Arcturus size and scale context

Arcturus is a bright orange giant and the brightest star in the northern celestial hemisphere. It also races unusually fast across the sky for such a bright star, shifting by about two arcseconds per year because of its high motion relative to the Sun. 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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Solar System Planets From Electron to Atoms Stars To Scale Birth And Death Of Stars Black Holes To Scale

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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

Aldebaran

Aldebaran is a red giant branch star in Taurus with a cool orange surface and a diameter about 45 times the Sun’s. It lies in front of the Hyades cluster by chance, so it appears to sit among the bull’s-head stars without actually belonging to that group.

Scale fact62.8 million kmdiameter

Object class: Red giant branch star
Mass: ~1.03 solar masses
Host: Aldebaran system
Estimated age: ~6.4 billion years
Composition: Hydrogen and helium
Temperature: ~3,900 K surface

Stars

Rigel

Rigel is the blue-white supergiant that marks Orion’s foot and dominates the constellation’s lower half. Although it looks solitary to the eye, it is actually part of a multiple-star system built around a spectacularly luminous hot primary star.

Scale fact103 million kmdiameter

Object class: Blue supergiant star
Mass: ~21 solar masses
Temperature: ~12,000 K surface
Estimated age: ~8 million years
Composition: Hydrogen and helium