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Event Horizon Telescope Captures First-ever Image of a Black Hole

Damian Pope, PhD, Senior Manager Scientific Outreach, Perimeter Institute for Theoretical Physics

What is the Event Horizon Telescope?
The Event Horizon Telescope (EHT) is a network of radio telescopes spread across the globe. By pooling data from each instrument, it achieves the same effective resolution as a dish the size of the entire planet!

What did it discover?
The EHT collaboration has just released the first event-horizon-scale images of M87*, a supermassive black hole at the centre of galaxy M87. The image shows an asymmetric ring of light surrounding a circular shadow. The ring of light is not the accretion disk, it is the footprint of the relativistic jet created by M87*. The asymmetry is evidence for the direction of the black hole’s spin. The size of the shadow reveals the mass of M87* which can then be used to calculate the radius of the event horizon. Note, the shadow is not the event horizon.

Why is this big news?
Prior to this release, every image of a black hole was either an artist’s rendition or a computer simulation based on our best understanding of light and gravity. The M87* images are the first-ever direct images of black hole — empirical data to test our theories. The shape, size, and relative brightness of the shadow match predictions based on Einstein’s general theory of relativity. These images provide support for general relativity in the most extreme environment to date.

How can you learn more and engage your students with the discovery?
Perimeter Institute has resources to bring this cutting-edge physics into your classroom.
To build your background, visit Inside the Perimeter for a comprehensive news story, summary videos, and a panel discussion explaining the results. You can also challenge your students to align the EHT telescopes in this interactive simulation.

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