Most astronomical observatories are up high. That gives them a clearer view of the heavens.
But some go deep. They’re submerged in the oceans, or buried deep in the ice at the south pole. They use the water, ice, and the solid Earth to screen out most energy and particles. That occasionally allows them to catch a neutrino — a “ghostly” particle that’s raced far across the universe.
Huge numbers of neutrinos are produced by the Sun and other stars. The most powerful appear to come from some of the most violent places in the universe — like the regions around giant black holes. So neutrinos can reveal details about what’s happening in those locales.
But neutrinos zip through space, stars, and planets. They almost never interact with other matter. The only way to “catch” one is to look for a rare flash of light created when a neutrino does hit something.
Those flashes are overpowered by radiation and particles from other sources. So astronomers have built — or are in the process of building — giant observatories in the ice at the south pole, and deep under water. They consist of hundreds or thousands of light detectors spread across a wide volume. The water and ice block out most sources of interference.
Astronomers in China are working on the biggest of all. It would cover several miles of the South China Sea, and contain almost 25,000 detectors — a giant, wet telescope for catching ghostly particles.