Moon phases

The Moon has phases because it moves constantly. Every day, it revolves around itself, slowly changing its position in relation to the Earth. It completes a full rotation around the Earth in about 28 days, the same time it takes to complete a full revolution around itself. So it often changes its location in relation to the Sun and the Earth.

In short, it’s not the moon’s light that changes, but our perception of the Sun’s brightness on its movements, which are very different from those of the Earth. Here’s a link to the Moon’s rotation and revolution around the Earth.

The phases of the Moon confirm that it is always in action, and that its movement is perpetual.

• Phase 1: New Moon: also known as the Black Moon, invisible to us
  Phase 2: First crescent: very thin, narrow
  Phase 3: First quarter: visible half-disk
  Phase 4: Waning Gibbous Moon: almost full
  Phase 5: Full Moon: completely visible side illuminated by the sun
  Phase 6: Waning gibbous moon
  Phase 7: Last quarter: half the moon is visible
  Phase 8: Last crescent: before disappearing and resuming its lunation cycle
• https://fr.wikipedia.org/wiki/Fichier:Moon_phases_00.jpg

Since its unique motion doesn’t correspond to ours, and it’s simply continuing its celestial orbital movement, part of its face will always seem hidden from us. Since we both rotate, but at different speeds, the Moon always presents us with the same face. In fact, the Moon’s visible face is quite different from its hidden face.

By adding a line along the center of the moon:

• Descending : You’ll see the letter “d or q” in the sky
  Ascending: You will see the letter “b or p” in the sky

It’s a handy mnemonic trick. Of course, you can only see it if the sky is clear and not too cloudy.

As I pointed out earlier, the Moon doesn’t produce light. It’s more like a mirror reflecting the Sun’s light. Depending on the alignment of the Moon, Earth and Sun, the Earth can cast a shadow on the Moon, reducing its clarity. This is known as a lunar eclipse. During a total eclipse, however, some of the Sun’s light can pass through the Earth’s atmosphere.

The blue light of the Sun’s rays is diffused by the Earth’s atmosphere, while the red light passes through.

Chantale Hébert

B.A., AMI, M. Éd.