Seeing the source of gravitational waves
In a landmark event that ushers in a new era for space research, astronomers recently observed a cataclysmic collision of two neutron stars in a far-off galaxy. That collision, known as a k ilonova, took place 130 million years ago, but the signals didn’t reach Earth until this August. Preceded by a death dance in which the collapsed stars spiraled toward each other, the collision created a flash of intense light and a burst of gravitational waves—faint ripples in the fabric of space-time that were theorized by Albert Einstein a century ago. The waves were detected by two facilities of the Laser Interferometer Gravitational-Wave Observatory (LIGO). Astronomers then trained their telescopes and other detection devices on the site, and were treated to a veritable cosmic fireworks display of gamma rays, radio waves, X-rays, and visible light. Until now, scientists had identified gravitational waves only from the collision of black holes, which aren’t visible. LIGO spokeswoman Laura Cadonati compared the difference to “the transition from looking at a blackand- white picture of a volcano to sitting in a 3-D IMAX movie that shows the explosion of Mount Vesuvius.” The kilonova created heavy metals such as gold, platinum, and lead, confirming long-held theories about the origins of these elements, reports CNN.com. Scientists say being able to see the source of gravitational waves will help them explain other phenomena, including how fast the universe is expanding.