Sirius at closer distances
Sirius is the brightest star in the night sky, and it earns that mostly by being close rather than by being large. Walking it inward shows how much of a star's brightness is proximity and how little of it is size.
- 2,380,000 km
- 120 hours
- star
How big does Sirius actually look from Earth?
At 8.6 ly, Sirius spans 0.01 arcseconds across your sky — a small fraction of the width of the full Moon. Light crosses that gap in 9 years.
The brightest star in the sky, at the distance that makes it so. Still a point.
How big would Sirius look from one light year away?
At 1 ly, Sirius spans 0.05 arcseconds across your sky — a small fraction of the width of the full Moon. Light crosses that gap in 1 year.
Brighter, but geometrically still a point of light.
How big would Sirius look from a tenth of a light year?
At 0.1 ly, Sirius spans 0.52 arcseconds across your sky — a small fraction of the width of the full Moon. Light crosses that gap in 36.5 days.
The glare grows long before the disc does.
How big would Sirius look from a hundredth of a light year?
At 0.01 ly, Sirius spans 5.19 arcseconds across your sky — a small fraction of the width of the full Moon. Light crosses that gap in 3.7 days.
Roughly an Oort-cloud pass.
What would Sirius look like inside the Solar System?
At 37,399,468 km, Sirius spans 3.6° across your sky — about 7.0 times the width of the full Moon. Light crosses that gap in 2.1 minutes.
Well inside the orbit of Mercury. Apparent size is calculated; the consequences are not simulated.
At this distance, Earth would not survive. Enjoy the view.
What Perigee calculates and what it renders
The apparent size is calculated, but the light, colour and environmental treatment are an authored visualization. Perigee does not model heat, radiation, gravity or tides.
How Perigee calculates apparent size