Looking Up: Mira the 'wonderful' star

Stars are wonderful. In fact, one remarkable star you can see tonight (if clouds go away) is Mira, named after the Latin word for "wonderful."

Also known as Omicron Ceti (but not so wonderful sounding, maybe), the star is one of the most well-known variable stars in the sky, changing brightness on a regular basis and on a broad scale. For a long time so dim it required a telescope to find it among many other faint stars, Mira is currently near maximum light and easily seen with unaided eyes. Be sure to find it and tell your neighbors that Mira is back.

Observed going through its brightness cycles for around 400 years, the star became even more wonderful in 2007, when NASA spied a long, faint tail streaming off the star, making it appear very much like a comet. Material blows off the star in its travels and forms a tail 13 light years long -- about 20,000 times the average distance of Pluto from the sun. Nothing like this has ever been observed around any other star.

The tail was picked up in a photograph recording ultraviolet light from the Galaxy Evolution Explorer space telescope orbiting Earth. Earth's atmosphere hinders ground observers from recording much of the ultraviolet light streaming down from stars.

Mira is classified as a red giant, an older star that has greatly expanded its gaseous girth. Such stars form a nebulous outer shell called a planetary nebula, one of the most famous being the Ring Nebula in constellation Lyra. In Mira's case, the star is breaking speed limits through the galaxy and leaving its nebulous shell in shatters in the form of this unusual tail.

Unfortunately you won't see the tail, but Mira -- and many other variable stars -- can be fascinating to watch and keep track of the magnitude from night to night or week to week. Thousands of backyard space bugs (better to say "amateur astronomers") have taken on serious study of variable stars as members of the American Association of Variable Star Observers (AAVSO). This is one area where astronomy hobbyists (another way to say it) can make valuable contributions to science. Unlike professional astronomers, the amateurs have a precious commodity -- their time -- to devote to prolonged and methodical observations. Likewise, amateurs have left their mark discovering comets, tracking strength of meteor showers and hunting down supernovae in distant galaxies, which show unexpectedly like a faint star among the "fuzz" of the galaxy in the hobbyist's eyepiece.

You don't have to commit yourself to dedicated observing programs, of course; casual observations whenever you have a chance are as near as the sky over your own back yard for your interest and enjoyment.

Mira is an estimated 400 light years from your town. Its brightness change was first recorded in 1596 by a German theologian and astronomer (these vocations can go together, contrary to some viewpoints!) David Fabricius. Every 333 days or so, the star rises from relative obscurity as a 9th- or 10th-magnitude star to as bright as 2nd- or 3rd-magnitude (similar to the principal stars of the Big Dipper). It is located in the constellation Cetus the Whale, situated in the "tail" of the whale and just past due south about 7 p.m. in mid-January. From mid-northern latitudes, look about halfway up the sky with an appropriate star chart in hand.

Although Mira's peak was in the last week of December 2008, it should be visible to the unaided eyes all month.

While Mira pulsates on its own, other stars vary in brightness due to a fainter star in orbit that periodically passes in front, dimming the brighter star. Easily the most well known is Algol, in constellation Perseus, which at 7 p.m. in mid-January is right overhead. Also called Beta Persei, it probably should be called "wonderful" as well. Every 2.8 days, Algol dips from magnitude 2.1 to 3.4 and back, taking several hours to fade and rebrighten. You can compare it with nearby stable stars of similar magnitude.

Last-quarter moon is Jan. 17, and new moon is Jan. 26, allowing for darker evening skies to see the stars. Be sure to enjoy dazzling, wonderful planet Venus high in the southwest after dusk. Look for Saturn rising in the east about 9 or 10 p.m.

Your (wonderful?!) comments, observing reports and photos, as well as questions may be sent to pbecker@wayneindependent.com. As this column is being carried nationwide thanks to GateHouse News Service, please mention which paper or Web site you read this column. Keep looking up!