the young ladies in his time. After the untimely demise of his wife Eurydice on their wedding day, Orpheus rescued her from the underworld but left his lyre behind. Jupiter sent the vulture to retrieve it. Thus, on star maps we often see the lyre carried by a vulture. To the northeast of Lyra is the bright star Deneb that represents the tail of the beautiful swan Cygnus. Tracing a line of stars from Deneb towards the south, we note the body and long neck of the swan terminating in the star Albireo that marks the eye of the swan. (Look at Albireo with a small telescope and you will note a colorful double star.) To the sides of the swan we can trace out his wings. Cygnus was the close friend of Phaeton who was the son of Helios the god of the sun. When Phaeton lost control of his father’s horses and was knocked from the sky by a thunderbolt from Jupiter, Cygnus dove into the river Eridanus to recover his friend’s body. For this kind deed he was placed in the sky to be a reminder to all of us that it is good to help a friend. For some people the swan can be found more easily if imagined as “The Northern Cross” with the top of the cross in Deneb and the bottom of the upright marked by Albireo. The wings of the swan then become the cross arm of the cross. Finally, to the south is the bright star Altair in Aquila the eagle. Jupiter sent his royal bird to earth to bring the boy Ganymede to Mount Olympus to become the cup bearer for the gods. Celestial Calendar: July 19, 6:57 p.m. EDT – Full Moon July 21 – Sun appears to move from Gemini the twins into Cancer the crab July 26, 7:00 p.m. EDT – Last Quarter Moon August 2, 4:45 p.m. EDT – New Moon August 5-­6, Midnight EDT – Jupiter 0.2º north of the moon * * * * * * * * * * PARI is a public not-­for-­profit public organization established in 1998. Located in the Pisgah National Forest southwest of Asheville, NC, PARI offers educational programs at all levels, from K-­12 through post-­graduate research. For more information about PARI and its programs, visit www.pari.edu. Follow PARI on Twitter at http://twitter.com/Astronomy_PARI. “Like” PARI on Facebook at www.facebook.com/Pisgah.Astronomical.Research.Institute. For further information or questions about this Mountain Skies column, contact Dr. Bob Hayward at [email protected]. Graphics produced with The Sky Astronomical Software, Software Bisque.