Red giant
A red giant is a star that has expanded and cooled after exhausting the hydrogen in its core.
How big is it?
0.465 AU across
Diameter · rounded model
A little perspective
Red giant vs Earth–Sun distance: length comparison
The Earth–Sun distance is about 2.15 times the diameter of a red giant.
A red giant is a star that has expanded and cooled after exhausting the hydrogen in its core.
The Earth–Sun distance, or astronomical unit, is the standard measure of separation between Earth and the Sun used in astronomy.
Both rulers start at the same zero and share one linear scale. Artwork keeps its original proportions. A ruler represents the selected distance or a measurement not visible in this view.
Measurements, assumptions & sources +
Red giant
Diameter: 0.465 AU; rounded model.
An explicitly chosen giant-star example, not a universal evolutionary stage.
Defined examples — our methodology
The marked diameter is calibrated. Unmeasured illustration details are representative.
Earth–Sun distance
Distance: 1 AU; definition.
One astronomical unit is exactly 149,597,870,700 m. It is a useful Earth–Sun orbital scale, not the separation at every instant. Light takes about 8 minutes 19 seconds to cross it.
NIST — 2022 CODATA fundamental constants
The marked distance is calibrated. Unmeasured illustration details are representative.
Use the visual comparison to explore its scale, then check the measurements and sources.
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Why this measurement?
Why we use 0.465 AU
We compare the diameter of a red giant. This is an illustrative comparison value, not a claim that every example is the same.
An explicitly chosen giant-star example, not a universal evolutionary stage.
The marked horizontal span follows the measured feature, not the edges of the image. How calibrated comparisons work →
Recorded properties
Dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 0.465 AU | Not recorded | rounded model | |
| 1.2 M☉ | Not recorded | rounded model |
Around this scale
Explore nearby values.
Compare examples with lower, similar and higher values. Each card names the measurement being compared.
Nearest lower valuePlanets, moons and spaceSirius A2,379,000 kmDiameterSirius A is the brighter main-sequence star in the Sirius binary system.
Nearest higher valuePlanets, moons and spaceEarth–Sun distance1 AUDistanceThe Earth–Sun distance, or astronomical unit, is the standard measure of separation between Earth and the Sun used in astronomy.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
There’s always another scale
Follow your curiosity.
SpaceSun1,391,000 kmThe Sun is the star at the centre of the Solar System.
SpaceJupiter139,800 kmJupiter is a giant planet composed mainly of hydrogen and helium, orbiting the Sun beyond the asteroid belt.SpaceNeutron star20 kmA neutron star is the dense remnant core left after a massive star explodes as a supernova, composed mostly of neutrons.SpaceEarth–Sun distance1 AUThe Earth–Sun distance, or astronomical unit, is the standard measure of separation between Earth and the Sun used in astronomy.
SpaceBetelgeuse6.511 AUBetelgeuse is a red supergiant star in the constellation Orion that changes in brightness over time.SpaceSirius A2,379,000 kmSirius A is the brighter main-sequence star in the Sirius binary system.SpaceNeptune’s orbital distance30.11 AUNeptune’s orbital distance is the average separation between Neptune and the Sun.SpaceEarth–Moon distance384,400 kmThe Earth–Moon distance is the average space between the centres of the Earth and the Moon.