If we could stand just far enough back in the fields, with a long cosmic telescope, we could see the whole of our solar system and its 194 moons! Only Mercury and Venus have no moons, but the planet with the most moons is Jupiter, with no less than 79!
Why does the Moon have 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.
Examples of phases:
- 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
The dark side of the Moon.
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.
How can you tell the difference between a waxing and waning Moon?
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.
Lunar eclipses :
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.
B.A., AMI, M. Éd.