o become an amateur astronomer you don’t have to be an expert or know a lot of facts about the universe. You just need to be interested in learning about the things we see in the sky and get some basic tools and information that will help you to do that.
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 need 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.
Learn the Constellations
Most amateur astronomers agree that learning the constellations is the first thing that really helped them enjoy the night sky. This is actually more important than having or using a telescope right away. Knowing something about the night sky is the first requirement for successful telescope use.
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.
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.
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 10×42 or 10×50 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 $50 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 and/or camera 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, or similar events available in most other large cities. 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.
Observe the Moon
Most calendars show some of the most important information about the moon. These are the phases of the moon: new, first quarter, full, and third quarter. The phases help us know when the moon rises and how to locate it in the sky at any time. For example, if the moon is full, it will rise in the east at sundown because the moon is fully illuminated by the Sun setting in the west. If the moon is “new” (totally dark), it will be setting in the west just as the sun is setting because it is between Earth and the sun. Here is a Web page that explains the phases and calculates the phase of the moon for any day: http://www.moonconnection.com/moon_phases.phtml
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.
Observe the Milky Way
Here in Colorado, we are blessed with many dark places to observe the Milky Way, a cloudy river of milky light that completely crosses the sky. The Milky Way is actually not a cloud at all, but is comprised of billions of individuals stars, as well as huge areas of gas and dark dust. This is the galaxy in which we live. From Colorado In the summer, we have a view (in the Southern sky) toward the center of the Milky Way galaxy. In winter, we look out away from the galaxy’s center to the Orion arm of the Milky Way galaxy.
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.
NEVER look directly at the Sun with your eyes (even with sunglasses!) or with binoculars. Some telescopes can be used to look at the Sun, but ONLY if they have a special Solar filter.
Observe the Solar System
While the stars don’t move very much, Solar System objects, including the Sun, our moon, planets, asteroids and comets, are always changing their positions in the sky. In some cases, this is caused by the tilt of the Earth on its axis, which changes how high in the sky the Sun rises during the year and creates our seasons. In other cases this movement is caused by the rotation of the planets and the Earth around the Sun. For drawings of this rotation and additional information on the planets, try visiting the Solar Views Web site.
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.)
NEVER look directly at the Sun with your eyes (even with sunglasses!) or with binoculars.
Some telescopes can be used to look at the Sun, but ONLY if they have a special Solar filter.
The Denver Astronomical Society provides safe viewing of the Sun through filtered astronomical telescopes at Colorado Astronomy Day each Fall in association with the University of Denver and the Denver Museum of Nature and Science. In 2015, this will take place on October 17th.
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 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 many large and small chunks, which gradually came together because of gravitational attraction. 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 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 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.”
These are pieces of comets, asteroids, and planets that we see only when they crash into the Earth’s atmosphere and ignite momentarily due to friction caused by Earth’s atmosphere. Most meteoroids are the size of sand grains, but the largest can be several feet or yards across. When a meteoroid enters the earth’s atmosphere, it is commonly called a meteor or “shooting star.” Extremely bright meteors that explode when they heat up are called bolides or fireballs. When a meteor lands on the Earth, it becomes a part of the Earth — a meteorite.
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 seem to originate in Perseus in early August) and the Leonids (which originate in the constellation Leo in mid November.)
Learn About the Stars
There are many kinds of “objects” in the universe. But almost all of the objects have something to do with the evolution of 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 caused by the proximity of stars of contrasting colors. New stars are created when gravity causes immense clouds of dust and gas (that once made up older stars) to condense. This material “ignites” in a nuclear fusion reaction when the pressure of gravity increases its temperature to several million degrees.
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 vision is 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. The most famous double star is Albireo, the eye of the constellation Cygnus, the swan.
Open (or Galactic) Star Clusters
These loose collections of stars, which often contain several hundred members, are formed together when very large clouds of gas and dust are compressed by gravity and pressure waves in galaxies. The most well-known open cluster in Colorado skies is called the Pleiades or “seven sisters,” named after the 6 or 7 brightest stars that can be seen with the naked eye. These clusters are commonly found in the spiral arms of galaxies.
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. Many globular clusters look like hazy balls when viewing them through a small telescope. Others can be resolved into thousands of stars. Look at them out of the corner of your eye (a trick called called “averted vision”) to see the brightest stars.
What Can You See With a Telescope?
Many celestial objects can only be seen with telescope because they are very small and relatively dim when viewed from Earth. Some of these objects are within our galaxy, which is named the “Milky Way” after the name given to the appearance of its huge disk from the inside. Others are galaxies outside the Milky Way. Distance in space is measured in “light years.” One light year is the distance it takes light to travel in one year as it speeds along at over 186,000 miles per second. That is just over 6 trillion miles! While the objects we can see in our Milky Way galaxy are usually between 5 and 100,000 light years away, the nearest large galaxy (Messier 31, or the Andromeda Galaxy) is over two million light years away.
When an average-sized star like our Sun becomes unable to generate enough heat and energy to create heavier elements, it cools, expands slowly, collapses violently, and then expands again, giving off colorful layers or rings of super-heated elements that were created over millions or billions of years by the star’s nuclear reactions. Where the large star used to be is a tiny, dense white or blue dwarf star, often surrounded by a disk that can resemble a hazy blue-green planet when seen in a telescope. When our Sun experiences this process in several billion years, it will become a red giant star with a diameter larger than the orbit of Mars before it collapses.
When stars form from large clouds of dust and gas, they may heat up the remaining material (causing it give off, or emit, heat and light) or their light may reflect off the material. In photographs, emission nebulae are red, reflection nebulae are blue. To our naked eyes they look white or slightly greenish or bluish. Some bright nebulae are the remnants of supernovas — stars larger than our Sun that violently exploded, leaving behind a black hole, a pulsing and spinning star called a “Pulsar,” or sometimes (as was recently discovered) NOTHING.
When a large area of dust blocks the light from a bright nebula, it can look like a hole in the nebula. Most of these, like the Horse Head Nebula in Orion, are very dim. However, there are several parts of the sky where dark nebulae are easily observed with the unaided eye and binoculars. One of these is a large dark area that looks like a gap in southwest side of the Milky Way.
The closest galaxy to our own is the Andromeda Galaxy, named after the constellation in which it can be found. This galaxy is the farthest object that can be seen without a telescope, although binoculars are required for a good view. Through small telescopes we can see many hundreds of other galaxies that are very far away. “Spiral galaxies” look like our Milky Way, with huge arms of dust, gas clouds, and billions of stars, many of which are in large groups called galaxy clusters. “Elliptical galaxies” lack these features, looking like big globular star clusters.
This Web page provides just a quick review of some activities and information that can help you become an amateur astronomer. For more detailed information, you will want to visit the Web sites of Sky and Telescope and Astronomy magazines. The Sky and Telescope site features handy computer applications for plotting the positions of the moons of Jupiter and Saturn on any night of the year. Both sites provide on-line star charts and information on astronomy books, computer programs, and equipment.
Astronomy Magazine: 15 Things You Need to Know Before Buying a Telescope
Sky & Telescope: Choosing a Telescope
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 and Open Houses on the 1st Quarter moon Saturday of every month 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 (except for October, December, and March) that are open to all 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