EXPLORIT Science Center - Astronomy Club Newsletter

We will discuss Leo, a constellation that is quite prominent during May evenings. We will also make planispheres, which are a virtual necessity for finding your way around the sky. We'll be checking the performance of our telescopes as we prepare for the summer observing session. So bring your telescopes and binoculars and let us hope for clear skies!

APRIL'S "DUAL MEETING" Our first dual meeting with the UC Davis Astronomy Club was great. Most of the members of the UC Davis club were, appropriately enough, college-aged. I was gratified that some members of our club were able to make an appearance, and several children were there to represent our "junior members."

We had a talk on double stars and extrasolar planets by Club President, Jason Cosman. Jason's talk focused on using the Doppler effect to detect luminous bodies (e.g. dim stars) or very dim bodies (e.g. large planets) that orbit brighter stars. He also showed that not all stars that appear "double" are actually gravitationally bound together. Some "visual doubles" merely appear "double' because of the way they lie along our line of sight.

After the presentation in Roessler Hall, we adjourned to the roof of the Physics building for entertaining stories about the legends behind the constellations and especially the circumpolar stars. Many telescopes were available, including the 4" Alvan Clark scope dated 1876. As Joseph Ashbrook noted in 1969: "There is a fascination about the name Clark among all telescope enthusiasts. . . .To the present day the reputation of the Clarks' lenses large and small is widespread, and the dream of many an amateur is to own a Clark telescope." Incidentally, S.W. Burnham discovered about 400 "double stars" with a 6-inch Clark refractor. Views through the UC Davis Clark scope were perfect. Thanks to the Club for this evening of information and fun, and I hope we can organize other meetings in the future.

Interested in the UCD Astronomy Club? Visit their web site at: http://maxwell.ucdavis.edu/~astro/. The club offers public viewing of the night sky from the roof of the Physics/Geology building, and in the Hutchison Hall observatory on various nights during the academic quarter. Current objects of interest such as constellations, planets, galaxies and nebulae, are pointed out and shown through the telescope(s).

Note, public viewing only takes place when the sky is clear! For more information and a list of viewing nights, please visit their online schedule. No internet access? Contact me and I will try to get the information you need.

Part I. The club set up two tables and three telescopes at the Davis Farmers' Market to introduce the public to Astronomy Day and our Club. One of the scopes was the club's 18.5 inch telescope, and it impressed the large number of passersby. To view the sun, I put a solar filter on my 8" SCT, but most of the viewing took place where Ben Granett was projecting an image of the Sun using his 6" Dobsonian. Explorit's Mr. Cordiality, Tom Wickersham, fielded questions about the 18.5" scope and Explorit, while I manned my 8 inch scope. We were busy answering questions about the Club, the Sun, and Explorit from 8:00 a.m. to 1:00 p.m. (the market's official close). Special thanks go to my sister and my wife who helped assemble and dismantle the 18.5 inch scope, and to Club member Ben Granett, who patiently answered the question "What are those spots on the sun?" at least 50 times during the 5 hours!

Part II. First, my apologies to those of you who attempted to follow my directions to the Dixon Astronomy Day event at Northwest Park. Instead of the "Pedrick" Road exit, I should have specified the "Pitt School" exit. After 45 minutes of driving around (and stopping to ask directions 3 times), I finally reached the proper rendezvous( half an hour late), at the corner of a large urban park.

This was not a dark sky site! Two streetlights were within 20 feet of the location, but that didn't matter tonight. Joseph Roeper of Dixon organized this event to do some "sidewalk astronomy." And who better to assist him than the regional band of "Sidewalk Astronomers" from Sacramento? I met Douglas Wolfe of the Sacramento Sidewalk Astronomers and several of his fellow club members. Inspired by John Dobson's work in San Francisco, several members had accompanied John to Death Valley and other areas bringing "telescopes to the people." It was a new experience for me to be among amateurs hawking the night sky to passersby. "Hey you! Come over here and see the moon!" People loved it. A constant troop of first-time Saturn watchers and long distance lunar explorers took some time out of their Saturday night routines to put their eyes to the eyepieces. Keep telling Dixon to "Look Up!" Joseph!

Q. Which planets are composed mostly of gases?
A. The planets beyond Mars. That is: Jupiter, Saturn, Uranus and Neptune, and Pluto. Most of the stuff these planets are made from would be gasses here on Earth (where it is warmer). Most of these gases are frozen on these planets, however.

Q. Which planet is icy in composition?
A. Water forms ice grains once you get past the asteroid belt between Mars and Jupiter. Out beyond Uranus and Neptune gases such as ammonia and methane freeze. Pluto is usually the farthest planet from the sun, so it would be the most icy of the planets. However, when it is at its closest approach to the sun, some of its ice "melts" into gas---so it is the most icy planet, but it is not always completely icy.

Q. Describe the protoplanet nebular hypothesis.
A. This is probably the most widely held theory about how the solar system formed. Very simply, the solar system formed from a cloud of dust and gas (mostly hydrogen gas). Due to gravitation, most of the material (about 90 percent or more) became the sun. Generally, heavier material was drawn to the center, where the sun was, while the lighter atoms remained in the outer regions farther away from the sun. Planets formed from gravitational differences in the outer areas. Small clumps of matter swept up more material and became larger. These bodies collided with each other and grew. Eventually, they became the planets we have today. So planets closer to the sun are generally made of heavier atoms (such as iron) , and those farther away are generally made of lighter atoms (such as sulfur). The planets probably formed about 4.5 billion years ago. Evidence for this hypothesis is in the chemical make up of the planets, and the evidence of craters, and the results of computer simulations.

Q. Explain how the sun produces energy.
A. At the center of the sun, it is 27 million degrees hot and a pressure about 200 billion times more than are in your bicycle tires. In that place approximately 700 million tons of hydrogen atoms are fused to eventually form helium atoms. This fusion converts 5 million tons of matter into energy, which begins to "boil" out to the sun's surface--a journey that could take over 1 million years. The major reason this happens is because of the extreme force of gravity at the center of the sun.

Note: These are short simple answers. But science is always discovering new things and scientists often discover that we had the wrong answer after all. That is what makes science exciting, but also makes it impossible to be sure you have the "right" answer all the time. For older readers and adults, try http://seds.lpl.arizona.edu/nineplanets/nineplanets/nineplanets.html

The Astronomy Club is hosted by Dennis Smith with the assistance of Tim Feldman and other eager astronomy buffs. The club is for everyone - adults, children, knowledgeable or ignorant. Come to listen, look and learn, or to share your expertise or experience.

ASTRONOMY CLUB NEWSLETTER

May 2000 Issue