Snapping a black hole’s silhouette is like photographing an orange on the moon.
The year 2019 is here. With it, we’ve been promised a splendid moment in astronomy. For years, the Event Horizon Telescope has been working to bring us the first ever telescopic photograph of the event horizon of a black hole.
Astronomers orchestrated radio dish telescopes across the world into an Earth-size virtual camera for a bold new experiment attempting to deliver the first-ever image of a black hole. The telescope collaboration is set to make a big announcement of results this week, and members also described their research approach at a talk in March.
Black holes are extreme warps in space-time that are so strong, their massive gravity doesn’t even let light escape once it gets close enough.
Black holes are massive structures when compared to planets and humans. But what seems large to us, is, on a galactic scale, teeny-tiny. So photographing a black hole’s event horizon complicated.
To observe the supermassive black hole at the center of the Milky Way galaxy, or to view another of the project’s targets — the supermassive black hole at the core of the supergiant elliptical galaxy Messier 87 — the EHT team had to turn Earth into a virtual telescope platform. That’s because the magnifying power of a telescope is limited to the size of its dish, and by using an array of instruments across the world, the team is effectively breaking up the dish and scattering the pieces globally to make one big space eye.
The unveiling will take place almost exactly a century after images of stars askew in the heavens made Einstein famous and confirmed his theory of general relativity as the law of the cosmos. That theory ascribes gravity to the warping of space and time by matter and energy, much as a mattress sags under a sleeper, and allows for the contents of the universe, including light rays, to follow curved paths.
General relativity led to a new conception of the cosmos, in which space-time could quiver, bend, rip, expand, swirl like a mix-master and even disappear forever into the maw of a black hole.
To Einstein’s surprise, the equations indicated that when too much matter or energy was concentrated in one place, space-time could collapse, trapping matter and light in perpetuity.
Einstein disliked that idea, but the consensus today is that the universe is speckled with black holes waiting to vacuum up their surroundings. Many are the gravitational tombstones of stars that have burned up their fuel and collapsed.
Any lingering doubts as to their existence vanished three years ago when the Laser Interferometer Gravitational-Wave Observatory, or LIGO, detected the collision of a pair of distant black holes, which sent a shiver through the fabric of space-time.
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The size of any black hole is always proportionate to its mass, so some may only be a few times the mass of our sun, which are called stellar black holes, while others are millions or billions of times the mass of the sun — supermassive black holes believed to anchor the constellations of galaxies.
The Event Horizon Telescope project has pinpointed two supermassive black holes to study: Sgr A*, which lays at the heart of our Milky Way galaxy, and M87, a giant elliptical galaxy located in the constellation Virgo.