general interest, hobbies

A -Z Guide To Backyard Astronomy

Are you fascinated by stars, comets, planets, and other celestial bodies you can glimpse in the night sky? Many aspiring astronomers start out at home, in their own backyard. It is possible to observe quite a lot about our solar system using basic telescopes or even the naked eye, but there are also many tools that can help you identify what you’re seeing and learn more about what’s out there.

Identifying Constellations

constellations-and-names-and-asterismsSince the beginning, mankind has looked at the distant stars trying to make sense of their patterns. It is human nature to “connect the dots” in a meaningful fashion. Throughout history, all cultures and civilizations have associated constellations with myth and legend.

The word constellation is the name of a starry group forming a recognized pattern. Twelve are located along the ecliptic plane—the “signs” of the zodiac: Aquarius, Aries, Cancer, Capricorn, Gemini, Leo, Libra, Pisces, Sagittarius, Scorpius, Taurus and Virgo. The celestial sphere contains 88 constellations.

What constellations can be seen in the Spring?

We’ve learned the movements of the sky and the celestial dome. If we watched all night the constellations would change from one season to the next during its course. Let’s begin identifying constellations seen between 9:00 and 10:00 p.m. in mid-March—the time of vernal equinox.

In the northern hemisphere, face north and identify the “Big Dipper”—Ursa Major. You’ll find it upside down and just west of Polaris.

Northwest is pentagon-shaped Auriga. On the northeast horizon—the bright orange star Arcturus signifies Bootes. Overhead on the ecliptic plane you will see the bright stars—Castor and Pollux—the heads of the stick figures of Gemini. West is red Aldeberan—alpha in V-shaped Taurus. East is white Regulus and the backwards “question-mark” of Leo. South is the brightest star in the northern sky—Sirius—alpha Canis Major.

Southwest is hourglass-shaped Orion and its three bright “belt” stars. East of Sirius is a handful of bright stars—Puppis. Low southeast is box-shaped Corvus.

In the southern hemisphere, Taurus will appear northwest, with Gemini low north and Leo northeast. Orion is west, while Canis Major is overhead. Brilliant star Canopus in Carina is almost due south while the brilliant stars of the Milky Way in Vela lead southeast to the “Southern Cross”—Crux.

SPRING CONSTELLATIONS

    • Antlia
    • Cancer
    • Canes Venatici
    • Canis Minor
    • Carina
    • Centaurus
    • Chamaeleon
    • Coma Berenices
    • Corvus
    • Crater
    • Crux
    • Hydra
    • Leo
    • Leo Minor
    • Lynx
    • Musca
    • Puppis
    • Pyxis
    • Sextans
    • Ursa Major
    • Vela
    • Virgo
    • Volans

What constellations can be seen in the Summer?

During Summer Solstice the hours of daylight are longer for the northern hemisphere and shorter for the southern. The night skies have changed dramatically—the stars of Spring are setting and those of Fall will rise soon. Let’s look beginning around mid-June at 10:00 p.m.

In the northern hemisphere, faint box-shaped Ursa Minor stands directly above Polaris and Ursa Major northwest. Northeast is brilliant Vega—alpha in the faint parallelogram of Lyra. Overhead, orange Arcturus and faint kite-shaped Bootes command the zenith. West, the mighty Leo is diving towards the horizon head-first, and keystone-shaped Hercules has well risen east.

Look for bright Spica on the ecliptic to guide you to Virgo. Exiting southwest is box-shaped Corvus. High southeast, bright red Antares and the long “J” of Scorpius begin to climb, followed by “teapot-shaped” Sagittarius rising southeast. Between Spica and Antares is faint triangle-shaped Libra.

In the southern hemisphere, Arcturus and Bootes are north with Leo setting northwest. Hercules is northeast with Aquila rising east. Overhead Virgo dances. Crux is southwest and Centaurus commands center stage. Scorpius moves higher south and the starry river of the Milky Way is pouring out of Sagittarius.

For both hemispheres, this is an exciting time as our galactic center now begins coming into view and the Milky Way (our own galactic arm) rises higher.

SUMMER CONSTELLATIONS

    • Apus
    • Boötes
    • Ara
    • Circinus
    • Corona Australis
    • Corona Borealis
    • Draco
    • Hercules
    • Lepus
    • Libra
    • Lupus

What constellations can be seen in the Fall?

Now our view of the celestial globe has changed to the Autumnal Equinox. The stars of Summer are setting and within hours the stars of Winter will rise. Let’s look between 9:00—10:00 p.m. starting around mid-September.

In the northern hemisphere Ursa Major is on the northern horizon. Northwest, Bootes is setting while W-shaped Cassiopeia and Perseus are rising. Overhead huge, cross-shaped Cygnus commands attention flying along the Milky Way. To its west, Lyra and brilliant Vega are above the setting Hercules.

East, the large diamond-shaped “Great Square” of Pegasus dominates. Scorpius sets southwest, while teapot-shaped Sagittarius tips—spilling the “steam” of the Milky Way from its spout. High south, small cross-shaped Aquila stands with bright Altair marking its place. Southeast, smile-shaped Capricornusand the faint stars of Aquarius are rising.

In the southern hemisphere, Cygnus marks the north, flanked by Lyra and Hercules northwest and Pegasusnortheast. Overhead stands Capricornus, while Sagittarius and the westering Scorpius show well. On the horizon Crux has moved southwest. The triangle of Tucana is higher southeast and bright Archenar shows the way to the long snake-shape of Horologium.

FALL CONSTELLATIONS

    • Andromeda
    • Aquarius
    • Aquila
    • Capricornus
    • Cassiopeia
    • Cepheus
    • Cygnus
    • Delphinus
    • Equuleus
    • Grus
    • Indus
    • Lacerta
    • Microscopium
    • Octans
    • Pavo
    • Pegasus
    • Phoenix
    • Sculptor
    • Pisces
    • Piscis Austrinus
    • Sagitta
    • Tucana
    • Vulpecula

What constellations can be seen in the Winter?

Winter Solstice means shorter daylight hours in the northern hemisphere and the coming of summer in the southern hemisphere. Let’s check what constellations are seen between 9:00 and 10:00 p.m. beginning around mid-December.

In the northern hemisphere, Ursa Minor now dangles below Polaris. Ursa Major is northeast while Cygnus falls northwest. High north, the glittering chains of Perseus dominate and W-shaped Cassiopeia slips west. Pentagon-shaped Auriga is high northeast. Pegasus sets west, while above is V-shaped Taurus and the star cluster called “The Pleiades.” East, Castor and Pollux mark returning Gemini. Southwest, is exiting Aquarius and the small circle of Pisces.

Look southeast where magnificent Orion is rising once again!

In the southern hemisphere, Cassiopeia holds the northern horizon with Perseus placed higher—flanked by Pegasus northwest and Auriga northeast. At the zenith, variable star Mira marks faint Cetus while Aquarius sets west and Orion commands the east. South, star Archenar stands high with triangle-shaped Hydrus below. Small cross-shaped Grus flies southwest while bright Canopus lights the way to Carina. Low on the southern horizon is Crux—the “Southern Cross.”

WINTER CONSTELLATIONS

    • Aries
    • Auriga
    • Caelum
    • Camelopardalis
    • Canis Major
    • Cetus
    • Columba
    • Dorado
    • Eridanus
    • Fornax
    • Gemini
    • Horologium
    • Hydrus
    • Mensa
    • Monoceros
    • Orion
    • Perseus
    • Pictor
    • Reticulum
    • Taurus
    • Triangulum

What constellations can be seen all the time?

Remember our learning constellation and how it turned in a small circle around the pole—a circumpolar constellation. The northern circumpolar constellations revolve around Polaris—the “North Star”—but it isn’t as bright as you might think. Look for the two stars at the end of the “bowl” of the Big Dipper which point up to Polaris.

There are five northern circumpolar constellations: Ursa MajorUrsa MinorCassiopeiaCepheus and Draco. They completely circle the north celestial pole in 24 hours—but don’t forget sidereal time. They advance by 4 minutes for each “Earth Day.”

In the southern hemisphere, there’s no pole star bright enough to be a navigation aid—yet a southern pole exists!

As ancient mariners traveled further south, they used the Southern Cross to help guide them since Sigma Octantis is too dim. While Crux turns close to the southern pole, it’s like northern Ursa Minor—a small circle in the dome of the night sky. Southern circumpolar constellations are: CruxMuscaCircinusApusOctansChamaeleon, and Carina.

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Observing the Planets

An important lesson we’ve learned is the location of the ecliptic plane—the imaginary path the Sun and Moon takes across the sky. This is the same path the planets in our solar system share, making them viewable from Earth.

We can observe the planets with our eyes, binoculars, or a telescope. Remember the great “race track” of the ecliptic plane means sometimes the inner planets may hide in front of—or behind—the Sun. The same is true of watching the outer planets. There’s times when Earth is behind the Sun and we cannot see them, or they may be located in a place along the ecliptic plane during daylight hours.

The planets are viewable during many different times of the year. There are many on-line resources that can tell you when and where they will appear, as well as many periodicals which chart the planets’ paths.

Can I observe the Planets with just my eyes?

Yes! It is very easy, even from light polluted areas, to follow these planets: Mercury, Venus, Mars, Jupiter and Saturn. They shine brightly enough to follow their movements without any special equipment.

The outer planets are dimmer because they are much further away. With a pair of binoculars as help, it’s also easy to see Uranus and Neptune—but they aren’t very big or very bright. Pluto is so small and distant that it takes at least a medium-sized telescope and careful work with a star chart to identify.

Once you have gained confidence in the position of the ecliptic, it will not be hard to watch the movements of the bright planets from night to night. They are easy to recognize and it won’t be long before you’ll be identifying them—not by luck—but as an amateur astronomer!

Where do I look for the Planets?

The two inner planets—Mercury and Venus—are closer to the Sun than Earth. We will always see them just after the Sun sets, or just before the Sun rises. The ring of their orbit is much smaller than Earth’s, so they will only appear a short distance above the horizon—setting shortly after the Sun, or rising just before. Mercury is sometimes bright enough to be spotted easily, but it helps to use binoculars. Venus outshines every star in the sky!

As we move outward on the ecliptic, we find Mars. Since its orbit around the Sun is slightly longer than ours, there will be long periods of time when Mars is easily visible. Do you remember retrograde motion? When the Earth catches up with Mars it will appear to slow down on its path across the sky as we approach it, stand still as we come alongside, and move the other way as we pass it. Retrograde motion also happens with the outer planets, but the process is much slower. The planets all follow the same rule—the ecliptic plane.

When should I look for the Planets?

Mercury

Mercury is usually in the evening sky three times a year, and three times in the morning. The best time to see Mercury is just after sunset near the vernal equinox. Since it orbits the Sun in just 88 days, it moves fast! If you are able to see Mercury through a telescope, you can watch as it enters a slim crescent phase as it passes between us and the Sun—just like our Moon!

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Venus

Another planet that goes through phases is inner Venus. Orbiting the Sun every 244 days, we see Venus for months at a time instead of just days. It will appear in the evening for about six weeks as it comes out from behind the Sun, growing higher and brighter each night until it reaches a point between the Earth and Sun…and becoming a crescent in the telescope! A week or two later it will appear just before the Sun rises. It stays there for about 9 months until it once again returns to the evening.

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Mars

Mars’ viewing year begins when it first makes its appearance in the morning on the opposite side of our solar system. There it stays until we begin to catch up with it and it rises earlier each day. As the cycle continues, it’s not long until Mars reaches opposition, meaning it (or any outer planet) rises as the Sun sets. As we pass, it becomes brighter and larger.

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Jupiter

Next up is Jupiter—orbiting the Sun once every twelve years. Jupiter is visible most of the year, beginning in the morning until sidereal time carries it to the early evening hours. With a much slower orbit of 30 years, graceful old Saturn will be viewable much of the year as well—shuttling slowly along the ecliptic plane. Far away Uranus and Neptune and Pluto can viewed whenever their respective constellations are visible.

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Following the clockwork precision of the planets along the ecliptic plane and keeping track of their positions will help you understand just how our solar system moves!

Why do some planets seem to move differently?

Above all, the planets follow the rules of retrograde motionsidereal time, and their position on the ecliptic plane. The only exception is Pluto, whose orbit is slightly inclined to the ecliptic.

Keep in mind Mercury is so close to the Sun that we can only see it briefly. Both it and Venus appear before the Sun rises or after the Sun sets. Both of these planets orbital rings are smaller than Earth’s, so they will never go completely across the sky.

Unless Earth is behind the Sun from the viewpoint of the outer planets, they are always there—following sidereal time. Remember, each night the sky changes by four minutes… If an outer planet begins in the morning sky at 5:00 a.m., it will be 75 days before it rises at midnight, or 150 days before it appears at 7:00 p.m.!

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How do I distinguish a planet from a star?

Because a planet will always appear in a constellation of the zodiac, it’s important to learn their stars. Planets don’t really appear to the unaided eye like a star. The light from a star is generated by the star itself—appearing to “twinkle.” The light from a planet looks different —it’s reflected—shining steadily.

Mercury can be difficult because the sky is never really dark when it appears. It’s a dusty reddish color, no brighter than the stars around it. Nothing in the sky—except for the Sun and Moon—outshines Venus! It reflects 68% of the sunlight off its atmosphere and shines with a steady, white light.

Mars appears reddish. When far away, it’s small and dim—yet it will be one of the brightest objects in the night as we draw closer.

Jupiter is far brighter than most stars. It will call attention to itself. Saturn is slightly dimmer, glowing with a creamy, yellow light. Uranus is just barely visible unaided—like a tiny, greenish disc no bigger than a star.

Neptune is blue and in binoculars it will also look like a small, steady disc. Pluto is a very dim, stellar-sized point and can only be seen with a larger telescope.

A small telescope will show you the phases of both Mercury and Venus, while a pair of binoculars will reveal the dark equatorial bands and four Galilean moons of Jupiter.

Bigger binoculars will reveal the ring-shape of Saturn, but even beginners’ telescopes will clearly show its ring system and brighter Moons. The same small telescope will capture Mars as a small red marble when it’s far away; yet reveal dark markings and bright polar caps when it is close. No matter what size telescope or binoculars you use, Uranus and Neptune are so very distant that the best you will ever see is a small, softly colored disc.

Do you think a large telescope would make the planets easier to study? Not necessarily. Seeing details on planets is possible with a small telescope when the conditions are right. Larger aperture only improves resolving power—it can’t change bad seeing. You don’t need a giant telescope to find enough details on our solar system neighbors to keep you interested for the rest of your life!

Star Charts

star_chartsImagine yourself in a strange city with lots of streets—or lost in the countryside at a crossroads. This is a whole lot like how it feels when you begin astronomy and look up at all those stars! Relax. Just like here on Earth, all the wonderful places you can visit in the Cosmos are plotted and mapped out in diagrams called star charts. Once you become familiar with using them, they aren’t much different than using a terrestrial map to take you to a certain location.

You’ll learn constellations have borders—just like a state or country. They have lines—not unlike marked roads. Star charts even have stars numbered and lettered just like a street address. So what happens when you are looking up an unfamiliar town? Just like a road map, celestial coordinates will guide you just as surely as the letters in one row and the numbers in another on a terrestrial map. Locating an object that is at 6 hours and 45 degrees is the same as finding a town in column D, row 10. Just like learning the streets and landmarks in a new town, it won’t be long until you’re navigating the skies with ease!

What are star charts?

Star charts are portions of the celestial globe printed in a flat format. They might come in a variety of sizes and printing styles but they all have a common ground—they’re expressed in terms of Right Ascension (RA) and Declination (Dec)—just like latitude and longitude. The stars are plotted as dots—the brighter the star, the larger the dot. On almost all star charts, the primary stars of any constellation are expressed with Greek letters—alpha for the brightest and omega for the dimmest.

Another common point is the symbols used to denote types of sky objects—such as a circle with a cross through it for a globular cluster, or an oval for a galaxy.

Some charts include constellation boundaries, while others give constellation lines. Many include Bayer or Flamsteed numbers for some bright stars… And all list catalog object numbers such as M16 for Messier object 16, or NGC 7331 for New General Catalog object 7331. Don’t be scared. They are really quite easy to use once you become familiar with them and most have keys to the symbols and Greek letters printed on each page.

Where do I go to find star charts?

When you are very first beginning in astronomy, it is a wise idea to visit your public library. Check for periodicals, such as Sky and Telescope and Astronomy. These contain monthly all-sky views which will show you what constellations are visible and where. In the reference section, you will also find your library has many types of printed star charts—either in an atlas of their own, or in an observing guide. Once you have learned your constellations, you are on your way to learning to read a star chart. After you have gained some experience, you might wish to purchase your own atlas of maps, or a laminated chart to take along in the field. There are also many fantastic websites that offer small locator charts for specific objects—as well as free downloads of star chart programs. Start with the basics and you’ll learn quickly which star charts are right for you.

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How do I learn to read them?

Reading a star chart becomes easy once you learn the rules by which it is written. No matter what chart you use, look for your cardinal directions—north, south, east, and west. Star charts are presented just as if you were looking at the sky. North is up, south is down. But, the sky moves from east to west—so east is to the left and west is to the right. Star charts can also be separated into squares. Along one border is Right Ascension (RA). It will be expressed in hours.

Along the other border will be Declination (Dec)—expressed in degrees. If you know an object’s celestial coordinates, you can pinpoint its place on the map by using that combination. If you are looking at a chart for an object to visit, look for the largest dots to help you identify the constellation. Remember the primary stars—the ones you can see easily—are expressed as Greek letters. Once you find an object you would like to view, it’s almost as easy as matching the star chart to the sky.

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ASTRONOMY EQUIPMENT

Before you purchase any type of astronomical equipment, the best thing you can do for yourself is to be prepared. The hobby of astronomy can become a costly one—but even a small, well-placed investment can lead to a lifetime of learning and pleasure. Remember there are many considerations that you must take into account—such as the area you will be viewing from, what you are hoping to explore, and how much money you are willing to invest.

The only definitive answers are the ones that you will find within yourself! A salesman is just that—a salesman. Telescopes purchased from a department store, no matter what they claim, or what brand name they use, will be a disappointment. Choose your place of purchase just as carefully as you would choose a specialist in a medical field. Astronomy is a science and those best qualified to help you will be those who practice astronomy.

What is the best equipment for a beginner?

The very best piece of astronomical equipment for a beginner is one you might already own—a pair of binoculars. They are a simple, highly portable, and inexpensive set of “twin telescopes”… Yet, even the beginner might want something just a bit more. Your first telescope should be one that you can learn from and will teach you—bought from a reputable company such as Meade Instruments or Celestron. It should be of ample size to gather enough light, and have enough resolving power to help you explore—but not be so complicated as to turn an observing experience into an ordeal.

 Be wary of telescopes which have a computerized system of “GoTo” objects. They add to expense and generally provide so many complicated procedures to use as to make them unpleasant for the beginner. Your first telescope should be sturdy, uncomplicated, and quality. We will soon discuss the different designs of telescopes and what may work best for you. 

What is the best equipment for a child?

Small hands don’t mean a small mind. Children become wonderful amateur astronomers and many of them find complete delight in a pair of very rugged binoculars. For the youngest, the best are inexpensive, able to withstand inquisitive hands and the inevitable drop! Many models are coated with durable rubber on breakable edges at no additional expense.

Like binoculars, there are telescopes better suited to young hands—but they don’t come from your local department store. Many reputable companies offer durable, practical telescopes that are able to withstand learning hands and develop inquisitive minds! They range from small tabletop models that can be carried on a shoulder strap, to larger types that require nothing more than a starry night.

The very best of these for a young child is one that has no complicated mount system and durable optics to withstand abuse.

Children’s telescopes available from an astronomical dealer are very close in price to those available in a department store. The few extra dollars you might spend will mean the difference between a scope that falls apart immediately, or one your child will have for years!

If your child is older, then they are quite ready for an intermediate telescope.

You want to get them something they will use! Look for a quality name in optics, a sturdy mount, and a size in aperture that suits your budding astronomer. Many young adults will develop a lifelong passion from their beginning years with a telescope—so quality is very much an issue. Poor performance will mean a quick loss of interest, while a quality telescope will endure into adulthood.

I live in a rural area, what type of equipment should I consider?

It is very possible to practice a great deal of astronomy from a city setting. While light pollution will stop you from seeing many deep space objects—you can still very much enjoy a variety of things without ever leaving your rooftop or suburban backyard!

Because light plays a very important role in what you can see, the ideal scope for a city dweller is one that has high quality optics, yet is small in size. A giant telescope cannot improve the quality of the skies and a too-large telescope can often become a hassle when considering storage space or transporting up and down stairways.

Consider a spotting scope—which is like a very powerful single tube binocular. A small, quality refractor is also a good choice for high-light settings. If your backyard allows you to see many stars on a routine basis, then you will also have no problems with a small to medium reflector telescope as well as a small catadioptric. While binoculars are always a consideration, unless you are able to get to a dark site—they are a little less practical since their “view” is less spectacular on limited objects.

Observing with Your Eyes

The best astronomical equipment you can own is your eyes. With nothing else, you can see all kinds of wonders in our Universe…from galaxies a million light-years away to a Moon that’s only a quarter of a million miles distant. There are many wonderful things that you can observe with no special equipment: star clusters, planets, meteor showers, satellites and aurora await you!

The most important thing to remember is your eyes need time to adjust. This is called dark adaptation. If you’re in a very bright room and walk into one with no light, chances are you’ll trip over that sofa you can’t see—even when it is right in front of you. This is absolutely true of observing the stars. If you go from a brightly lit house to the dark outdoors, you’ll trip right over that star cluster you can’t see! Everyone’s eyes adjust to the dark at a different rate, so give yourself plenty of time to “see in the dark.”

What kind of astronomy can I practice with just my eyes?

As we’ve learned, we can easily follow the clockwork motions of the ecliptic and the celestial sphere. Before you think that seems like nothing, ask yourself how many of your friends can tell you what constellations you can see, where the planets are, or why the Moon has phases. You see? You’ve learned so much already that you can even tell from a stick in the ground when we are approaching an equinox!

Once you’ve learned the constellations, so much awaits you.

There are many star clusters that can be seen with no special equipment. For example, the three stars in the belt of Orion are known as Collinder 70. The cluster of stars in Taurus is Messier 45—The Pleiades. From a dark sky site you can even see other galaxies and nebulas! All it takes is some practice and knowing where in the sky to look. Besides, there are other terrific things to do. Meteor showersauroraoccultationseclipses, and even satellite watching require nothing more than just your attention—knowing when and where to look.

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Understanding Magnitude

Understanding the magnitude and the capability of the human eye is important when learning about naked-eye astronomy. Magnitude is a numerical value that relates to the brightness of an object. The larger the number, the dimmer the object. The brightest objects in the sky will actually have a negative magnitude. For instance, the sun has a magnitude of negative twenty-seven. The dimmest star visible with a large telescope has a magnitude of twenty-five. The naked eye is capable of seeing stars with a magnitude no greater than a six.

When planning a naked-eye astronomy session, it is important to remember that a variety of factors can affect your ability to see objects in the night sky. For instance, the use of bright lights like flashlights and phones can reduce visibility. Events which may be out of your control can also affect visibility. These incidences could include light pollution, cloud cover, inclement weather, and untreated physical eye ailments such as nearsighted vision.

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Objects Visible In The Night Sky

When gazing up at the sky, the most obvious objects are the plethora of stars. However, stars are just one of the many objects that can be seen by the human eye. In addition to the constellations and stars, the following objects can be seen: the moon, galaxies, comets, asteroids, and satellites. Although airplanes are not considered a component of astronomy, it is important to distinguish satellites from the aircraft’s exterior lights.

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Meteor Showers

When do meteor showers occur?

Here is a list of some of the best meteor showers of the year, how many fall per hour, and the constellation from which they seem to appear—the radiant. Just remember when meteor watching that dark skies are essential—and the Moon will stop you from seeing anything but the brightest!

What causes meteor showers?

Each time a comet orbits our Sun, it leaves a fine trail of debris behind. As we orbit the Sun, we pass through the debris stream and we see meteor showers! Almost all meteor showers come from comet debris, but there are a few belonging to asteroid debris.

As you’ve seen, a meteor shower’s fall rate can vary greatly. While we’re able to predict when Earth will pass through a stream, we aren’t yet able to predict accurately how dense the stream will be. Our solar system’s giant vacuum cleaner—Jupiter—has such powerful gravity that it will pull the debris stream apart as it passes through on its orbit.

Most meteors are no bigger than a grain of sand—burning up in a blaze of glory as they pass through our atmosphere. While they’re in space, they’re referred to as meteoroids. When they fall visibly, they’re meteors, and—if they survive to fall to Earth—they become meteorites.

Some very large meteorites have been found here on Earth, and each one of them is unique. Check at a local museum or observatory… You just might find a collector who will let you handle some of these “pieces of space!”

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Equipment

Binoculars

bin_range-binoculars

image credit: www.popastro.com

If you already own a pair of binoculars, don’t discard them because you think they aren’t suited to astronomy. Even if they aren’t the best design or the highest of quality, they are a readily available tool that can be used—tonight!

If you do not own a pair of binoculars and are interested in acquiring them—then there are a few guidelines to help you choose a pair that’s right for you. Remember that they don’t always have to be expensive to be suitable…and that larger is not always better. Many excellent pairs of binoculars are easily available from local retailers—the most important part is choosing the right model to serve your interests best.

Are all binoculars made the same?

While at first glance all binoculars might seem to be created equal, there are two distinct common types—the porro prism and roof prism designs. Each works on the same principle: correcting the image and refocusing the light back to the secondary lens—but only one model is best suited to astronomy.

Porro prism binoculars are the bulky, offset binoculars that are most common—and fortunately the best for astronomical applications. They come in a variety of sizes and expense ranges, but even the least of these can become an invaluable astronomy companion—either as an observing tool or a spotting aid.

The roof prism design tends to be more streamlined and will appear as a twin set of optics mounted side-by-side. While there is nothing wrong with these, they tend to deliver dimmer images on astronomical targets and are more expensive.

In researching binoculars, you may also find the reversed porro prism, but this design increases the fold of the light’s path, losing brightness.

All binoculars have one thing in common—a central focus. This moves the secondary lenses in or out. Be sure to look for models that also include focusing of the right lens as well.

What type of binoculars is best for astronomy?

binoculars-porro-prismAs you may have already deduced, the porro prism design is best for astronomy—but remember that any pair of binoculars is better than no pair of binoculars! Try this simple experiment: Cover one eye while looking at the starry sky. How many stars can you see in a given field? Now look at it with both eyes. Chances are you’ll see close to half as many more. The act of viewing the sky with two sets of eyes not only increases contrast, but allows a “stereo” view.

When choosing a porro prism model, you are using a design that allows the maximum amount of light to enter your eye. The larger the aperture—the light gathering surface—the more light is collected, making images brighter. But, remember—this also means added weight.

The secondary lens is more directly related to your eyes’ ability to see the light.

Let’s discuss this equation…

For a pair of 7 X 35 binoculars, the “7” represents the amount of magnification, while the “35” represents the diameter of the front lens. If the aperture were increased—say 7 X 50, that would mean that you would have the same magnification, but would have nearly twice the light gathering power. This means you could spot far fainter things! But, the higher the magnifying power, the closer your eyes must be to the lenses to focus.

Where should I buy binoculars?

Quite simply put, there are thousands of places where you can purchase a pair of binoculars. The one to choose is the one that best suits your needs.

If you are looking for a pair of binoculars for a child, there is nothing wrong with an inexpensive purchase from a local department store or sporting goods supply. Durable porro prisms at small aperture can be obtained for as little as $30 and will start your young stargazer along the path.

If you are a beginner who is looking for a pair of binoculars suited for casual astronomy, there is no reason that commonly purchased ones cannot suit your needs.

You will find sporting goods stores and camera shops will usually carry the higher end models—yet there are many companies specializing in astronomical binoculars readily found on-line for around the same price.
But, if you are very serious about using binoculars as your sole source of astronomical equipment, it is best to begin with a dealer that specializes in astronomy-related equipment. Chances are that if you are willing to invest a significant amount of money, you’ll want a model that’s best suited to astronomical applications.

Just remember… Even a very inexpensive set of binoculars can become the most practical piece of equipment you own—be it from an on-line specialist or the corner store!

Suggested online shops:

    1. Amazon.com
    2. Binoculars.com

What should I look for?

Now that you’re ready to look at binoculars, what will be the first pair you pick up? That’s right. The porro prism model. They are easy to tell from their zig-zag, old-fashioned shape. If they are compact, designed side-by-side, or look like a little box, put them down. What suits a bird-watcher or a hunter does not suit an astronomer.

Ask to examine the binoculars. The correct ones will be hinged in the middle to allow you to adjust for your eye width. While some models may have both the right and left lens adjustment, they must at least have a right diopter—meaning the right lens can be adjusted for your right eye independent of the central focus. Closing your left eye, adjust the right diopter until a distant object is in focus.

Then open both eyes and use the central focus to bring everything sharp. If you see a double image, an outline of color, have to press your eyes against the lenses or cannot bring a distant point to clean focus—these are not for you.

When you have found a suitable pair, examine the lenses in the light. White reflections mean poorly coated optics while dark appearing, or green to purple reflections are the most desired. Now hold them at a distance and look down at the eyepieces. Are both fields evenly illuminated? If the edges are squared off, they may have a low quality prism. Holding them to your eyes, pass your hand first in front of one lens—then the other. If the image seems to switch locations, these binoculars are out of collimation—a serious defect.

What size and power are best for me?

Unfortunately, there are no hard and fast rules about what size binoculars will work best for you. Everyone’s eyes are different and binoculars are much like fitting a pair of glasses to someone’s needs. One of the first things to consider is  eye relief the distance you must hold the binoculars from your eyes to achieve proper focus. Anything less that 9mm will be hugely uncomfortable, while eyeglass wearers will need about 15mm of eye relief.

The next is to understand exit pupil. This is nothing more than the amount of light our eyes can receive. Divide the larger number by the smaller number on the binoculars to get the exit pupil size. For example: 5 X 35. This works out to a perfect 7mm exit pupil—the maximum any human eye can achieve.

Any larger number is a waste—reducing the amount of light collected by the aperture.

Since chances are that many of us will never experience absolute dark and maximum dilation, some of the very best to consider are those that have around a 5mm to 6mm exit pupil. For example, 5 X 30, 7 X 42 or 10 X 50. Binoculars in this range are still small and light enough to be handheld, while larger models would probably require a tripod, or a method of steadying them.

Choose what’s comfortable for you. If you are interested in mounting them on a tripod, there is no reason not to go with a larger model—just remember your exit pupil equation. For all purpose hand-held astronomy, 10 X 50 is the best bet.

Choosing a Telescope

parts-of-telescope

image credit: dummies.com

For the first-time buyer, choosing a telescope means an endless array of styles and price ranges that can sometimes be confusing. Fortunately the choice of design is far less important than a few key elements—the most important of which is light gathering ability. No matter which you choose you will see the lunar landscape like you never thought possible, details on planets, bright galaxies and nebulas—as well as stunning star clusters.

Before you buy, remember it is aperture—the diameter of the mirror or lens that collects the light—rather than magnifying power that you are looking for. Any telescope you should consider is one that has interchangeable eyepieces, a good finderscope, a smooth working focuser, a steady, rugged mount and quality optics. All telescopes are capable of magnifying power simply by switching eyepieces. Before you even consider a department store telescope, remember a quality astronomical scope from a reputable dealer doesn’t necessarily cost more!

What types of telescopes are there?

Unlike binoculars, telescope design is not critical to astronomical use. While they will come in a variety of colors, styles, sizes, lengths, and manufacturers—they will all be only one of three designs: the refractor telescope which uses a series of lenses to gather light, the reflector telescope which uses a mirror, or a catadioptric which uses both.

What is a refractor?

refractor-telescopeThe refractor telescope is one which uses a primary lens at the front of the telescope to collect light and focus it at the eyepiece located on the opposite end of the telescope tube.

This design is often chosen by those who enjoy high power views of earthly subjects, as well as the Moon and planets. Most models provide enough aperture—light gathering ability—to make them very suitable for plenty of other astronomical targets. Small models, such as 60mm, 80mm and 90mm (the diameter of the front lens) are very popular for beginners because they are durable, maintenance free, and offer crisp views.

Because the eyepiece is located at the end of the scope, it is often necessary to use what is called a right angle attachment.

This will place the eyepiece in a comfortable location for the viewer, but you will always have to view from the opposite end of the scope. When you look at a refractor, picture it aimed towards the zenith and what position you would have to be in to use it.

While quality small aperture refractors are relatively inexpensive, large ones are not. If you are looking for light gathering ability, remember that a 100mm aperture refractor can cost up to 500% more than a reflector!

What is a reflector?

reflector telescopereflector telescope (often called a newtonian) is one that uses a parabolic mirror at the base of the telescope tube. This mirror is called the primary. The light is gathered and refocused back upwards towards a smaller, secondary mirror, where the eyepiece near the front of the scope then focuses the image.

As a rule, the reflector telescope can offer far more aperture at an affordable price. This makes it a good choice for the budget-minded, serious beginner. Apertures of 150mm offer views so far superior to the small refractor that they are very worth the small difference in price.

Beginner reflectors, such as the 114mm, are even less expensive and will provide a lifetime of enjoyment.

The major drawback to this style of telescope is that the exposed mirror surface may need occasional cleaning or a refocusing of its optics in a procedure called collimation. While this might sound a little frightening, if you take care to keep the optics covered when not in use and avoid beating the telescope around, it is rarely necessary and no different than dusting and tuning a beloved guitar.

What is a catadioptric?

catadioptric-telescopeThe last on our list of telescope types is a hybrid known as the catadioptric. It uses both a primary mirror and a front lens called a corrector plate to optically perfect the incoming light. It then bounces it back to a small secondary mirror located on the corrector plate and back again to the rear where the eyepiece fine tunes it. You will sometimes hear these telescopes referred to as cassegrain or maksuktov.

While these telescopes are considerably more expensive than a reflector, they are still less expensive than a refractor of comparable size. Their major strong points are portability and high quality images. They are the choice for those wishing to begin in astrophotography and offer terrestrial views as well.

More information

Binocular & Telescope Mounts

A Mount for Your Telescope or Binoculars

Now that you have made a choice, there is one other thing to consider—the mount. Unless you have chosen a pair of binoculars that can easily be handheld, the mount will be the second most important factor for your observing comfort. Most telescope packages will be offered with a mount designed for that particular telescope – but understanding the mount and the role it plays can be critical to the package you choose.

Just like telescope designs, mounts also come in several designs… those made for binoculars; and the altazimuthequatorial and dobsonian mounts for telescopes. With the exception of certain types of binocular mounts and the dobsonian style, these will also include a three-legged device called a tripod. The mount is half the system and even the very highest quality optics are useless without a durable and rugged mount.

What is a binocular mount?

binocular-moaunt

image credit: www.teleskop-express.de

While a pair of large binoculars can be adapted to fit almost any style of mount and tripod, there are three types you see most commonly used.

The first is a parallelogram like device that is weighted on one end. These hold the binoculars perfectly steady at any angle and allow the viewer to adjust manually with a smooth and uncomplicated motion while holding the binoculars. These are generally expensive, but many plans are available to build your own.

The second is a fluid panhead device on a tripod just like a camera mounts on. It will allow the viewer to adjust the binoculars at any angle using controls and offers the stability of the tripod. These are considerably less expensive and available anywhere camera supplies are available.

The third is called a monopod, sometimes referred to as a “finnstick.” Very lightweight, very portable and inexpensive, it is a single, adjustable height post to which binoculars mount at any angle. While the viewer must hold the post steady, it greatly reduces muscle strain from balancing larger models.

What is an equatorial mount?

equatorial-mount

image credit: highpointscientific.com

Although equatorial mounts come in an array of styles, they all work on exactly the same principle—one axis of the device is aligned to the celestial pole. Their mechanism unlocks to make large adjustments, then locks in place allowing the viewer to use slow motion controls to move in small increments of right ascension (RA) and declination (Dec).

They often include devices called setting circles which allow the viewer to set the scope in the general area by using celestial coordinates. Some models even include a polar alignment scope allowing precise alignment.

This type of construction allows for use of a motorized drive unit which will track the celestial object as the Earth moves—an essential for those wishing to experiment with astrophotography.

At the other end of the mount is the counter balance—a weight that is at least equal to that of the telescope body and provides stabilization.

When choosing an equatorial mount, look for heavy construction and a minimum of plastic—especially on moving parts.

This assembly then connects to the tripod, which should be of sufficient strength and durability to carry its load.

A large, heavy telescope on a flimsy mount is unacceptable. Lightweight aluminum tripods are fine for a small scope, but will fail soon on heavy ones. If the size of the counterbalance is larger or heavier than the mount—expect stripped gears and failed tripod legs. Don’t be afraid to bump a mount when shopping.

A good one will stabilize in 2 seconds while looking through the eyepiece. It’s better to know before you buy than watch your telescope fall!

Although an equatorial mount might seem complicated at first, they are quite easy to learn and are the choice offered with most mid-to-large telescopes. Their styles might vary, but the principle will remain the same.

What is a dobsonian mount?

dobsonian mount is nothing more than an uncomplicated rocker box that swivels on its base. The telescope tube has two circular knobs on debsonian-mounteither side which sit in the cradle of the rocker box and allow the telescope to make perfect vertical or horizontal movements. The system is well-balanced and while it will stop where you leave it, a “dob” requires manual adjustment as the Earth rotates under the sky.

The dobsonian is very inexpensive, has very few moving parts, and is so simple that even a small child can use it. It divides the telescope into two major components—optical tube and rocker box. You set the tube in the box and you are ready to go!

While this will never be the choice of the astrophotographer because it doesn’t “track,” the dobsonian design is perfect for every level—from beginner to pro. No exposed moving parts means less things to get broke or lost, while its low cost means aperture at a far more affordable price!

If there is a drawback to this design, it’s that smaller size can mean an uncomfortable position to view or aim for a taller person. This is easily solved by either using the scope in a seated position or elevating it on a steady platform. Even a couple of concrete blocks will suffice to give it added height!

What is an altazimuth mount?

Like a dobsonian, the altazimuth mountworks free of locked down controls, allowing the viewer to move the telescope in perfect horizontal and vertical increments. Like the equatorial, the altazimuth is set upon a tripod.

Because there are fewer moving parts and less weight, the altazimuth does not require a counterbalance and is usually offered with a small refractor. With its left-to-right, up-and-down movements, a quality altazimuth will also stop exactly where you leave it, but must be readjusted as the Earth moves. This makes it an excellent choice for both the beginner and those wishing to use a small refractor.

What’s the best mount for me?

In this instance, I can only speak from years of experience with many different styles and sizes of telescopes. What works well for me, may not for you, but I will try to point out my reasoning.

If you are interested in a small refractor and have no plans for astrophotography, the altazimuth is perfect. It is exceedingly easy for the beginner to use and offers plenty of stability for those advancing in astronomy.

If you are interested in a larger refractor, or a small reflector between 4.5″ and 8″, you can learn to use an equatorial mount.

I would highly recommend this because it’s more comfortable and better suited to an adult—yet not so complicated as to be intimidating. The equatorial requires a little more disciplined set-up, but it is a great study companion and will allow additional accessories such as a tracking device or computer guidance. However, there is absolutely nothing wrong with a dobsonian mount for the small to mid-size reflector. It makes the aperture far more affordable, and its ease of use is a very strong reason to choose this style.

Computer guidance systems can also be added to the dobsonian style.

If those great big telescopes that can reach the faraway galaxies are what takes your fancy—look no further than the dobsonian. From the 10″ to 16″ range, the eyepiece is at a very comfortable height for the adult viewer. The only thing you need to consider is the weight and size of the optical tube.

If you are interested in astrophotography, using the large refractor, reflector or catadioptric design, an equatorial mount is a must. Many come equipped with drive units that will automatically track a celestial object during long exposure astrophotography.

Telescopes & Binoculars

Amateur telescope making

Resources For Educators

Solar System

Ask an Astronomer answers the most burning question about a topic in astronomy or about an object in space?

The Nine Planets provides detailed information with regards to the solar system. This website is suitable for young adults and older.

Views of the Solar System offers a multitude of good introductory content about the solar system, including images, movies, animations, and illustrations (many copyrighted). The site is best for young adults and adults.

The Planetary Photojournal provides excellent copyright-free images of the bodies of our solar system. Aimed at ages 11 and up, the site is easy to navigate.

Windows to the Universe provides background information at beginner, intermediate, and advanced levels in many topics, including the solar system, Earth, and Jupiter.

NASA’s Science Mission Directorate helps teens up with NASA’s latest mission results and peruse their multimedia pages for awesome images and podcasts. You can also follow NASA tweets!

Earth as a Peppercorn is a large-scale outdoor model of the solar system that can be used in place of or in addition to the Explore! solar system scale activities.

From Earth to the Solar System (FETTSS) is a collection of free high-resolution images covering the topics astrobiology, planetary science, and astronomy. The images can be downloaded for free from this NASA website and printed and displayed as exhibits or in other formats.

NASA’s Solar System Missions site provides information about all the missions in our solar system — past, present, and future — with links to the mission Web pages. Many of the missions listed have educational materials.

Eyes on the Solar System combines video game technology and NASA data to create an environment for users to ride along with NASA spacecraft — including Juno — and explore the cosmos. Appropriate for ages 8 and up.

Evolution of the Solar System is a graphic timeline of our solar system’s birth and evolution. There is a gallery and accompanying activity for youth ages 12–17.

Astronomy

Identify local astronomical societies by entering your zip code at Astronomical League or searching at Sky and Telescope.

Check out a short tour of interesting objects in this month’s night sky Space Telescope Science Institute’s Tonight’s Sky movie, updated monthly. This is an especially useful resource for coordinating with your local astronomical society to showcase constellations, deep sky objects, and planets. Happy stargazing!

Use the tools at the Night Sky Network’s Night Sky Planner to plan a stargazing event or connect with current sky events. Find sky charts, information about the rise and set times for the Sun and Moon, Moon phase, and weather forecasts for your location.

Stellarium is planetarium software that shows exactly what you see when you look up at the sky, during the day or night. It’s easy to use, and free. Appropriate for use with children ages 10 and up.

The Solar System Ambassadors Program is a public outreach program in which volunteers communicate the excitement of JPL’s space exploration missions and information about recent discoveries to people in their local communities.

Phil Plait’s Bad Astronomy site offers a knowledgeable take on common misconceptions in astronomy and space science — and at the movies. Lots of fun and very informative, this site written for young adults to adults helps educators tackle misconceptions directly.

The Afterschool Universe Program Curriculum consists of 12 sessions that cover topics such as stars, galaxies, and more.  The hands-on activities are targeted at middle school out-of-school-time settings and have been rigorously pilot-tested and evaluated. Facilitators can find training videos on the Afterschool Universe YouTube channel.

Magnetic Fields

The Exploratorium offers Auroras: Paintings in the Sky, where you can find a self-guided tour about the auroras (or northern and southern lights) and Earth’s magnetic field.

Visit www.spaceweather.com for news, information, and images relating to the Sun and Earth, including auroras. For a fee, skywatchers of all ages can sign up for the astronomy alert service, Spaceweather PHONE.

Missions

Living in Space – Check out what the astronauts eat, wear, and much more on this interesting website.

NASA’s Juno webpage provides information on the JUNO mission as well as images, animations and audios. This site is great for older children and adults.

NASA’s New Horizons webpage offers information about the mission to the dwarf planet Pluto and the Kuiper Belt. The site is appropriate for older children and adults.

The Cassini spacecraft successfully went into orbit around Saturn in 2004. In December 2004 it released the Huygens probe, which reached the surface of Titan in January 2005 and provided a wealth of information about this moon. Videos and more has tons of videos and animations for people of all ages.

The Mars Exploration Rover mission sent rovers Spirit and Opportunity to the surface of Mars to search for evidence of past water — and they found it! Life as we understand it requires water. The findings of the Mars rovers will prompt future exploration looking for evidence of past or present life on the Red Planet.

The MESSENGER mission to the planet Mercury launched in 2004 and arrived at this little-studied planet in 2011.

The Stardust mission sampled the tail of Comet Wild 2 in January 2004 and returned sample material in January 2006. Comets are “leftovers” from the formation of our solar system, and samples will help scientists understand what the composition of our early solar system was like and what processes occurred in the development of our wide “neighbourhood.”

Child-friendly Apps

There are many apps that can help learn about the stars, planets in the sky but many can be confusing for kids. The apps we found have been tested with kids and were found to be both fun and learning.

Star Walk Kids: As you hold your phone up and point it towards the sky, Star Walk Kids follows your motions using the built-in gyroscope to match the map on your screen to the stars seen from your location.

Kids Discover Space: An interactive book is packed with over 200 spectacular images, interactive diagrams, timelines, fun facts and surprises.

Galaxies by Kids Discover: Top-notch animation, engaging activities, and the entire app is very intuitive. Kids will have fun while learning.

GoSkyWatch Planetarium: Displays the sky view at the correct orientation when held at any angle, not just landscape or portrait. Simple operation, no buttons to press or modes to select, just point to the sky to start exploring.

Sun by KIDS Discover: For kids who want to know all about this recycled, middle-aged and rather common star that gives us life, Sun is the one.

Computer Games

There are also many great computer games that help kids discover more about space and our solar system. We selected the most interesting ones in our opinion to help children learn, in a more interactive and funny way.

Fly to Mars : This Fly to Mars game is a simulation of sending a spacecraft to Mars. You need to launch your rocket in anticipation of where Mars will be in seven months time.

Build a Solar System: Great game for students looking to explore the rotation and orbit of the planets in our solar system

Deflect an Asteroid: Earth is below, and there are various rocks on screen. Push them off any side except the bottom. Earth is down there. Earth doesn’t want your rocks.

Planetary Pinball : A “pinball” game that uses charged particles in various magnetic fields

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