A computer image generated by NASA shows objects orbiting Earth, including those in geosynchronous orbit at a high altitude. The objects are not to scale.
The Space Fence is down. That's the message we get from the SatWatch site, following up on our report last month that the U.S. Air Force was poised to shut down the radar system that tracks thousands of objects orbiting Earth. It had been in operation since 1961.
Glaciers in the Alps of Europe pose a scientific mystery. They started melting rapidly back in the 1860s. In a span of about 50 years, some of the biggest glaciers had retreated more than half a mile.
But nobody could explain the glacier's rapid decline. Now, a new study from NASA's Jet Propulsion Laboratory uncovers a possible clue to why the glaciers melted before temperatures started rising: Soot from the Industrial Revolution could have heated up the ice.
The Voyager 1 spacecraft launched in 1977 on a mission to Jupiter and Saturn. It kept on going. Today it's billions of miles from Earth, and scientists have been predicting it will soon leave the solar system.
A meteor trail is seen above a residential apartment block in the Urals city of Chelyabinsk on Feb. 15.
Credit AFP/Getty Images
The bus-sized meteor that slammed into Russia in February, causing a massive shock-wave and injuring hundreds of people, sent a plume of dust into the stratosphere that circled the globe in just four days and lingered for months, NASA says.
The Feb. 15 meteor at Chelyabinsk near Russia's southern border with Kazakhstan measured 60 feet across and weighed 12,000 tons. It detonated 15 miles above the city.