Sky Watch

Traversing the Depths And Heights of the Sky

By Blaine P. Friedlander Jr.
Special to The Washington Post
Tuesday, September 5, 2006; Page B08

Adjust your spurs and holster your binoculars: Get ready for high moon.

Now through the end of 2007, we're in a period of a major lunar standstill. This means the moon will transit higher than what we normally see, and two weeks later, it will transit lower than what we normally view. Much like having a high sun in the summer and a low sun in the winter, the moon goes through a cycle of range every month in the sky.

"In general, the moon does in a month what the sun does in a year," said Judith Young, an astronomy professor at the University of Massachusetts. "In the period of the major lunar standstill, the moon transits five degrees higher in the sky than the summer sun, and then two weeks later, it transits lower in the sky than the winter sun."

The moon reaches its northernmost maximum Sept. 15, transiting high in the sky in the morning and rising and setting farthest north. Incidentally, that's the northern extreme for moonrise and moonset. The moon reaches its southernmost limit Sept. 30, transiting low in the sky, rising and setting farthest south. Next month, the moon reaches its northernmost Oct. 12 and its southernmost Oct. 27.

This kind of lunar cycle runs for 18.6 years, and the last major standstill happened in 1987-89. The cycle started last year, and we'll enjoy the next minor lunar standstill -- where monthly fluctuation in the altitude of lunar transit is minimal -- nine years from now. Enjoy the higher-than-high moons, because the next series doesn't run until 2024-26.

More information about the lunar standstill can be found at http://www.umass.edu/sunwheel/pages/moonteaching.html .

Autumnal Equinox

In September, find Jupiter at negative first magnitude (bright) low in the southwestern sky at dusk. The morning sky features Saturn, a zero magnitude object (bright), rising a few hours before the sun. Venus is hard to find low on the eastern horizon at sunrise.

All things being equal, the autumnal equinox is Sept. 23, at 12:03 a.m. Eastern time, according to the U.S. Naval Observatory. Thus fall begins in the northern hemisphere and spring begins in the southern hemisphere.

Neither the partial lunar eclipse (Thursday), nor the annular solar eclipse (Sept. 22) will be visible from North America. The lunar eclipse is visible mainly in Asia and Europe, while the path of solar eclipse is on the Atlantic Ocean, between South America and Africa.

Down-to-Earth Events

Today -- Astronomer Cole Miller explains "Colliding Black Holes in a Computer" at the University of Maryland observatory's open house in College Park. View the heavens after the lecture, weather permitting. 9 p.m. Information: 301-405-6555 or http://www.astro.umd.edu/openhouse .

Sept. 11 -- "The Stars Tonight" at Arlington Planetarium, adjacent to Washington-Lee High School, Arlington. 7:30 p.m. See the night sky through telescopes, weather permitting. Information: 703-228-6070 or http://www.arlington.k12.va.us/instruct/science/planetarium/ .

Sept. 20 -- David Rupke, an astronomer who researches galactic evolution, explains "Blowing Bubbles" at the University of Maryland observatory's open house in College Park. After the lecture, scan the sky through a telescope, weather permitting. 9 p.m. Information: 301-405-6555 or http://www.astro.umd.edu/openhouse .

Sept. 23 -- Join Sean O'Brien of the National Air and Space Museum for a Saturday Star Party at Sky Meadows State Park, near Paris. 7 p.m. to 11 p.m. $4 parking fee. Information: 540-592-3556 or http://www.dcr.state.va.us/parks/skymeado.htm .

Blaine Friedlander can be reached at PostSkyWatch@aol.com.

© 2006 The Washington Post Company