Forget July’s blue moon. For September’s full moon, you’ll probably see red. Catch a compelling, cosmic treat Sept. 27 and 28: It’s a full harvest moon featuring a total lunar eclipse.

As Earth travels around the sun, the planet always casts a shadow. Late in September, the moon moves across that shadow, and we are in a perfect place to watch a total lunar eclipse. By the way, it’s the largest full moon of the year.

The partial phase starts at 9:07 p.m. Sept. 27, when our lunar neighbor cruises into the Earth’s penumbral shadow, according to Fred Espenak, a NASA alumnus and noted eclipse expert. Over the following hour, the moon advances into the umbral shadow. At 10:11 p.m., the moon reaches totality, completely engrossed in the umbra, or the darkest part of the shadow — and that’s when skygazers may bask in an orange-red moon. (Espenak’s Web site: www.eclipsewise.com.)

The reddish totality lasts 1 hour 12 minutes, according to Espenak, beginning at 10:11 p.m. and ending at 11:23 p.m. Entering the second partial phase, you’ll see the shadow depart the moon’s surface — and that partial phase ends at 12:27 a.m.

Sadly, this is the last total lunar eclipse in the tetrad, which is a series of four total lunar eclipses in a row. The next tetrad series will be in 2032 and 2033, but there are an astounding six tetrads remaining in this century.

Note that there’s a partial solar eclipse Sept. 13, but it’s a Southern Hemisphere event seen only from southern Africa, part of Antarctica and the Indian Ocean. Catch it live online at Slooh.com, where you also can see the total lunar eclipse Sept. 27 and 28, too.

Spy planetary action in the morning: Find the boisterous, bright Venus in the predawn eastern sky in September. It now rises just before 5 a.m., and by mid-month just before 4 a.m., and is quite bright at ­minus-4.5 magnitude.

Wake up early when September ends, and Venus becomes an exquisite, minus-4.8 magnitude, that planet’s most brilliant point, before it slightly dims through the rest of the year, according to the U.S. Naval Observatory.

In the planetary parade, Mars falls back from Venus in the eastern morning sky in September’s early days. Our neighboring red planet is a relatively dim 1.8 magnitude.

Jupiter climbs back into the morning eastern heavens by mid-September. The giant, gaseous planet can be seen at minus-1.7 magnitude (bright) just before sunrise.

In the evening, find the ringed Saturn (zero magnitude, bright) in the south-southwestern sky. It sets after 11 p.m. now, and after 10 p.m. by mid-month.

Breaking from summer’s heat, it’s time for a chill: The autumnal equinox falls Sept. 23 at 4:21 a.m. Eastern time, according to the Naval Observatory.

Down-to-Earth events:

●Saturday — “Exploring the Sky,” hosted by the National Park Service and the National Capital Astronomers in Rock Creek Park, near the Nature Center south of Military and Glover roads NW. 8 p.m. ­www.capitalastronomers.org.

●Saturday — “Crushed, Fried and Spaghettified: Why You Shouldn’t Get Too Close to a Black Hole,” a talk by astronomer Cole Miller at the University of Maryland Observatory, College Park. 9 p.m. ­www.astro.umd.edu/openhouse.

●Sept. 7 — Think holiday gifts: Apollo 11 astronaut Buzz Aldrin, the second man to walk on the moon, signs copies of his new children’s book, “Welcome to Mars,” at the museum shop, National Air and Space Museum. 11 a.m. to 1 p.m. www.airandspace.si.edu.

●Sept. 11 — “Meteorites from Mars,” a talk by Mark H. Thiemens, physical sciences dean at the University of California at San Diego. Hosted by the Philosophical Society of Washington at the John Wesley Powell Auditorium, adjacent to the Cosmos Club, 2170 Florida Ave. NW. 8 p.m. www.philsoc.org.

●Sept. 12 — “Women in Aviation and Space,” activities throughout the day, but NASA astronaut Mary Cleave (who flew on the space shuttle Atlantis) talks at 11 a.m. and 1:30 p.m. in the Moving Beyond Earth gallery (213). National Air and Space Museum. 10 a.m. to 3 p.m. www.airandspace.si.edu.

●Sept. 12 — “Aqueous Alteration on Asteroids,” a talk by astronomer Margaret McAdam, at the National Capital Astronomers meeting at the University of Maryland Observatory, College Park. 7:30 p.m. ­www.capitalastronomers.org.

●Sept. 13 — “The New Horizons Mission to Pluto,” a talk by Mike Summers, George Mason University planetary scientist, at the Northern Virginia Astronomy Club meeting, 163 Research Hall, George Mason University, Fairfax. 7 p.m. www.novac.com.

●Sept. 14 — “Stars Tonight,” at the David M. Brown Planetarium, 1426 N. Quincy St., Arlington. 7:30 p.m. $3. www.­friendsoftheplanetarium.org.

●Sept. 19 — “Mayan Numbers and Calendars,” a presentation at the Montgomery College planetarium, Takoma Park, 7 p.m. www.ow.ly/JEJ6V.

●Sept. 19 — Sean O’Brien of the National Air and Space Museum guides you through the heavens at Sky Meadows State Park, Delaplane, Va. Parking, $5. Arrive before dark. 7-10 p.m. Park phone: 540-592-3556. www.tinyurl.com/q92udac.

●Sept. 20 — “New Horizons,” a talk by astronomer Silvia Protopapa, at the University of Maryland Observatory, College Park. 9 p.m. ­www.astro.umd.edu/openhouse.

Friedlander can be reached at PostSkyWatch@yahoo.com.