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Tuesday, June 25, 2024

EarthSky Tonight—September 12, Moon, Venus and a double star

Courtesy of EarthSky
A Clear Voice for Science

Our chart shows the moon, the planet Venus and the star Zubenelgenubi as they appear about one hour after sunset. The sky scene, though specifically for mid-northern latitudes in North America, will look similar at mid-northern latitudes all around the world. However, European and Asian observers will see the moon somewhat closer to Zubenelgenubi, the constellation Libra’s rather faint yet visible star.

Bright star in east? Might be planet Jupiter, nearly at its closest since 1951.

If you have binoculars, zoom in on Zubenelgenubi. You will see this single point of light blooming into a double star. It might be a true binary – two stars revolving around a common center of mass. If so, its orbital period could be as long as 200,000 years.

Observers in the southern hemisphere see the moon and Zubenelgenubi over Venus – not to Venus’ upper left. Moreover, these objects set later after dark in the southern skies. Venus – the first of these bodies to set – stays out for only about one and one-quarter hours after sunset at our mid-northern latitudes.

Through the telescope, Venus now appears as a waning crescent. Yesterday, we asked if the terminator – shadow line – on Venus disk represented a Venusian sunrise or sunset. Answer: sunset.

Tonight catch the moon, Venus and Libra’s double star low in the southwest at nightfall!

Written by Bruce McClure


“False Dawn” This Week: Zodiacal Light Easier to See

Andrew Fazekas
for National Geographic News
Published September 9, 2010


Astronomy Picture of the Day from NASA/JPL

CHANDRA Photo Album

U.S. Naval Observator Astronomical Information center

Universe Today

StarDate Online

Sky and Telescope

National Geographic

Space Com

Amazing Space

The York County Astronomical Society

Scope City

James S McDonnell Planetarium

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