Astronauts onboard the International Space Station report seeing flames that behave like jellyfish. Video of the microgravity phenomenon is a must-see.

Almost 30 years after the Montreal Protocol put the brakes on ozone-depleting chemicals, one compound remains stubbornly and mysteriously abundant in the atmosphere.

A NASA sounding rocket has confirmed that the solar system is inside an ancient supernova remnant. Life on Earth survived despite the nearby blasts.

Astronomers are not only discovering planets around distant suns, they are also starting to measure those worlds with astonishing precision.

Wake up early in mid-August to see Venus and Jupiter shining side-by-side.

Comet Siding Spring is about to fly historically close to Mars. The encounter could spark Martian auroras, a meteor shower, and other unpredictable effects. Whatever happens, NASA's fleet of Mars satellites will have a ringside seat.

Which is brighter--a flurry of Perseid fireballs or a supermoon? Sky watchers will find out this August when the biggest and brightest full Moon of 2014 arrives just in time for the peak of the annual Perseid meteor shower.

A mysterious X-ray signal from the Perseus cluster of galaxies, which researchers say cannot be explained by known physics, could be a key clue to the nature of Dark Matter.

NASA's New Horizons spacecraft is only a year away from Pluto. Researchers are buzzing with anticipation as NASA prepares to encounter a new world for the first time in decades.

The summer of 2014 will be bathed in moonlight as three perigee "supermoons" occur in consecutive months: July, August, September.