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The Shallow Sky

Ecliptic Trick-or-Treating

Akkana Peck


It's been a long summer, with not much chance for planetary observing, but by the end of October, Venus should be up high enough in the sky around sunset to point out to trick-or-treaters. Jupiter and Saturn rise shortly thereafter, making a nice naked-eye grouping with Aldebaran and the Hyades in the eastern sky. Set up a telescope next to the candy dish this Halloween and give some youngsters (and their parents) a real treat this year!

On Jupiter, you can point out some of the moons (at least three will be visible during trick-or-treating hours) and the reddish equatorial bands and greyer polar zones. More experienced observers may see the fainter temperate bands, and transient features such as festoons (bluish swirls), white spots, and barges (dark spots). Alas, there won't be any moon or shadow transits for Halloween, and the Great Red Spot is on the other side of the planet until long after trick-or-treaters have gone to bed, but you can observe them on other nights!

Or you can wow your guests with beautiful Saturn, with its rings tilted at 24 degrees, enough to see the outer edge of the A ring all the way around (except for the area where Saturn's shadow falls upon it). Trick-or-treaters will love any view of the rings, and they'll be able to see Cassini's Division between the A and B rings, but during quiet moments of good seeing (later in the evening, when the planet is higher up in steadier air), look for the fainter C ring as a translucent grey band inside the B ring, and for the elusive darkening in the A ring, the source of so much controversy (is the "Encke Minimum" the same feature as the "Keeler Gap", and did DiVico really discover it first?) The banding on the planet itself is also lovely, much more subtle in its yellows, browns and creams than the obvious and colorful bands of Jupiter.

Venus is in gibbous phase, which probably won't be obvious to most trick-or-treaters, but at magnitude -4, it should be a lovely naked-eye sight. Be sure to point it out, if you have a clear western horizon.

Uranus and Neptune, too, continue to be well placed for observing this month, in Capricornus. With a medium-sized telescope from dark skies, you can probably see some of their moons: last month a group of SJAA observers picked up four of Uranus' moons, and Triton, Neptune's large moon, using the 30" at Fremont Peak; some of them were bright enough to be visible in 8" and 10" scopes. A planetarium program is the easiest way to locate moons of the outer planets.

Far Pluto is already fairly low in the southwest at nightfall this month. It's certainly still observable, but will become a harder target as the month wears on.

Mars rises a few hours before the sun. It probably won't show much detail in a telescope yet, but early risers can keep an eye on it and anticipate the upcoming Mars opposition next year.


Mail to: Akkana Peck
Copyright © 2000 San Jose Astronomical Association
Last updated: July 19, 2007

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