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Monday, July 22, 2024

Earthsky Tonight—11: Altair, guide star to two small constellations

Courtesy of EarthSky
A Clear Voice for Science

Look in the east at nightfall and evening to locate a sparkling blue-white star not far from the horizon. That is Altair, the brightest star in the constellation Aquila the Eagle, and the second brightest star in the Summer Triangle. The Summer Triangle formation is made up of the three bright summer stars, Vega, Deneb and Altair. The Summer Triangle lights up the eastern sky on June evenings.

Once you have found Altair, it is a short hop to two small yet distinctive constellations, Delphinus the Dolphin and Sagitta the Arrow. Hold your hand an arm length away to find both star formations roughly one hand-width away from Altair. The Dolphin is found to the lower left of Altair, and the Arrow to Altair’s upper left.

Two fingers held at an arm length covers over, or nearly covers over either constellation. Even so, it is surprising how well these little star patterns stand out in a dark country sky. How many Dolphin stars can you see? One story claims that there are nine visible stars, said to represent the nine muses.

According to Greek sky lore, Sagitta is the arrow used by Hercules to save Prometheus from having his liver torn out by Aquila the Eagle.

Written by Bruce McClure

Astronomy Picture of the Day from NASA/JPL

CHANDRA Photo Album

U.S. Naval Observator Astronomical Information center

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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