Ryukyu Astronomy Club Newsletter
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Volume 1, Issue 4 June 2002

Next Club Meeting - June 8th
Conference Room B at the Camp Lester Naval Hospital

May Meeting
The May meeting of the Ryukyu Astronomy Club was held the 11th of May, 2002 in the Navy Hospital's Conference Center. Only four members attended but we hope that was due to the terrible weather - we had rain all that day and night. There was a presentation on deep sky objects (DSOs) with an introduction of open clusters. Future presentations will focus on other DSOs such as globular clusters, nebulae and galaxies. Afterwards everyone sat around and chatted about astronomy before calling it a night.

Things to See This Month
On June 11th Okinawa will be treated to a partial solar eclipse. (The June Sky and Telescope even includes the time of the event for Naha, Okinawa - probably due to our contact with them to receive their Astronomy Day aids.) The Moon will make first contact with the Sun (so to speak) at about 6:30 AM. At approximately 7:23 the Moon will produce the maximum coverage of the Sun's surface, biting into the Sun about halfway. Due to the early time of day and the relatively small coverage, this will not produce much of a darkening of the sky. The final contact will be about 8:24 as the Moon moves from in front of the Sun.

To get a safe view will require either a safe filter or a method to project the image onto a light surface. Solar filters suitable for normal viewing of the Sun are safe for viewing eclipses as well - so if you have a solar filter for your telescope or binoculars this would be an excellent time to use it. It is also safe to view an eclipse through #14 welder's glass, but since welder's glass is not reliably marked, this can be extremely dangerous and lead to permanent eye damage.

Projection methods are very safe and allow a group of people to observe simultaneously. A simple and effective projection viewer can be made with two small pieces of white poster board, say 9 inch square. Cut a small opening about 1" square in the center of one of the pieces. Tape a piece of aluminum foil to cover the opening. Then use a straight pin or needle to poke a tiny hole in the foil. (Alternately you can poke the pin hole directly in an uncut piece of poster board, but the edges of the hole will be ragged and the image will suffer.) During the eclipse, let the light pass through the pin hole and project onto the second piece of poster board. Move the poster board closer together and further apart to adjust the size and sharpness of the image.

Now let's just hope for a clear morning on the 11th!

Neutron Stars
What might happen if a star a bit larger than our Sun was to run out of gas - well, hydrogen really. The enormous energy released in a star by the fusion of hydrogen is what supports it's great weight. The out-rushing radiation keeps all that weight from crushing down into an incredibly dense core. When the hydrogen runs out on a star larger than our Sun, the result is often a nova or possibly a supernova - an extraordinary explosion that blows much of the star's mass out into space. But sometimes not everything is dispersed. In some cases an incredibly dense sphere remains - a neutron star.

The three main building-blocks of atoms are electrons, protons and neutrons. Electrons are negatively charged and protons are positively charged. Like magnets, two electrons will repel each other (as will two protons) unless they are part of an atom. Atoms with electrons and protons can only get so close together before the repulsion force prevents them from getting any closer. A sphere of pure electrons cannot exist, nor can a sphere of pure protons.

But, neutrons have no charge, so a sphere of pure neutrons can become incredibly dense. The remnant of a supernova - a neutron star - is such a sphere. Astronomers are still forming theories on the deep core of neutron stars, but basically it consists of particles (mostly likely neutrons or more exotic forms of matter) that are closer together than is possible in normal matter. The shell of a neutron star is almost certainly about 200 meters of solid iron.

Beyond their composition, neutron stars are odd in other ways. Despite their high density and large mass, they spin at an incredible rate - sometimes more than 100 revolutions per second. And a mechanism that is not yet fully understood turns that rotation into pulses of X-rays and other radio waves. In fact, in the 1960s astronomers detected fast, blinking radio wave sources that they named pulsars due to the detection of these pulses. They soon decided that the only likely source for these pulsars were neutron stars. And the density of their matter is incredible - imagine a spoonful of matter that weighs more than a billion tons!

In the year 1054, Chinese astronomers noted a brilliant star that wasn't there before - a supernova in the constellation we now call Taurus. It was so bright they recorded it was visible for 23 days - in full daylight! Today it is known as the Crab Nebula - object 1 from Messier's catalog. The cloud of energized gas that we can see in telescopes harbors a neutron star, visible only by the X-rays it continually emits. The X-rays indicate it rotates at 30 times per second. Consider taking a ball the size of a city, with the mass of our Sun, and spinning it at 30 times per second - conditions that are truly unbelievable. Viewing M1 will be the closest most of us will get to seeing a neutron star.

Visit http://imagine.gsfc.nasa.gov/docs/science/know_l1/pulsars.html to learn a little more about neutron stars in largely non-technical terms. Visit http://csep10.phys.utk.edu/astr162/lect/neutron/neutron.html for a more technical discussion.

Other Club Business
We are still on the look-out for a good dark site that is within easy driving distance. Maeda point on Zampa Cape looks promising and we will attempt it this month if the weather permits. Other suggestions are welcome. Additionally, it would be nice to find a truly dark site somewhere far North or South. The ideal location would allow for tent camping and have restroom facilities. We would likely only use such a site once or twice a year (as a group activity) for a true all night star party. Keep this idea in mind when you are traveling around the island.

Clear Skies!


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