From the December 2005 issue

Glenn Chaple’s observing basics: Blinded by the moonlight

December 2005: Bright moonlit skies hide fainter meteors, diminishing the visual impact of these cosmic fireworks.
By | Published: December 1, 2005 | Last updated on May 18, 2023
Would you attend a Fourth of July fireworks display if it were held at midday? Probably not. The midday Sun would all but obliterate the event. For a similar reason, skygazers tend to pass up meteor showers that occur around Full Moon. Bright moonlit skies hide fainter meteors, diminishing the visual impact of these cosmic fireworks.
The Full Moon
This 0.25-second exposure of the nearly full moon was taken with a 6.1-inch Astro-Physics refractor and double green filters.
Gregory Terrance
Such is the case with this year’s Geminid meteor shower. Among the richest and most reliable of the annual meteor showers, the Geminids are expected to reach peak activity the evening of December 14. Unfortunately, a nearly Full Moon will be on hand to spoil the fun. But even if you’re not a meteor aficionado, step outside for 15 to 20 minutes, just to see what’s going on. Meteor showers can be unpredictable, and you never know what you’ll see.

We’ll have better luck with the Ursids. This meteor shower tends to fall under the radar for two reasons. It’s a relatively minor event, averaging a mere 10 meteors hourly (although brief outbursts of 50 or more per hour have been reported), and it occurs at a time of year when most of us are caught up in the holiday rush. I’ve never witnessed an Ursid meteor for the aforementioned reasons, plus clouds have foiled my efforts in recent years. Weather permitting, I’ll be outside the evening of December 22, reclining in a lawn chair and bundled up against the cold as I gaze northward toward the shower’s radiant: Beta (β) Ursae Minoris. A bright gibbous Moon won’t rise until nearly midnight, so I’ll have several hours to capture my first Ursid. Because I’m competitive, I challenge you to an Ursid meteor count — who sees the most in a single hour. Any takers?

A few gift ideas
Visit to read my review of the book The Stargazing Year by Charles Laird Calia. A delightful, fact-filled, month-by-month romp through our night skies, as well as a humorous account of the author’s attempt at constructing an observatory, The Stargazing Year is a must-read for novice and experienced skywatchers alike. After you buy Calia’s book, be sure your subscription to Astronomy will carry you through until the end of 2006.

Finally, pick up a copy of our annual guide, Explore the Universe 2006. As the New Year arrives, read Calia’s chapter on January. Use the all-sky map from the January issue of Astronomy to locate the sky sights Calia describes and the January notes from Explore the Universe 2006 for enrichment. Then, go outside and get to know the heavenly wonders that greet our eyes that month. Do the same in February and ensuing months.

I recommend this tactic for the beginner eager to learn about our night sky’s stars and constellations. But you veterans might enjoy reviewing old night-sky friends as Calia presents them.

The great Mars hoax of 2005
As I reflect on the past year, I’m amused by the fact that the biggest astronomical event of 2005 never happened — at least, not in 2005. Early last summer, several readers e-mailed me inquiring about an unusually close August opposition of Mars they had heard about. One report claimed that, to the unaided eye, Mars would appear as large as the Full Moon! Locally, several acquaintances, including my brother, asked me about this story. I was surprised because Mars was due for an opposition, but not until November. Were the heavens suddenly coming undone? A little detective work provided the answer.

Apparently, descriptions of the close opposition of August 2003, still out there on the Internet, confused people who didn’t read the date carefully. The result was a false rumor — NASA ultimately called it the “Mars hoax” — that a great opposition would occur in August 2005. Lesson: Read carefully any astronomical info gleaned from the Internet. Better yet, check out for the real story.

Next month: We explore the Moon and take a “power trip.” Clear skies.