Astronomers creates giant, earth-sized telescope to capture image of a black hole
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| Black holes may not have event horizons, but fuzzy surfaces./PBS |
The closest astronomers have come to directly “seeing” a
black hole happened last year, when the LIGO observatory detected the
spacetime-warping gravitational waves radiating from a pair of black holes that collided some 1.3 billion years ago.
That’s cool. But for astronomers, it’s not enough. What’s
eluded them is a view of the event horizon, the boundary of the black
hole from which, when crossed, there is no return. After the event
horizon, gravity is so intense that not even light can escape.
But, this week, a massive international array of the most powerful radio telescopes on the planet set its sights on the most camera-shy subject of all, the black hole. Badassly known as the Event Horizon Telescope, the global web of telescopes seeks to capture the first image of the supermassive black hole at the center of the Milky Way.
Normal radio telescopes aren’t capable of seeing the closest known black hole to Earth, affectionately known as Sagittarius A*,
though at 26,000 light years away, it isn’t exactly close. Researchers
have gazed at the suspected black hole for years, so at least they know
where to look — you can’t exactly find these things on the fly.
Paradoxically, the rim of a black hole is actually extremely bright,
as soon-to-be black hole food heats up while sliding toward the event
horizon, nearing the point of no return. That’s how scientists are able
to locate a black hole’s neighborhood, but to really get a good look
isn’t half as easy.
While it isn’t unusual for a radio telescope to actually
be comprised of a whole bunch of telescopes in something known as an
array, the Event Horizon Telescope (EHT) takes that to the next level,
combining a collection of the world’s most sophisticated telescope
arrays into one seriously powerful mega-array.
Those telescopes are located all over the world, from the Atacama Submillimeter Telescope Experiment in Chile’s northern desert to Hawaii’s James Clerk Maxwell Telescope on Hawaii’s Mauna Kea. The collaboration even includes the South Pole Telescope,
located near the southernmost point on the planet. Their spacing around
the globe is a feature, not a bug — maximizing the distance between the
mega-telescope’s component parts effectively ups the resolution of the
resulting combined image.
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Even with the international collaboration, it’s a tricky
task. Looking for an event horizon is like looking for a needle in a
haystack, except the needle isn’t visible at all — you can only just
barely discern its subtracted outline in the surrounding hay. It isn’t a
search for nothing, but rather a search for the edge of nothing. (Whoa.)
The Event Horizon Telescope’s observations will run from April 5 to April 14,
intercontinental good weather permitting. That means they’re well
underway now, so let’s hope that the Event Horizon Telescope,
purpose-built for black hole hunting, has a shot at doing what nothing
else can.
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