by Geoff Chester, USNO Public Affairs | 23 July 2024 NGC 6888, the Crescent Nebula in Cygnus imaged 2023 August 14 from Mollusk, Virginia with an Explore Scientific AR102 10.2-cm (4-inch) f/6.5 refractor, Optolong L-eNhance tri-band filter, and a ZWO ASI183MC CMOS imager The Moon wanes in the morning sky this week, climbing northward along the ecliptic to end the week among the rising stars of winter. Last Quarter occurs on the 27th at 10:52 pm Eastern Daylight Time. Luna brackets Saturn on the mornings of the 24th and 25th. On the morning of the 30th she forms an attractive triangle with ruddy Mars and bright Jupiter as morning twilight gathers. This formation occurs among the stars of the two naked-eye star clusters in Taurus, the Pleiades and the Hyades. It’s worth getting up early for! The July campaign for the citizen-science Globe at Night program runs from the 26th until August 4th. The focus of this month is the constellation of Cygnus, the Swan, one of the signature constellations of the summer sky. Cygnus is easy to find. Its brightest star, Deneb, is the northernmost and faintest of the three bright stars that make up the Summer Triangle asterism. You will find the Triangle rising in the eastern sky at the end of evening twilight. Deneb marks the Swan’s “tail”, and its long neck stretches to the center of the Triangle, ending with the star Albireo. Under suburban skies you can trace out the bird’s “wings”, and it only takes a small bit of imagination to trace out a stick-figure swan, seemingly flying southward along the Milky Way. In mythology, Cygnus has represented a swan in many Greek legends. Perhaps the most familiar is the story of Leda and the swan. The ever-opportunistic (and lecherous) Zeus, admiring Leda’s beauty, disguised himself as a swan to seduce her. The result of this tryst produced four other characters in Greek literature: Helen of Troy, Clytemnestra, and the Gemini twins Castor and Pollux. Another version is that the poet Orpheus was transformed into a swan after his brutal murder and placed into the sky next to Lyra, his harp. Under dark skies the constellation lies on top of one of the bright star clouds of the Milky Way, and owners of small telescopes can easily get lost among the innumerable stars of our home galaxy. To contribute to the Globe at Night database, go to the site’s web app, where you will be presented with star charts to help you determine the faintest stars that you can see with the naked eye. Your participation will contribute to the global effort to track the spread of light pollution and its impacts on nocturnal biology. Cygnus abounds with star clusters and glowing nebulous gas clouds. It also sports the sky’s most attractive double star, Albireo. It resolves into its two components in just about any small telescope, and the components themselves are very colorful. I like to call Albireo the “Navy Double” since its components shine with very distinctive blue and gold tints. The stars are located some 400 light years away, but there is some controversy as to whether they form a true binary system. They may just happen to lie along our line of sight, but either way Albireo is always a popular target at star parties. Late evening skywatchers can finally get a look at the planet Saturn before midnight. The ringed planet rises at around 10:30 pm in the southeast, and by midnight should be about 15 degrees above the horizon. Saturn is gradually wending his way through the dim stars of the constellation of Aquarius, so you should have no trouble spotting his yellow glimmer in an otherwise sparse star field. If you look at him with a small telescope, the planet’s rings may be hard to see at first. They are tipped just over two degrees to our line of sight, and look like two short lines sticking out from the planet’s equatorial cloud belt The rest of the planetary action takes place in the pre-dawn sky, where you will find the ruddy glow of Mars closing in on much brighter Jupiter. All of this takes place in the Pleiades and Hyades star clusters in Taurus as Mars shoots the gap between the clusters. Don’t confuse the red planet with the red tinged star Aldebaran a few degrees to the south. Jupiter lies just east of Aldebaran and is slowly wending his way between the “horns” of Taurus, with Mars in hot pursuit. Mars will pass Old Jove in mid-August, but you should plan to get up early on the morning of the 30th to catch the Moon, Mars, Jupiter, and Aldebaran in the pre-dawn light. It should be a spectacular photo opportunity.