The Northern Cross Asterism

Northern Cross
Courtesy: Photo via Flickr user Janne.

The Northern Cross is an astronomical asterism in the northern hemisphere of the celestial sphere, corresponding closely with the constellation Cygnus The Swan. It is much larger than the Southern Cross and consists of the brightest stars in Cygnus, Deneb, Sadr, Gienah, Delta Cygni and Albireo. The ‘head’ of the cross, Deneb, is also part of the Summer Triangle asterism.

Like the Summer Triangle, the Northern Cross is an indicator of the seasons. Near midnight during summer, the Cross lies virtually overhead at mid-northern latitudes; whereas the Cross can be seen during spring in the early morning to the East. In the autumn the cross is visible in the evening to the West until November. It never dips below the horizon at or above 45° north latitude, just grazing the northern horizon at its lowest point. From the southern hemisphere it appears upside down and low in the sky during the winter months.

In Johann Bayer’s 17th-century star atlas, the Uranometria, it was suggested that Alpha, Beta and Gamma Cygni formed the pole of the Christian Cross, while Delta and Epsilon formed the cross beam. The variable star P Cygni was then considered to be the body of Christ.

Check out our asterisms category for more information about different asterisms and view this article for information about what an asterism is.

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