Star Magnitude Calculator
Calculate the brightness ratio between stars using apparent magnitude.
Compare stellar magnitudes.
Magnitude Comparison
Apparent magnitude measures how bright a star appears from Earth. Lower numbers = brighter.
The magnitude scale:
- Each magnitude step = 2.512× brightness difference
- A difference of 5 magnitudes = exactly 100× brightness
Brightness ratio formula:
Ratio = 2.512 ^ (m1 - m2)
or equivalently:
Ratio = 10 ^ ((m1 - m2) / 2.5)
Notable star magnitudes:
| Object | Magnitude | Notes |
|---|---|---|
| Sun | -26.7 | Closest star |
| Full Moon | -12.7 | Reflected sunlight |
| Venus (max) | -4.6 | Brightest planet |
| Sirius | -1.46 | Brightest night star |
| Vega | 0.03 | Reference standard |
| Polaris | 1.98 | North Star |
| Naked eye limit | +6.0 | Dark sky limit |
| Hubble limit | +31.5 | Faintest observable |
Key insight: Negative magnitudes are brighter than positive ones.