Star Puffs:

The topic will be "Star Puffs," that is, stars that appear other than the familiar pin-points of light that we see in telescopes and binoculars. We will have slides illustrating the photographic work of David Malin (Anglo-Australian Observatory) and more recent pictures by the Hubble Space Telescope. Our subjects will be the Eta Carinae Nebula, the Helix Nebula, the Crab Nebula, and the debris from supernova 1987A.

Unfortunately, views of these objects will be primarily confined to slides. Eta Carinae and supernova 1987A are too far south for observation from our latitude. The Helix Nebula (also known as NGC 7293) is half as large as the full moon, but very difficult to observe from Davis. It requires a very clear dark sky, and its position in the southern constellation Aquarius means it won't be well placed for viewing this month until the pre-dawn hours. Similarly, the Crab Nebula (also known as M1) is too close to the Sun for viewing this month.

However, there are several "puffed stars" that are more easily visible in the evening sky in June: the Cat's Eye (NGC 6543) in Draco; NGC 6210 in Hercules; and that old stand-by of summer star parties: the Ring Nebula (M57) in Lyra. After midnight is the best time to view the Dumbell Nebula in Vulpecula (M27) and Blinking Planetary (NGC 6826) in Cygnus.

More information on the stellar "life cycle" is on the evening sky map attached (for a free copy via the internet see www.skymaps.com).

So bring your telescopes and binoculars and let us hope for clear skies!

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Our May Meeting. Ten members came to our meeting May 6 at 8:00 p.m. - - despite the inclement weather. We had fun discussing Leo, a constellation that is quite prominent during May evenings. We also made planispheres, which are a virtual necessity for finding your way around the sky.

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Yes, our growing town will be the site of a large event sponsored by Astronomy Magazine to popularize the fun and education we enjoy as amateur astronomers! Would you like to be involved in it? Explorit's Tom Wickersham (530-756-0191) asks members of the club to assist either during the day at an Explorit booth or in the evening during the event's Star Party. Also, please inform friends and acquaintances about this upcoming event. Tom and I will try to keep you informed as details become more final. (Unfortunately, I will be out of the country during the event.) The DAVIS STAR SHOW is being coordinated by Patty Kurtz at Astronomy Magazine, Kym Calvert at the Davis Conference & Visitor's Bureau [(530) 297-1900] and amateur Kris Koenig of Chico.

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Q. Do we always see the same side of the Moon?
A. The part of the moon that we see from Earth is more-or-less always the same part of the Moon. If you look at this site: http://tqjunior.advanced.org/3645/phases_moon.html you will see how the Moon's phase changes but always has the same side toward Earth. More information is at this site: http://www.galaxies.com/Lesson/lesson2.htm

Q. Does the sun rise in the same place each morning?
A. Do you live north of the Equator, in Europe or North America, for instance? If you do, and if you go out every day between late December and mid-June to see where the sun rises and sets, you will notice that the points on the horizon where you see the sun rise and set are moving farther toward the North each day. If you go out and watch where the sun rises and sets from July through November, you will notice that the sun rises and sets farther to the South each day. This phenomenon is due to the tilt of the Earth's axis as it orbits the sun.

Q. How do the outer planets' motions in the sky appear from earth?
A. At certain times during our yearly orbit around the sun, it appears to us as though the outer planets (Mars and further) move back and forth against the stars. You can see this by pretending you are the Earth, moving around the sun. Make the sun approximately 4 feet away from you, and as you "orbit" the sun, watch a stationary (unmoving) object, approximately 10 or so feet away. That is "Jupiter." Of course, Jupiter does move in its orbit around the sun, just as the Earth does. But for this demonstration, we'll slow it down. Next, notice that, as you move around the "sun," the stationary object ("Jupiter") covers up different parts of the scenery behind itself. This apparent motion is due not to "Jupiter" moving, but to your motion. This apparent back and forth motion makes it seem to observers on Earth as though Jupiter moves with a little wiggle.

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To Receive These Bulletins via E-mail Contact Dennis Smith at: densmith@dcn.davis.ca.us

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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.