What's at the center of everything

Look toward the constellation Sagittarius on a dark summer night and you're facing the middle of our galaxy. You won't see it. Thick clouds of dust block the visible light. But behind that dust, roughly 26,000 to 27,000 light-years away, is the thing the whole Milky Way turns around: a supermassive black hole called Sagittarius A* (say "sadge-ay-star").

It has about four million times the mass of the Sun, packed, as the Nobel committee put it, into "a region no larger than our solar system" (Nobel Prize, 2020).

So how do you study something you can't see?

Follow the stars

Starting in the early 1990s, two teams spent decades watching the center of the galaxy. One was led by Reinhard Genzel at the Max Planck Institute for Extraterrestrial Physics, using ESO's telescopes in Chile. The other was led by Andrea Ghez at UCLA, using the Keck Observatory in Hawaiʻi. They used infrared light, which gets through the dust, and new techniques to undo the blur from Earth's atmosphere.

They found stars moving around an invisible point very fast. The best-known is S2. It loops around the center every 16 years on a long, stretched-out orbit. At closest approach it comes within about 20 billion kilometers of the black hole, about 120 times the Earth–Sun distance, while moving at almost 3% of the speed of light (ESO, 2018).

Only one thing explains that much mass in that little space. The two teams' results agreed, and in 2020 Genzel and Ghez shared half of the Nobel Prize in Physics "for the discovery of a supermassive compact object at the centre of our galaxy." Roger Penrose received the other half for showing that black holes follow directly from Einstein's general relativity (Nobel Prize, 2020).

S2 also tested Einstein. When it passed closest in 2018, the black hole's gravity stretched its light to longer wavelengths, just as relativity predicts (ESO, 2018; UCLA/Science, 2019). Two years later, astronomers confirmed that S2's orbit doesn't close like a simple ellipse. It slowly swings around in a rosette pattern, another effect Einstein predicted (ESO, 2020).

The record has since moved on. In August 2026, the GRAVITY+ team announced S301, the fastest known star in the galaxy. It finishes an orbit in just 8.7 years and reaches about 25,000 kilometers per second at closest approach. It gets close enough that astronomers hope to use it to measure the black hole's spin within about a decade (ESO, 2026).

The picture of a shadow

On May 12, 2022, the Event Horizon Telescope (EHT) Collaboration released the first image of Sagittarius A*. The image came from observations made in 2017 by eight radio observatories around the world, linked together to act like one telescope the size of Earth. More than 300 researchers spent five years on it (EHT, 2022).

The black hole itself is completely dark, so the image shows its shadow: a dark center inside a bright ring of hot gas, with the light bent by gravity. From Earth, it looks about as big as a donut on the Moon would look.

It was harder to capture than the first-ever black hole image (M87*, in 2019), even though Sagittarius A* is much closer. Gas around our black hole circles it in minutes, so the scene kept changing. One EHT scientist compared it to photographing a puppy chasing its tail. The final image is an average of thousands of images. In 2024, the EHT showed the same ring in polarized light, which revealed strong, twisted magnetic fields spiraling at the black hole's edge (ESO, 2024).

A picky eater

Movies taught us that black holes swallow everything. The real one at our center doesn't.

NASA's Chandra X-ray Observatory watched the hot gas around Sagittarius A* for about five weeks. It found that less than 1% of the gas within the black hole's pull ever reaches the event horizon. Most of it gets thrown back out before it falls in (NASA Chandra, 2013). As one researcher put it, "black holes do not actually devour everything that's pulled towards them."

The black hole isn't quiet, though. NASA's James Webb Space Telescope found that the disk of gas around it flickers constantly, with five to six big flares a day and small bursts that last seconds (NASA Webb, 2025). In 2013, Chandra caught an X-ray flare 400 times brighter than normal. It may have come from an asteroid being torn apart, or from tangled magnetic fields snapping. Scientists still aren't sure (NASA, 2015).

The neighborhood

Zoom out and the black hole is part of a bigger system. The Milky Way is a barred spiral: a long bar of old stars, tens of thousands of light-years long, runs through its middle (NASA APOD/Spitzer, 2005). That bar funnels gas inward into the Central Molecular Zone, a dense, turbulent ring of cold gas around the center (Henshaw et al.).

The CMZ has a puzzle in it. It holds enough dense gas to build huge numbers of stars, yet it forms stars about ten times slower than standard models predict (Longmore et al., 2013). In 2026, ALMA released its largest image ever, a map of this gas showing tangled filaments and dozens of molecules, including methanol and ethanol (ESO, 2026).

Why we named ourselves after it

There's a line we come back to: I am filling the black hole inside me with space. It isn't advice. It's just an honest description of what curiosity can do. When something feels empty, learning about something huge and real can fill it.

The real Sagittarius A* turns out to be a good model. It's steady and patient, it lets most of the noise fly past, and it keeps a whole galaxy in orbit.

That's what we're trying to build at The Galactic Center: a place where news on space, crypto, energy, and the world economy comes together with a few useful tools.

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Sources

• Nobel Prize in Physics 2020, press release. https://www.nobelprize.org/prizes/physics/2020/press-release/
• Event Horizon Telescope, "Astronomers Reveal First Image of the Black Hole at the Heart of Our Galaxy" (May 12, 2022). https://eventhorizontelescope.org/blog/astronomers-reveal-first-image-black-hole-heart-our-galaxy
• ESO eso2208 (2022). https://www.eso.org/public/news/eso2208-eht-mw/
• ESO eso1825, S2 gravitational redshift (2018). https://www.eso.org/public/news/eso1825/
• ESO eso2006, S2 Schwarzschild precession (2020). https://www.eso.org/public/news/eso2006/
• Do et al., Science (2019), S0-2 relativistic redshift. https://www.science.org/doi/10.1126/science.aav8137
• ESO eso2612, S301 (Aug 19, 2026). https://www.eso.org/public/news/eso2612/
• ESO eso2406, EHT polarized image (2024). https://www.eso.org/public/news/eso2406/
• NASA Chandra (2013), "less than 1 percent." https://www.chandra.harvard.edu/press/13_releases/press_082913.html
• NASA Webb (2025), constant flares. https://science.nasa.gov/missions/webb/webb-reveals-rapid-fire-light-show-from-milky-ways-central-black-hole/
• NASA Chandra (2015), record X-ray flare. https://www.nasa.gov/news-release/nasas-chandra-detects-record-breaking-outburst-from-milky-ways-black-hole/
• NASA APOD (2005), Spitzer barred spiral. https://apod.nasa.gov/apod/ap050825.html
• Henshaw et al., "Star Formation in the Central Molecular Zone of the Milky Way." https://arxiv.org/abs/2203.11223
• Longmore et al. (2013), CMZ star formation rate. https://arxiv.org/abs/1208.4256
• ESO eso2603, ALMA ACES (Feb 2026). https://www.eso.org/public/news/eso2603/