Star light, star bright, the first star you see tonight might not be a star at all. In fact, it might be a comet -- if you live in Australia, that is. This week, the McNaught Comet, known officially as C/2006 P1, will make its way through Australian and New Zealand skies in one of the brightest arcs on record.
Just how bright? Brighter even than Halley's Comet, and bright enough to be seen with the naked eye.
Last Friday, the comet reached its perihelion -- the point at which it comes nearest the sun -- and may have rivaled Venus for brightness, according to reports. Such is the power of the Sun's reflected light. At its perihelion, comet McNaught was still nearly 16,000,000 miles, or 0.17 astronomical units, away from the Sun.
The McNaught Comet is best seen at sunrise or sunset, but experts caution stargazers to shield their eyes from staring directly into the sun, even when using binoculars. (No less an astronomer than Galileo was said to go blind from too much sun-gazing, although experts suggest the real cause of his blindness was the more earthly condition of cataracts or glaucoma.)
NEOs and SOHO
Comet McNaught was discovered in August of 2006 by Robert McNaught, one of two staff members at the Siding Spring Survey in Australia. Using a telescope called the Uppsala Schmidt, the survey scans the skies for NEOs, or Near Earth Objects, in conjunction with its sister program in the northern hemisphere, the Catalina Sky Survey based near Tucson, Arizona. NEOs include not only benign comets but more sinister comets, asteroids and other objects that may impact the Earth.
The McNaught Comet was a routine discovery and one of 29 made with the Uppsala Schmidt telescope in the last three years. And while it will no doubt be seen by thousands of eyes on the ground, it will also be the object of scrutiny from SOHO, the space-based Solar & Heliospheric Observatory launched jointly by NASA and the European Space Agency to examine the sun.
In fact, SOHO examines the sun from the inside out -- that is, from the Sun's core to the furthest reach of its outer corona. (The corona is the uppermost layer of the sun's atmosphere. It can be seen, much like a halo, during a solar eclipse, and it gives rise to solar wind.)
Comet McNaught will pass through SOHO's field of vision in such a blaze that researchers expect it to overpower the satellite's on-board cameras, which are designed to observe faint solar corona and not ultra-bright comets.
In the Northern Hemisphere, reports indicate the McNaught Comet has been seen by the naked eye as far north as Norway and as far south as the plain states in the U.S. Few experts believe it will be as bright as 1965's record-setting Ikeya-Seki, but it may be the brightest comet in the last 40 years, according to a statement from the Siding Spring Survey.