The Northern Cross

Take a closer look at Deneb, the northernmost and faintest star in the Summer Triangle. Off to the south, or the right, of Deneb are three stars. The middle star is labeled Sadr in the chart above. Farther to the south, or right, is the fainter star Albireo.

These stars make up what is known as the Northern Cross. Deneb marks the top of the cross. Sadr is at the intersection of the arms of the cross, and Albireo is at the bottom of the cross.

Deneb to Albireo spans 22°. If you hold your outstretched hand at arm's length against the sky, the width from your thumb to your little finger covers about 25°. The Northern Cross should fit within your outstretched hand.

References:

Constellation Cygnus
Star Science in the Autumn Sky

The Summer Triangle

Go outside about half an hour after sunset. One by one, the brightest stars in the sky will start popping out. If you look directly overhead, the first three stars to appear form the asterism known as the Summer Triangle. Even though it's almost autumn, the Summer Triangle is still high overhead at nightfall.

Vega, the star farthest to the west, is the brightest among the three. Altair, towards the south, is the second brightest. Deneb, the one farthest north, is the faintest.

Unlike other asterisms that usually belong to a single constellation, the three stars of the Summer Triangle belong to three different constellations. Vega is the brightest star in the constellation Lyra. Altair is in the constellation Aquila. And Deneb belongs to the constellation Cygnus.

References:

Skywatchers Guide: Summer Triangle helps orientation, observation

How to Find Scorpius

If you can find Sagittarius, you can find Scorpius. Like Sagittarius, Scorpius is low in the southern sky and is just to the west (right) of Sagittarius. Its brightest stars look somewhat like a scorpion. Or perhaps you can think of it as a skewed letter J or a giant letter S or even a fish hook.

This is what it looks like next to the teapot asterism in Sagittarius.


This is close-up view of it.


Note the orange star near the upper end of Scorpius. It is the brightest star in the constellation and is therefore given the alpha designation, i.e., Alpha Scorpii. The star is better known, however, as Antares, meaning rival of Ares (Mars). Antares is the 16th brightest star in the sky.

Also note that the farther north you live, the less likely you are to see the bottom part of Scorpius.

References:

Fishhook? Snake? Letter "J"? It's Scorpius the Scorpion!
The Brightest Stars

The Teapot: How to Find Sagittarius in 2008

Sagittarius is easy to find this summer because Jupiter is right next to it. So the first step in finding Sagittarius is to find Jupiter. Look to the southeast after sunset. Jupiter is the brightest object in the sky. It is so bright that it can be seen before it gets totally dark.

Once you find Jupiter, look just to the west (right) of it. The brightest stars in Sagittarius look like a teapot. The teapot is another famous asterism. It is about 13° wide, slightly wider than your fist held at arm's length.

This is what Sagittarius looks like with constellation lines drawn. Jupiter is just to the left of the teapot.


This is the same view without constellation lines.


And this is a wide view of the southern sky. Can you still find the teapot? Hint: Start with Jupiter and look just to the right of it.

Asterisms

In astronomy, an asterism is a distinctive pattern of stars that is not a constellation. It can be the most distinguishing feature of a single constellation, or it can be spread out over a few constellations. The Big Dipper is an asterism, not a constellation, and is the most famous asterism in the sky.

Here are some well-known asterisms:

Big Dipper in Ursa Major
Little Dipper in Ursa Minor
Summer Triangle
Northern Cross in Cygnus
Teapot in Sagittarius
Keystone in Hercules
W in Cassiopeia
Great Square in Pegasus
Sickle in Leo
Orion's Belt

References:

Wikipedia
List of Asterisms

The Little Dipper

If you can find Polaris, you can find the Little Dipper in the constellation Ursa Minor. As shown in the chart below, Polaris marks the tip of the handle of the Little Dipper.


Finding the Little Dipper in the city can be a challenge. Most of its seven stars are rather faint. Here are the Little Dipper and Big Dipper with outlines drawn. The Little Dipper is on the right.

Here they are without the lines. Again, the Little Dipper is on the right.

This is what they look like from most big cities.

As you can see, only three of the Little Dipper's stars are visible -- Polaris and the two stars at the front of the bowl. The shape no longer looks familiar. Light pollution makes a big difference in what you can see in the sky.

The Big Dipper

One of the most recognizable groups of stars in the sky is the Big Dipper in the constellation Ursa Major. Most people learn to find it as children. For those who missed that lesson, go outside after dark just as the stars are starting to come out and look to the northwest. The stars of the Big Dipper are fairly bright and should be one of the first ones to appear in the evening. See if you can recognize the shape from the chart above.

If you're having trouble finding it, remember that the Big Dipper is huge, spanning 25°. Hold your hand at arm's length against the sky with your thumb and pinky finger extended. The width between those two fingers is approximately 25°. Don't forget to try your planisphere, if necessary.

Once you've located the Big Dipper, look for Mizar, the second star from the end of the handle of the Big Dipper. It is a double star, meaning it is actually two stars even though it appears a single star to the naked eye. Alcor is its companion star. Mizar and Alcor are easy to split in binoculars. If your eyes are very sharp, you might be able to see both stars without binoculars.

The Sickle

Now that you know where Regulus is, you can identify the constellation Leo, the lion. The head of Leo looks like a backward question mark or a sickle. Regulus is at the bottom of the sickle. The lion's body follows to the southeast (upper left). This is what it looks like in the early evening:


At this time of year, Leo is getting ready to set, so look for Leo soon after dark. Leo is highest in the sky in the spring. If you familiarize yourself with Leo now, you'll be able recognize it in the early spring when it rises in the east looking like this: