The brightest object in the night sky, our Moon is an unmistakable sight.
Beyond its skyward motion and changing phases, naked-eye lunar observations yield tremendous scientific knowledge.
1.) The Earth is round.
Arctic versus Antarctic perspectives are completely flipped, with latitudinal variations indicating Earth’s shape.
Additionally, the Earth’s shadow during lunar eclipses reveals our planet’s spheroidal nature.
2.) The Moon’s orbit is elliptical, not circular.
Changes in the Moon’s apparent size indicate large variations in its distance from Earth.
Additionally, more than 50% of its face is visible over time, as it orbits Earth quicker when closer and slower when farther.
3.) How reflective is the Earth?
The unlit part of the Moon is brightened by Earthshine: sunlight reflected from Earth.
Observing the light from the unilluminated portion teaches us the reflectivity of Earth.
4.) Earth’s atmosphere bends red light more than blue.
During moonset/moonrise, the Moon appears redder, as blue light is scattered away.
That red light is bent, meanwhile, preferentially illuminating the Moon during lunar eclipses.
5.) The Moon has mountains, valleys, and high crater walls.
During solar eclipses, Baily’s beads reveal the lunar topography.
The lunar shadow’s irregular shape on Earth, during total eclipses, reveals the heights of crater walls.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.