StarsOut
Should you go outside tonight?
Drop everything — go outside
Near-perfect conditions. Nights like this are rare.
Rio de Janeiro
10.0
out of 10
Peak 2h
10.018:00–20:00
Prime 21–01
10.021:00–01:00
Best this week
10.0Fri, Jul 17
Moon
Waxing Crescent
5% lit
Moon doesn’t interfere — perfect darkness
🔭 Moon up: 08:21–19:58
Full moon: Jul 29
Sky now
Clear · 0%
Measured at SBRJ · 1km away · 48min ago
Sun ↓ 17:24·Dark from 18:24·0% clouds
Alert me on good nightsSky quality tonight
Best: 18:00–20:00This week’s nights
America/Sao PauloHow the score works
60% weight
Cloud cover
Layer-weighted across the best 2-hour window of the night. Low clouds block everything, thin high cirrus still lets bright stars through.
40% weight
Moon darkness
A new moon boosts the score. A full moon near midnight washes out all but the brightest stars. We ease the penalty after midnight when the moon is setting.