The Glossary of Telescopes

When you enter into any new area of science, you almost always find yourself with a baffling new language of technical terms to learn before you can converse with the experts.  This is certainly true in astronomy both in terms of terms that refer to the cosmos and terms that describe the tools of the trade, the most prevalent being the telescope.  So to get us off of first base, let’s define some of the key terms that pertain to telescopes to help you be able to talk to them more intelligently. 

The first area of specialization in telescopes has to do with the types of telescopes people use.  The three designs of telescopes that most people use are the Refractor, the Reflector and the Schmidt Cassegrain telescope. 

*    The refractor telescope uses a convex lens to focus the light on the eyepiece. 

*    The reflector telescope has a concave lens which means it bends in.  It uses mirrors to focus the image that you eventually see. 

*    The Schmidt Cassegrain telescope uses an involved system of mirrors to capture the image you want to see.

*    A binocular telescope uses a set of telescopes mounted and synchronized so your view of the sky is 3-D.

Beyond the basic types, other terms refer to parts of the telescope or to the science behind how telescopes work.

*    Collimation is a term for how well tuned the telescope is to give you a good clear image of what you are looking at.  You want your telescope to have good collimation so you are not getting a false image of the celestial body.

*    Aperture is a fancy word for how big the lens of your telescope is.  But it’s an important word because the aperture of the lens is the key to how powerful your telescope is.  Magnification has nothing to do with it, its all in the aperture.

*    Focuser is the housing that keeps the eyepiece of the telescope, or what you will look through, in place.  The focuser has to be stable and in good repair for you to have an image you can rely on.

*    Mount and Wedge.  Both of these terms refer to the tripod your telescope sits on.  The mount is the actual tripod and the wedge is the device that lets you attach the telescope to the mount.  The mount and the wedge are there to assist you with a superior viewing session and to keep your expensive telescope safe from a fall.

*    An Altazimuth Mount refers to the tripod of the telescope that holds the device in place and makes it useful during a star gazing session.  The altazimuth mouth allows the telescope to move both horizontally (which is the azimuth) and vertically.  In this way you have full range to look at things close to the horizon or directly overhead.

*    Coma has a different meaning than the one we are used to, and that’s a good thing.  The coma is the blurry area on the outer rims of your view through the telescope.  How big the coma is and to what extent it interferes with your viewing will have is important to the effectiveness of your telesscope.

*    Planisphere.  A fancy word for a star chart.  It is nothing less or more than a detailed map of where everything is in the cosmos and how to find the star you wish to study by keying off of known stars.

*    Barlow.  This refers to a specialized type of lens that you can buy to enhance the magnification of your telescope. 

These are just a few of the basic concepts of telescope operation.  We deliberately picked the ones you have to know to discuss telescopes intelligently.  But your education into the more complex aspects of astronomy and telescope design and operation will go on for as long as you are a lover of astronomy, which we hope is for the rest of your life.

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Space

While it was just a TV show, that little speech at the beginning of the original Star Trek show really did do a good job of capturing our feelings about space.  It is those feelings that drive our love of astronomy and our desire to learn more and more about it. 

The thing that is most exciting about studying the universe is also the most frustrating and that is that no matter how expert we get, we are always just getting started.  But if it’s any consolation, some of the most advanced minds in science and from history always felt that way about space.  Even the greats such as Copernicus and Einstein looked up into space and felt like they were just a spec in the presence of such infinity.

Of course space is not infinite.  It has to be finite which means somehow there must be an end to it.  But if there is, nobody on this tiny planet has figured out where it is.  The only thing that has brought us to “the end of the universe” is our limited ability to see any deeper into space. 

But conquering the final frontier of space means more than just seeing more stars and planets and building the biggest telescope we can.  There are some mind blowing concepts about how space works that we have ahead of us to conquer.  The big bang and the expanding universe alone was enough to set your mind to spinning.  But then we have the coming of Einstein and the theory of relativity to set the entire idea on its ear.  All of a sudden space is not just three dimensions but the dimension of time becomes exportable and the twisting and maybe even travel through time seems almost possible.

The frontier of space is as much a journey of the mind as it is of distance.  When Steven Hawking showed us the mysteries of black holes, all of a sudden, time and space could collapse and be twisted and changed in those intergalactic pressure cookers.  If not for the wonders of radio astronomy, these ideas would remain just ideas but slowly science is catching up with theory.

But the brilliance of mathematicians and genius minds like Hawking and Einstein continue to stretch our concepts of space.  Now we have the string theory that could revolutionize everything we know about space, time and how the universe relates to itself.  We can’t just say, no, we have discovered enough.  It’s the final frontier.  The Starship Enterprise would not stop exploring so neither can we.  Because there is a hurdle still ahead that has a name but no real answer to it yet.  It’s called the Unified Field Theory and those that know tell us that when the Einsteins and Hawkings of our day crack that theory, every other theory will fall into place.

These exciting concepts seem some tools to put the enormity of space in context.  That may also be the value of science fiction.  Not only are science fiction writers often the visionaries of what comes to be in the future but they give us the idea that space is knowable, that despite how big it is and how small we are, we can conquer this frontier like we have conquered others before us.

For mankind, that is often enough.  If we can get the vision that we can conquer something, even if it is something so massive, so impossibly huge, it seems that we are capable of anything.  And the love of astronomy, maybe unlike any other force on earth, has brought together mankind toward that common goal of conquering the universe.  The quest to establish an international space station and to cooperate on spreading our reach off of this planet seems to find commonality between nations that otherwise cannot get along on the surface of the earth.

That alone may be a reason that we must continue to support astronomy locally and the space program nationally.  It is something that seems to bring peace rather than war and make us a better people.  But more than that it is as though this is what we were created to do.  To reach out to the stars may be our destiny.  If so then our love of astronomy is more than a hobby, it’s a calling.

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Pictures in the Sky

One of the earliest activities we engaged in when we first got into astronomy is the same one we like to show our children just as soon as their excitement about the night sky begins to surface.  That is the fun of finding constellations.  But finding constellations and using them to navigate the sky is a discipline that goes back virtually to the dawn of man.  In fact, we have cave pictures to show that the more primitive of human societies could “see pictures” in the sky and ascribe to them significance.

Constellations also have been important in culture and navigation long before we had sophisticated systems of navigation.  Early explorers, particularly by sea, relied exclusively on the night sky to help them find their way to their destination.  In fact, when “Columbus sailed the ocean blue in 1492” and “discovered” America, he could not have done it without astronomy and the help of navigation of the cosmos, much of which is made possible because of the important constellations. 

When learning to find the great constellations in the sky, we use the “find one, you found them all” system.  That is because the easiest constellation to find will guide us to the rest of them.  That constellation is The Big Dipper.  Look to the northern sky on a clear night and widen your field of vision from just focusing on one star and it will pretty much jump out at you.  In will look like a big kitchen pot or ladle, right side up in the fall, upside down in the spring.

When you have the big dipper under control, you can pretty easily find the North Star.  This is the star that those ancient sailors depended on the most to find their way to land.  Start with the far edge of the bowl of the Big Dipper, the side that is opposite the handle.  There are two stars that make up that side of the bowl.  So start at the bottom of the pot and mentally draw a line to the top star of the bowl.  These two stars are “pointing” to the North Star.  Just keep following that line, curving a bit with the sky and the bright star that you come to is the North Star.  You can impress your friends or family if you know the scientific name for this star is Polaris.

The North Star can then take you to The Little Dipper.  The key here is that Polaris is the tip of the handle of The Little Dipper and the bowl hangs down from the handle like it was hanging up in the kitchen.  Be patient with this one as the stars that make up The Little Dipper are dimmer than The Big Dipper.  But it pretty cool once you find it.

These are the obvious starting places but from The Little Dipper you can find the constellation known as “The Swan” or Cygnus.  Just use the same system you used to find The North Star but continue drawing that line that started in those pointer stars in the bowl of The Big Dipper.  Go about half as far as you went to find Polaris and you are there.  You will see a trapezoid of stars about as big as The Big Dipper.  This trapezoid forms the tail of The Swan.

That line that we are drawing from the pointer stars is our roadmap to another well known constellation which is Cassiopeia.  If you use that line and imagine you are directly under the two pointer stars, you will se a big “W” just off to the left of the line.  This is the constellation Cassiopeia, the wife of the king of Egypt, Cepheus, in Greek mythology.  There are so many more wonderful constellations to find and a good star map can continue your quest.

Like Cassiopeia, all of the constellations have wonderful stories and myths related to Greek culture.  It is just as fun to find the star clusters themselves as it is to enjoy the rich culture related to that constellation.  For all of the signs of the zodiac, for example, there is a related constellation in the sky.  So whether you are serious about astrology or not, its fun to find the constellation that relates to your “sign” (or that of your children) and be able to see how the ancients related to these pictures in the sky.

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Moon Fever

Of all of the celestial bodies that capture our attention and fascination as astronomers, none has a greater influence on life on planet Earth than it’s own satellite, the moon.  When you think about it, we regard the moon with such powerful significance that unlike the moons of other planets which we give names, we only refer to our one and only orbiting orb as THE moon.  It is not a moon.  To us, it is the one and only moon.

The moon works its way into our way of thinking, our feelings about romance, our poetry and literature and even how we feel about our day in day out lives in many cases.  It is not only primitive societies that ascribe mood swings, changes in social conduct and changes in weather to the moon.  Even today, a full moon can have a powerful effect on these forces which we acknowledge even if we cannot explain them scientifically.

The most obvious physical phenomenon that is directly affected by the gravity of the moon are the tides of the ocean.  The tides are an integral part of how maritime life is regulated and the comings and goings of the fishing world in coastal communities.  But not very many people know that at certain times of the year when the orbits of the earth bring the sun and moon into right alignment, there can even be tidal effect on inland bodies of water and even on the solid earth.  Eons ago, when the moon’s orbit was closer to the Earth, it was the effect of the moon that caused massive changes in the topography of the land and on continental drift as well.  This reflects the powerful effect the moon has had on both human history and on global geographical history as well.

You may sometimes wonder where the moon came from.  Was it a planet that traveled too close to Earth and was captured in our orbit?  Actually, the prevailing theory of modern science is that the moon was the result of a large scale collision with the still developing Earth early in its development which caused this large “chuck” to spin off into an orbiting body.  This explains the similarity in composition as has been confirmed by many of the moon exploratory space missions that were conducted by NASA.

But this background also highlights another important influence the moon has had on Earth’s development that is seldom recognized and that is the stabilization of Earth’s orbital pattern.  Most know that Earth is not round but more of an egg shaped orb.  To be blunt, the Earth would wobble.  Without the moon’s stabilizing influence, this shape would shift dramatically so the tilt of the axis, that is the polar caps would shift dramatically with each seasonal rotation producing climacteric, changes much more violent and drastic than we are used to.  It is possible that life as we know it could not have developed here had the moon not been there to “keep the Earth in line” and continue to stabilize the orbital position of the Earth so our climate could remain stable and mild.

A third significant influence of the moon comes from that origin as coming from a collision which “ripped” the body of the moon from the developing core of the Earth.  Because of this disruption in how the core of our planet developed, the metals that are usually intact in the core of the planet are actually scattered up and down the geography of the earth in diverse ways.  Usually the metals of the planet are all concentrated deep in the core.  But because of the collision which took the moon out to orbit, metals that have been crucial to the development of our industrial and technological cultures are readily available and easy for use to mine.  This again, is something we can thank the presence of that lovely moon in the sky for.

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Comets

The one thing we love the most in the world of astronomy is a good mystery.  And if there was ever a mysterious and yet very powerful force of nature that we witness in the night skies, it is the coming of the mighty comet.

The arrival of a comet within view of Earth is an event of international importance.  Witness the huge media attention that the Haley or Hale-Bopp have had when they have come within view The sight of these amazing space objects is simultaneously frightening and awe inspiring. 

Above all, it is during these comet viewings that the astronomer comes out in all of us.  But what is a comet?  Where did it come from?  And how does it get that magnificent tail?

We should never confuse comets with asteroids.  Asteroids are small space rocks that come from an asteroid belt between Mars and Jupiter.  While still quite stunning to see, they pale in comparison to the arrival of a comet.  Asteroids also have received considerable study by the scientific community. 

Not as much is known about comets.  As a rule, comets are considerably larger than asteroids.  The composition of a comet is a mixture of nebulous, gasses, ice, dust and space debris.  One scientist called the composition of a comet as similar to a “dirty snowball” because the composition is so diverse and changeable.  The center or nucleus of a comet is usually quiet solid but the “snowball” materials often create a “cloud” around that nucleus that can become quite large and that extends at great lengths behind the comet as it moves through space.  That trailing plume is what makes up the comet’s magnificent tail that makes it so exciting to watch when a comet comes within view of Earth.

The origins of comets is similarly mysterious.  There are a number of theories about where they come from but it is clear that they originate from outside our solar system, somewhere in deep space.  Some have speculated they are fragments left over from the organization of planets that get loose from whatever gravitational pull and are sent flying across space to eventually get caught up in the gravity of our sun bringing them into our solar system. 

Another theory is that they come from a gaseous cloud called the Oort cloud which is cooling out there after the organization of the sun.  As this space debris cools, it gets organized into one body which then gathers sufficient mass to be attracted into the gravity of our solar system turning into a fast moving comet plummeting toward our sun.  However, because of the strong gravitational orbits of the many planets in our solar system, the comet does not always immediately collide with the sun and often takes on an orbit of its own. 

The life expectancy of comets varies widely.  Scientists refer to a comet that is expected to burn out or impact the sun within two hundred years as a short period comet whereas a long period comet has a life expectancy of over two hundred years.  That may seem long to us as earth dwellers but in terms of stars and planets, this is a very short life as a space object indeed. 

Scientists across the globe have put together some pretty impressive probes to learn more about comets to aid our understanding of these visitors from beyond.  In 1985, for example, the United States put a probe into the path of the comet Giacobini-Zinner which passed through the comets tail gathering tremendous scientific knowledge about comets.  Then in 1986, an international collation of scientists were able to launch a probe that was able to fly close to Haley’s comet as it passed near Earth and continue the research.

While science fiction writers and tabloid newspapers like to alarm us with the possibility of a comet impacting the earth, scientists who understand the orbits of comets and what changes their paths tell us this is unlikely.  That is good because some comets reach sizes that are as big as a planet so that impact would be devastating.  For now, we can enjoy the fun of seeing comets make their rare visits to our night sky and marvel at the spectacular shows that these visitors from beyond put on when they are visible in the cosmos.

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Bonding with the Universe.

As parents, we often worry about what our children are getting excited about.  We hope we can guide them to “bond” with healthy things like a love of learning, of family and of healthy social activities.  But we also worry they will bond with the wrong people like internet stalkers or the wrong crowd at school.  Wouldn’t it be great if we could harness that tremendous energy and desire to latch onto something and bond with it and help our children “bond” with the universe through a love of astronomy?

Kids love to get excited about what you are excited about.  So there lots of ways you can “spring” the fun of astronomy on them that will jump start them on a long and happy exploration of the hobby of astronomy.  Here are a few to get your imagination going.

*    Work it into an evening in the backyard.  If you know the night sky will be particularly exciting the night of a big family barbecue, plan to have some blankets out there.  Then as everybody else is playing Frisbee, just lay out a blanket, lay flat on your back and start staring up into the sky with a binoculars.  Like the old prank of staring at a far away spot to get people’s interest, your kids will see what you are doing and what to know what is going on.  As you let them take a peek, their curiosity will take off like a wild fire and they are hooked.

*    A surprise visit to the country.  Sometimes it is hard to see the vast display of stars from within the city.  So if you announce that you are going to show them a surprise one night and have them pile into the car, their curiosity will be going wild as you leave the city.  When you find that quiet park, field or lake side spot, all you have to do is point up and say “just look” and the magnificence of the night sky will do the rest.

*    A special Christmas gift.  You can buy your children an affordable and durable beginner’s telescope along with some easy star maps written just for kids.  Imagine when they open this exciting gift and want to know how to use it.  Don’t be surprised if you are setting up the new telescope in the snow to show them the great things they will see in the cosmos with the gift that Santa wanted them to have.  The gift of astronomy.

*    Unleash the power of a meteor shower on them.  You can keep your eye on the events that are predicted for the sky watchers in your area.  When the next big meteor shower is about to explode over your area, watch the weather for a clear night and get your kids excited about what they are about to see.  As the lights begin to go off over head and you create fun and interesting narration to this dramatic display, the children will be addicts for life for the great experiences that can be had as students of astronomy.

*    Plan a surprise event in with something you are already doing.  For example, on vacation, you can plan your route on a cross country trip to bring you within visiting distance of one of the great multimillion dollar telescopes in this country.  By contacting them ahead of time, you can be sure they are conducting a tour that coincides with your visit.  Just imagine if they can look up at a telescope that is bigger than their house and maybe look through the eyepiece as some amazing cosmic sight, it will be the hit of the vacation.

Astronomy is a great activity to introduce on a family camping trip.  As the family sits around the fire after a fun night of camping, all you have to do is just look up and go “Wow, look at that!” When those little heads look up, they will look back down changed children, children in love with the stars.

Astronomy is a healthy passion for your kids and one they can grow with their entire lives.  And there is probably no better gift you can give them than the love of the stars, of science and of nature that is all wrapped up together when your kids bond with the universe through astronomy.

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