SJAA Ephemeris February 2001 | SJAA Home | Contents | Previous | Next

The Shallow Sky

Giants Start Sinking

Akkana Peck


The twin gas giants, Jupiter and Saturn, still rule the night sky. Still ensconced in the Hyades star cluster, they're surrounded by a myriad stars of roughly the right magnitude to be confused with planetary moons. Using a small telescope, can you tell the moons from the stars? Hint: color and steadiness (the moons should twinkle less than nearby stars) should help set them apart from nearby point-source stars.

This month is a good month to watch the giants before they start sinking into the sunset sky. This has been a fascinating Jupiter apparition, with the Great Red Spot showing redder than it has in years, lots of turbulent activity in the SEB separation trailing behind the spot, white rifts appearing and disappearing from the North Equatorial Band, a new thin tropical band appearing in the north, and numerous though faint festoons streaming into the equatorial zone. It changes from day to day - don't miss it!

Saturn has also been very interesting: its generous ring tilt makes the gap in the A ring much easier to see than in past years, and there's been some nice color in the banding on the planet. As we race ahead of Saturn in our shorter orbit, we should be able to watch the shadow of Saturn on its own rings grow throughout the month.

Turn to look to the western sky, and you can't miss Venus, blazing to its greatest brilliancy of the year, magnitude -4.6, on the night of the 22nd. If you haven't pointed a telescope at it yet, or even if you have, late February is a good time to do so: it's still high enough to get a good look, but it's moving into crescent phase and growing rapidly larger. You may be able to see it change over a period of a week or two: keep watching! If you start early, while it's still high in the sky, look for the difficult greyish markings on the surface of its clouds, or for the even more elusive "ashen light" that some observers swear sometimes illuminates the dark side of Venus. No explanations for this phenomenon are really satisfactory: it could conceivably be volcanic or atmospheric activity on Venus, or it could be purely imagination on the part of the observers who have reported it. I haven't seen it myself, and I'm not convinced it exists - but you can bet I'll be looking for it just in case!

Early risers (or people staying up late) can get a preview of this year's Mars opposition. The red planet rises after midnight and is already starting to grow and show small amounts of detail. In addition, it's quite close to Antares, whose similarity in color and brightness earned it its name, the "Rival of Mars" (Ares being the Greek equivalent of the Roman god Mars); don't miss the battle as Mars passes its rival and grows brighter in the process. On the morning of February 21, it passes very close to Beta Scorpii; the two should make a nice sight in a telescope.

Mercury, Uranus, Neptune and Pluto are not well placed for observing this month.

February is also the beginning of the season for looking for the zodiacal light. This faint band of light, extending upward from the horizon at sunset (or at sunrise at other times of year) and following the ecliptic, is caused by dust and debris orbiting the sun in the plane of the ecliptic - think of an extremely wide belt of microscopic asteroids. It's very faint and very large - think Milky Way - so you usually need very dark and transparent skies to see it. Take a look!


Mail to: Akkana Peck
Copyright © 2001 San Jose Astronomical Association
Last updated: July 19, 2007

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