Sagittarius A* size and scale context

Sagittarius A* is the supermassive black hole at the center of the Milky Way. Event Horizon Telescope observations imaged the glowing material around it, resolving a radio source about 52 million kilometers across around a black hole of roughly 4.3 million solar masses. Read its scale context, comparisons, and journey links on the canonical object page.

Scroll up for smaller

Scroll down for larger

Between the smallest and the largest, perspective is everything.

About

Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.

Guides turn parts of that scale into curated essays, while focused views let you explore the same range through specific groups of objects.

Editorial

Solar System Planets From Electron to Atoms Stars To Scale Birth And Death Of Stars Black Holes To Scale

Views

Planets of the Solar System Stars of the Universe Black holes Subatomic scale

Return to Earth hello@scaleofspace.org

Between the smallest and the largest, perspective is everything.

About

Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.

Guides turn parts of that scale into curated essays, while focused views let you explore the same range through specific groups of objects.

Editorial

Solar System Planets From Electron to Atoms Stars To Scale Birth And Death Of Stars Black Holes To Scale

Views

Planets of the Solar System Stars of the Universe Black holes Subatomic scale

Return to Earth hello@scaleofspace.org

Stars

Sun

The Sun is the star at the center of the Solar System and the engine behind every climate and orbit within it. It fuses about 600 million metric tons of hydrogen each second, while photons created in the core can take roughly 250,000 years to work their way to the visible surface.

Scale fact1.39 million kmdiameter

Object class: G-type main-sequence star
Mass: ~333,000 Earth masses
Temperature: 5,772 K surface
Estimated age: ~4.6 billion years
Composition: Hydrogen and helium

Black holes

Sagittarius A*

Scale fact24.5 million kmevent horizon diameter

Object class: Supermassive black hole
Host: Milky Way
Mass: ~4.3 million solar masses

Black holes

M87*

M87* is the supermassive black hole at the center of Messier 87. The Event Horizon Telescope’s 2019 image of its glowing ring became the first direct image of a black hole’s immediate surroundings, turning a previously inferred boundary into a measurable true-scale object.

Scale fact~38 billion kmevent horizon diameter

Object class: Supermassive black hole
Host: Messier 87
Mass: ~6.5 billion solar masses