Constellations | Moon | Milky Way | Solar System | Stars | Deep Sky | Binoculars & Telescopes | More Info

One of the best tools to help in becoming an amateur astronomer is the one you are now using -- your computer. But some things about the universe can be learned more easily by getting out and looking at the sky. That's what we will focus on here.

Many people think that you have to have a telescope to be an astronomer. But the earliest astronomers didn't have telescopes. They studied the movements of the sun, moon, stars, planets, and comets in the sky with their unaided eyes, and noticed that some times of the year had more "shooting stars" than others, that sometimes the planets seemed to move backwards, and many other unexplained things. It took ancient astronomers many thousands of years to figure out how and why the celestial objects move as they do. Our current knowledge is based on their discoveries.

This page is designed to provide information for a wide range of readers who are interested in becoming amateur astronomers -- from children attending middle or high school to adults. As such, it will be a bit too complex for some readers, and a bit too simplistic for others. We will be refining and augmenting this page based on your comments and suggestions.

Constellations are like the “countries” of the sky. The stars in constellations form patterns that people thought looked like animals, characters in ancient myths, and objects. Learning these patterns and their names is the best way to find your way around the night sky, for their stars and boundaries form a road map, as well as a calendar that has been used by man for thousands of years.

A Planisphere

The best way to learn the constellations is to actually identify them yourself in the night sky. Helpful tools are a planisphere and a flashlight with a red bulb or lens cover that won't reduce your ability to see dim stars. A planisphere is a constellation map printed on a round plastic or cardboard dial.  The dial allows you to select the time and date, showing the location of constellations visible in the northern and southern sky when you are observing.

The planisphere teaches that the stars move in a predictable way. Like the sun and moon, the stars rise in the east and set in the west. That is because the earth is rotating on its axis from west to east. The stars in the sky are relatively fixed, moving only slightly relative to each other over periods of many years. However, if we were to observe the constellations several million years from now, they would look very different than they do today.

You don't need a telescope to observe the constellations. In fact, the view through a telescope will only show small parts of constellations. However, a pair of binoculars will let you scan the constellations to make the stars in them look brighter. Binoculars will also show you many more stars and will allow you to see craters on the moon.

10x50 Binoculars The first number refers to the magnification, the second to the aperture of the objective (large) lenses in millimeters.

Learn About Binoculars and Telescopes
A pair of binoculars is a great way to view celestial objects in more detail. Many households have at least one pair of binoculars lying around. These may be adequate for your needs.  If you need to buy a pair, select 10x42 or 10x50 wide-field binoculars (see picture and caption to the right.) These are the best size for starting out and provide the best value for size and magnification. Make sure that the lenses and eyepieces are coated and are made of glass. Acceptable binoculars of this size can range in price from about $60 to $400 (and much more for high-end brands.) Be sure to compare the views through various brands before you purchase.

A discussion of the options for selecting a telescope is beyond the "scope" of this article, however, most amateurs agree that it's smart to avoid "special deals" in on-line auctions and department or discount store specials. Try to go to a store that specializes in astronomy equipment so you can select a telescope that is appropriate for your interests and needs.

Another way of learning about telescopes up close is to attend one of the DAS Open Houses at Chamberlin Observatory. There you can see and ask about many different kinds and sizes of amateur telescopes. And you can also look at various astronomical objects through them. You can also view the moon, planets, and star clusters through the large, 20-inch aperture, 27-foot long Clark Refractor in Chamberlin Observatory.

Here is a Web page that calculates the phase of the moon for any day: http://tycho.usno.navy.mil/vphase.html

A pair of binoculars will show that the moon has many dark areas (called seas or "maria.") These are actually flows of lava from inside the moon that occurred several billion years ago. Lighter areas are often pockmarked with many large and small craters.

Antonio Cidadao has provided a way to compare how the moon looks to our unaided eyes with how it looks through binoculars and through small telescopes HERE.

When you explore the Milky Way with a pair of binoculars, you will see many large loose clusters of stars. These are called open or galactic clusters. You may also see some smaller fuzzy balls.  These are actually tight groups of up to hundreds of thousands of stars called globular clusters.

Sadly, the Milky Way is no longer visible from Denver and most of its suburbs because of light pollution. But the mountains and the Eastern plains are still good places to see it. Many amateur astronomers support the International Darksky Association (IDA), which words to educate people about the importance of dark night skies to human health, spiritual well-being, and astronomy, as well as the lighting options that can reduce light pollution and reduce the wasted energy it represents, while providing safe and secure lighting.

The Sun
A safe way to begin observing the Sun indirectly is to make a pinhole projector out of a long cardboard box. If the projector is set up correctly, you should see a small image of the Sun. The Exploratorium provides instructions for making and using a projector HERE. When doing this, never look at the Sun, just at the image projected through the pinhole.

If you're anxious to see the Sun, but don't have a special solar telescope, Go to Space Weather's Web site and click on the red-orange ball on the left side. There you will see the latest picture of the Sun, often showing sun spots (magnetic storms on the Sun) and prominences (arcs of super-heated material flowing out from the sun.)

The Denver Astronomical Society provides safe, filtered viewing of the Sun through astronomical telescopes at Colorado Astronomy Day each Fall in association with the University of Denver and the Denver Museum of Nature and Science.  In 2007, this will take place on September 22nd. Click HERE for current information on Colorado Astronomy Day and HERE for a collection of photos from last year's event.

Planets
Planets orbit around stars, like our Sun. Planets near the Sun (Mercury, Venus, Earth, and Mars) are small and rocky because the Sun’s heat caused them to lose most of the gas envelopes that once surrounded their metallic cores. Planets farther from the Sun (Jupiter, Saturn, Uranus, and Neptune) still have this gas envelope. Planets are round because gravity causes high spots to fall. Over millions of years, this results in a smooth spherical surface, except for bumps like mountains. (Even Mt. Everest is a tiny bump relative to the entire Earth.)

Moons
Moons orbit around planets. All of the planets in our solar system have moons except Mercury and Venus. Our moon (Luna), was probably created when a large object collided with Earth, knocking off a big chunk. You can view the four brightest moons of Jupiter with a pair of 10X50 binoculars. The first person to see a moon orbiting another planet was Galileo, who first saw the four bright moons of Jupiter on January 7, 1610. Galileo was also the first person to use a telescope for astronomical observing.

Asteroids
Asteroids are actually minor planets that orbit the Sun. There are many thousands of asteroids, but astronomers estimate they could all fit in a globe less than half as big across as our moon. Many asteroids are found between the orbits of Mars and Jupiter. Others are found in areas very far from the Sun, beyond the orbit of Pluto, the former planet recently demoted to a "minor planet."

Comets
Comets are made of ice and dust. The tails of comets are created when hot particles flowing from the Sun heat up ice and dust and cause it to steam like a kettle. The comets we can see are those that orbit the Sun. The particles they emit are always blown away from the Sun. Therefore, when they are moving away from the Sun, comets actually are moving in the direction of their “tails.”

Meteors
These are pieces of comets, asteroids, and planets that we see only when they crash into the Earth’s atmosphere and ignite momentarily to form "shooting stars." Most meteors are the size of sand grains, but the largest can be several feet or yards across. Regular meteor showers occur several times per year and are named after the constellation in which they appear to originate. Two big shows are the Perseids (which originate in Perseus in early August) and the Leonids (which originate in the constellation Leo in mid November.) When a meteor enters the earth's atmosphere, it is called a meteorite. Extremely bright meteorites are called bolides or fireballs.

Stars
Most of the celestial objects are made up of stars, but stars are beautiful in themselves. While most stars look white, in a telescope they can be seen to have many colors, such as blue, yellow, orange, and red. Some stars can even look green or violet to our eyes, but this is an illusion. A star is created when gravity causes immense clouds of dust and gas to condense. This material ignites in a nuclear reaction when the pressure of gravity increases its temperature to several million degrees.

Double Stars
Many stars in the heavens are actually two or more stars that orbit each other. “Splitting” double stars by looking at them with high power telescopes can often reveal vibrant color contrasts. An easy double star to see if your eyes are very good is Mizar, the second star from the end of the handle of the Big Dipper. Its companion, called Alcor, is even easier to see in binoculars or a small telescope. In larger telescopes, Mizar is seen to actually be two separate stars. More than half the stars in the sky may be double or multiple stars.

Open Star Clusters
These loose collections of stars, which often contain several hundred members, were formed together when  The most well-known open cluster in Colorado skies is called the Pleiades or "seven sisters," named after the 7 brightest stars that can be seen with the naked eye.

Globular Clusters
These tightly packed collections of thousands or even millions of stars actually orbit our galaxy and some may have been formed when our galaxy was born about 12 billion years ago. Look at them out of the corner of your eye (a trick called called “averted vision”) to see the brightest stars.

The Exploratorium provides a long list of great Web sites, featuring "cool" astronomy projects, on its Web site: http://www.exploratorium.edu/learning_studio/cool/astronomy.html

As your knowledge and experience grows, you will want to obtain star charts and books that help you increase your enjoyment of what can become a lifetime hobby -- or even your occupation.

And don't forget that the Denver Astronomical Society hosts Public Nights every Tuesday and Thursday at the University of Denver's Historic Chamberlin Observatory. There you can see a multi-media astronomy lecture program, take a tour of the observatory, and view the moon, planets, and other celestial objects through a large refracting telescope that has been in operation since 1894.

The DAS also holds monthly general meetings that are open to those with an interest in astronomy or in joining the society. These meetings usually feature exciting and informative presentations by experts on various aspects of astronomy.

- Darrell Dodge, DAS