Comet ISON, a rare type of comet from outside the solar system, has brightened "considerably" in recent days and could be on the cusp of visibility to the naked eye in the night sky, scientists say.
Scientists are calling on the astronomy community and amateur skywatchers to closely monitor the comet as it nears a close pass by the sun later this month. They want to see whether the comet continues to brighten, and what that could mean is happening to it.
Astronomers have been tracking ISON since last September, when scientists from Belarus and Russia who are part of an international collaboration called the International Scientific Optical Network spotted its faint impression on images captured by a telescope near Kislovodsk, Russia. It has been observed by the Hubble Space Telescope, recently by the Messenger spacecraft orbiting Mercury, and by amateur astronomers.
But it remains to be seen how bright the comet could appear from here on Earth. Some early projections suggested it could become a "comet of the century" that could shine nearly as brightly as the moon, though those expectations have been tempered significantly.