Albedo is the fraction of incoming light or radiation that a surface reflects back into space, expressed as a decimal from 0 to 1 or as a percentage. A surface with albedo 0 is a perfect absorber (appearing completely black), while albedo 1 represents a perfect reflector (appearing brilliant white). Most real surfaces fall somewhere between these extremes.</p><p>This concept profoundly impacts planetary temperatures and climate. Fresh snow has an albedo of 0.8-0.9, reflecting up to 90% of sunlight and staying cool even under intense solar radiation. In contrast, Earth's oceans have an albedo of only 0.06, absorbing 94% of incoming light and contributing significantly to global warming. Venus, shrouded in highly reflective sulfuric acid clouds, boasts an albedo of 0.77—the highest in our solar system—yet remains scorchingly hot due to its extreme greenhouse effect.</p><p>The term "albedo" derives from the Latin word for "whiteness" and was coined by astronomer Johann Heinrich Lambert in 1760. Understanding albedo is crucial for climate science, as decreasing ice coverage (high albedo) and increasing dark ocean exposure (low albedo) creates a positive feedback loop that accelerates warming. Astronomers also use albedo measurements to determine the composition and surface properties of distant planets, asteroids, and moons without direct observation.