Humanity's view of the universe is being obscured by increasing amounts of space junk, glare from city lights and radio signals, endangering astronomers' ability to study the cosmos, scientists warned.

"Astronomy addresses the fundamental questions that many of us wonder about: Where do we come from? What's going to happen to our sun? What is the evolution of the universe?" Andrea Dupree of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said Monday. "This is a science that we really can't afford to lose."Astronomers depend on their ability to use a variety of types of telescopes on Earth and in space to detect faint energy in such forms as visible light, X-rays and infrared signals.

"This means that astronomers look to place their instruments in many places. On the surface of the Earth, we search for high mountain tops or we search for quiet valleys and we search for deserted plains," she said.

David Crawford of the Kitt Peak Observatory in Tucson, Ariz., said light pollution already has made it impossible for people in most places to simply enjoy the stars, and it is threatening astronomers' ability to work.

"Light pollution, which continues getting worse and has in many places gone up exponentially, will remove forever our view of this natural wonder - the universe," he said.