Phases of the Moon
- The Moon rises and sets just like the Sun – this is due to the Earth’s spin.
- The Moon reflects the light of the Sun, making it visible.
- The Moon changes phase because it is in orbit around the Earth. This series from one full moon to the next is called the lunar phase cycle.
- The Earth orbits the Sun every 365.25 days.
- The lunar orbit around the Earth takes 27.3 days.
- The lunar phase cycle lasts 29.5 days. It is longer than the lunar orbit because the Earth is continuously moving relative to the Sun and so the Moon takes a few extra days to get into the right position again for us to observe the same initial phase again.
- We see more or less of the reflected light on the Moon as it makes its way around the Earth. The dark regions are not in the Earth’s shadow but are instead parts of the Moon facing away from the Sun.
- The Moon’s orbit is tilted by 5 degrees relative to the orbital plane of the Earth around the Sun. It moves up and down slowly with each orbit. This is why we see a bright Full Moon approximately once a month but don’t see a solar eclipse as often.
- We always see one side of the Moon – this is because the Moon spins at the same rate as its orbit – once every 27.3 days. It turns on its axis just enough for us to never see the far side from Earth.
- A solar eclipse happens when the Moon lies directly between the Earth and the Sun. The Moon’s shadow is small on the Earth, only people who are directly beneath the shadow witness a total solar eclipse. The phase here is New Moon.
- A lunar eclipse happens when the Moon moves into the Earth’s shadow (opposite to the Sun). It glows red due to bending of red sunlight by the Earth’s atmosphere onto the face of the Moon. The phase here is Full Moon.
Our Solar System and Beyond: Teaching Primary Science
Our purpose is to transform access to education.
We offer a diverse selection of courses from leading universities and cultural institutions from around the world. These are delivered one step at a time, and are accessible on mobile, tablet and desktop, so you can fit learning around your life.
We believe learning should be an enjoyable, social experience, so our courses offer the opportunity to discuss what you’re learning with others as you go, helping you make fresh discoveries and form new ideas.
You can unlock new opportunities with unlimited access to hundreds of online short courses for a year by subscribing to our Unlimited package. Build your knowledge with top universities and organisations.