Week of March 9-15, 2014

Stargazers who spend time in rural locations get to see remarkable celestial phenomena that are often invisible — and sometimes completely unknown — to those living near the bright lights of a city.

For example, the number of stars scattered across the clear, dark skies of the mountains or deserts is easily in the thousands. How many people get to enjoy such a sight? Then there's the Milky Way, the starry belt of light that represents the central plane of our galaxy; and the distant star clusters, nebulae and galaxies known to astronomers as "deep sky objects," many of which are visible to the naked eye as hazy patches of light when viewing far from the devastating effects of light pollution.

All of these are visible on most nights of the year from rural locations, but there's another remarkable phenomenon — one that can be seen during late dusk only during late winter and early spring; it's known simply as the zodiacal light.

This mysterious glow was described nearly a millennium ago by the Persian poet, Omar Khayyam in his famous book "The Rubaiyat." Today we know that it is produced when sunlight is scattered from dust particles spread along the plane of our solar system. Most of these are continually generated by passing comets or by collisions among asteroids; each is only about four-hundredths of an inch across and separated by an average distance of five miles.

Because it generally appears brightest in the direction of the sun, we can see the zodiacal light best only after the end of evening twilight or before the onset of morning twilight, and then only at times when the plane of our solar system (the ecliptic) forms a steep angle with the horizon. These conditions — along with an absence of moonlight — occur for only a few weeks after evening twilight in February and March, and before morning twilight in September and October.

To see it this week, you must head to a dark, rural site far from the blazing lights of cities and suburbs, and you'll need a clear and dark sky to your west. If you have these, begin looking about an hour after sunset for a large and softly glowing pyramid with its wide base near the western horizon and its tapered end above the constellation Taurus.

In its brightest parts, the zodiacal light easily exceeds the brilliance of the Milky Way, which, at this time of the evening, appears to flow mostly from south to north across the heavens. You may it easier to spot the zodiacal light about an hour and a half after sunset, but much later than that it will simply disappear into the darkness.

Stargazers who have never seen the zodiacal light tend to expect a much smaller or brighter glow. Often it appears to ascend to one-third or even halfway up in the western sky. Its base typically appears to be some 15 degrees wide, and the cone tapers to only about 5 degrees wide at the top.

Good luck with this one ... it's a challenge. But if you spot it, you'll be talking about it for many years to come.

Talk with Dennis Mammana at www.facebook.com/DennisMammana and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.