# Is there any practical use for astronomy?

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Although astronomy is very cool and the things we are learning are awesome, is there really any practical use to knowing the things we know about the universe?

Do other fields of science draw from the current tome of astronomical knowledge?

This question begs the question, does everything need a practical use? The answer is a resounding no. What's the practical use of the Louvre, or of your local neighborhood public park where you enjoy weekend barbecues?

There are some things that are very worthwhile that have little or no economical gain. Your local neighborhood public park in fact has negative economic gain. Admission is free, but maintenance is not. Think of how much money your city would make if they sold it to a condominium developer, and how much money it would save by not having to pay to have the park maintained.

Despite having no obvious economic gain, some things are nonetheless worth quite a bit. Many of the sciences fall in this category. For example, what is the practical use of archeology? (There are some, but that's not the point.)

Astronomy, like archeology, the Louvre, and your local public park, doesn't need a practical economical purpose. The purpose of the science is good enough.

That said, there are practical applications of astronomy. The key application has been and still is navigation. Knowing the location of a ship at sea or the orientation of a vehicle in space requires astronomy.

A less direct but still very important application of astronomy is in how it informs physics. Kepler was an astronomer, not a physicist. (Those two disciplines were very, very distinct in Kepler's day). Yet Kepler's work informed Newton on how to describe gravitation. More recently, astronomy has informed physics that its standard model was not quite correct. The observed neutrino flux from the Sun (see http://en.wikipedia.org/wiki/Solar_neutrino_problem) was a third of what physics at the time said it should be. This resulted in a change to the standard model. Neutrinos have a small but non-zero mass, and they oscillate from one form to another.

Astronomy continues to inform physics to this day. Physicists (and astronomers) remain clueless with regard to what constitutes dark matter and dark energy. But whatever they are, they certainly do exist.

Other fields of science don't "draw from Astronomy" the same way they don't "draw from cartography". It may not be increasing the technology we have right now, but it will help us get around much safer once we're out in the universe. Basically right now we have an extremely detailed (every single road) map of the entire United States (or other very large country) but we can only walk. We know a large quantity of information that is not currently useful. Get a car (spaceship) that can go far and suddenly all that information becomes much more useful. You know where to go to get fuel, where you want to sightsee, where you want to shop. It is not useful in and of itself, but it is extraordinarily useful at increasing the efficiency of other activities once you can use it properly.

Astronomy has several practical applications/spin-off. For instance, in developing rocket engines, NASA accidentally invented an extremely efficient fire extinguisher, very beneficial for firefighters. Imaging technology for telescopes is used in cameras, spaceship insulation led to teflon, figuring out how to go to the bathroom in space led to better dialysis apparatus, and much, much more. Investigating the unknown always leads to new and unforeseen insight.

However, I think that for most astronomers, this is not the reason we do astronomy. With the risk of sounding a little pretentious, I thnk that the goal of astronomy is to explore the unknown, find our place in this incredible cosmos, learn about the origin of ourselves, and simply find out as much as possible about Nature. Not unlike people did 500 years ago and before, seeking to map out the world and find out what's beyond the horizon.

Okay, that did sound pretentious. I still think it's true, though.

One practical use of astronomy (I actually don't go along with the premise that it needs to be directly useful - there are many examples of blue-skies research turning into applications and I don't see why astronomy should differ; there is also the issue of inspiring and training the next generation of scientists: something that astronomy and astrophysics is particularly suited to) is in space weather forecasting.

An understanding of solar activity, coronal mass ejections and the geocoronal environment has led to power generation grids, satellite operators etc. being able to take action to minimise the damage and disturbance caused by forecasted geomagnetic storms.

Going back a bit, astronomy used to be fairly critical for navigation! I guess we've all got used to GPS…

Are you willing to include all of astronomy, including the basics of mapping the positions and movements of astronomical features?

If so, then astronomy has been the theoretical and practical underpinning of basically all timekeeping and navigation, for all of human history, and every other technology or practice that depends on them. You can't get more practical than "when do I plant the crops" or "which direction do I sail to get to my destination," both of which have life-and-death consequences.

Everything is in space. Everything! Where else would it be? So anything anyone imagine as "practical", is in space. It is the only place to go.

From the point of view of public interest in sciences, astronomy has immense pubic appeal, perhaps only second to dinosaurs: it has a real "wow" value. It can be readily appreciated by non-scientists and provides a brilliant entry in science education.

The other aspect of astronomy is that it en-trains other sciences: nuclear physics, high energy physics, plasma physics, fluid dynamics, relativity, radiation processes, and so on. Astronomy, or astrophysics, pushes the boundaries of and contributes to all of these subjects.

Perhaps the most remarkable, in terms of "everyday use", is Einstein's General relativity without which our GPS navigation systems would be hopelessly wrong (and difficult to correct).

No, there isn't a practical value. How much was wasted on the Hubble Telescope, then how much more was wasted correcting the lenses to actually get a clear picture? How much was wasted on a Mars Lander that crashed upon arrival?

If people want to pay for astronomy out of their pocket, fine. Don't dig into mine just so I can hear about how some galaxy was doing 10 billion years ago. If anything spend the money on oceanography- an area that is of much greater concern to those of us living here and not in the clouds.

Coming late to the party:

I don't want to jump into the game of weighing one scientific discipline against another - this is plain stupid. Saying that Romanistic is less valuable to mankind than Geoscience is nonsense. We can argue what a valuable science is, but the result of that discussion is purely subjective.

What about philosophy - the origin of all scientific research? Zero immediate economic return.

Pure fundamental research does not have any other goal except curiosity. Einsteins theory of relativity or quantum theory were considered without any practical application for decades! Now you own a gazilion devices at your home that contain laser LEDs and carry around GPS devices in your pocket.

i just wanted to share a few pointers that you can find easily via Google:

"What have the Astronomers ever done for us" So if you ever used a calendar, a GPS to navigate your car, were in need of MRT or own a CCD-Camera the practical use of astronomy should be obvious to you.

Astronomy in Everyday Life

Why is Astronomy Important? - arXiv An article by Dr. Robert Aitken

Benefits to the Nation from Astronomy

Astronomy is maybe the most basic scientific discipline. From its start mankind was looking up to the stars and wondering about the universe. < ant>

## What is the practical use of astronomy that isn't immediately apparent?

As a layperson i really enjoy reading about the mind boggling vastness of space and all the things in it. But does it have any practical use in daily life? Or is it more like Art. It's cool because we can?

Do you like using GPS or taking advantage of global telecommunications networks?

oh should have specified that i meant the deep space telescopes and everything beyond our solar system.

It seems very doubtful that even with advanced tech we'll be traveling to other stars

You could have asked the same question to the researchers investigating electricity and magnetism a few centuries ago. They would have had a hard time predicting the full consequences of their discoveries. Basic science is extremely important for the evolution of our society, and we cannot always predict its outcomes.

To add my two cents to this: we never are really sure what new technology will come from so it's always a good idea to pursue knowledge even if it doesn't seem useful at the time. When I was going to study pure math people would ask me what the point is all the time. We use a lot of techniques in computer science that started off as "useless" pure mathematics.

The thing with science is it's nothing more than knowledge. You don't really know if and when it will be useful. It's the engineers who look at the science and say 'I can do something with that' who turn knowledge into practical artifacts.

More 'practically', astronomy along with other sciences has determined that at some point there will be a big chunk of rock or ice hurtling towards the Earth. Early warning and the technology to do something about such an event could be critical.

There are a lot of scientists who do applied work. For example the CCD was invented by two physicists and first made into an imaging device by another physicist. Tons of examples and it still happens.

People are giving science answers, but there's a technology one too. Exploration has always driven technology - when you're doing something new, you need to create new tools and technology. The imaging arrays in digital cameras (originally CCDs, now often cmos) were really first scaled up for astronomical use. We see today many flight imaging technologies, spectroscopy, etc being built for this imaging - especially designing way to look at wavelengths for which there are not currently commericial applications.

## Binoculars for Astronomy

Astronomy is best when you get outside and look into the skies with your own eyes. And the best way to get started is with a set of binoculars for astronomy. They’re light, durable, easy to use, and allow you to see objects in the night sky that you just couldn’t see with your own eyes. There are so many kinds of binoculars out there, so we’ve put together this comprehensive guide to help you out.

Everyone should own a pair of binoculars. Whether you’re interested in practicing serious binocular astronomy or just want a casual cosmic close-up, these portable “twin telescopes” are both convenient and affordable. Learning more about how binoculars work and what type of binoculars work best for astronomy applications will make you much happier with your selection. The best thing to do is start by learning some binocular “basics”.

What are binoculars and how do they work?
Binoculars are both technical and simple at the same time. They consist of an objective lens (the large lens at the far end of the binocular), the ocular lens (the eyepiece) and a prism (a light reflecting, triangular sectioned block of glass with polished edges).

The prism folds the light path and allows the body to be far shorter than a telescope. It also flips the image around so it doesn’t look upside-down. The traditional Z-shaped porro prism design is well suited to astronomy and consists of two joined right-angled prisms which reflects the light path 3 times. The sleeker, straight barrelled roof prism models are more compact and far more technical. The light path is longer, folding 4 times and requires stringent manufacturing quality to equal the performance. These models are better suited to terrestrial subjects, and are strongly not recommended for astronomy use.

If you’re using binoculars for astronomy, go with a porro prism design.

Choosing the Lens Size
Every pair of binoculars will have a pair of numbers associated with it: the magnifying power times (X) the objective lens size. For example, a popular ratio is 7X35. For astronomical applications, these two numbers play an important role in determining the exit pupil – the amount of light the human eye can accept (5-7mm depending on age from older to younger). By dividing the objective lens (or aperture) size by the magnifying power you can determine a pair of binoculars exit pupil.

Like a telescope, the larger the aperture, the more light gathering power – increasing proportionately in bulk and weight. Stereoscopic views of the night sky through big binoculars is an incredible, dimensional experience and one quite worthy of a mount and tripod! As you journey through the binocular department, go armed with the knowledge of how to choose your binoculars lens size.

Why does the binocular lens size matter? Because binoculars truly are a twin set of refracting telescopes, the size of the objective (or primary) lens is referred to as the aperture. Just as with a telescope, the aperture is the light gathering source and this plays a key role in the applications binoculars are suited for. Theoretically, more aperture means brighter and better resolved images – yet the size and bulk increases proportionately. To be happiest with your choice, you must ask yourself what you’ll be viewing most often with your new binoculars. Let’s take a look at some general uses for astronomy binoculars by their aperture.

Different Sizes of Binoculars
Binoculars with a lens size of less that 30mm, such as 5X25 or 5X30, are small and very portable. The compact models can fit easily into a pocket or backpack and are very convenient for a quick look at well-lit situations. In this size range, low magnifications are necessary to keep the image bright.

Compact models are also great binoculars for very small children. If you’re interested in choosing binoculars for a child, any of these models are very acceptable – just keep in mind a few considerations. Children are naturally curious, so limiting them to only small binoculars may take away some of the joy of learning. After all, imagine the thrill of watching a raccoon in its natural habitat at sundown… Or following a comet! Choose binoculars for a child by the size they can handle, whether the model will fold correctly to fit their interpupilary size, and durability. Older children are quite capable of using adult-sized models and are naturals with tripod and monopod arrangements. For less than the price of most toys, you can put a set of quality optics into their hands and open the door to learning. Children as young as 3 or 4 years old can handle 5X30 models easily and enjoy wildlife and stargazing both!

Binocular aperture of up to 40mm is a great mid-range size that can be used by almost everyone for multiple applications. In this range, higher magnification becomes a little more practical. For those who enjoy stargazing, this is an entry level aperture that is very acceptable to study the Moon and brighter deep sky objects and they make wonderful binoculars for older children.

Binoculars up to 50-60mm in lens size are also considered mid-range, but far heavier. Again, increasing the objective lens size means brighter images in low light situations – but these models are a bit more bulky. They are very well suited to astronomy, but the larger models may require a support (tripod, monopod, car window mount) for extended viewing. Capable of much higher magnification, these larger binocular models will seriously help to pick up distant, dimmer subjects such as views of distant nebulae, galaxies and star clusters. The 50mm size is fantastic for older children who are ready for more expensive optics, but there are drawbacks.

The 50-60mm binoculars are pushing the maximum amount of weight that can be held comfortably by the user without assistance, but don’t rule them out. Available in a wide range of magnifications, these models are for serious study and will give crisp, bright images. Delicate star clusters, bright galaxies, the Moon and planets are easily distinguishable in this aperture size. These models make for great “leave in the car” telescopes so you always have optics at hand. For teens who are interested in astronomy, binoculars make an incredible “First Telescope”. Considering a model in this size will allow for most types of astronomical viewing and with care will last through a lifetime of use.

Binoculars any larger than 50-60mm are some serious aperture. These are the perfect size allowing for bright images at high magnification. For astronomy applications, binoculars with equations like 15X70 or 20X80 are definitely going to open a whole new vista to your observing nights. The wide field of view allows for a panoramic look at the heavens, including extended comet tails, large open clusters such as Collinder Objects, starry fields around galaxies, nebulae and more… If you have never experienced binocular astronomy, you’ll be thrilled at how easy objects are to locate and the speed and comfort at which you can observe. A whole new experience is waiting for you!

Binocular Magnification
When choosing binoculars for astronomy, just keep in mind that all binoculars are expressed in two equations – the magnifying power X the objective lens size. So far we have only looked at the objective lens size. Like a telescope, the larger the aperture, the more light gathering power – increasing proportionately in bulk and weight. Stereoscopic views of the night sky through big binoculars is an incredible, dimensional experience, but for astronomical applications we need these two numbers to play an important role in determining the exit pupil – the amount of light the human eye can accept. By dividing the objective lens (or aperture) size by the magnifying power you can determine a pair of binoculars exit pupil. Let’s take a look at why that’s important.

How do binoculars magnify? What’s the best magnification to use? What magnifying power do I choose for astronomy? Where do I learn about what magnifying power is best in binoculars? Because binoculars are a set of twin refracting telescopes meant to be used by both eyes simultaneously, we need to understand how our eyes function. All human eyes are unique, so we need to take a few things into consideration when looking at the astronomy binocular magnification equation.

By dividing the objective lens (or aperture) size by the magnifying power you can determine a pair of binoculars exit pupil and match it to your eyes. During the daylight, the human eye has about 2mm of exit pupil – which makes high magnification practical. In low light or stargazing, the exit pupil needs to be more around 5 to be usable.

While it would be tempting to use as much magnification as possible, all binoculars (and the human eye) have practical limits. You must consider eye relief – the amount of distance your eye must be away from the secondary lens to achieve focus. Many high “powered” binoculars do not have enough outward travel for eye glass wearers to come to focus without your glasses. Anything less than 9mm eye relief will make for some very uncomfortable viewing. If you wear eyeglasses to correct astigmatism, you may wish to leave your glasses on while using binoculars, so look for models which carry about 15mm eye relief.

Now, let’s talk about what you see! If you look through binoculars of two widely different magnifying powers at the same object, you’ll see you have the choice of a small, bright, crisp image or a big, blurry, dimmer image – but why? Binoculars can only gather a fixed amount of light determined by their aperture (lens size). When using high magnification, you’re only spreading the same light over a larger area and even the best binoculars can only deliver a certain amount of detail. Being able to steady the view also plays a critical role. At maximum magnification, any movement will be exaggerated in the viewing field. For example, seeing craters on the Moon is a tremendous experience – if only you could hold the view still long enough to identify which one it is! Magnification also decreases the amount of light that reaches the eye. For these reasons, we must consider the next step – choosing the binocular magnification – carefully.

Binoculars with 7X magnifying power or less, such as 7X35, not only delivers long eye relief, but also allows for variable eye relief that is customizable to the user’s own eyes and eyeglasses. Better models have a central focus mechanism with a right eye diopter control to correct for normal right/left eye vision imbalance. This magnification range is great for most astronomy applications. Low power means less “shake” is noticed. Binoculars with 8X or 9X magnification also offer long eye relief, and allows comfort for eyeglass wearers as well as those with uncorrected vision. With just a bit more magnification, they compliment astronomy. Binoculars 10 x 50 magnifying power are a category of their own. They are at the edge of multipurpose eye relief and magnifying power at this level is excellent across all subject matter. However, larger aperture is recommended for locating faint astronomy subjects.

Binoculars with 12-15X magnifying power offer almost telescopic views. In astronomy applications, aperture with high magnification is a must to deliver bright images. Some models are extremely well suited to binocular astronomy with a generous exit pupil and aperture combined. Binoculars with 16X magnification and higher are on the outside edge of high magnification at hand-held capabilities. They are truly designed exclusively as mounted astronomical binoculars. Most have excellent eye relief, but when combined with aperture size, a tripod or monopod is suggested for steady viewing. If you’re interested in varying the power, you might want to consider zoom binoculars. These allow for a variety of applications that aren’t dependent solely on a single feature. Models can range anywhere from as low as 5X magnification up to 30X, but always bear in mind the higher the magnification – the dimmer the image. Large aperture would make for great astronomy applications when a quick, more magnified view is desired without being chained to a tripod.

Other Binocular Features
The next thing to do is take a good look at the binoculars you are about to purchase. Check out the lenses in the light. Do you see blue, green, or red? Almost binoculars have anti-reflection coatings on their air to glass surfaces, but not all are created equal. Coatings on binocular lenses were meant to assist light transmission of the object you’re focusing on and cancelling ambient light. Simply “coated” in the description means they probably only have this special assistance on the first and last lens elements – the ones you’re looking at. The same can also be said of the term “multi-coated”, it’s probably just the exterior lens surface, but at least there’s more than one layer! “Fully coated” means all the air-to-glass surfaces are coated, which is better… and “fully multi-coated” is best. Keeping stray light from bouncing around and spoiling the light you want to see is very important, but beware ruby coated lenses… These were meant for bright daylight applications and will rob astronomical binoculars of the light they seek.

Last, but not least, is a scary word – collimation. Don’t be afraid of it. It only means the the optics and the mechanics are properly aligned. Most cheap binoculars suffer from poor collimation, but that doesn’t mean you can’t find an inexpensive pair of binoculars that are well collimated. How can you tell? Take a look through them with both eyes. If you can’t focus at long distance, short distance and a distance in-between, there is something wrong. If you can’t close either eye and come to focus with the other, there’s something wrong. Using poorly collimated binoculars for any length of time causes eye strain you won’t soon forget.

Price range for Astronomy Binoculars
So, how much? What does a good pair of binoculars for astronomy cost? First look for a quality manufacturer. Just because you’ve chosen a good name doesn’t mean you’re draining your pocket. Smaller astronomy binoculars of high quality are usually around or under $25. Mid-sized astronomy binoculars range from$50 to $75 as a rule. Large astronomy binoculars can run from a little over$100 to several hundred dollars. Of course, choosing a high-end pair of binoculars of any size will cost more, but with proper care they can be handed down through generations of users. Keep in mind little things that might be good for your applications, like rubber-coated binoculars for children who bang them around more, or fog-proof lenses if you live in a high humidity area. Cases, lens caps and neck straps are important, too.

Some Suggested Binoculars
The purpose of this guide was to help you understand how to choose the best binoculars for astronomy. But if you trust me, and just want some suggestions… here you go.

For all purpose astronomy binoculars, I’d recommend the Celestron Up-Close and Ultima Series as well as Meade Travel View. Nikkon and Bushnell binoculars in this size range are an investment, and best undertaken after you decide if binocular astronomy and this size is right for you. Amazon.com offers a wide range of these binoculars.

While so much information on binoculars may seem a little confusing at first, just a little study will take you on your way to discovering astronomy binoculars that are perfect for you!

## Shared Flashcard Set

five types of astronomers divided by what they study:

1. planetary

4. Galactic

5. Extragalactic

astronmetry is the study of the sun, moon, and planets.

currently it relates to scientists who are trying to model the creation and change of distant plants and stars, as well as predict the occurance of meteor showers, eclipses, and the apperance of comets

what did Kepler do?

four concepts that cosmology encompasses:

1. string theory

2. dark matter

3. dark energy

4. # of universes

5. cosmic rays

the elctromagnetic radiation that passes through the earth's atmosphere is

1. visible light which comes in which some distortion

2. radio waves which have no distortion

optical astronomy data can come in four forms:

2. photometry, which measures the amount of light coming from an object

4. polarimetry, where the polarization state is measured

the two ways to collect radio wave data:

1. one singular radio wave antennas, called radio telescopes

2. a network of linked radio telescopes

the nine major advantages of collecting astronomy data in
AN

3. stable atmosphere, thin surface boundary layer

4. little pollution, dust aersols to get in the way of telescopes

6. easy to conduct long-duration, continous monitoring

7. magnetic pole brings increased low-energy cosmic ray fluxes

9. ice absorbs particles from celestial bodies

the four major disadvantages to AN astronomy data collection

there are four disadvantages to collecting astronomy data in AN

1. humidity: the relative humidity is often high

2. sky coverage: you can only ever see one half of the sky

3. the amount of time it is astronomically dark is lower in AN than in spots nearer the equator. Though darkness can last months, if the sun isn't far enough below the horizon, it gets in the way

4. Auroral activity is frequent

the future of astronomy data collection in AN: we are gonna get more and more data there in the future. A medium/large aperture telescope has potential to do things we thought we could only do from space

3 reasons why AN is the best place to look for meteorites

1. no background material to make looking for them hard. just flat ice

2. low/no sediment accretion on top of meteors

3. you can't get meteors confused with earthen rocks because there aren't any. to expand on that, there isn't a bias towards meteors that look different from earthen rocks. there also isn't a bias towards larger meteors

## Moon Theme Printables for Kids

### Phases of the Moon and M is for Moon Printables

We have been loving these printables. I decided to Laminate most of them which make them easy to wipe clean and reuse. Dry erase markers are perfect on these sheets too. You can see The Best Homeschool Essentials Here. These items make my life and homeschooling so much easier.

The moon holds so many mysteries it is fascinating to explore.

## Telescopic observations

Before Galileo Galilei’s use of telescopes for astronomy in 1609, all observations were made by naked eye, with corresponding limits on the faintness and degree of detail that could be seen. Since that time, telescopes have become central to astronomy. Having apertures much larger than the pupil of the human eye, telescopes permit the study of faint and distant objects. In addition, sufficient radiant energy can be collected in short time intervals to permit rapid fluctuations in intensity to be detected. Further, with more energy collected, a spectrum can be greatly dispersed and examined in much greater detail.

Optical telescopes are either refractors or reflectors that use lenses or mirrors, respectively, for their main light-collecting elements (objectives). Refractors are effectively limited to apertures of about 100 cm (approximately 40 inches) or less because of problems inherent in the use of large glass lenses. These distort under their own weight and can be supported only around the perimeter an appreciable amount of light is lost due to absorption in the glass. Large-aperture refractors are very long and require large and expensive domes. The largest modern telescopes are all reflectors, the very largest composed of many segmented components and having overall diameters of about 10 metres (33 feet). Reflectors are not subject to the chromatic problems of refractors, can be better supported mechanically, and can be housed in smaller domes because they are more compact than the long-tube refractors.

The angular resolving power (or resolution) of a telescope is the smallest angle between close objects that can be seen clearly to be separate. Resolution is limited by the wave nature of light. For a telescope having an objective lens or mirror with diameter D and operating at wavelength λ, the angular resolution (in radians) can be approximately described by the ratio λ/D. Optical telescopes can have very high intrinsic resolving powers in practice, however, these are not attained for telescopes located on Earth’s surface, because atmospheric effects limit the practical resolution to about one arc second. Sophisticated computing programs can allow much-improved resolution, and the performance of telescopes on Earth can be improved through the use of adaptive optics, in which the surface of the mirror is adjusted rapidly to compensate for atmospheric turbulence that would otherwise distort the image. In addition, image data from several telescopes focused on the same object can be merged optically and through computer processing to produce images having angular resolutions much greater than that from any single component.

The atmosphere does not transmit radiation of all wavelengths equally well. This restricts astronomy on Earth’s surface to the near ultraviolet, visible, and radio regions of the electromagnetic spectrum and to some relatively narrow “windows” in the nearer infrared. Longer infrared wavelengths are strongly absorbed by atmospheric water vapour and carbon dioxide. Atmospheric effects can be reduced by careful site selection and by carrying out observations at high altitudes. Most major optical observatories are located on high mountains, well away from cities and their reflected lights. Infrared telescopes have been located atop Mauna Kea in Hawaii, in the Atacama Desert in Chile, and in the Canary Islands, where atmospheric humidity is very low. Airborne telescopes designed mainly for infrared observations—such as on the Stratospheric Observatory for Infrared Astronomy (SOFIA), a jet aircraft fitted with astronomical instruments—operate at an altitude of about 12 km (40,000 feet) with flight durations limited to a few hours. Telescopes for infrared, X-ray, and gamma-ray observations have been carried to altitudes of more than 30 km (100,000 feet) by balloons. Higher altitudes can be attained during short-duration rocket flights for ultraviolet observations. Telescopes for all wavelengths from infrared to gamma rays have been carried by robotic spacecraft observatories such as the Hubble Space Telescope and the Wilkinson Microwave Anisotropy Probe, while cosmic rays have been studied from space by the Advanced Composition Explorer.

Angular resolution better than one milliarcsecond has been achieved at radio wavelengths by the use of several radio telescopes in an array. In such an arrangement, the effective aperture then becomes the greatest distance between component telescopes. For example, in the Very Large Array (VLA), operated near Socorro, New Mexico, by the National Radio Astronomy Observatory, 27 movable radio dishes are set out along tracks that extend for nearly 21 km. In another technique, called very long baseline interferometry (VLBI), simultaneous observations are made with radio telescopes thousands of kilometres apart this technique requires very precise timing.

Earth is a moving platform for astronomical observations. It is important that the specification of precise celestial coordinates be made in ways that correct for telescope location, the position of Earth in its orbit around the Sun, and the epoch of observation, since Earth’s axis of rotation moves slowly over the years. Time measurements are now based on atomic clocks rather than on Earth’s rotation, and telescopes can be driven continuously to compensate for the planet’s rotation, so as to permit tracking of a given astronomical object.

## How the Church Aided 'Heretical' Astronomy

Many people know that the Roman Catholic Church once waged a long and bitter war on science, and on astronomy in particular. But that seemingly well-established fact of history, it turns out, is wrong.

While it is true that the church condemned Galileo, new research shows that centuries of oversimplifications have concealed just how hard Rome worked to amass astronomical tools, measurements, tests and lore.

In its scientific zeal, the church adapted cathedrals across Europe, and a tower at the Vatican itself, so their darkened vaults could serve as solar observatories. Beams of sunlight that fell past religious art and marble columns not only inspired the faithful but provided astronomers with information about the Sun, the Earth and their celestial relationship.

Among other things, solar images projected on cathedral floors disclosed the passage of dark spots across the Sun's face, a blemish in the heavens, which theologians once thought to be without flaw.

In a new book, ''The Sun in the Church'' (Harvard, 1999), Dr. John L. Heilbron, a historian of science, reveals the ubiquity of the solar observatories, which heretofore were little known among scholars. And he shows that the church was not necessarily seeking knowledge for knowledge's sake, a traditional aim of pure science. Rather, like many patrons, it wanted something practical in return for its investments: mainly the improvement of the calendar so church officials could more accurately establish the date of Easter.

When to celebrate the feast of Christ's resurrection had become a bureaucratic crisis in the church. Traditionally, Easter fell on the Sunday after the first full moon of spring. But by the 12th century, the usual ways to predict that date had gone awry.

To set a date for Easter Sunday years in advance, and thus reinforce the church's power and unity, popes and ecclesiastical officials had for centuries relied on astronomers, who pondered over old manuscripts and devised instruments that set them at the forefront of the scientific revolution.

According to Dr. Heilbron, the church ''gave more financial and social support to the study of astronomy for over six centuries, from the recovery of ancient learning during the late Middle Ages into the Enlightenment, than any other, and probably, all other, institutions.''

Dr. Heilbron, 65, is professor emeritus and vice chancellor emeritus at the University of California at Berkeley and a senior fellow at Worcester College, Oxford, England. He lives in England and travels widely to study old solar observatories.

In a telephone interview last week, Dr. Heilbron said he was astonished by the old instruments, which he first saw eight years ago in Bologna, Italy, at the Basilica of San Petronio.

''The church itself was beautiful, somber,'' Dr. Heilbron recalled. ''When the sun crawled across that floor, there was nothing else. That's what you had to look at. It was intense.''

After discovering that other churches throughout Europe had solar observatories, he produced a book rich in old drawings, equations, geometrical figures and astronomical lore.

Dr. Owen Gingerich, a historian in Cambridge, Mass., at the Harvard-Smithsonian Center for Astrophysics, praised the work as re-creating a lost world.

''It's a very important piece of scholarship,'' Dr. Gingerich said.

In the book and an article in The Sciences, a journal of the New York Academy of Sciences, Dr. Heilbron shows that the observatory findings (usually made in sight of a cathedral altar) often contradicted church dogma of that time.

The Jesuits, for instance, used observatories to confirm theories about Earth movement, which they were forbidden to teach.

Over the centuries, Dr. Heilbron said, observatories were built in cathedrals and churches throughout Europe, including those in Rome, Paris, Milan, Florence, Bologna, Palermo, Brussels and Antwerp. Typically, the building, dark inside, needed only a small hole in the roof to allow a beam of sunlight to strike the floor below, producing a clear image of the solar disk. In effect, the church had been turned into a pinhole camera, in which light passes through a small hole into a darkened interior, forming an image on the opposite side.

On each sunny day, the solar image would sweep across the church floor and, exactly at noon, cross a long metal rod that was the observatory's most important and precise part. The noon crossings over the course of a year would reach the line's extremities -- which usually marked the summer and winter solstices, when the Sun is farthest north and south of the Equator. The circuit, among other things, could be used to measure the year's duration with great precision.

The path on the floor was known as a meridian line, like the north-south meridians of geographers. The rod, in keeping with its setting and duties, was often surrounded by rich tile inlays and zodiacal motifs.

The instruments lost much of their astronomical value around the middle of the 18th century as telescopes began to exceed them in power. But the observatories still played a significant role because the solar timepieces were often used to correct errors in mechanical clocks and even to set time for railroads.

One of the observatories also impressed Charles Dickens, who in his book ''Pictures from Italy'' wrote that he found little to like in Bologna except ''the Church of San Petronio, where the sunbeams mark the time among the kneeling people.''

Today, the surviving cathedral solar instruments are lovely anachronisms that baffle most visitors, who are usually unaware of their original use or historical importance.

The traditional view of the church's hostility toward science grew out of its famous feud with Galileo, condemned to house arrest in 1632 for astronomical heresy.

Since antiquity, astronomers had put Earth at the center of planetary motions, a view the church had embraced. But Galileo, using the new telescope, became convinced that the planets in fact moved around the Sun, a view Nicholas Copernicus, a Polish astronomer, had championed.

The censure of Galileo, at age 70, hurt the image of the church for centuries. Pope John Paul II finally acknowledged in 1992, 359 years later, that the church had erred in condemning the scientific giant.

Dr. Richard S. Westfall, a historian of science, in 1989 wrote that Rome's handling of Galileo made Copernican astronomy a forbidden topic among faithful Catholics for two centuries.

Not so, Dr. Heilbron claims. Rome's support of astronomy was considerable.

''The church tended to regard all the systems of the mathematical astronomy as fictions,'' Dr. Heilbron wrote. ''That interpretation gave Catholic writers scope to develop mathematical and observational astronomy almost as they pleased, despite the tough wording of the condemnation of Galileo.''

To illustrate, Dr. Heilbron examined four cathedrals: San Petronio in Bologna, Santa Maria degli Angeli in Rome, St. Sulpice in Paris and Santa Maria del Fiore in Florence.

For the great Basilica of San Petronio, he showed how a solar observatory was erected in 1576 by Egnatio Danti, a mathematician and Dominican friar who worked for Cosimo I dei Medici, the Grand Duke of Tuscany, and who advised Pope Gregory on calendar reform. The church observatory produced data long before the telescope existed.

By 1582, the Gregorian calendar had been established, creating the modern year of 365 days and an occasional leap year of 366 days. Danti was rewarded with a commission to build a solar observatory in the Vatican itself within the Torre dei Venti, or Tower of the Winds.

The golden age of the cathedral observatories came later, between 1650 and 1750, Dr. Heilbron writes, and helped to disprove the astronomical dogma that the church had defended with such militancy in the case of Galileo.

Among the best known of the rebel observers was Giovanni Cassini, an Italian astronomer who gained fame for discovering moons of Saturn and the gaps in its rings that still bear his name, as does a \$3.4 billion spacecraft now speeding toward the planet.

Around 1655, Cassini persuaded the builders of the Basilica of San Petronio that they should include a major upgrade of Danti's old meridian line, making it larger and far more accurate, its entry hole for daylight moved up to be some 90 feet high, atop a lofty vault.

''Most illustrious nobles of Bologna,'' Cassini boasted in a flier drawn up for the new observatory, ''the kingdom of astronomy is now yours.''

The exaggeration turned out to have some merit as Cassini used the observatory to investigate the ''orbit'' of the Sun, quietly suggesting that it actually stood still while the Earth moved.

Cassini decided to use his observations to try to confirm the theories of Johannes Kepler, the German astronomer who had proposed in 1609 that the planets moved in elliptical orbits not the circles that Copernicus had envisioned.

If true, that meant the Earth over the course of a year would pull slightly closer and farther away from the Sun. At least in theory, Cassini's observatory could test Kepler's idea, since the Sun's projected disk on the cathedral floor would shrink slightly as the distance grew and would expand as the gap lessened.

Such an experiment could also address whether there was any merit to the ancient system of Ptolemy, some interpretations of which had the Earth moving around the Sun in an eccentric circular orbit. Ptolemy's Sun at its closest approach moved closer to the Earth than Kepler's Sun did, in theory making the expected solar image larger and the correctness of the rival theories easy to distinguish.

For the experiment to succeed, Cassini could tolerate measurement errors no greater than 0.3 inches in the Sun's projected face, which ranged from 5 to 33 inches wide, depending on the time of year. No telescope of the day could achieve that precision.

The experiment was run around 1655, and after much trial and error, succeeded. Cassini and his Jesuit allies, Dr. Heilbron writes, confirmed Kepler's version of the Copernican theory.

Between 1655 and 1736, astronomers used the solar observatory at San Petronio to make 4,500 observations, aiding substantially the tide of scientific advance.

''It's a great topic,'' Dr. Heilbron said from Belgium, adding that he was planning to write at least one more book on the hidden influence of the solar observatories.

## Tagai’s story

Tagai was a great fisherman. One day he and his crew of 12 were fishing from their outrigger canoe. They were unable to catch any fish, so Tagai left the canoe and went onto the nearby reef to look for fish there.

As the day grew hotter and hotter, the waiting crew of Zugubals (beings who took on human form when they visited Earth) grew impatient and frustrated. Their thirst grew, but the only drinking water in the canoe belonged to Tagai. Their patience ran out and they drank Tagai’s water.

When Tagai returned, he was furious that the Zugubals had consumed all of his water for the voyage. In his rage he killed all 12 of his crew. He returned them to the sky and placed them in two groups: six men in Usal (the Pleiades star cluster) and the other six Utimal (Orion). He told his crew to stay in the northern sky and to keep away from him.

Tagai can be seen in the southern skies, standing in a canoe in the Milky Way. His left hand is the Southern Cross holding a spear. His right hand is a group of stars in the constellation Corvus holding a fruit called Eugina. He is standing on his canoe, formed by the stars of Scorpius.

## Handbook of CCD Astronomy

##### This book has been cited by the following publications. This list is generated based on data provided by CrossRef.
• Publisher: Cambridge University Press
• Online publication date: June 2012
• Print publication year: 2006
• Online ISBN: 9780511807909
• DOI: https://doi.org/10.1017/CBO9780511807909
• Subjects: Observational Astronomy, Techniques and Instrumentation, Physics and Astronomy, Practical and Amateur Astronomy, General and Classical Physics
• Series: Cambridge Observing Handbooks for Research Astronomers (5)

Email your librarian or administrator to recommend adding this book to your organisation's collection.

### Book description

Charge-Coupled Devices (CCDs) are the state-of-the-art detector in many fields of observational science. Updated to include all of the latest developments in CCDs, this second edition of the Handbook of CCD Astronomy is a concise and accessible reference on all practical aspects of using CCDs. Starting with their electronic workings, it discusses their basic characteristics and then gives methods and examples of how to determine these values. While the book focuses on the use of CCDs in professional observational astronomy, advanced amateur astronomers, and researchers in physics, chemistry, medical imaging, and remote sensing will also find it very valuable. Tables of useful and hard-to-find data, key practical equations, and new exercises round off the book and ensure that it provides an ideal introduction to the practical use of CCDs for graduate students, and a handy reference for more experienced users.

### Reviews

‘[Howell’s] broad experience in CCD astronomy is evident throughout the book. Overall the book is well written and nicely printed … I highly recommend it for anyone interested in CCD astronomy.’

Ken Herkenhoff Source: EOS

‘As an introduction to CCD imaging in astronomy, this handbook will serve well both the serious amateur and the fresh professional. For a wide range of objects, in optical to high-energy astronomy, the author shows admirably where the techniques suffer, how they can be corrected and what can be achieved. We recommend this handbook to all interested in CCDs, photometry and spectroscopy.’

Source: Irish Astronomical Journal

‘… provides an ideal introduction to the practical use of CCDs for graduate students, as well as a handy reference for more experienced researchers.’

‘This handbook provides a concise and accessible reference on all practical aspects of using CCDs. Tables of useful and hard-to-find data, and key practical equations round the book off and ensure that it provides an ideal introduction to the practical use of CCDs for graduate students, as well as a handy reference for more experienced researchers.’

Source: Orion (Société Astronomique de Suisse)

‘It is an excellent book and can be recommended to all who value a clearly written explanation of CCD technology, and one that can also be regarded as relevant to applications other than astronomy.’

Source: Imaging Science Journal

'… much of the text will be invaluable to amateurs … This is a slim paperback volume … but has a high quantum efficiency of content and should be on the bookshelf of every amateur who claims to take the application of CCDs seriously.'

Source: Webb Society Quarterly Journal

'The 2nd edition…provides a compact and very readable account of all the practical aspects of CCD cameras. …aimed both at the 'fresh' professional astronomer and at the seasoned amateur who would like to venture more deeply into this technology. …The tables and diagrams are plentiful, clear and useful. …hard facts are clearly explained and well presented for the serious astronomer.'

## Speech on Astronomy for Students

With the ambitious plans of space pioneers such as Elon Musk, the frontiers of space are making headlines again. SpaceX has captured our imaginations and the hope of putting a man on Mars could be achieved in many of our lifetimes. This brings the subject of astronomy into our thoughts. Without knowledge of astronomy dreams of space travel would be irrelevant.

Astronomy, it has been said, is the oldest and the noblest of the sciences. However, it is one of the few sciences for which most present-day educators seem to find hardly if any, a room in their curriculum of study for the young, in spite of its high educational and important value.

It is, we are told, too abstract a subject for the youthful student without much relevance in gaining everyday life skills. This is perhaps true of theoretical or mathematical astronomy and the practical astronomy of the navigator, surveyor and engineer, but it is not true of general, descriptive astronomy. There are many different aspects of this vast science, and some of the simplest and greatest truths of astronomy can be grasped by the interested child of any age, and as we grow more information can be absorbed.

Knowledge of the sun, moon, stars and planets, their motions and their physical features, is an interesting and important education as they are as truly a part of nature as are the birds, trees and flowers, and the man, woman or child who lives beneath the star-lit heavens.

The beauties of the universe of which we are a part if ignored are like the experience of one who walks through fields or forests with no thought of the beauties of nature that surrounds them.

It can be a simple matter simple task to become acquainted with the various groups of stars as they cross our meridian (south or north), one by one, day after day and month after month in the same routine.

When the sparrow returns once more to nest in the same woods in the springtime, Leo and Virgo may be seen rising above the eastern horizon in the early evening hours. When the ponds freeze in the late autumn and the birds have gone southward the belt of Orion appears in the east and Cygnus dips low in the west. When we once come to know brilliant blue-white Vega, ruddy Arcturus, golden Capella and sparkling Sirius we watch for them to return each in its proper season and welcome them like revisiting acquaintances.

Stars of the Zodiac – Astronomy for Students

We may start studying the constellations or groups of stars at any month in the year and we will find the constellations given for that month on or near the meridian at the time indicated.

We should consider for a moment the constellations are all continually shifting westward as the stars and the moon and the planets as well as the sunrise daily in the east and set in the west. This is due to the fact that the earth is turning in the opposite direction on its axis.

In twenty-four hours the earth turns completely around with respect to the heavens or through an angle of 360°.

During the course of one year, the earth makes one trip around the sun and faces in turn all parts of the heavens. That is, it turns through an angle of 360° with respect to the heavens in a year or through an angle of 360° ÷ 12 or 30° in one month.

As a pathway of our revolution around the sun, which is also in a west to east direction, we see that all the constellations are gradually shifting westward at the rate of 30° a month. It is for this reason that we see different constellations in different months. The turning of the earth on its axis means we see different constellations at different hours of the night.

The apparent journey of the sun among the stars is called the ecliptic. the belt of the heavens eight degrees wide on either side of the ecliptic is called the zodiac. The constellations that lie within this belt of the zodiac are called zodiacal constellations. The zodiac was divided by the astronomer Hipparchus, who lived 161-126 B.C., into twelve signs 30° wide, and the signs were named for the constellations lying at that time within each of these divisions.

Zodiacal constellations are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius and Pisces. With the exception of Libra, the Scales, all of these constellations are named for people or animals and the word zodiac is derived from the Greek word meaning “of animals.”

Our sun is but a star-traveling through the universe. It is accompanied in its journey to unknown parts of space, that lies in the general direction of the constellation Hercules, by an extensive family of minor bodies consisting of the eight planets and their encircling moons, one thousand or more asteroids, numerous comets, and meteors without number, all moving in prescribed paths around their king: the sun.

The most important members of the sun’s family are the planets, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, named in the order of their position outward from the sun.

The gravitational control of the sun extends far beyond the orbit of Neptune and there are reasons for believing in the existence of at least one or two additional planets on the outskirts of the solar system. however, there are thought to be a billion, billion planets in the universe.