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| Favorite Star Patterns on Jun 29, 2009

Northern Cross: Backbone of the Milky Way

The Northern Cross isn’t one of the 88 official constellations. Instead, it’s an “asterism” or recognizable pattern of stars. It’s part of the constellation Cygnus the Swan.

How to find it

The Northern Cross is a clipped version of the constellation Cygnus the Swan, and is really an asterism – a pattern of stars that is not a recognized constellation. However, most people have an easier time making out the Northern Cross than they do Cygnus the Swan.

The first step to locating the Northern Cross (or Cygnus the Swan) is to find the Northern Cross’ most brilliant star, Deneb. Deneb marks the top of the Northern Cross. Deneb is perhaps just as well known for being one the three brilliant stars of the Summer Triangle, along with the even brighter stars Vega and Altair. Knowing the three stars of the Summer Triangle gives you good footing for locating the Northern Cross, which is embedded within the Summer Triangle asterism.

Roughly halfway between Altair to Vega, and somewhat offset toward Deneb, look for the brightest star is that part of the sky. That’s Albireo. Although a modestly bright star, Albireo is easy to see on a clear, dark night. Since there are no similarly bright stars near Albireo, it is fairly easy to find. Once you locate Deneb and Albireo, you’re only a hop and a skip away from piecing together the Northern Cross.

Backbone of Milky Way

The Northern Cross, a clipped version of the constellation Cygnus the Swan. Photo credit: Janne

The Northern Cross serves to point out the Milky Way – the luminescent river of stars passing through the Northern Cross and stretching all across the sky. You need a clear, dark sky to see this “milky” swath of sky, but it’s a sight well worth pursuing. This hazy band is really an edgewise view of the galactic disk. Keep in mind, however, that all the naked-eye stars outside this band still belong to our home galaxy, the Milky Way.

When you look at the Northern Cross, you’re looking directly into the Milky Way disk, where the soft glow of millions of stars glazes over the heavens. In fact, the galactic plane (equator) runs right through the Northern Cross, encircling the sky above and below the horizon. On some clear, dark night, use binoculars and the Northern Cross to enjoy the star fields, stars cluster and nubulae that abound within the disk of the Milky Way galaxy!

Marker of Seasons

As seen from mid-northern latitudes, the Northern cross is out for at least part of the night all year around. It’s out all night in summer. On summer nights, the Northern Cross shines in the east at nightfall, sweeps high overhead after midnight, and swings to the west by daybreak. By the time autumn arrives, the Northern Cross is still out from nightfall till midnight, but it appears high overhead at evening and sets in the northwest after midnight. On winter evenings, the Northern cross stands upright over your northwest horizon.

When you see the Northern Cross in the east on summer evenings, it’s sideways to the horizon. On autumn evenings, the Northern Cross beams high overhead but runs diagonally across the sky. Our sky chart shows the Northern Cross on a winter evening, when this wondrous star formation stands vertically to the horizon!