Starry, starry nights

Posted: Sunday, January 10, 2010

The starry sky is now at its best with the most prominent stars being well placed high in the south: blue Rigel and red Betelgeuse in Orion, Sirius beneath it, Procyon to its left, Pollux and Castor higher up, Capella almost in the Zenith, and Aldebaran and the Pleiades completing the splendor.

The Big Dipper starts out close on the northern horizon but Cassiopeia, Perseus, and Andromeda are close to the Zenith. In the west Cygnus and Pegasus are about to set while bright Vega, being circumpolar in Alaska, stays close to the horizon.

Leo's Regulus and Mars rise in the evening, trailing Gemini and Cancer low in the east.

The chart shows the sky around 10 p.m in early January and 8 p.m. in late January. I inserted grid lines showing the altitude at 30, 60, and 90 degrees, and the azimuth also in increments of 30 degrees, starting from north. I chose not to show all constellations -- e.g. faint constellations Eridanus, Cetus, Pisces, Aquarius in the southwest are missing -- because the chart is already crowded enough.

Jupiter remains the brightest night object (save our moon of course) in the entire sky in the early evening hours; look for it above the southwestern horizon.

Neptune is near Jupiter, Uranus to the upper left just below the circlet of Pisces which itself is south of Pegasus' Great Square.

All three planets are joined by the waxing crescent moon from the 17th through the 19th.

Mars is visible all night, rising just ahead of Regulus in the evening in the northeast. The full moon is near Mars on the 29th.

Saturn rises around 1 a.m. in the east, ahead of Virgo's Spica. The waning gibbous moon is near it on Feb. 2.

Venus is in superior conjunction on the other side of the sun, hidden by its glare.

Mercury rises just ahead of the sun in mid to late January but it's so low on the southeastern horizon in Alaska that it's close to impossible to spot -- unless you happen to be in Chinitna Bay during a clear January dawn, looking in that direction.

Earth is nearest the sun on Jan. 3 (91.4 million miles) while we will be farthest on July 6 (94.5 million miles).

I accidentally forgot to write about a couple of things last semester -- but I do have excuses.

There was a partial lunar eclipse during the full moon on Dec. 31 visible from Alaska. The reason I missed it is threefold: the eclipse map I'm using shows that predominantly Africa, Asia, and Europe saw the eclipse; the Earth's shadow cut out only a very small portion of the moon; and the moon appeared very low above the Western horizon during morning dawn at around 10 a.m.

So as not repeat the same lapse, I refer to June 26, 2010, midnight through 4 a.m., during which time we can see a similar partial lunar eclipse from southern Alaska.

And this one I definitely won't forget to mention in detail: a great total lunar eclipse on Dec. 21, 2010, visible from all of North America.

There was a "blue moon" on Dec. 31. The reason I missed it is onefold: astronomically it's not important (only for calendar aficionados it's interesting).

But in response I read up on it and found out that our current interpretation of what a blue moon is, is founded on a misinterpretation perpetuated by the venerable astronomy sources Sky & Telescope magazine (see the article "What's a Blue Moon" on and the popular StarDate radio show. To call the second moon in a month a blue moon rests on an S&T error made in 1945 and spread to a wide audience by StarDate in 1980.

Instead the presumably original definition for a blue moon is based on the given names for each full moon throughout the year as listed in the Farmer's Almanac. Each season usually hosts three full moons, e.g. winter the Full Wolf, Snow, and Worm Moon, with names adopted and adapted by European settlers from Algonquin tribes.

However, the moon's phases take a 29.5 day long cycle, so about every third year will see a season with four full moons instead of three. The third of those four full moons within one season was called a Blue Moon. That definition presumably goes back to a computus used 500 years ago in England for calculating the date for Easter which could be messed up if there are four full moons in winter. To keep the last full moon of the season as the correct one, the third one was renamed "belewe," an Old English word meaning either "blue" or "betrayer," hence the name origin. Now the first, second, betrayer, third, would keep the Easter calculation (first Sunday after first full moon after spring equinox) intact.

According to that original definition autumn of 2010 will see four full moons with the Full Corn in September, the Full Harvest in October, the Full Blue on November 21, and the Full Beaver Moon in December.

Andy Veh is an associate professor of physics and mathematics at Kenai Peninsula College.

Subscribe to Peninsula Clarion

Trending this week:


© 2018. All Rights Reserved. | Contact Us