An international team of astronomers has captured the first image of a supermassive black hole at the center of our own galaxy, the Milky Way.
The image, produced by a global team of scientists known as the Event Horizon Telescope (EHT) collaboration, is the first direct visual confirmation of the presence of this unseen object, and comes three years after the first-ever image of a black hole of a distant galaxy.
“For decades we have known of a compact object at the heart of our galaxy that is four million times more massive than our Sun,” said Harvard University astronomer Dr Sara Issaoun.
“Today, right now, we have direct evidence that this object is a black hole.”
The image does not show the black hole itself – because it is completely dark – but the ultra-hot plasma* and gas that surrounds the phenomenon* in a bright ring-like structure.
This luminous halo* swirls around the edge of the black hole beyond which nothing, not even light, can escape its gravitational pull*.
Dr Issaoun said that from Earth the black hole would be about the same size as a donut on the surface of the Moon.
Geoffrey Bower, EHT project scientist, Academia Sinica in Taiwan, said: “These unprecedented* observations have dramatically improved our understanding of what is happening at the very center of our galaxy.”
The black hole was given the name Sagittarius A* (pronounced A-star), or Sgr A* for short, because it was detected in the direction of the constellation Sagittarius.
Located 27,000 light-years from Earth, its existence has been presumed since 1974 when an unusual radio source was detected at the center of the galaxy.
In the 1990s, astronomers mapped the orbits of the brightest stars near the center of the Milky Way, confirming the presence of a supermassive compact object there, work that led to the 2020 Nobel Prize in Physics.
Although the presence of a black hole was considered the only plausible explanation*, the new image provides the first direct visual evidence.
Capturing images of such a distant object required linking eight giant radio observatories across the planet to form a single virtual “Earth-sized” telescope called the EHT.
“The EHT can see three million times sharper than the human eye,” said German scientist Thomas Krichbaum of the Max Planck Institute for Radio Astronomy.
“So when you’re sitting in a beer garden in Munich (Germany), for example, you could see the bubbles in a glass of beer in New York (US).”
The EHT watched Sgr A* for multiple nights for several hours straight, an idea similar to long exposure photography and the same process used to produce the first image of a black hole, published in 2019. This black hole is called M87* because it is in the galaxy Messier 87.
The M87* and Sgr A* are similar, although the Sgr A* is 2000 times smaller than the M87*.
“Close to the edge of these black holes, they look amazingly similar,” said Sera Markoff, co-chair of the EHT Scientific Council and professor at the University of Amsterdam.
The two black holes behaved as German-born physicist Albert Einstein predicted in his 1915 theory of general relativity. His theory was that instead of being an invisible force that pulls objects together the others, gravity is a curvature or a deformation* of space. The more massive an object, the more it distorts the space around it.
The image of Sgr A* is the result of the work of more than 300 researchers in 80 countries over a period of five years. Their research was published in The Astrophysical Journal Letters.
- plasma: an electrically charged gas
- phenomenon: something that is seen to exist or happen but is difficult to explain
- Halo: circle of light
- gravitational pull: when gravity brings objects together
- unprecedented: never done, seen or known before
- constellation: group of stars forming a recognizable pattern
- plausible: believable, seem likely to be true
- warping: bend or warp
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- What is the global team of scientists known as?
- How many times bigger than our Sun is the Sgr A* black hole?
- Why was the name of the black hole Sagittarius A* or Sgr A* abbreviated?
- What is the name of the first black hole that scientists captured an image of?
- Who invented the theory of general relativity?
LISTEN TO THIS STORY
1. Condense it
This report is quite long and contains a lot of details. Rewrite the article for someone short on time so they can capture the gist of the story in less than 100 words.
Weather: allow 25 minutes for this activity
Curriculum links: English; Science
Brainstorm a few possible titles for your new short story. Think about what will grab people’s attention and make them want to read it. Decide your best.
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Program links: English
Wow word recycle
There are a lot of wow words (ambitious vocabulary pieces) used in the article. Some are in the glossary, but there might be others in the article that you think are also exceptional.
Identify any words in the article that you think are not common words, and particularly good choices for the author.
Select three words you have highlighted to recycle them into your own sentences.
If some of the words you identified are not in the glossary, write your own glossary for them.