Telescopes Excellent Gifts for Christmas 2008
They Will Be Appreciated in International Year of Astronomy 2009
Sep 20, 2008
In the 17th Century, Holland’s Hans Lippershey, Italy’s Galileo Galilei and England’s Isaac Newton developed the telescope. Their contributions and the instrument will be highlighted when the world celebrates the International Year of Astronomy 2009 (IYA2009).
Because IYA will open January 15-16, 2009, the telescope may be a very appreciated 2008 Christmas gift for children, amateur astronomers and outer space buffs.
IYA2009 is sponsored by the International Astronomical Union and UNESCO. They say its purpose is "to help the citizens of the world rediscover their place in the Universe through the day- and night-time sky, and thereby engage a personal sense of wonder and discovery." The opening ceremony will be held in Paris.
Some historians credit Lippershey with inventing the telescope. They say he placed two lenses at opposite ends of a long tube and sold the idea to the Dutch military, but was never able to obtain a patent.
Galileo Developed Refracted Telescope
Galileo is credited with improving Lippershey’s "spyglass" into the first refracted telescope. He wrote that he constructed "so excellent an instrument that objects seen by means of it appeared nearly one thousand times larger" than with normal vision.
Newton later developed the first reflecting telescope, using a mirror instead of a lens to capture the light and do away with the normal halo effect common to refractor telescopes. Choosing between refractor and reflector types is one of the serious decisions to be made in selecting a telescope.
The first decision, however, is deciding what the telescope will be used for. Is it for a child who might develop an interest in seeing a few planets and stars or is it for someone with a serious interest in astronomy?
Cheap "Department Store" Instruments
Telescope experts look critically at what they call cheap "department store" instruments. But that might be all a kid needs until he shows a serious interest in the science. Something under $200 may also suit the needs of a casual adult star gazer.
These units require few accessories and most all parts come as standard equipment, so few decisions are needed.
More expensive and sophisticated instruments require more decisions regarding the specifications of interchangeable lenses and accessories. They can run into thousands of dollars.
Refractor Telescope Preferred for Viewing Planets
Omni-Optical says the refractor telescope is preferred for viewing moons, planets and the sun; for terresterial viewing; for reliability, maintenance, ease of use and sturdiness.
The reflector telescope is considered better for viewing galaxies and other deep space. It’s large aperture scopes are compact and light and its cost-per-inch of aperture is less than that of the refractor.
Experts warn against falling for telescopes that are sold on the basic of their magnification power. In the book, How Stuff Works, Dr. Craig Freudenrich says the magnification or power "has little to do with the optical performance of the telescope and is not a primary consideration."
Large apertures are a better indicator of optical performance. But Freudenrich says that in most cases a 3-inch aperture is sufficient on a refractor and a 4-to-8 inch aperture is usually sufficient on a reflector telescope. Bigger apertures can be tough to handle and move.
Other checkpoints: Make sure the focuser moves smoothly and the mount is steady. Look for an eye-piece holder that has a 1.25 or 2-inch diameter so that it will accept most eyepieces.
References:
- International Year of Astronomy 2009.com
- How Stuff Works.com
- Molecular Expressions/Florida State University website
- Omni-Optical.com
- Dr. Craig Freudenrich, "How Telescopes Work", how stuff works.com
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