How Far Away From Earth Could We See the Sun with the Unaided Eye?

-- Chris | January 1, 2024

Question:

If I were standing on a exoplanet from another solar system and looked up at the night sky; how many light years could you make out our suns light? Basically how far can we see our suns light without the aid of an instrument if looking back?

-- Chris

Answer:

The Sun’s absolute magnitude, which is its brightness if it were located at a distance of 10 parsecs (about 32.6 light years), is about 4.83. The human eye can see stars down to about apparent magnitude 6 or so. Using the relationship between apparent (m) and absolute (M) magnitude:

M = m – 5*log10(d(pc)) + 5

…we can calculate that our Sun’s absolute magnitude of 4.83 would appear to be as bright as a star with apparent magnitude 6 if it were at a distance of about 17.1 pc, or about 55.8 light years.

-- Jeff Mangum

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