StarTalk Podcast: Cosmic Queries – Lunar Geology

Moon's Colors

The Moon's color is often misunderstood, with many assuming it to be white or light gray. Raquel Nuno clarifies that the Moon's surface is actually quite dark, akin to black lava rocks found in Hawaii or Iceland. This darkness is due to ancient volcanic plains, while the lighter regions are composed of different minerals, yet still dark gray 1. The brightness we perceive is largely due to the Sun's reflection and the contrast against the night sky. Neil deGrasse Tyson humorously notes, "The Moon is as dark as the sidewall of your black tires," reflecting only a small percentage of sunlight 1.

   

Far Side

The far side of the Moon is often mistakenly referred to as the "dark side," a misconception Raquel Nuno addresses. She explains that the Moon is tidally locked to Earth, meaning we only see one side, but both sides receive sunlight 2. Neil deGrasse Tyson points out that while Pink Floyd's album title "The Dark Side of the Moon" is misleading, Gary Larson's "The Far Side" is scientifically accurate. Raquel emphasizes that understanding this distinction is a measure of science literacy 2.

   

Craters

Earth's geological activity erases many craters, unlike the Moon, which preserves them due to its lack of atmosphere and tectonic activity. Raquel Nuno notes that Earth has about 150 recognized craters, but processes like erosion and tectonics obscure them 3. She describes the Moon as a "witness" to Earth's history, having experienced similar impacts without the erasing effects present on Earth 4. Chuck Nice humorously compares Earth to a "contaminated crime scene," constantly being "bleached over" by natural processes 3.