Favorite Star Patterns

Northern Cross: Backbone of Milky Way

A crosslike pattern inside a triangle pattern.
The constellation Cygnus represents a graceful swan. But many also see it as a cross, and so these stars have become known as the Northern Cross. The entire cross patttern (or swan) fits inside a larger asterism, created by the 3 bright stars Vega, Deneb and Altair: the famous Summer Triangle.

How to find the Northern Cross

The Northern Cross is a clipped version of the constellation Cygnus the Swan. It’s an asterism, or pattern of stars that’s not a recognized constellation. It lies embedded within another, much larger asterism, the Summer Triangle. You’ve got to have a dark sky and a good imagination to see a swan in the stars of Cygnus. But the Northern Cross is easy to see, even if your sky is less than pristine.

Here’s step #1 to finding the Northern Cross (or Cygnus the Swan). Look for the most brilliant star in the Cross, Deneb. Deneb marks the top of the Northern Cross. It’s also well known as one the three bright stars of the Summer Triangle, along with Vega and Altair.

Roughly halfway between Altair and Vega, and somewhat offset toward Deneb, look for the brightest star in that part of the sky. That’ll be 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’s fairly easy to find.

Once you locate Deneb and Albireo, you’re halfway to piecing together the Northern Cross. All you need now is the crossbar, which most people see as three moderately bright stars. In the illustration below, you’ll see these three stars extending about halfway out into the wings of Cygnus the Swan.

Chart of starry sky with picture of long-necked flying swan constellation and Deneb, Altair, and Vega labeled.
The Northern Cross is an asterism, or noticeable pattern of stars. It’s within the constellation Cygnus the Swan. The Northern Cross and Swan are inside an even-larger asterism, consisting of 3 bright stars, called the Summer Triangle. Image via Bob Mohler.

Backbone of the Milky Way

In a dark sky, the Northern Cross serves to point out the Milky Way, the edgewise view into our own galaxy. The Milky Way appears in a dark sky – in the evening in northern summer – as a luminescent river of haze, passing directly through the Northern Cross. This hazy band stretches all across the sky on late July and August evenings.

You probably know this “haze” is really myriad stars. You can see the haze explode into stars by aiming binoculars toward the Milky Way.

Keep in mind, also, that all the stars we see with the eye alone belong to our home galaxy, the Milky Way.

When you look at the Northern Cross, you’re looking directly into the Milky Way’s flat disk, where most of our galaxy’s stars reside. 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, star clusters and nebulae that abound within the disk of the Milky Way galaxy!

Star chart with stars in black on white with constellation Cygnus the Swan, and nearby Lyra the Harp.
The constellation Cygnus appears in the lighter area. Its primary stars make a distinct cross-like pattern, forming an asterism known as the Northern Cross. On the right on this chart you see the distinctly shaped constellation Lyra the Harp with its brightest star Vega. To use this chart on July or August evenings – when Cygnus is in the east – give the chart a single rotation to the left. Image via IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)/ Wikimedia Commons.

Northern Cross as a 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 Northern Hemisphere summer nights, the Northern Cross shines in the east at nightfall, sweeps high overhead after midnight, and swings to the west by daybreak. When you see the Northern Cross in the east on summer evenings, it’s sideways to the horizon.

By the time northern autumn arrives, the Northern Cross is still out from nightfall until midnight, but it appears high overhead in the evening and sets in the northwest after midnight.

When winter comes, the Northern Cross is standing upright over your northwest horizon.

Constellations Cygnus, Aquila, Lyra labeled, and stars Vega, Deneb, Altair labeled on sky photo.
View larger. | The Summer Triangle is made of 3 bright stars – Vega, Deneb and Altair – in 3 different constellations. The Northern Cross – a cross pattern within the constellation Cygnus the Swan – lies within the Summer Triangle. Image via our friend Susan Gies Jensen in Odessa, Washington.

Bottom line: The Northern Cross is an “asterism” or recognizable pattern of stars, part of the constellation Cygnus the Swan. Charts and more here to help you find it in your sky.

July 18, 2021
Favorite Star Patterns

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Bruce McClure

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