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In Focus for the First Time: Sagittarius A*

Astronomers reveal the first image of the supermassive black hole at the heart of our Milky Way galaxy. 
Read the press releases:

Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with NASA’s Universe of Learning partners: Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and NASA Jet Propulsion Laboratory.
Video imagery:
  • Images of the radio telescopes on the ground: ESO, ALMA (ESO/NAOJ/NRAO), IRAM/Diverticimes, NOEMA, F. Xavier Cuvelier, mediomix, Thalia Traianou (Max Planck Institute for Radio Astronomy) and B. Tafreshi (
  • Planetary scale of the Event Horizon Telescope: ESO/L. Calçada
  • Zoom into Sagittarius A*: ESO/L. Calçada, N. Risinger (, DSS, VISTA, VVV Survey/D. Minniti DSS, Nogueras-Lara et al., Schoedel, NACO, GRAVITY Collaboration, EHT Collaboration (Music: Azul Cobalto)
  • First image of Sagittarius A*: EHT Collaboration
  • Illustration of Chandra X-ray Observatory in space: NASA/CXC/D.Berry
  • X-ray, Radio, & Infrared Images of Sagittarius A*: Chandra X-ray: NASA/CXC/SAO; Swift X-ray: NASA/GSFC/Swift; Hubble near-infrared: NASA/HST/STScI
  • Sagittarius A* Flare time lapse: NASA/CXC/A. Hobart

Writer: Claire Blome
Designer: Joe Olmsted
Editorial and design input from Dr. Kimberly Kowal Arcand (Center for Astrophysics | Harvard & Smithsonian), Dr. Christopher Britt, Holly Ryer 
Music from Music for Non-Profits


Where do we fit in all this?
Images of spiral galaxies with background points of light.
Text, What is out there?
How does the universe work?
An array of telescopes.
Text, We've long wondered what lies at the center of the Milky Way. Bottom banner, In Focus for the First Time: Sagittarius A-star. Text, In 2008, researchers provided the first definitive evidence that it is a supermassive black hole by precisely tracing the stars that orbit it.
A large telescope moves in time lapse.
Text, They estimated it is 4.6 million times the mass of the Sun.
A telescope points as stars move behind.
Text, But there was still no visual confirmation.
Black holes themselves emit no light.
An array of telescopes in the snow.
Text, Fortunately, the gas and dust that immediately surround black holes do.
Researchers recently combined the observing power of an international array of ground-based radio telescopes to create an image.
Triangles over the Earth.
Text, The collective known as the Event Horizon Telescope began staring at the center of our galaxy.
Geometric shapes superimposed on the Earth.
Text, The array acts like a telescope as big as the Earth itself--with the power to resolve details as small as a donut on the moon.
Neon images of Scorpius and Sagittarius superimposed on a radiographic image of a band in the sky. The image moves inside the band to a screen filled with stars and moves closer into the field of stars into a dense cluster of stars
The stars appear in hazes of gas in red and blue. It moves closer still to four points of light in a square against a dark background. One of those points enlarges and fills the screen.
Text, The result is the first image of the Milky Way's supermassive black hole, called Sagittarius A (character of a star), (pronounced A-star).
A blurred orange circle with three spots of bright light.
Text, We're looking at our black hole almost face-on.
This means we can better understand its ring of gas and dust as it orbits again and again.
The gas and dust complete an orbit in mere minutes.
In contrast, the gas and dust around a supermassive black hole that is 1,000 times larger takes days or weeks to complete an orbit.
At the same time this observation was taken, NASA telescopes also began observing Sagittarius A-star.
A model of a silver cylindrical space telescope.
Text, One of the outstanding questions about black holes is exactly how they collect, ingest, or expel material orbiting them.
A cover opens at the end, concentric circles are inside.
Text, A combined image of the X-rays in the region just outside the black hole was captured by NASA's Chandra X-ray Observatory and the Neil Gehrels Swift Observatory.
A round purple cloud against a background of orange and blue points of light
Text, Purple and blue depict hot gas that was blown away from massive stars near the black hole.
Patches of bright white light are inside the purple gas.
Text, Chandra also caught X-ray flares just outside the black hole's event horizon -- the point of no return.
Blue shapes with white lights move.
Text, How do the X-ray flares relate to what's in the radio images? And how does the spin of the black hole affect their energy?
An arrow points to Sagittarius A-star, a white patch in a formation of blue light with white patches. Text, We don't yet know -- there is much more research to be done.
Researchers will continue to process and analyze the incredible amount of new data.
The orange circle with evenly spaced light patches fills the screen.
Text, Their ongoing research will ultimately expand our knowledge of some of the most mysterious objects in the universe ... and how they affect the galaxies they inhabit.
The orange circle slowly recedes into a background of black.
The image fades to black.