Five Amazing Things About Black Holes
Credit: EHT Collaboration
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Five Amazing Things About Black Holes

10 April, 2021 / Read time: 3 minutes

To celebrate two years since the EHT Collaboration, in which ALMA had a key rol, released the first image of a Black Hole, we are happy to share five impressive things about these incredible objects.

1. Before knowing what black holes were, in 1784 geologist John Michell called them dark stars! The idea of black holes stems from Albert Einstein's theory of general relativity, which says that light is affected by gravity.

Artist impression of the heart of galaxy NGC 1068, which harbors an actively feeding supermassive black hole. Arising from the black hole’s outer accretion disk, ALMA discovered clouds of cold molecular gas and dust. This material is being accelerated by magnetic fields in the disk, reaching speeds of about 400 to 800 kilometers per second. This material gets expelled from the disk and goes on to hide the region around the black hole from optical telescopes on Earth. Essentially, the black hole is cloaking itself behind a veil of its own exhaust. Credit: NRAO/AUI/NSF; D. Berry / Skyworks

2. The first simulation of a black hole was a drawing of the accretion disk, made by hand, around a black hole, based on computer calculations by French astrophysicist Jean-Pierre Luminet in 1979.

Credit: CNRS Phototheque

3. Black holes are regions in space where gravity is extreme. Everything that comes too close is sucked in, and nothing can ever get out again. Even light, traveling at 300,000 kilometers per second, cannot escape the gravitational grip of a black hole!

Sagittarius A*, taken by NASA's Chandra X-Ray Observatory. Ellipses indicate light echoes. Credit: NASA/CXC/Caltech/M.Muno et al.

4. Black holes cause huge jets of matter! - Most of the matter near the edge of a black hole ends up falling into it. However, some of the surrounding particles escape moments before capture and are propelled into space at great distances in jets.

M87 Jets as seen by th EHT. Credit: EHT Collaboration

5. The Event Horizon Telescope (EHT) collaboration, which produced the first-ever image of a black hole released in 2019, has a new view of the massive object at the Messier 87 (M87) center galaxy: how it looks in polarised light. This is the first time astronomers have been able to measure polarization, a signature of magnetic fields, this close to the edge of a black hole.

This image shows the polarised view of the black hole in M87. The lines mark the orientation of polarisation, which is related to the magnetic field around the shadow of the black hole. Credit: EHT Collaboration

Impressive isn't it? We anticipate that next week, from April 12 to 16, NASA will organize its Black Hole Week, so you can continue to be surprised by these incredible objects, formerly called "dark stars."

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