It may come as a surprise that the Moon actually casts no light of its own. You heard that correctly — the Sun is lighting up our Moon just like it lights up our days here on Earth. The Earth spins like a top in a circle once every 24 hours, giving us one day and one night during that time.
Like every other object in the Solar System, our Moon travels around another object. What makes the Moon somewhat unique is that it spins on its axis at exactly the same time. As a result, we always get to see the same side of the Moon, no matter where in the world we are. Such a phenomenon is known as tidal locking, and a few other objects in the Solar System act the same way.
As the Moon revolves around the Earth, its position in relation to the Sun changes with each passing day. Traveling at speeds of miles per hour kilometers per hour , the Moon covers a lot of ground in a short amount of time. Imagine the Moon traveling in a circle around our planet.
The relative positions of our Sun, Earth, and Moon, cause these changes. As our Moon orbits around Earth, the side facing the Sun is always illuminated, just like Earth's daylight side is illuminated by the Sun.
What we see from Earth , however, is a different story. From Earth, the Moon's surface looks dark because the illuminated side is facing away from Earth. Between the new and full Moon, the amount of Moon we see grows — or waxes from its right side toward its left side.
As it passes the full Moon stage, the amount of illumination decreases — or wanes — from right to left. Finally, the Moon returns to its position between the Earth and the Sun, and on Earth we observe the new Moon again. In the southern hemisphere, illumination of the Moon increases from the left to the right side in the waxing phase and the dark part increases in coverage from left to right in the waning phase, which is opposite of the northern hemisphere.
No matter where on Earth an observer is, however, the phases of the Moon occur at the same time. What causes a lunar eclipse? Pictures of the Moon's phases often make it look like there should be a lunar eclipse during each full Moon and a solar eclipse during each new Moon. However, two things have to happen for a full lunar eclipse. First, the Moon has to be full, so there is only an opportunity for a lunar eclipse about once each month. The moonlight we see on Earth is sunlight reflected off the Moon's grayish-white surface.
The amount of Moon we see changes over the month — lunar phases — because the Moon orbits Earth and Earth orbits the Sun. Everything is moving. During a lunar eclipse , Earth comes between the Sun and the Moon, blocking the sunlight falling on the Moon. Earth's shadow covers all or part of the lunar surface. Our Moon doesn't shine, it reflects. Just like daytime here on Earth, sunlight illuminates the Moon.
When sunlight hits off the Moon's far side — the side we can't see without from Earth the aid of a spacecraft — it is called a new Moon. The rest of the month we see parts of the daytime side of the Moon, or phases. These eight phases are, in order, new Moon , waxing crescent , first quarter , waxing gibbous , full Moon , waning gibbous , third quarter and waning crescent.
The cycle repeats once a month every During a lunar eclipse, Earth comes between the Sun and the Moon, blocking the sunlight falling on the Moon. During some stages of a lunar eclipse, the Moon can appear reddish. You can unsubscribe anytime. Before we describe the phases of the Moon, let's describe what they're not. Some people mistakenly believe the phases come from Earth's shadow cast on the Moon. Others think that the Moon changes shape due to clouds.
These are common misconceptions, but they're not true. Instead, the Moon's phase depends only on its position relative to Earth and the Sun. The Moon doesn't make its own light, it just reflects the Sun's light as all the planets do. The Sun always illuminates one half of the Moon. Since the Moon is tidally locked, we always see the same side from Earth, but there's no permanent "dark side of the Moon.
The new Moon occurs when the Moon, Earth, and Sun all lie along approximately the same line. Since the Sun is behind the Moon from Earth's perspective, the side of the Moon that faces Earth is dark.
At full Moon , the three bodies also lie approximately in a line, but this time, the Moon is on the opposite side of Earth, so the Sun illuminates the whole side facing us. At first quarter and last quarter , the Moon lies perpendicular to a line between Earth and the Sun. We see exactly half of the Moon illuminated by the Sun — the other half lies in shadow.
The "quarter" used to name these phases refers to the respective fraction of an orbit that the Moon has completed since new Moon.
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