© 2004 The Science Center of Connecticut
By Jason T. Archer

Contents

Half the fun of astronomy is being able to look up into the sky, pick out various objects, and to just know your way around the sky. To be able to actually view a galaxy or supernova remnant is a most impressive sight. It adds a whole new dimension to the study and enjoyment of astronomy. Read below for a basic introduction to start becoming a star gazer. Words in bold have definitions that can be found in the Key Terms in Night Sky Observing at the end of this article.

The Eyes Have It!
Contrary to popular belief, much of the sky can be seen with the unaided eye; constellations, planets, the Moon and a few deep sky objects can all be seen. All one needs are a dark site, star maps and a red flashlight. Give your eyes a good thirty minutes to dark adapt. As you look up into the night sky, more and more stars will appear as your eyes adjust.

To use a star map, face south with the south on the star map at the bottom so it reads left to right. Hold the star map overhead with the top of the star map facing back towards the north. This puts the right hand side towards the west and the left to the east. If you are using a Star and Planet Locator, the procedure is the same. Just be sure to set it to the correct date and time.

Find objects you already know first and go from there. Hop from constellation to constellation; learn their shapes and the brighter stars in each one. Good guideposts are the Summer Triangle, composed of Altair in Aquila, Deneb in Cygnus and Vega in Lyra; or the Winter Triangle, composed of Sirius in Canis Major, Betelgeuse in Orion and Procyon in Canis Minor. Go to the Seasonal Observing Guide (link to Seasonal Observing Guide) for the major stars and constellations of each season.

You'll notice that as the sky rotates about the North Star, some constellations like Ursa Major, Ursa Minor and Cassiopeia never set. These are known as circumpolar constellations. Constellations that lie nearer to the celestial equator, like Orion, Leo and Ophiuchus, rise and set each night. Some constellations will not be visible from your latitude.

To observe the planets, pick up a current issue of Sky and Telescope or Astronomy magazines. It will tell you what planets are visible, when, where and at what time of the night. There are a few deep sky objects that can be seen with the unaided eye if optimum seeing conditions are present. The Andromeda Galaxy (M 31) in Andromeda and the Pleiades (M 45), an open cluster in Taurus, are just a few examples.

Stop! Don't Buy That Telescope Yet... Got Binoculars?
Viewing with binoculars can be very rewarding. Most everyone has pair and they are a good start to observing. If you like what you see through them then your next logical step would be to buy that telescope you've always wanted.

Binoculars low power and wide field make them ideal. They have the advantage over telescopes in that you are using both eyes so you will get a higher resolution, an enhanced view of color and contrast, and a greater ability to detect faint objects.

Binoculars work on folded optics, whereby incoming light passes into a primary lens, through a series of prisms, and out eyepieces.

All binoculars have a set of numbers used to determine the binocular size. The first number is the magnification and the second number is the size of each objective lens in millimeters. For example, 7X35 means that this binocular has a magnification of 7X and objective lenses of 35 mm. Sizes range from about 6X30 to 30X80. Small binoculars are good for deep sky objects because of their wide field of view, whereas larger binoculars are good for planets, moon and comet observing, because of their high magnification and smaller field of view.

Binoculars of 8-10X magnification are the largest you should use if you are going to hold them by hand. Binoculars larger than this are classified as giants and should be mounted, because you will not be able to hold them steady due to their large weight. For the smaller binoculars, the best way to hold them is up near the objective lenses, for balance and stability.

To determine which binoculars are right for you, consider where you'll be observing. If you observe in a suburban area, the best binoculars are 7X35 or 10X50. If the observing is done from a dark, non-light polluted area, then use 7X50 or 10X80.

There is even a book all about using binoculars. It is called Touring the Universe through Binoculars – A Complete Astronomer's Guidebook by Philip S. Harrington.

Galileo Had One so I Want One…Telescopes
I think everyone at one time or another has wanted to get a telescope. They expand our reach into the universe. Reaching deep into the depths of the cosmos and revealing normally unseen morsels of our place in space. There is something very pure and basic about owning a telescope. It is a way for us to commune with our universe. For me it reminds me of my childhood were I could play scientist and maybe discover something never before see by us humans.

However, as cool as it is to buy that telescope you've always wanted they do require patience and practice to get the full enjoyment out of them. I like to compare using a telescope to playing a musical instrument. At first you have no idea what you are doing and your notes sound bad. But, with time you are playing beautiful melodies and doing things you never thought you could. I'll have more on this later.

There are two basic types of telescopes: refractors and reflectors. Refractors use a series of lenses to collect light and focus it into an eyepiece. Refractors are great for observing the Moon and planets. Reflectors on the other hand use a series of mirrors to focus light into the eyepiece. They are an ideal telescope for they're low cost and ability to observe the Moon, planets, and deep sky objects.

Keep in mind that one does not need a high-tech, expensive telescope. For a beginning and/or serious amateur, a six-inch reflector is quite sufficient. With a six-inch, all 110 Messier objects can be seen, as well as numerous double stars and planets.

The method to set up a telescope is determined by the type of mount the scope has. Scopes usually have one of two types of mounts: altitude-azimuth or equatorial. The altitude-azimuth allows the telescope to move up and down in altitude (measured in degrees) and around in azimuth (measured in compass direction). Dobsonian is the most popular kind of altitude-azimuth mount, named after former monk and telescope designer John Dobson.

The problem with these kinds of mounts is that they make it difficult to move the scope in right ascension and declination, and make it difficult to maneuver near the zenith. The equatorial mount moves in right ascension and declination. This is ideal, for the coordinates of deep sky objects are given in this system. The only problem is that equatorial mounts make it difficult to maneuver the telescope near the North Celestial Pole.

To set up an alt-azimuth scope, simply place the scope on level ground and you're ready to go. The procedure to set up and align an equatorial mount is a little more involved. Again, place the scope on level ground. The key is to align the right ascension axis with the North Celestial Pole. This allows the scope to move in right ascension and declination along with the sky.

There are three basic techniques to finding objects with a telescope. One technique is the use of setting circles. Most scopes with an equatorial mount have setting circles - a calibrated scale encircling the right ascension and declination axes that give the position of the telescope on the night sky. To calibrate the setting circles, position the scope on a bright star, one whose coordinates are known. Once the star is centered in the field of view, rotate the setting circles to the star's coordinates. The scope will now be aligned, and depending on how good the polar alignment and setting circles are, you will be able to find other objects just by knowing their coordinates.

A second technique is known as star hopping. With this method you fix the scope of a star you're familiar with and "hop" from one star to another until you reach the desired object. Star hopping is a technique that requires practice and patience. This is how I like to observe. It is like following a treasure map to that pot of gold in the sky.

The third method I am not going to say much about. Many telescopes come with computer database of celestial objects. All you need do is properly align the telescope, call up your desired object and hit GOTO. The telescope automatically tracks to the object. Personally, I like to star hop. Think of it as playing a video game. Sometimes you win and sometime you loose, but playing the game and discovering new things are always fun.

Stand Still Will You... Observing Conditions
Because we are viewing the celestial sphere through the Earth's atmosphere, the atmosphere has a big effect on what we see and how well we see it. These observing conditions can be broken down into the seeing and transparency of the atmosphere. Seeing is defined as the steadiness of the image. It is due to minute differences in the refractive index of air from one place to the next. Think of air as being a group of lenses of different sizes; each light ray through each lens will refract a different way. The transparency of an object is the limiting magnitude of the sky due to clouds, light pollution, haze, etc.

Scales have been developed so the measure of observing conditions is universal. ALPO, the Association of Lunar and Planetary Observers rate the seeing as 0.0 - 10.0 where 0.0 is the worst and 10.0 is absolutely still. A second scale is the Antoniadi scale, which uses roman numerals from I to V where,
I - perfect seeing with no quiver
II - slight undulations with moments of calm lasting a few seconds
III - moderate seeing, with moments of large air tremors
IV - poor seeing with consistent troublesome undulations
V - very bad seeing, scarcely allows making of a rough sketch.

Transparency is measured by identifying the magnitude of the dimmest star, which can be seen, usually near the zenith, with the unaided eye. An important point to realize is that seeing and transparency don't necessarily go together. For example, on hazy nights the air is still so the seeing is good, but the transparency is poor.

The Moon Doesn’t Look Like Cheese
The Moon is our closest neighbor, so a lot of detail can be seen. A fun project is to sketch the moon at its different phases. To observe the moon, one should use low magnification and a small aperture. Too high of a magnification will cause a very unsteady, bright image. To cut down on the brightness, one can "stop" down or decrease the size of the telescope opening, or use a neutral density filter. On the moon, one will see craters, mountain ranges, maria, etc., all of which are very beautiful. Try looking along the Moon's terminator. The contest between light and dark help resolve a great deal of features and textures.

Observing Isn't Just done at Night
The Sun, believe it or not, can be observed safely through a telescope, but only using special safety methods. There are two safe methods that can be used. Before any solar observing is done, certain safety tips must be followed:

1. NEVER LOOK AT THE SUN WITH THE UNAIDED EYE!
2. Never look at the sun through any type of magnifying device without a full aperture solar filter.
3. Always remove the finder scope to prevent accidental viewing.
4. Never use eyepiece filters.

There are two techniques to viewing the sun SAFELY. The first and safest is the projection method. This is where you project an image of the sun onto a screen via the telescope's eyepiece.

The following steps can be used.

• Orient the scope to minimize the scope's shadow.
• Use a simple eyepiece (i.e. one that does not have several elements glued together)
• Use an aperture mask with a hole cut to one side of the secondary

Another technique is with the use of an aperture filter. This cuts down the amount of light entering the scope my only allowing 0.001% of the light to enter. There are two basic types of filters: 1) metal on glass; and 2) mylar. The metal on glass has a nickel alloy surface, is very durable and allows one to see a yellow/orange image, thus a "real" image of the sun. The peak wavelength of the sun falls in the yellow range of the spectrum. The mylar filter is a metal alloy on mylar plastic and results in a blue image. This can result in missing fine detail.

Why does one observe the sun - sunspots. Sunspots are excellent indicators of the sun's activity and may be connected with the weather on Earth. For more information on doing sunspot counts, go to http://www.aavso.org/observing/programs/solar/. This is the American Association of Variable Star Observers Solar Program.

Again, never ever look at the sun with the naked eye. I can't stress this enough.

That Looks like a Star but it Isn't…Observing the Planets
Planet is Greek for "wandering star" because while a planet can look like a star and even twinkle at times they appear to move among the stars as seen night after night. The planets can be divided into inferior and superior. The inferior planets will show a full range of phases and will appear close to the sun. The superior planets will show gibbous or full phases and will appear anywhere near the ecliptic.

Mercury
Mercury is difficult to observe because it is always within 28 degrees of the sun and its disk is never larger than 10". The best times to observe are just after sunset or just before sunrise. This will put Mercury very near the horizon.

Venus
Venus is the brightest of the planets, and can be seen during the day with the unaided eye. It is usually seen as a brilliant "evening star" or "morning star" around sunrise or sunset. It is completely shrouded with clouds, so even though it is the closest planet to earth, telescopic observers can never see surface features. Venus, like the Moon, shows phases.

Mars
This much talked and written about planet is best observed at its closest approaches during opposition. In this position the most detail will be seen and the planet will be visible all night long. As a result of Mars' rotation, many different features can be seen. Through a six-inch scope with average observing conditions, dust storms, polar ice caps, and albedo features can be seen. The polar ice caps are the most impressive features, and their size will change with the Martian seasons.

Jupiter
Jupiter is a very beautiful planet and can easily be seen through any scope or binoculars. Like Mars, it is best viewed at opposition. The four largest moons (Europa, Callisto, Io, and Ganyamede) can be seen orbiting the planet. Many times a transit, when a moon crosses the face of the planet resulting in a shadow can be seen. The moons will also be occulted by Jupiter, or pass behind it. As one observes Jupiter, one will notice that Jupiter is not round but oblate due to its rapid rotation. The most prominent object is the Great Red Spot, along with its belts and zones.

Saturn
Saturn is just as impressive and popular to observe as Jupiter, and like Jupiter it can be seen in most telescopes and binoculars. The Encke and Cassini divisions are easy to distinguish in larger scopes. At perihelion, Saturn's Great White Spot will erupt. Also, two of its 31 moons, Titan and Rhea are visible in even the smallest scopes. In fact the Cassini-Huygens Spacecraft is currently in orbit about Saturn. Click here for more information, http://saturn.jpl.nasa.gov/home/index.cfm.

Uranus, Neptune and Pluto
Uranus and Neptune are visible as blue/green disks with no discernible features. Pluto requires an aperture of at least 8 inches, as it reaches only 14th magnitude.

Stars Come in Pairs…Observing Double Stars
Many stars are double, triple and even sextuple star systems. This is where multiple stars orbit around each other. Our Sun is rare in this aspect for it is a single lonely star that has no companion. Each season's multiple star systems to observe can be found under the Seasonal Observing Guide. There are four basic criteria for looking at double stars.

The resolving power is one's ability to distinguish between two adjacent objects in the sky. The higher one's resolving power, the smaller the separation one will be able to split. The quality of the scope goes without saying, the better the scope, the better the image. For an average scope, the best double stars to look at are those with components of fairly equal brightness. If one of the components is too bright, it wills in essence, "drown out" the dimmer companion. The seeing conditions are essential. The better the seeing conditions, the more stable and crisp the image will appear. Keep in mind that even under good seeing conditions, the stars will not be point-like, but will have some small diameter called the Airy disk. Bad seeing will "blow up" an airy disk. Bad seeing tends to blend the airy disks of the two stars together so it may look like a single star. The better, more experienced observer will be able to look at an airy disk and determine whether it is a double star or not, no matter what the seeing conditions.

More than Meets the Eye... Deep Sky Objects
They are called deep sky objects because they are out there... way out there being light years away from us. Deep sky objects consist of galaxies, nebulae, open clusters, and globular clusters. Examples are the Ring Nebula M-57 in Lyra, the Great Globular M-13 in Hercules, and M-31 the Andromeda Galaxy. They look like fuzzy cotton balls through the eyepiece in light polluted areas but away from city lights fine details such as individual stars and dark dust lanes can be seen.

Start with a low power eyepiece (i.e. a wide field of view); this enables one to look at large areas of the sky. The key is to first look for a "fuzzy blob"; this will be what a deep sky object looks like at low power. Stay with low power when looking at large objects such as open clusters or diffuse nebulae. High power is to be used when looking at small objects or when detail is needed, i.e. to better see the structure of a galaxy. The problem with greatly magnifying an object is that it not only magnifies the image but also magnifies any flaws in the optics. It will also produce a very unstable image. Observing deep sky objects is an art. It takes practice to be able to find dim objects and to resolve them clearly.

There are six key points to consider when observing deep sky objects or any objects for that matter.

A great reference for finding deep sky objects is the book Turn Left at Orion by Guy Consolmagno and Dan M. Davis.

Beginning Projects for Amateurs
An excellent and very popular project is the Messier Marathon. During the two weeks surrounding the Vernal Equinox, almost all of the 110 Messier objects can be seen. A good test for an observer is to try to find as many of these objects as one can in a single night. The only object that can't be seen is M30 in Capricornus, as it lies too close to the sun. Another project for amateurs is to go through and find as many objects as one can in the New General Catalogue.