Moon phases and illumination – basics and applications
How it works
The Moon orbits the Earth and is illuminated by the Sun. One half of the Moon is always lit by the Sun. The visible shape of the Moon as seen from Earth, the lunar phase, depends on the relative positions of the Sun, Earth and Moon. There are often eight phases distinguished: new moon, waxing crescent, first quarter, waxing gibbous moon, full moon, waning gibbous moon, last quarter and waning crescent. The lunar phases repeat about every 29.5 days. The Moon does not shine by itself, but reflects sunlight. The different lunar phases therefore do not arise from the Earth's shadow, but because we see different-sized parts of the illuminated half of the Moon.
The visible lunar phase depends on how the Sun, Earth and Moon are positioned relative to one another: depending on the position, we see more or less of the illuminated half of the Moon.
An example
What is the lunar phase called in which the entire side of the Moon visible from Earth is illuminated?
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50 Exercises
To the learning unit →Own explanation and own practice exercises by AmyMath. Subject reference framework: Astronomy. The topic assignment may vary by federal state.