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This Earth-spanning telescope will peer deep into black holes

X-ray image of the Milky Way’s own black hole Sagittarius A*.

Our planet just became a giant telescope.

Scientists are harnessing a global network of radio telescopes to glimpse at the gigantic black hole at the center of the Milky Way. The goal is to capture the first-ever images of a black hole and glean more data about these mysterious gravity-pulling fields.

From April 5 to 14, hundreds of astronomers around the world will coordinate observations to create the equivalent of an Earth-sized telescope dish, called the Event Horizon Telescope (EHT).

"These are the observations that will help us to sort through all the wild theories about black holes. And there are many wild theories," said Gopal Narayanan, an astronomy research professor at the University of Massachusetts Amherst who is part of the EHT project.

Image: X-ray: NASA/UMass/D.Wang et al., IR: NASA/STSc

Sagittarius A* is the black hole at the center of the Milky Way galaxy.

"With data from this project, we will understand things about black holes that we have never understood before," he said this week in a statement.

Although the black hole Sagittarius A* has a mass 4 million times that of the sun, it’s still 26,000 light years away, making it impossible to image with just a single telescope.

"That’s like trying to image a grapefruit on the surface of the moon," Narayanan said.

The EHT project links up eight millimeter-wavelength telescopes in Hawaii, Arizona, California, Mexico, Chile, Spain, and Antarctica. Together, participating observatories will study the event horizon at the center of the Milky Way.

Image: NASA/JPL-Caltech

An artist’s drawing shows the current view of the Milky Way galaxy, the center of which is a supermassive black hole.

The strategy of joining several telescopes to create a simulated larger dish area has actually been used for decades, Narayanan said. But this project is the first time millimeter-wavelength Very Long Baseline Interferometry has been used on such a massive scale.

Throughout the 10-day campaign, the global telescope will also study the supermassive black hole at the center of galaxy Messier 87, which lies 53.5 million light-years from Earth. That black hole is 6 billion times the mass of our sun, so the event horizon around it is even larger than that of Sagittarius A*.