Albeda

Meet Albeda, a planet who sends some sunlight straight back to space.

Albedo is the fraction of incoming light that a surface reflects, from 0 for a perfect absorber to 1 for a perfect reflector. Clouds, ice and snow are bright and reflect a lot; oceans and forests are dark and absorb most of the light falling on them. A planet's overall albedo sets how much solar energy it keeps to warm itself.

Averaged over the whole globe, NASA puts the sunlight arriving at the top of Earth's atmosphere at about 340 W/m². With an albedo of about 0.30, Earth absorbs roughly 0.70 × 340 ≈ 238 W/m².

Albedo matters for climate. When bright sea ice melts it exposes darker water, which absorbs more sunlight and warms further, the ice–albedo feedback. Astronomers also use albedo to estimate the sizes of asteroids from their brightness.

Albedo is not a fixed number. It changes with cloud cover, season, snow and the angle of the sunlight, and it depends on wavelength, so a surface can be bright in visible light but dark in infrared.