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Mercury magazine

Summer 2009 - Volume 38, Number 3

Summer 2009 - Volume 38, Number 3

Table of Contents



[15] Star-filled Nights and Galileo Moments, Ken Hewitt-White
Four hundred years ago, Galileo Galilei aimed his telescope at the heavens and began a scientific revolution. This summer, celebrate the International Year of Astronomy by looking up.

[20] Creating Readable Electronic Articles, Alan Gould
More and more journals are switching from paper copies to making the material available online. Here are some simple things to keep in mind if you’re creating digital content.

[24] Is Space Art Dead? (Part II), Lynette R. Cook
The evolving demand for space art has created trying times for space artists. In the conclusion of this article, Lynette Cook explores how artists are adapting to their new reality.

[31] Astronomy in the News
More discoveries at Mercury, a shrinking red giant star, and tidal debris from colliding galaxies -- these are some of the discoveries that have recently made news in the astronomical community.


[4] Editorial, Paul Deans
Look Up, Look Waaaaaay Up

[5] First Word, James G. Manning
Past, Present, and Future Perfect

[7] Astronomer's Notebook, Jennifer Birriel
Mystery of the Missing Supernova

[8] Planetary Perspectives, Daniel D. Durda
Kepler's New Worlds

[9] Armchair Astrophysics, Christopher Wanjek
A Black Hole's Elusive Signal

[10] Echoes of the Past, Katherine Bracher
25 Years Ago: Future of Space Astronomy

[11] Annals of Astronomy, Clifford J. Cunningham
Copernicus vs. Tycho and Buchanan

[12] Education Matters, David Bruning
Profiting from Magnitudes

[13] Societal Impact, Katy Garmany
The ASP's Bok Award

[37] Society Scope/ASP Supporters
ASP Award Winners

[42] Sky Sights, Paul Deans
The Sky of August, September, and October

[45] Reflections, Andrew Chaikin
Forty Years Past

Star-filled Nights and Galileo Moments

by Ken Hewitt-White

I'll never forget my first "Galileo moment." It was January 15, 1966, and the sunset sky over Ottawa, Ontario, was crystal clear. A novice stargazer, I was outside with my 2.4-inch refractor (a telescope with a main lens 2.4 inches in diameter) that I'd bought with the profits from my newspaper route. I wanted to see some planets and on that particular evening I had a fielder's choice: Venus and Mars were sinking in the west, Saturn was a bit higher, and Jupiter was ascending in the east.

During this summer of the International Year of Astronomy, I urge you to head outside and stargaze. To help, I've selected a number of targets you can explore with small optics (or just this article and your imagination) that are visible from early summer to early autumn. Ready? Let's gaze skyward.

Creating Readable Electronic Articles

by Alan Gould

Every year, more and more journals are switching from mailing paper copies to subscribers to putting material on the Internet either for free or via password-protected access. The primary driving force behind this is simple economics: the cost of publishing material online is a minuscule fraction of the expense of printing articles in a paper journal and mailing it.

The majority of people over 40 greeted the advent of online journals with much sadness and even some derision. "You'll take my hard copy out of my cold, dead hand before I'll read a journal online" has been the overt or implied attitude of many readers. Yet those same readers, simply by the sheer convenience and richness of information available on the World Wide Web, are forced to admit that they are reading more and more material on their computer screens.

Is Space Art Dead? (Part II)

by Lynette R. Cook

Broad, sweeping changes in the art world at large have eroded the ground beneath freelancers since the 1980s. The royalty-free CD containing clipart and illustrations (and the appearance of stock-image libraries); the maturity of the personal computer and the sophistication of graphics software; and the availability of spectacular space imagery from the Hubble Space Telescope and other telescopes and probes are just three examples of why many space artists feel the bottom is dropping out of their profession.

Are professional space artists just complaining, or do our comments reveal actual truths and major shifts in the space-art universe? To find out, I next took my investigation to a few key space-art users and sellers in order to get their perspective: Novaspace Galleries, which identifies itself as the world’s largest source for authentic space memorabilia; a number of astronomy and science magazines; and Science Photo Library, an image bank that pays their artists and photographers a royalty for every image used by their clients (unlike the stock houses described in the first half of the article).

Astronomy in the News
Vertical Structures in Saturn's Rings

NASA / JPL / Space Science Institute

The search for ring material extending well above and below Saturn's ring plane has been a major goal of the imaging team during Cassini's "Equinox Mission," the two-year period containing exact equinox — that moment when the Sun is seen directly overhead at noon at the planet's equator. This novel illumination geometry lowers the sun's angle to the ring plane and causes out-of-plane structures to cast long shadows across the rings' broad expanse, making them easy to detect.

The 5-mile-wide moon Daphnis orbits within the 26-mile-wide Keeler Gap in Saturn's outer A ring, and its gravitational pull perturbs the orbits of the particles forming the gap's edges. The eccentricity, or the elliptical deviation from a circular path, of Daphnis' orbit can bring it very close to the gap edges. There, its gravity causes larger effects on ring particles than when it is not so close. Previous Cassini images have shown that as a consequence, the moon's effects can be time-variable and lead to the waves caused by Daphnis to change in shape with time and with distance from the moon.

However, the new analysis also illustrates that when such a moon has an orbit inclined to the ring plane, as does Daphnis, the time-variable edge waves also have a vertical component to them. This result is backed by spectacular new images taken recently near equinox showing the shadows of the vertical waves created by Daphnis, and cast onto the nearby ring, that match the characteristics predicted by the new research.

Scientists have estimated, from the lengths of the shadows, wave heights that reach enormous distances above Saturn's ring plane -- as large as 1.5 kilometers (1 mile) -- making these waves twice as high as previously known vertical ring structures and as much as 150 times as high as the rings are thick. The main rings -- named A, B and C -- are only about 10 meters (30 feet) thick.