What is the biggest black hole as seen from Earth?
And what are our prospects for observing its event horizon?
“Never look down to test the ground before taking your next step; only he who keeps his eye fixed on the far horizon will find the right road.”
If you collapse a large enough mass into a small enough volume, you’ll create a black hole.
Every object has a gravitational field, and without enough speed, you can’t leave it; you can’t reach escape velocity.
For black holes, where escape velocity is bigger than the speed of light at the event horizon, nothing can escape, not even light.
Black holes are formed from the collapse of incredibly massive objects: ultramassive stars imploding in supernovae at the end of their lives.
But common, stellar mass black holes, at 1–100 times the Sun’s mass, are surpassed by rarer, supermassive ones.
Almost every galaxy has one, including our Milky Way.
At 4 million solar masses, our black hole is only 26,000 light years away.
Other, larger, more distant galaxies, like Messier 87, have even larger black holes, reaching into the billions of solar masses.
Later this decade, an array of radio telescopes — the Event Horizon Telescope — comes online.
With a resolution of 10 micro-arc-seconds (μas), it should see the Milky Way’s supermassive black hole’s event horizon.
With an angular diameter of 37 μas, no other black hole appears larger from Earth.
Mostly Mute Monday tells the story of a single astronomical phenomenon or object primarily in visuals, with no more than 200 words of text.
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