A once-in-a-lifetime comet is approaching the sun — and it will be visible for the first time in 160,000 years. The comet will also be at its closest point to the Earth and might become the brightest ...

Dark comets are often small, just a few metres to a few hundred metres wide. This leaves less surface area for material to escape and form into the beautiful tails we see on typical comets.

NASA scientists are closely studying a new class of celestial objects known as "dark comets", the little-known celestial objects which have been challenging the human understanding of both comets ...