Sirius A size and scale context

Sirius A is the brightest star in Earth’s night sky and the luminous primary of the Sirius binary. The same system also contains Sirius B, a white dwarf, so Sirius lets us see a bright main-sequence star and a stellar remnant bound together in one nearby pair. Read its scale context, comparisons, and journey links on the canonical object page.

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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.

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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

Stars

Sirius A

Scale fact2.38 million kmdiameter

Object class: A-type main-sequence star
Mass: ~2 solar masses
Host: Sirius system
Estimated age: ~240 million years
Composition: Hydrogen and helium
Temperature: ~9,900 K surface

Stars

Procyon A

Procyon A is the bright F-type primary of the Procyon binary and has begun to swell beyond an ordinary main-sequence star. Its faint companion, Procyon B, is already a white dwarf, so the pair gives astronomers a nearby before-and-after snapshot of stellar evolution in one system.

Scale fact2.84 million kmdiameter

Object class: F-type subgiant star
Mass: ~1.48 solar masses
Host: Procyon system
Estimated age: ~1.9 billion years
Composition: Hydrogen and helium
Temperature: ~6,580 K surface