The Official Publication of the Bucks-Mont Astronomical Association, Inc
©2002 BMAA, Inc
- by Antoine Pharamond
Well, three very productive Executive meetings have resulted in a proposed revision to our By-Laws. A vote to ratify the new By-Laws will be held at the January General Membership meeting, or at the next meeting with a quorum present.
'NASA Space Place' column inside
Wednesday, December 4 at 8:00p - BMAA General Meeting at Peace Valley
Wednesday, December 18 at 8:00p - BMAA Business Meeting at Peace Valley
The next BMAA General Meeting is scheduled for Wednesday, January 8 at 8:00p
BMAA MESSAGELINE - 215/579-9973
The CONSTELLATION is the official publication of the Bucks-Mont Astronomical Association, Inc, a 501(c)3 non-profit organization incorporated in the Commonwealth of Pennsylvania and exists for the exchange of ideas, news, information and publicity among the BMAA membership, as well as the amateur astronomy community at large. The views expressed are not necessarily those of BMAA, but of the contributors and are edited to fit within the format and confines of the publication. Unsolicited articles relevant to astronomy are welcomed and may be submitted to the Editor.
Reprints of articles, or complete issues of the CONSTELLATION, are available by contacting the Editor at the address listed below, and portions may be reproduced without permission, provided explicit acknowledgement is made and a copy of that publication is sent to the Editor. The contents of this publication, and its format (published hard copy or electronic) are copyright ©2002 BMAA, Inc.
In an effort to transmit the CONSTELLATION electronically to the membership of BMAA, please provide a current e-dress to the Editor. Abbreviated issues are available on the web site, but complete editions will be e-mailed to members in good standing.
Submission deadline for articles is the 15th of the month prior to publication.
WYCOMBE PA 18980-0333
Bucks-Mont Astronomical Association, Inc
2002 Calendar of Events
StarWatch Chairman: Antoine Pharamond, 215/412-9291 email@example.com
Information Line - 215/579-9973
NASA Space Place
Enlightened by the Darkness
- by Diane K Fisher
On the clearest of nights, I may see a dozen stars from my suburban backyard near Los Angeles. Unfortunately, my studies of space and astronomy have been confined to books and the pictures taken by others. Seldom have I experienced for myself a truly dark, clear, moonless sky.
One of those rare times was a summer camping trip in Bryce Canyon, Utah. I lay on my sleeping bag in an open area away from trees. I saw millions of stars (so it seemed) and the cloud of the Milky Way streaking across the sky. Nothing of planet Earth was in my view. It was then I glimpsed my true situation in the universe, a speck of dust clinging to a tiny stone hurtling through the darkness of a cold, infinite universe. I was awestruck by the beauty of the stars and the darkness-and terrified!
In the light of day and a more "down-to-Earth" state of mind, I wondered: With around 100 billion galaxies out there, why is it still so dark out there?
Until the 20th century, astronomers thought the universe was infinite. They were perplexed though, because in an infinite universe, no matter where you look in the night sky, you should see a star. Stars should overlap each other; the sky should be blazing with light and hot as the sun. This problem became known as "Olber's Paradox."
Astronomers now realize that the universe is not infinite. A finite universe-that is, a universe of limited size-even one with trillions of stars, just wouldn't have enough stars to light up all of space.
Although a finite universe is enough to explain the darkness, the expansion of the universe also contributes. As light travels from a distant galaxy to us, the space through which the light is traveling is expanding. Therefore, the amount of energy reaching us dwindles all the time, thus causing the color of the radiation to be "redshifted." (The wavelength is stretched out due to cosmic expansion.) The more distant the galaxy, the more redshifted the light. The largest redshift astronomers have measured comes from radiation that was emitted when the Universe was only 300,000 years old. This radiation has taken over 12 billion years to reach us and although it began as infrared radiation, it is now seen as the microwave background radiation.
GALEX (Galaxy Evolution Explorer) is a NASA space telescope that will survey the universe, including galaxies with redshifts that indicate their light has been traveling for up to 10 billion years (or 80% of the history of the universe). Read about GALEX at http://www.galex.caltech.edu/. For budding astronomers, print out The Space Place New Millennium Program calendar at spaceplace.nasa.gov/calendar.htm to identify great sky watching opportunities.
The GALEX (Galaxy Evolution Explorer) mission will do a broad survey of galaxies in various stages of evolution and identify interesting objects for further study by the Hubble Space Telescope.
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Diane K Fisher is the developer and writer for
The Space Place web site.
This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
The planets are coming
- by Bernie Kosher
Early evenings in December we find Saturn well up by 10 or so, and Jupiter about two hours behind. But the main show will be later in 2002, primarily from June through October, when Mars makes its closest approach and therefore largest presentation in 500 years.
The two gas giant planets are both bright and large, and offer spectacular viewing for the amateur. Even a small, good scope will show much detail. A three-inch refractor in steady air will easily show more detail on these planets than I can readily draw. A 6" will bring out at least five of the moons of Saturn and possibly show the Enke minimum in the A ring. Just as a side note, the division in the A ring ascribed to Enke was first noted by Keeler, and should probably be called the Keeler Gap or Division.
Mars will be a sight to behold when it reaches maximum size at about 25 seconds of arc.
However, we must be ready for the subtle detail on the 'red planet' by training the eye to see faint and low contrast details. So start on the giant planets by checking at every opportunity. You will not 'see' at first look. Training the eye requires many minutes of patient waiting for those moments of extra stable seeing and becoming accustomed to the 'normal' appearance. When those seconds of really stable seeing occur we can then pick up faint markings previously not even suspected.
When I first started making an effort to see detail on the planets, I was sure my scope was inferior. At the time I was using an 8" f/5 reflector. I ascribed my failure to see the details, on Jupiter in particular, drawn by people with smaller scopes to a loss of contrast due to a large secondary mirror (1.8" diameter) and a slight overcorrection amounting to about 1/4 true wavefront error. But I continued to try. After a number of sessions I began seeing some traces of markings in the equatorial bands.
One night, when the seeing was exceptionally stable, I fired up the scope and prepared myself to see the same few dark bands and a scheduled transit of Io. Not paying particular attention to the body of the planet, I watched Io encroach on the disk, appearing brighter than the ball of the planet (due to limb darkening). But this night, instead of losing the satellite disk as it went further onto the planet, it remained visible. Then it would appear to blend in for a few minutes, and reappear. How odd. Well, I realized the satellite was moving across festoons and loops projecting from the North and South Equatorial Belts.
I have written before about the Red Spot currently being more a pale pinkish gray. This night Io crossed 'below' the Red Spot and appeared a distinct yellowish against the planet and made the spot appear redder than I had seen it since the mid '60s, when it was a much darker orange.
The moral of all this........be prepared to spend some time each observing session. More than just a few minutes of watching are necessary to pick out the minutest detail. Herschel and others have stated that it requires several minutes for the eye to become accustomed to the glare of the planet. So give it a bit of time.
Some hints. Try different powers. Refocus every few minutes to rest the eye. Try a Barlow instead of short focus eyepieces. Perhaps a color filter will make contrast improvements. Be sure to stay warm, and avoid uncomfortable positions. Need I remind you to keep both eyes open? Squinting is very tiring to the eye.
Pay close attention to the area under scrutiny, but also keep the eye moving every half minute or so. Staring tires the eye.
I'm asking a favor of those who do observe these planets. There are a number of notes in various books about aspects of the planets which interest me. If you do observe, here's a list of things to pay some extra attention to, and if you would pass them on to me I would be grateful. Even if the observations are negative. Simple drawings or notes are much better than memory, even if your draftsmanship is as poor as mine. A 'strip' drawing is easy to make and need not be perfect to convey more than words.
Jupiter...(note- for those just starting on the planets- belts are dark, bands are light- consult any decent book for further inf.) (Also, Jupiter is currently moving into a position where the equator is aligned with the Earth and the satellites can eclipse each other)
a) note the limb darkening.....as satellites move onto or off the disks make a note of which appears darker or brighter and if there is a color contrast
b) there have been reports of the satellites 'flickering in brightness' as they move onto or off the disk.....this may be illusory but I'd like to hear it anyway
c) look carefully at the equatorial belts for festoons, loops and especially light or dark spots
d) phase effects....the moons may be hidden by the slight darkening for a few minutes or seconds while apparently not touching the ball of the planet
e) make an estimate of brightness of each moon, and look to see if a disk is visible
f) when a moon is in transit, see how long and where it is visible, and whether it show a disk
g) how many and how wide are the belts in relation to each other
i) uneven darkness of the belts
j) detail on the red spot or the red spot hollow (light or dark spots or arcs)
And of course anything else.
Saturn...ring and moons
a) how many moons and how bright?
b) Cassini's division should be easy. Does it look equally dark on both sides? Is it equally wide? Are there any local brightening or darkening?
c) intensity gradients in the A B or C rings.....local light effects
d) crepe ring intensity, dark crossing the ball of Saturn, light at the ansae (the ansa is the furthest extension of the rings on the east or west)
e) relative widths of the A, B, and C rings
f) does the planet look centered in the rings? I know that sounds odd, but look for it anyway.
g) look for Daroff's dots at the point where the rings go behind the planet (these are dark dots about half the ring thickness....once seen they are obvious)
h) Terby's spot....an apparent brightening at the ring/planet boundary
i) at the inner ansae of the B ring. look for local darkening, which may be spoking and on the planet itself
a) belts, bands, spots
b) limb darkening, and polar darkening effects
c) the shape of the planet (some observers have seen strange flattening or lumpiness, apparently a seeing effect)
d) any evidence of color anywhere (usually requires a large amateur scope)
e) if you are fortunate enough to observe an occultation of a star, note the dimming in the rings and the fading in the atmosphere at the limb and anything else of interest.
Naturally, I would like to know the conditions. Rate the seeing on a simple scale. Pickerings scale is almost universally used, being from 1 to 10 (some also add 11 and 12), with 1 being useless and 10 perfect. The numbers relate to the size of the diffraction disk of a star in focus at high power. Seeing of 1, 2, or 3 would indicate star images are bloated to beyond the first diffraction ring and the night is useless for fine detail. Seeing 4 is marginally useful, with the stars twinkling badly and enlarged to the size of the first ring. Seeing 5 and 6 have the first ring occasionally visible in the image. Seeing of 7 approaches 'good' and is about what we would call the limit for true useful observing. Seeing of 8 or 9 would indicate the first diffraction ring is always visible but in some degree moving or broken. Seeing 10 is a fantasy in our neck of the woods. I'm not sure I've ever seen a 10 for more than just a few seconds. Sometimes in the summer or spring, hazy skies on a night of unchanging temperature with no wind will produce seeing that will reveal the planets in their glory.
Anyhow, let me know how you make out.
And then comes Mars. Your eye will be ready for the faint detail and low contrast. You really can see all the detail shown in most Earth based photos, but not from your living room couch.
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- BMAA member Bernie Kosher <firstname.lastname@example.org> provides 'Observing' each month. [ -ed]
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