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The next PAS meeting is Friday May 11, 2018

7:30 pm, Room 5015, Foothill College

"Giant Reflectors of the 20th Century and Beyond"

by Dr. Ken Lum, Part IV

The reflecting telescope was invented by Sir Isaac Newton, and proposed by a few others in the late 17th Century in an effort to solve the problem of chromatic aberration that was plaguing refractors of the time. These early reflectors used metal mirrors made from a highly reflective metal alloy of copper and tin known as speculum metal. Development of this type of telescope reached its zenith in the late 18th Century due to the efforts of Sir William Herschel, a German immigrant who settled in England. With such telescopes Sir William, along with his sister, Caroline, discovered the planet Uranus along with numerous and previously unknown nebulae (we would call them ‘faint fuzzies” today) and star clusters along with a host of newly discovered comets. Adding their observations to those of Charles Messier in France, Herschel, and others developed the first deep sky object catalogues which eventually became the New General Catalogue (NGC) still in use today. In Ireland in the 1840s, Sir William Parsons, the 3rd Earl of Rosse pushed metal mirror technology even further with the building of the 72” “Leviathan of Parsonstown”. With this telescope, Parsons became the first person to see the spiral structure of what later became known as spiral galaxies.

        But reflector technology took the second half of the 19th Century to mature until silver on glass mirrors could be reliably produced. Then, even larger telescopes of up to 100” could be built with American astronomer, George Ellery Hale and his instrument maker, George Willis Ritchey leading the way at Mt. Wilson in southern California. With these telescopes, Hale and others were to make the most spectacular discoveries and setting the stage for the foundation of modern physical astronomy as we know it today.

Dr. Lum is retired from the practice of Emergency Medicine. Since high school he has also been an enthusiastic amateur astronomer, having built two telescopes at the Adler Planetarium in Chicago and a large Newtonian reflector when he re-entered amateur astronomy in 1986. He pursued his interest in astronomical photography during the 1990s and continues to study the history of astronomy and astronomical instrumentation. Dr. Lum is currently interested in ways to enhance the performance of small telescopes with the use of a photomultiplier eyepiece and astronomical video cameras. Since 1994, he has been traveling with the Antique Telescope Society, which annually visits different historical astronomical observatories.

Next Speaker in June 2018 -- please check back for details.      

 Location: Foothill College room 5015, next to Parking Lot 5
Bring $3 for a parking permit, and please avoid parking in STAFF spaces



The Peninsula Astronomical Society is a group of some 200 Bay Area astronomy enthusiasts of all ages and backgrounds. Some members are professionally trained in astronomy, others are just starting and have never looked through a telescope before. One thing that we all have in common is an interest in the sky.

The PAS holds meetings on the second Friday of each month at 7:30 pm on the campus of Foothill College in Los Altos Hills, CA (between San Jose and Palo Alto).  The meetings are usually held in Room 5015, next to Parking Lot 5 (see map). Each meeting features a speaker (or speakers) bringing us up to date on different topics in astronomy. The public is welcome to attend these meetings; there is no charge to attend.  Note, however, that there is a $3 charge for parking - visitor parking permits are available from the machines in the parking lots.  Please do not park in spaces marked "Staff" - you will be ticketed!

As part of its commitment to bringing astronomy to the public, the Peninsula Astronomical Society operates the Foothill College Observatory (click here for more information). The Observatory is staffed by members of the society who volunteer to conduct the regularly scheduled public programs.

In addition to operating the Foothill Observatory, the PAS has its own observatory in the nearby Santa Cruz Mountains. This location has AC power and room for members to set up their own telescopes at our monthly star parties. This site is also the home of the society's 12" telescope, available for member use after a checkout.

For informaton about membership in the PAS, click here.



PAS Logo clothing and other cool items are available at Cafe Press - click on the T-shirt:

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