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Learning the Constellations

In this introduction to the night sky, you can get a start on being able to recognize some stars and constellations that are available to us on any clear night. Learning some of the constellations is the first step in locating the many beautiful objects of the night sky.

Although the night sky is most beautiful away from the light pollution of the city, don't let that stop you from getting a start on learning the sky. A quiet, safe place like a park or soccer field away from blaring lights where you can see a good portion of the sky is all you need.

We will begin with the most familiar summer constellations and stars in the Northern Hemisphere, as most people and families are out and about during these warm months of June through September.

But first, a few words about equipment and supplies: To begin your journey, you will definitely need a map (star chart) and a source of light to see it with. A compass might be a good thing to bring along as well, until you can easily find north by using the stars (our first lesson)!

A flashlight is needed so you can see in the dark to read your star chart. Unfortunately, standard white light flashlights are too bright and ruin your night vision, so we make a compromise. Red light is much better than white light since it affects night vision the least. So, tape some red construction paper, several layers of red cellophane, or several layers of red tail-light tape over the front of the flashlight lens. You could also paint the bulb or the lens with red finger nail polish or red paint. It usually takes quite a few layers and needs to be dimmer than you would think, so test it in the dark. It only needs to be light enough to see your chart. Best, of course, is to buy or build a red LED light for astronomy. Red light is the only light to use at a star party.

A book of constellations or set of star charts is the next important item. “Nightwatch” by Terrance Dickenson is a good introductory book on general astronomy and it is includes great constellation charts. A circular star finder, called a Planisphere, will show the stars and constellations for the entire year. You just rotate the circles to match the date and the time, and it will show you the constellations and bright stars that are up for that period of time. Get the big, plastic ones. They come in different latitudes, so check to see if it's close to where you live. ( Portland is located at approximately 45.5 degrees north.) A good guide to identifying star patterns into constellations is a book called “The Constellations: A New Way to See them” by H. A. Rey (also author of the “Curious George the Monkey” series).

Warm clothes are a must, especially with children. It is surprising that even in the warm summertime, the night air can be cold when you are standing around looking at the stars. Also, bring a bit to eat and/or something to drink if you are going to be out for a while. Bring a chair as well.

Get your feet wet at a local Star Party. Check out the RCA Star parties or your local astronomy club for the dates and times. Besides getting expert help in identifying constellations, stars, and objects, you can also check out various telescopes and get a look at a number of beautiful objects of the night sky.

Stars and Constellations

Finding constellations and groups of stars is enjoyable, and being acquainted with the sky will be invaluable upon further exploration of the universe. Stars are giant balls of hydrogen gas that formed in gas clouds like the Orion nebula. They have so much mass, that the pressure in the deep interior is great enough to combine, or fuse, hydrogen atoms together. This fusion yields a great deal of energy, some of which we can see as visible light.

Stars come in great variety of sizes and brightness, or luminosity. Their surface temperatures determine their color. Very hot stars are blue or white, medium temperature stars like our sun are yellow, with the red stars being the coolest. Very bright blue or white stars can be much further away from us than cooler stars, even though they appear closer, although red super giants can also be seen at great distances from us.

Constellations are recognized patterns of stars that form animals or figures, many named from very ancient times. It is enjoyable to try to see the pattern form into something that has been recognized and named for many centuries, many dating back to the Ancient Egyptians and Babylonians.

The constellations also serve as a guide to locating objects in the sky, and are regularly used today by both amateur and professional astronomers. An astronomical object is usually spoken of as being "in" a certain constellation. (The globular cluster M13 is found in Hercules.)

 

Lesson 1 - Ursa Major (The Big Bear)

This is a huge constellation in the Northern Sky, and is visible year round in the Northern Hemisphere, although it is quite low in Autumn.

The most famous part of Ursa Major is the Big Dipper. It consists of the dipper and the handle. To find it, you first have to figure out where north is. This is where a compass comes in handy. In the summer, the Big Dipper is in the Northwest sky, with the handle pointing upwards.

Notice that the two stars that form the front part of the dipper point to the North Star, Polaris. Now, when you have found Ursa Major, you can find North. All the heavens rotate counterclockwise very near this point (Polaris) due to the rotation of the earth.

In the second star from the end of the handle, you will see two stars close together, Mizar and Alcor. They are known as an optical double and are a nice pair in binoculars. The brighter white star is Mizar. Star charts will show the apparent magnitude of a star. Mizar is a 2nd magnitude star, and Alcor is a 4th magnitude star. Mizar is also a true binary star, where two or more stars orbit each other. More than 50% of all stars are binary systems. Both Mizar and Alcor also have companion stars than cannot be detected visually. Try to determine which stars in the Dipper are dimmer or brighter than Mizar. Check on a chart of Ursa Major to see the apparent magnitudes of these stars.

The other constellation streaming out from Polaris is Ursa Minor, The Little Bear, or better known as The Little Dipper. The stars that make up the handle, other than Polaris, are difficult to see in the city. Try spotting the dipper stars.

Next, we are going to "star-hop" across the sky.

Pretend the handle of the Big Dipper is an arc that will lead you across the sky to the next bright yellow-orange star, Arcturus, in the constellation Bootes, ( boh-OH-teez), The Herdsman. Arcturus is a 0 magnitude star, and the 3rd brightest in the sky. Bootes is shaped like a long kite.

Next is the arc down to the blue-white star Spica, in the Constellation
Virgo
, The Virgin, the second largest constellation in the sky.

 
She holds a spike, (from the old English term) of wheat in her left hand, with Spica, being the ear of wheat. Spica is a 1st magnitude star. Notice that it probably is twinkling (or scintillating) because the light has to travel through a lot of our Earth's turbulent atmosphere as it is low in the sky in Summer, and by September is below the western horizon. Virgo is famous for its many galaxies, and best seen in Spring.

Remember the saying: Arc to Arcturus and drive a spike to Spica.

 

 

Lesson 2 - The Summer Milky Way

Now that we have spanned the sky, let's return to Polaris, and then move to the Northeast.

Here you will find the large "W" of Cassiopeia (Cas ee oh PEE uh), the Queen, rising in the Northeast. Many fine open clusters of stars are found here.

Below Cassiopeia near the horizon in July, is the constellation Perseus, (PER see us), the Hero. 

If you are in a dark sky away from city lights, you will be able to see the dim glow of stars running through these constellations. This hazy band is the Milky Way, our Galaxy. As you follow this band of haze across the sky, you are looking across part of the galaxy inside of which we live. Just a simple scanning through this region with binoculars will give an indication of the number of stars here.

Galileo was the first to record what he saw through his telescope in a letter to the Tuscan Court on January 30, 1609. "Besides the Moon, this spyglass has allowed me to discover a multitude of fixed stars never before seen, of which there are more than ten times as many as are naturally visible. Moreover, I have assured myself about what has always been a controversy among the philosophers, that is, what is the Milky Way."

Next, we come to the constellation Cepheus, (See fee us) the King, and husband to Cassiopeia.

Cepheus does not have any really bright stars and may be difficult to pick out, especially if the sky is dark and full of stars in the Milky Way.

Cepheus looks a bit like a house on its side. Follow a line from the "top" stars of Cassiopeia, which will point to Cepheus. Look for the steep roof pointed toward Ursa Major

Continuing to head south, a much more prominent constellation flying high overhead is Cygnus (SIG-nus), the Swan, also known as the Northern Cross.

The brightest star is the tail of the Swan, the alpha star of Cygnus, Deneb. Deneb (Arabic for tail) is very distant (1400 light years) and still a very bright 1st magnitude star. The middle or breast star of the swan is Sadr, a 2nd magnitude star. This is the point where the wings are crossing the body.

Representing the bill of the swan is the well known star Alberio. To the naked eye, Alberio appears to be a single, naked-eye 3rd magnitude star, but when viewed through a telescope, it separates into a truly beautiful binary star, one of the favorites of many. Look closely at Alberio and see if you can see that one star is blue and one is yellow.

Cygnus is especially beautiful in a dark sky and is great territory for binocular exploration. Just cruise your instrument down through the center of the constellation, and you can run into many star clusters and swirls of stars.

On the edge of the Milky Way and next to Cygnus is the small constellation Lyra (LIE- rah), the Lyre (harp) of Orpheus. The second brightest star of the summer sky and the most well known resides in Lyra, the white star Vega. It is a 0 magnitude star. It is not too distant at 27 light years.

The other stars making up Lyra's distinctive shape are 3rd and 4th magnitude stars.

We come to another bird as we move towards the south, the constellation Aquila (uh KWIL uh), the Eagle. In Greek legend, Aquila held the thunderbolts of Zeus.

Aquila 's most noticeable feature is the three stars forming a row. The brightest star in the middle of these is the white, 1st magnitude star Altair. Altair, with Deneb and Vega, form the Summer Triangle.

Now as we follow the Milky Way to the southern horizon, we come to the highlight of the summer, Sagittarius (sadge ih TARE ee us), the Archer. It's pretty difficult to find an archer here, so Sagittarius is better known for its more recognizable "teapot" shape, complete with a handle, spout, and even a spoon nearby.

Sagittarius is a truly a playground for the summer observer. There are many star clouds and clusters, both Globular Clusters and Open Clusters, as well as beautiful Nebulae. When you are looking at Sagittarius, you are looking toward the center of our galaxy, 28,000 light years away. If you have binoculars, cruising through Sagittarius is truly a wonderland in a dark, moonless sky. If you find yourself wondering what some of these fuzzy things are, you are ready for the next step.

For example, find the cap of the teapot, and go to the very top star, zeta Sagittariae. Locate this in your binoculars, and then move up and to the left. This fuzzy ball is the Globular Cluster M22, a very beautiful sight in a telescope. Armed with a star chart, you can locate many more objects, or just take in all the stars in the rich areas near the center of the Milky Way.

To the west of Sagittarius is a constellation that really looks like its namesake, Scorpius, the Scorpion. The heart of Scorpius is the red supergiant star Antares. If you replaced our sun with Antares, it would extend out to the orbit of Mars!

There is another fine Globular Cluster near Antares, the very beautiful M4. This is also visible in binoculars. Find Antares, which is the brightest star in the south, then move your binoculars west and south, and you should see another fuzzball of hundreds of thousands of stars. M4 is not as condensed as M22, and you can see many stars resolved with the humblest of telescopes.

This should get you started in exploring the night sky. Check out the list of books and sky charts that will lead you to the many wonders of the night sky.

2013 The Rose City Astronomers  All Rights Reserved