Compiled by Gregg Prescott, M.S.
Many of us watch the night skies, but what is it we are really seeing? The following information should help to give you a better grasp of the constellations you can view at night when stargazing.
You might want to consider downloading Stellarium, which is a free program that helps you determine what the stars look like on any given night from where ever YOU are located!
Six Tips for Perfect Stargazing
Here are my six steps to start stargazing — surprisingly, the first isn’t to rush out and buy a telescope!
Step 1: Buy a Red Torch
It takes between 40 minutes and an hour for your eyes to become fully adapted to seeing in the dark, but even astronomers need a little light to read a chart or tend to equipment. Unfortunately, any exposure to bright lights will instantly ruin your eye’s acclimatization to the dark.
The solution to this problem is to use a red light that won’t affect your ability to see in the dark. It’s best to resist using a rear bicycle light as bright red lights can be just as bad as any other color. A better idea is to buy a purpose-built red torch, just for astronomers.
Step 2: Buy a Planisphere OR Download an App!
Along with a red torch, the other item most astronomers have is a planisphere. These are very versatile star charts made of plastic that show you the night sky from your location, at any time of year. Some will even show you how to locate the planets. They are cheap and can be bought from most book shops.
Alternatively, there are a vast range of products online to help out. Internet applications and computer software are great but hard to use in the field, so a better option if you have a smartphone is to download an app. For the iPhone, “Star Walk” is by far the best application in my opinion.
Step 3: Subscribe to an Astronomy Magazine
There is no better way to keep up to date with what’s going on in the world of astronomy than subscribing to an astronomy magazine. Most countries have at least one or two good ones dedicated to the subject. Inside the covers, you will find news, equipment reviews, classified adverts and even monthly sky charts.
Be warned though, the monthly sky charts will be specific to the country of origin of the magazine. For the beginner, “Astronomy” is great in the US, and “Astronomy Now” in the UK. For more experienced astronomers, “Sky and Telescope” has more in-depth detail.
Step 4: Join Your Local Astronomical Club or Society
Whether you intend to stick with casual stargazing or want to get more involved, a great and very enjoyable way to enhance your new hobby is to seek out your local astronomical society.
These are excellent places to go for advice and help, and eventually you’ll find that observing with your new-found friends makes your observing sessions much more enjoyable. You will more than likely have the opportunity to try different types of telescopes so you can make an informed decision before you buy your own.
Step 5: Get Outside and Start Observing
Now it’s time for the most exciting bit: Get outside and start learning your way around the night sky. You will be amazed what you can see; those bright stars that aren’t on your planisphere are probably planets and on your first night under the stars you may have already spotted satellites, meteorites and the occasional passing aircraft. Time spent now familiarizing yourself with the sky will make your future enjoyment of the Universe much easier.
Step 6: Consider Future Equipment Purchases
Eventually you will want to see more and the only solution is to make that all-important purchase and buy yourself a pair of binoculars or even a telescope. The only words of advice here are to take your time and make sure you spend wisely. Time spent now learning your way around the sky and seeing what equipment is available, and hopefully trying it out at your local society, will be very well spent.
Stargazing – A Graphic Guide to the Heaven – How the Sky Works
The following videos are from a fantastic three part series on star gazing, despite the condescending remark of the Maya in the 1st video at the 17:55 marker:
“The Mayans had no clue about anything at all…they were useless.”
I beg to differ. While nothing “specific” happened on December 21, 2012, the Maya were not “useless” as they introduced new techniques and teachings in astronomy, medicine, agriculture and mathematics.
Sirius Stargazing: The Pleiades (M45)
In this episode, we look at the Pleiades Open Cluster in Taurus, one of the closest clusters and certainly the clearest in the night sky.
The Ancient Maya: Tools of Astronomy
Star-gazing reached incredible heights thousands of years before the Hubble. Learn the amazing advances made by the great ancient culture of Central America.
Take another fascinating trip through time to discover the precursors from centuries or even millennia ago of today’s cutting-edge technological breakthroughs. Using the latest scholarship, hands-on demonstrations, and dramatic reenactments, WHERE DID IT COME FROM? shows just how far ahead of their times they really were.
Without the aid of magnifying technology or even a firm idea of where they stood on the planet, the Mayan grasp of the universe through astrological observation was simply stunning.
Host Michael Guillen travels to Mexico’s Yucatan peninsula to get a firsthand look at the ancient world’s most skilled astronomers. Climb the giant pyramid of Kukulkan and see how it functioned as a giant solar observatory. Examine El Caracol at Tikal, which looks amazingly like a modern day observatory. Learn how the Maya used the sun to lay out their various temples and observatories and examine their incredibly complex and accurate calendar.
Orion’s Belt, Orion Nebula and Betelgeuse
Why Do Stars Move Across The Sky?
The Universe season 2 episode 10 – Constellations Full Length
Constellation Taurus, Pleiades and Aldebaran
How to Pick the Best Binoculars For Astronomy
by Jim Oneil
Astronomy is a hobby that a lot of people are engaged in because it is basically good, clean fun. Looking up and watching the stars is not fun though if you do not have the proper equipment that helps you to get the most of the star-gazing experience. The thing is that there is an awful lot of astronomy equipment out in the market. This makes choosing the right one a tad tricky.
So how do you choose which equipment would be the best for you? Well, the first thing that you have to do is figure out what kind of equipment you want and need. High-powered telescopes are great for a high definition viewing experience, however, if portability is more your thing, then binoculars is the best options for you. Binoculars make it possible for you to be able to engage in your hobby anytime and anywhere you want. There are a lot of types of binoculars that are available to the star-gazing enthusiast. You have your basic binoculars, camera binoculars, stabilized binoculars and the appropriately named astronomy binoculars.
The next thing you should do is to determine how much portability you want with your telescope. You can to have a bulkier model or a smaller, sleeker one. The thing is that the latter is less powerful, although they are much easier to store. You should also figure out the design of your binoculars, among the many that are offered out in the market. For optimum star viewing, the best choice would be the porro prism design.
Choosing the best lens size is the next thing to do. It is essential to have the best possible magnifying power and the best exit pupil for your binoculars. For the uninitiated, the exit pupil is the amount of light that your eye can accept. It is a given though that you will get a more stereoscopic view of the sky if you choose the larger lens sizes. They cause you to have brighter images with better resolutions. You have to remember that the larger the lens size, the bigger and bulkier the binoculars will be. So you have to decide if you want to sacrifice lens size to the binoculars’ actual size.
You also have to consider the stabilized binoculars vibrations will actually not affect the magnification of the lenses. You also need to choose a binocular that can be used with or without a tripod, since there might be times that you simply want to sit back, relax and not want to hold anything while you watch the sky.
Choosing a Telescope for Astronomy
Given the bewildering array of telescopes on the market, how does an enthusiastic but inexperienced consumer choose the right one? To answer this question we will explain the differences between specific telescope types, but for that discussion to be meaningful it is important first to understand some very basic points about astronomical telescopes in general.
Aperture is the Most Important Factor
The single most important specification for any astronomical telescope is its aperture-. This term refers to the diameter of the telescope’s main optical element, be it a lens or a mirror. A telescope’s aperture relates directly to the two vital aspects of the scope’s performance: its light-gathering power (which determines how bright objects viewed in the scope will appear), and its maximum resolving power (how much fine detail it can reveal). There are other criteria to be considered in selecting a telescope, but if you learn only one thing from this article, let it be this: the larger a telescope’s aperture (i.e., the fatter it is), the more you will see.
Don’t Get Hung Up on Power
Unfortunately, the first question most beginners ask is not “What is this telescope’s aperture?” but “What is its magnifying power?” The truth is, any telescope can be made to provide almost any magnification, depending on what eyepiece is used. The factor that limits the highest power that can be used effectively on a given scope is, you may have guessed, its aperture. As magnification is increased, and the image in the scope grows larger, the light gathered by the telescope is spread over a larger area, so the image is dimmed. There is also an absolute limit, determined by the physical properties of light, to the resolution that is possible with any given aperture. As the magnification is pushed beyond that limit the image fails to reveal any additional detail and gradually breaks down into a dim, fuzzy blob.
The maximum useful magnification for any telescope is about 50 times the aperture in inches, or two times the aperture in millimeters. This equates to about 100x to 120x with the smallest telescopes, which is enough to see such wonders as the rings of Saturn and cloud bands on Jupiter. The 2x per millimeter figure is a rule of thumb, and can vary up or down somewhat depending on the optical quality of the scope in question and the vision of the individual observer. Experienced observers usually use much less power; 0.5x to 1x per millimeter is more appropriate for most objects. Any manufacturer claiming that their 60mm telescope can provide good views at 450x (7.5 times the aperture in millimeters) is trying either to pull your leg or pick your pocket!
Bigger is Better, But…
While aperture is the most important specification of any telescope, there are exceptions to the rule that “bigger is better.” One is obvious: the need for portability. The largest amateur telescopes are very big indeed, and demand either housing in a permanent observatory or possession of a strong back, a truck, and a gang of muscular and motivated observing buddies! There is a line to be drawn between performance and portability, and where it will be drawn varies with the individual and his or her capacity for storage and portage. Beginners are encouraged to start out with a scope of sufficient aperture to feed their interest, but of a size that they can manage easily. Avoid succumbing to “aperture fever.” Those infected with this psychological malady choose the largest telescope they can afford without regard to portability. Their monster scopes soon gather dust in the garage, exiled for the crime of being too heavy and bulky, while the once enthusiastic would-be stargazers wind up frustrated or in traction.
The Sky IS the Limit
The second limitation on very large telescopes is less obvious, but becomes apparent after the first couple of viewing sessions: the Earth’s atmosphere limits how much we can see. Stars and planets viewed through a telescope appear to shimmer or wiggle, as their light passes through the air and is distorted. This effect is known to astronomers as seeing, and becomes more noticeable and bothersome as telescope aperture increases. It especially affects observations of the Moon and planets, where high power applied to reveal fine details also magnifies the air turbulence.
The amount of distortion due to seeing varies, depending upon the behavior of air currents in the upper atmosphere, and to a lesser extent upon the altitude and topography of the observing site. But on an average night, at an average site, air turbulence will limit useful magnification to 250x or 300x telescope, and prevent telescopes larger than about 8″ or 10″ aperture from achieving their full potential for high-powered viewing. Telescopes larger than 10″ are most often chosen by observers who want to gather as much light as possible for viewing dim galaxies, nebulas, and star clusters. These “deep sky” objects, affectionately called “faint fuzzies,” are most often viewed at much lower power than the planets, so seeing is less of a problem.
The last important topic to cover before delving into optical designs is that of mounts. Telescopes are offered on either altitude-azimuth (or altaz) mounts, which move up-down (altitude), left-right (azimuth), or equatorial mounts, which are tilted to align with the rotational (polar) axis of the Earth.
Altaz mounts are generally lighter and simpler to use, and are preferred if the telescope is to be used both for astronomy and daytime observing (or for daytime observing only). The better ones offer slow-motion controls to aid in moving the scope by small increments, and are useful for powers up to about 150x. The Dobsonian mount is a variation on the altaz mount. It employs unconventional (for telescopes) materials like plywood and Teflon in a compact mounting that moves easily, is extremely stable, and can adequately support large telescopes at a very low cost. Though there are no mechanical slow-motions or electric drives on a Dobsonian, a well-made example glides so smoothly on the Teflon bearings that with a little practice it is quite easy to track objects manually at 200x or more!
Equatorial mounts telescope are designed specially for astronomy, and are not recommended for terrestrial viewing. Their advantage is that they allow easier tracking of the stars across the sky. This motion can be achieved with either a single manual slow-motion control or an electric motor drive (or clock drive). The easier viewing they provide at high power makes equatorials preferred by observers who are most interested in the Moon and planets. Also, you’ll need an equatorial mount if you want to do astrophotography.
Different Scopes for Different Folks
Now that we understand these basic points of telescope performance and mounting, we can discuss the three basic optical designs of telescopes: the refractor, the reflector, and the compound (or catadioptric) telescope.
Refractor: A refractor is what most nonastronomers think of when they hear the word “telescope.” Its tube is most often long and skinny, mounted on a tripod, with a lens at one end and the eyepiece at the other. Refractors were the first type of telescope invented, and the finest refractors still provide the best images of any design for a given aperture. They are often chosen by observers with a dominant interest in the planets and Moon, because they can provide sharp, high-contrast views at high magnification and are less bothered by atmospheric “seeing” than the other designs. They also require less maintenance than reflectors or compound scopes, and are therefore popular with beginners. The refractor’s good performance at high power and relative insensitivity to light pollution makes it a good choice for a city-based observer, as the design performs best on the objects that are most easily seen from urban or suburban locations.
These advantages do not come without a price — literally: refractors are the most expensive telescopes per inch of aperture. Big refractors can cost several thousand dollars, and still are considered too small in aperture for serious deep-sky observing. The long focal length of most refractors restricts the field of view, making it difficult to take in large extended objects like some clusters of stars. And the long tube, with the eyepiece located at the back end, requires a tall tripod, which, if poorly made, can allow the scope to shake and shimmy in the breeze, rendering high-powered observing difficult.
Reflector: The reflector uses a mirror, rather than a lens, to gather and focus light. By far the most common design is the Newtonian reflector, which places a concave (dish-shaped) primary mirror at the bottom end of the telescope tube. A small secondary mirror at the other end directs the focused light out the side of the tube and into the eyepiece. Newtonians offer the largest aperture available at given price, and when well made, they can provide sharp, contrasty views that rival all but the finest refractors. A Newtonian’s low center of gravity and eyepiece location at the top of the tube allow for comfortable viewing with a more compact mounting, which can be made stable with much less bulk and cost than the tall mounting required by a refractor of similar aperture.
Big reflectors of 10″ aperture and larger on Dobsonian mountings are the most popular telescopes for astronomers who seek to gather “buckets of light” for deep-sky observing. These giant scopes perform best at remote dark sky sites, away from the glare of city lights. The value and versatility of the smaller 4.5″ to 8″ Newtonians, mounted either equatorially or as Dobsonians, makes them a fine choice for the beginner with general interests.
Newtonian reflectors require occasional maintenance. Unlike the lenses in a refractor, the mirrors in a reflector need periodic alignment, or collimation, for best performance. While many beginners seem intimidated by collimation, it’s really not difficult, and takes only a few minutes once you get the hang of it. A reflector’s tube is also more open to air and humidity than that of a refractor, and if left uncovered the mirrors can accumulate dust and grime, which necessitates occasional cleaning. While these maintenance concerns are often overstated, a Newtonian may not be the right choice for someone who finds the prospect of occasional tinkering with the telescope unappealing.
Catadioptric Telescope: The most modern of the three common designs for amateur telescopes is the compound, or catadioptric type, which uses a combination of lenses and mirrors to gather and focus light. The greatest advantage of this design is its compactness: the lenses and mirrors “fold up” the light path inside the telescope, reducing large-aperture scopes to a manageable size. If an equatorial mounting is desired, the smaller tube can be carried on lighter and more economical mounts than that required by a Newtonian of the same size. Compound telescopes are most popular with observers who desire both generous aperture and an equatorial mounting in a transportable package.
The names Schmidt-Cassegrain and Maksutov-Cassegrain refer to specific designs of compound telescopes, which use differently shaped lenses and mirrors to achieve a similar result. The Maksutov is often cited as offering better image quality, though there is little in the way of optical theory to support this opinion. Most probably the Maksutov has developed its reputation as the superior catadioptric design because its spherical optical surfaces are easier to make to very high precision than the more complex shapes demanded by the Schmidt. As a result, if a telescope maker practices anything less than the strictest quality control, their “average” Maksutov will outperform their “average” Schmidt. In top-quality telescopes from careful manufacturers, both designs can yield excellent images.
There are a few drawbacks to all compound designs. As in any telescope that employs mirrors, occasional alignment is required for peak performance. The cost of a compound is higher than that of a Newtonian of the same aperture, though still lower than the cost of a comparably sized refractor. Most significantly for the planetary observer, the secondary mirror in a compound is much larger than that in a Newtonian, and its presence in the light path of the scope reduces contrast somewhat for high-powered viewing. In general, astronomers who desire a highly capable, easily transportable telescope find these worthwhile compromises, and have made the compound scopes very popular.
Price is a Consideration
Budget is a factor in almost every telescope purchase decision, but there are at least three major price-related pitfalls to be avoided.
1) Don’t buy a flimsy, el cheapo scope at the mall with the intention of getting a taste of the sky and upgrading later. Many of those scopes are so poor-quality and frustrating that they can turn budding stargazers off of astronomy for good!
2) On the other hand, don’t give up on astronomy if the scope of your dreams is financially out of reach at this moment. There are many reasonably priced, high-quality beginner’s scopes that can reveal incredible wonders, while helping a novice define his or her particular observing interest.
3) Finally, if you are one of the fortunate few for whom price represents little obstacle, think twice before buying the biggest, most expensive telescope in stock. Many of the large, fully featured scopes favored by experienced observers are also the most complicated, and are too much to grasp for someone still trying to find the Big Dipper!
What About Astrophotography?
Before concluding, here’s a quick word for the beginner who wants to jump right into astrophotography through their new telescope: Don’t! At least, not until you have taken some time to learn the sky and become familiar with operating your scope. Photography of the heavens can be a wonderfully rewarding pastime, but is a combination of art and science with a steep learning curve that can discourage beginners who try to take on too much at once. Of course, if astrophotography is a primary interest there is nothing wrong with selecting a first scope based on its easy adaptability to camera work in the future. While most telescopes can be used for picture-taking (with varying prospects for success), the most important qualifications for a photographic instrument are a rock-solid equatorial mounting, and ease of attaching a camera so that it can be focused. For a variety of technical and economic reasons, compound telescopes of 8″ aperture and larger are most popular for photography. They also make fine instruments for general observing.
The Bottom Line
Which, then, is the right telescope? That’s a decision that must be made individually, but the three best pieces of advice are:
- The best telescope for you is the one you will use most often. A huge, optically wonderful scope will bring no joy if it is consigned to the closet!
- All else being equal, a larger-aperture (diameter) telescope will reveal more in the night sky than a smaller one (“I know, already!” you may be thinking.)
- Buy from a company that’s knowledgeable about telescopes and astronomy, and who will support you even after your purchase (since you will likely have questions).
Our advice is to select a well-made telescope, of a design matched as well as possible to your primary observing interest and most frequent observing site. Make sure it’s a size that can be handled easily (by your standards and no one else’s) and used often, and you will enjoy a lifetime of awe and wonder under the stars!