BEIJING, Nov. 6 (Xinhuanet) -- A comet unexpectedly exploded and brightened in the last couple of weeks, becoming a dramatic presence in the night sky, media reported Monday.

Comet Holmes, which appears in the northeastern sky as a yellowish fuzzy ball, can be seen by the naked eye, even in cities that pollute the night sky with light.

"This is a once-in-a-lifetime event to witness, along the lines of when Comet Shoemaker-Levy 9 smashed into Jupiter back in 1994," said Paul Lewis, director of astronomy outreach at the University of Tennessee.

Most comets build in size slowly, as streams of dust and gas form a nebulous atmosphere, known as a coma, around the solid core of a comet.

Comet Holmes, however, exploded in size and luminosity within hours on Oct. 23, because of some still-unexplained event that caused it to belch out a huge cloud of material.

"This is truly a celestial surprise," Lewis said. "Absolutely amazing."

But the comet is not as dramatic as some previous comets because it does not have the characteristic tail that makes some of these frozen wanderers so beautiful. Instead, it appears as a fuzzy, star-like object.

The comet can be found in the northeast by locating Cassiopeia, the W-shaped constellation that is a prominent feature of the autumn sky. Then, track to the lower right into the triangle-shaped constellation, Perseus. Comet Holmes is the yellow dot in the bottom left of that triangle.

(Agencies)