Moon Observer's Guide - Softcover

Peter-grego

Softcover

ISBN 10: 0540084190 ISBN 13: 9780540084197

Publisher: Philips, 2003

Synopsis

Ligt wear to cover. Shipped from the U.K. All orders received before 3pm sent that weekday.

About this title

About the Author

Peter Grego writes and illustrates MoonWatch, a monthly column in Astronomy Now, and edits three astronomy publications: Luna, the Journal of the Society for Popular Astronomy (SPA) Lunar Section, the SPA News Circulars and Popular Astronomy.

Excerpt. © Reprinted by permission. All rights reserved.

Introduction

Why Observe the Moon?

From all time the Moon has had the privilege of charming the gaze, and attracting the particular attention of mortals. What thoughts have not risen to her pale, yet luminous disk? Orb of mystery and of solitude, brooding over our silent nights, this celestial luminary is at once sad and splendid in her glacial purity, and her limpid rays provoke a reverie full of charm and melancholy.
Camille Flammarion, Astronomy for Amateurs, 1903

An evening twilight sky adorned with a gleaming crescent Moon is one of nature's most sublime spectacles. Our celestial neighbor has inspired poets and artists down the centuries, and though astronomers may know the Moon intimately these days, the lunar magic experienced by philosophers of old remains as powerful as ever.

Sunset, May 15, 2002. At the foot of the hill, my 33 lb backpack had felt comfortable on my back. Inside it is my trusty Maksutov telescope with its computer-driven altazimuth mount and lightweight aluminum tripod. Now, halfway up the hill, this "portable" instrument is growing heavy. Pausing to catch my breath, I turn to the darkening eastern sky. Rising toward the zenith is the deep purple swathe of the Earth's shadow -- the same shadow that tracks across the face of the Moon at a lunar eclipse. Several pale stellar flecks are now visible. Arcturus, the brightest of them, twinkles with orange starlight -- which, I muse, set out in 1965, the year I was born.

I continue up the slope toward the darkening orange-green sunset. As I near the brow of the hill, the distant cityscape of Birmingham, England, comes into view -- myriad streetlights amid dimming patterns of roads and buildings. Now on level ground, I round the line of oaks and sycamores to my left and scan the deep orange afterglow that hugs the sunset horizon. The first in tonight's grand planetary line-up, faint little Mercury, emerges from behind a tree trunk, just clear of the northwestern horizon. Saturn springs into view, higher in the sky, followed by a dim ruddy Mars and a truly dazzling white Venus. Finally, I catch sight of Jupiter and the crescent Moon, side by side in Gemini, their light playing through the leaves of an old oak. There's nobody around to hear my gasp of delight. Now at my observing site, I survey the whole splendid planetary array -- an alignment whose rarity has spurred me to to the top of Beacon Hill.

After setting up the telescope, which takes no more than five minutes, I gaze briefly at each planet though the eyepiece. For all the glamour of the planets, only one object can hold my fascinated gaze for more than a few moments the Moon. For the next couple of hours it will be mine to marvel at and explore. An observational drawing makes a fine record of the evening's viewing, but it also requires discipline and a certain degree of objective detachment. Tonight, I am enthralled by the shadow-play along the edge of the lunar crescent. My sketchpad and pencils will remain untouched this evening. I'm happy to be a bedazzled tourist now and again.

I stare at the Moon through a low-power eyepiece, taking in the whole gleaming crescent in the same field of view. I can see the faint, cool blue glow of earthshine on the dark side of the Moon. Beneath the prominent dark oval of the Sea of Crises near the eastern limb is the crater Cleomedes. As soon as I catch sight of it, my mind is transported back exactly nineteen years and a day, when the Moon was a crescent much like tonight, also in Gemini but then accompanied by Venus. Cleomedes was the first lunar crater I'd ever drawn. By any standards it was a clumsy effort -- in two hours of observing I reduced a remarkable crater to a wholly unremarkable sketch. Yet it had been a start, and I'd become hooked.

Since that time, through patient observing and recording, the lunar landscape has become to me a broadly familiar place, yet always full of wonder. Tonight only a sliver of Moon is visible, and the eastern lunar seas and their surrounding craters provide a visual delight until the Moon sinks into the haze above the city and its image dims, shimmers and degrades.

The Moon appears so big, bright and full of detail that the smallest optical instruments are capable of revealing more of its wonders. Through binoculars the crescent Moon is magnified into a sickle with a dented edge, while a telescope will transform it into a spectacular alien landscape. Most people who look at the Moon through the telescope do so for the pure visual pleasure it brings -- in its own way, an activity just as meaningful as the highest level of scientific enquiry. Anyone can admire the Moon and enjoy it at face value. Equally, everyone is at liberty to find out more about it.

Ever since Galileo first sketched the lunar craters, observers have wanted to keep a permanent record of their travels around the Moon's surface by sketching what they see through the eyepiece. Drawing the lunar landscape might seem an eccentric and outmoded pursuit, now that detailed images obtained by professional observatories and spacecraft are readily available. But lunar observers who take the trouble to sketch what they see will discover an immensely useful and rewarding activity which will improve every single aspect of their observing skills. It is the only way to thoroughly learn your way around the Moon -- looking at photographs is no substitute.

As you draw what you see through a telescope, your eye is being trained to register small details that the untrained eye might overlook. The Moon's surface is packed with very fine detail, and your ability as an observer to discern it will continually improve as you spend more hours at the eyepiece. With practice comes confidence and skill. The discipline of making accurate lunar drawings, learned at the eyepiece, will pay high dividends in other fields of amateur astronomy, such as planetary observation. If you can master the art of drawing lunar features, the planets and deep-sky objects will be easy to depict!

During the course of your lunar apprenticeship, the apparent confusion of the Moon's landscape, with its arcane nomenclature, gives way to an increasing familiarity. Once you have learned to record lunar features, you can begin to pursue programs of observation in earnest. These may be driven by a particular interest -- a passion for rayed craters, say -- or you can follow an observing program organized by an astronomical society.

Real discoveries can still be made by the skilled amateur lunar observer. Uncharted, unsuspected small-scale features can show themselves under very low angles of illumination. Lunar topography is virtually neglected by professional astronomers, so it's up to amateurs to keep the Moon under scrutiny. And it's possible that at some point in the future a small asteroid will carve out a new crater on the Moon large enough to be seen from the Earth. More than likely an amateur astronomer would be the first to detect such an impact and view the hot new blemish on the Moon's face.

Drawing is one specialized aspect of lunar observation. The Moon's surface can also of course be recorded in great detail by conventional photography, or by digital imaging using a digital camera, modified webcam, dedicated astronomical CCD camera or analogue/digital videography Learning how to master the appropriate techniques -- both at the eyepiece and in image processing at the computer -- can be just as demanding as learning how to observe and draw lunar features. Other, more exotic means of recording the Moon's surface include infrared imaging and spectroscopy.

As well as topographic studies, there are a number of exciting avenues to explore in the fleeting lunar phenomena that are occasionally visible. So-called transient lunar phenomena are apparent obscurations, glows or flashes on the Moon's surface which, because of their extreme rarity, observers must be vigilant and skilled to detect and record successfully. Occasionally the Moon passes in front of bright stars and planets. Such lunar occultations are a joy to observe and provide wonderful photo-opportunities. Across the world, thousands of amateurs routinely observe and time occultations of fainter stars. These timings are valuable scientific data, since they help in fine-tuning the parameters of the Moon's orbit and the rate of the Earth's rotation.

Bright occultations and solar and lunar eclipses make us more aware that the Moon is capable of producing some of nature's most spectacular sights. Equally as spectacular, the lunar landscape is accessible through the most modest optical equipment. Lunar observing is by far the most visually rewarding branch of amateur astronomy, and it's no wonder that for centuries the Moon has attracted some of the world's greatest telescopic observers. Our satellite's rugged surface provides the greatest show off Earth.

Peter Grego
Rednal, UK
February 2003

Edition details

• Publisher: Philips
• Publication date: 2003
• Language: English
• ISBN 10: 0540084190
• ISBN 13: 9780540084197
• Binding: Paperback