Skywatch: Jupiter stars in September’s cooling nights


September’s cooling nights feature the prominent Jupiter as the planet reaches “opposition“on Sept. 26, according to the US Naval Observatory.

Don’t worry. There are no enemy worlds involved: “Opposition” means that Earth is caught between the sun and a planetary object. Consider this concept: We get to watch a “full” Jupiter — much like a full moon.

Early this week, Jupiter rises about 9 pm in the eastern sky. By Labor Day weekend, the large, gaseous planet ascends the evening heavens starting around 8:30 pm It’s an incredibly bright -2.9 magnitude, spotted between the constellations Pisces (the fish) and Cetus (the whale).

Throughout the month, Jupiter rises earlier. By the date of opposition, Sept. 26, the planet rises at 7 pm, stays up all night, then sets at daybreak.

Jupiter reaches opposition annually. Last month, it was Saturn’s turn (Aug. 14), and we’ll see a bright Mars at its opposition Dec. 8.

The last time Jupiter was this large and bright — from Earth‘s perspective — was Sept. 21, 2010, and Oct. 29, 2011, according to the observatory. Our favorite fifth planet from the sun gets this close again on Aug. 25, 2033, Oct. 2, 2034, and Nov. 8, 2035 — when all three of those oppositions reach -2.9 magnitude, said astronomer Geoff Chester of the Naval Observatory.

The first-quarter moon trots past Saturn (zero magnitude, bright) in the constellation Capricornus on Sept. 7-8, in the southeastern heavens about 9 pm

The moon reaches full Sept. 10 and cruises past the dazzling Jupiter the next night, then approaches the fuzzy Pleiades cluster in the Taurus constellation Sept. 14-15.

Later in the evening now, the last-quarter moon scoots past the brightening Mars (also in Taurus, magnitude -0.4, bright enough to see) on Sept. 16-17. While our neighboring Red Planet rises around 11 pm in this early part of September, find it in the east-northeast after midnight.

The usually bright Venus is quite close to the sun, hugging the horizon and rising just before daybreak. It becomes hard to see and effectively hangs out near the sun for a few months before returning in December.

Pull your sweaters from storage, and get your yard rakes ready: The Autumnal Equinox — the official astronomical start to fall — occurs Sept. 22 at 9:04 pm Eastern time, but on Sept. 23 at 1 am Universal Time, according to the observatory.

* Sept. 3 — Gaze the heavens at the National Air and Space Museum’s Steven F. Udvar-Hazy Center in Chantilly, Va. Telescopes are provided by Northern Virginia Astronomy Club (NOVAC) volunteers. Meet at the bus parking lot, but park at the main visitor lot. 8-10 pm GPS: 14390 Air and Space Museum Parkway, Chantilly, Va., 20151. NOVAC: Museum information:

* Sept. 3 — Enjoy stars and a few evening planets at “Exploring the Sky,” hosted by the National Capital Astronomers at Rock Creek Park, near the Nature Center. 8 pm Face masks optional. The program will be canceled if it’s raining or very cloudy.

* Sept. 9 — “A First Interstellar Probe: Next Step to the Stars,” a lecture by physicist Ralph L. McNutt Jr. of the Applied Physics Laboratory, Johns Hopkins University. He will describe the proposed Interstellar Probe, a possible NASA mission. Hosted by PSW Science. 8 pm, Powell Auditorium at the Cosmos Club, 2121 Massachusetts Ave. N.W.

* Sept. 13 — “Opening the Infrared Treasure Chest with James Webb Space Telescope,” a lecture by Nobel Prize-winning physicist John C. Mather. He will discuss how NASA and its partners built the amazing telescope and will share early discoveries. 8 pm Online and at the Steven F. Udvar-Hazy Center, Chantilly. Detail:

* Sept. 24 — Appreciate the starry heavens “Astronomy for Everyone” at Sky Meadows State Park in Fauquier County. NASA Jet Propulsion Lab ambassadors provide an astronomy program, while NOVAC members will offer telescopic views. 7-10 pm GPS: 11012 Edmonds Lane, Delaplane, Va., 20144. Bring lawn chairs and blankets. NOVAC: Sky Meadows: Park fee: $10.

Blaine Friedlander can be reached at

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