Astronomy Hacks: Tips and Tools for Observing the Night Sky - page 86


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The tool on the cover of Astronomy Hacks is a refractor telescope. Although magnifying glasses and burning glasses had been known since classical times, and eyeglasses were in use by 1300, it was not until the final decade of the 16th century that instrument makers first created optical instruments for scientific exploration.

The first simple microscopes were built by brothers Zacharias and Hans Janssen, about 1595. Although the telescope seems a logical follow-on to the microscope, no evidence exists that any telescope was built prior to 1608. The invention of the telescope is sometimes credited to Zacharias Janssen or James Metius, but evidence suggests that spectacle maker Hans Lippershey was the first to construct a telescope.

One day, while holding a spectacle lens in either hand, Lippershey happened to view a nearby church steeple through both lenses and was astonished to see that it appeared larger than before. He mounted the lenses in a tube to adjust and preserve their spacing, and thereby invented the refractor telescope.

Lippershey applied to the Dutch government for a patent, which was denied because he was unable to prove that he was the sole inventor. The government officials, however, recognized the value of Lippershey's invention. They bought his original telescope for 90 florins and paid Lippershey well to produce additional telescopes for them.

Opticians and instrument makers throughout Holland were soon producing telescopes, and within a year telescopes were being made throughout Europe. In 1609, Galileo Galilei, after reading a description of the telescope, constructed his own instrument and turned it to the heavens. Galileo first used his telescope to discover the moons of Jupiter, sunspots, the phases of Venus, and the craters and valleys on the Lunar surface. With his telescope, Galileo proved the Copernican heliocentric theory by establishing that the apparent motion of Jupiter's four moons could be explained only if those moons orbited Jupiter, and that the phases of Venus established that Venus must be orbiting the Sun.

In 1671, Isaac Newton reinvented the second major type of telescope, the reflector, by using mirrors rather than lenses to collect and focus light. Since the 17th century, the craft of telescope making has been refined continually. We now have telescopes that enable us to see objects billions of light years away to the edge of our universe. There are also telescopes that capture energy such as radio wave emissions, gamma rays, and x-rays. But the refractor telescope, refined but essentially unchanged since the days of Lippershey and Galileo, remains a popular and useful scientific instrument.

Marlowe Shaeffer was the production editor and proofreader for Astronomy Hacks. Darren Kelly and Claire Cloutier provided quality control. John Bickelhaupt wrote the index.

Mike Kohnke designed the cover of this book, based on a series design by Edie Freedman. The cover image is an original photograph provided by Al Nagler. The background image is from Getty Images. Karen Montgomery produced the cover layout with Adobe InDesign CS using Adobe's Helvetica Neue and ITC Garamond fonts.

David Futato designed the interior layout. This book was converted by Keith Fahlgren to FrameMaker 5.5.6 with a format conversion tool created by Erik Ray, Jason McIntosh, Neil Walls, and Mike Sierra that uses Perl and XML technologies. The text font is Linotype Birka; the heading font is Adobe Helvetica Neue Condensed; and the code font is LucasFont's TheSans Mono Condensed. The illustrations that appear in the book were produced by Robert Romano, Jessamyn Read, and Lesley Borash using Macromedia FreeHand MX and Adobe Photoshop CS. This colophon was written by Lydia Onofrei and Robert Bruce Thompson.