You’re Always Surrounded by Neutrinos! - NASA Science (.gov)

A core-collapse supernova occurs when a massive star reaches the end of its life. After running out of hydrogen and other light elements to burn, the star makes a last ditch effort to counter gravity, fusing ever heavier elements at an ever faster pace. Eventually it reaches the point where heavy fusion extracts energy from the core rather than adds it. The core rapidly contracts, then recoils. The resulting explosion rips the star apart and briefly outshines an entire galaxy. But not all giant stars end with a bang. Some of them experience a core collapse so quick and dense that the core squeezes itself into a black hole. These stars end with a whimper rather than a bang. So what exactly causes this difference? Why do some stars explode and others not? What key features distinguish between the two? The answer could lie in an aspect of neutrinos known as flavor.

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Explanation: Scientists are melting holes in the bottom of the world. In fact, almost 100 holes melted near the South Pole are now being used as an astronomical observatory. Astronomers with the IceCube Neutrino Observatory lowered a long string knotted with basketball-sized light detectors into each vertical lake. The water in each hole soon refreezes. The detectors attached to the strings are sensitive to blue light emitted in the surrounding clear ice. Such light results from fast-moving secondary particles liberated when high-energy neutrinos emitted by powerful processes out in the universe collide with ice molecules. IceCube has now detected many illuminating neutrinos. Pictured in 2010, one of the last of IceCube's detector strings is lowered into the freezing abyss, making IceCube the largest neutrino detector ever created. In recognition of unprecedented discoveries, it was announced earlier this week that a founding leader of the IceCube Collaboration will be awarded the Nobel Prize in Physics.