M87 — The First Portrait
On April 10, 2019, humanity saw a black hole for the first time. The now-famous orange ring belongs to the supermassive black hole at the center of the galaxy M87 — a picture that took a planet-sized telescope, two years of computation, and an international team to make.
Image: EHT Collaboration. The first direct image of a black hole, released April 2019: M87*, about 6.5 billion solar masses, 53 million light-years away. The dark center is the shadow; one side of the ring is brighter because that gas is racing toward us.
Why M87 first?
M87 is a giant elliptical galaxy in the constellation Virgo, and its central black hole is a monster — roughly 6.5 billion times the Sun, one of the largest in our cosmic neighborhood. That size is precisely why it was chosen. Although it lies 53 million light-years away, far beyond our own Sagittarius A*, it is so enormous that its shadow appears about the same size on our sky. And because its gas orbits over days rather than minutes, the image holds still long enough to capture — unlike our own faster, smaller black hole, which took three more years to photograph.
M87 was already famous for one feature visible in ordinary telescopes: a jet of plasma thousands of light-years long, blasted out from near the black hole at nearly the speed of light. Astronomers had suspected a supermassive black hole was the engine behind that jet for decades. In 2019 they finally saw the engine itself.
A telescope the size of Earth
No single telescope on Earth could resolve something so small and distant — it's like reading the date on a coin in another city. So the Event Horizon Telescope linked eight radio observatories across the globe, from Hawaii to the South Pole to Spain, into one virtual instrument effectively the size of the whole planet. Each site recorded so much data — hundreds of terabytes a night — that it was faster to fly stacks of hard drives between continents than to send the data over the internet.
Then came two years of painstaking work combining the signals, timed against atomic clocks, into a single image. The result confirmed Einstein's general relativity in the most extreme gravity ever tested: the shadow was exactly the size and shape the theory predicted. The image earned the informal Hawaiian name Powehi, "the adorned fathomless dark creation."
What the picture is and isn't
"It's an ordinary photograph." — No; it's a radio image, reconstructed from data gathered by eight telescopes and assembled by careful computation, not a snapshot from a single camera. "The orange is the real color." — The color is added; the data are radio waves, and the hue was chosen to show brightness. "We're seeing the black hole itself." — We're seeing its shadow — the dark region — outlined by glowing gas; the black hole emits no light. And "the whole ring is equally bright" — it isn't: the lower part glows brighter because that gas is sweeping toward us at nearly light speed, exactly as relativity predicts.
Supermassive Black Holes · TON 618 · What Is a Black Hole? · Black Holes Hub · Glossary
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