Our Milky Way's central black hole has a leak. This supermassive black hole looks like it still has the vestiges of a blowtorch-like jet dating back several thousand years. NASA's Hubble Space Telescope hasn't photographed the phantom jet but has helped find circumstantial evidence that it is still pushing feebly into a huge hydrogen cloud and then splattering, like the narrow stream from a hose aimed into a pile of sand.

This is further evidence that the black hole, with a mass of 4.1 million Suns, is not a sleeping monster but periodically hiccups as stars and gas clouds fall into it. Black holes draw some material into a swirling, orbiting accretion disk where some of the infalling material is swept up into outflowing jets that are collimated by the black hole's powerful magnetic fields. The narrow "searchlight beams" are accompanied by a flood of deadly ionizing radiation.

"The central black hole is dynamically variable and is currently powered down," said Gerald Cecil of the University of North Carolina in Chapel Hill.

Although the chance of an asteroid impacting Earth is small, even a relatively small asteroid of about 500 feet (about 150 meters) across carries enough energy to cause widespread damage around the impact site. NASA leads efforts in the U.S. and worldwide both to detect and track potentially hazardous asteroids and to study technologies to mitigate or avoid impacts on Earth. If an asteroid were discovered and determined to be on a collision course with Earth, one response could be to launch a "kinetic impactor"—a high-velocity spacecraft that would deflect the asteroid by ramming into it, altering the asteroid's orbit slightly so that it misses Earth. NASA's Double Asteroid Redirection Test (DART) will be the first mission to demonstrate asteroid deflection using a kinetic impactor. 

DART will test kinetic impactor technology by targeting a double asteroid that is not on a path to collide with Earth and therefore poses no actual threat to the planet.

NASA's newest X-ray observatory rocketed into orbit Thursday to shed light on exploded stars, black holes and other violent high-energy events unfolding in the universe.

Chinese astronauts on Thursday beamed back a science lesson from the country's under-construction space station.

The lecture focused on physics, aiming to illustrate how the weightless environment affects buoyancy, the movement of objects and optics.