July 2001 Articles
Astro Chatter
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astro chatter
Astro Chatter
by Larry Kalinowski

Saturday, June 23rd, is the date for the WAS picnic. This event is always well attended and festivities begin around 4:00pm. If you attend, please bring a dish to pass or some kind of picnic goodie to share with others. If you have any astronomically related hardware or software to sell or swap, this is the place and time to show your wares. If you're into amateur rockets or kite flying, bring your equipment. Observing begins after twilight ends, and goes all night long, if weather permits. Visitors are welcome, of course. See you there.

By the time you read this, Mars will be out in full glory. The only bad thing about this year's close approach is the low angle the planet will make with the southern horizon during opposition. The next opposition, in 2003 will put the planet ten degrees higher in the sky. That combined with an even closer approach, will make Mars watching even more intrigueing. I can't wait to see the results amateurs will produce with those lower cost, more sensitive CCD's and video cameras.

If you'd like a new challenge, try to find the moons of Mars during the next couple of months. They can be found two and six Mars radii from the planet under darn good observing conditions, when the moons are at their farthest from the planet. Glare from the planet must be occulted with some mechanical device or by moving the planet out of the telescope field. This opposition and the next will provide the best opportunity for finding those satellites. To verify you've found one of the moons, watch it over a period of an hour to see if the moon remains the same approximate distance away from the planet and that the background stars move away. Other amateur observers have done it with at least an eight inch aperture. You can get information about where the moons will be located in the June, 2001 copy of Sky and Telescope, pages 102-104.

There's more than one way to detect extra-solar planets. The most popular method being the one that envoles measuring changes in radial velocity with a very sensitive spectrometer. The second method measures the change in stellar position, requiring extremely sensitive astrometry equipment. Both methods are possible because the common center of gravity between the star and planet cause the star to wobble or change position at a rate equal to the planets orbital period. A third and most interesting method is to measure the magnitude of a star and detect any changes in brightness caused by a planet that transits the star. This also requires sensitive equipment but it holds the most promising method for finding large quantities of planets because CCD's with the proper sensitivity can record stellar magnitudes in large areas of the sky. In fact, amateurs have already verified professional data using the same method. This third method will be used by the Kepler space probe, due to be launched during this decade. It'll be capable of observing a large portion of the sky, with a CCD capable of recording, for years at a time, hundreds of stellar magnitudes, even thousands, all at one time with that one chip. Since a planet the size of the Earth, at the same distance, transits a Sun sized star in about ten hours, It'll require long periods of observation and data collection. Of course, direct observation of a planet would be the quickest method for finding one, but telescopes capable of doing that aren't available yet. A proposed method for direct detection is being studied presently and surprisingly, it could be accomplished with two large sized telescopes using an interferometer detection scheme. The light coming from each telescope could be phased 180 degrees apart causing the star that is being studied, to disappear, leaving the light from any planet in the vicinity to remain visible, eliminating the problem of excessive glare from the asscociated star.

The June computer meeting, on the 28th, will be at Gary Gathen's home in Pleasant Ridge, MI. He's located at 21 Elm Park, three blocks south of I-696 and about half a block west of Woodward Ave. The July meeting will be on the 26th. New visitors will recieve a free planetarium program at the computer meeting. All meetings occur on the fourth Thursday of the month. Exceptions will be announced at the regular WAS meetings or passed along via the Boonhill.net WAS e-mail link.


The Warren Astronomical Society Paper
Volume 33, Number 7 July, 2001