#DOES EARTH REVOLVE AROUND THE SUN FULL#

#DOES EARTH REVOLVE AROUND THE SUN FULL#

When Apollo astronauts looked back on Earth from the Moon, they didn’t just see a globe, they marvelled at crescent, gibbous, full and new Earths depending on which phase our planet was going through. Mercury, Venus and Mars also have phases similar to the Moon which can be spotted at certain times with a telescope. The fact we can sometimes spot a faint outline of the dark sections of the Moon when it’s not full is because some of the light from the Sun is bouncing off Earth and lightly illuminating our lunar companion. The other half is shining out in the opposite direction to Earth. During a half moon, we see half of the Moon’s day side. The whole of the far side of the Moon is in sunshine, but we see (or rather don’t see) the side that’s in full shadow. This shows clearly that it’s not the Moon but our vantage point on Earth that changes, and explains the phases we see.įor instance, a new moon happens when the Moon is between the Earth and the Sun. This process is called ‘waning’.Īs the view from the Southern Hemisphere is the other way around, the Moon waxes from the left and wanes to the right. And then the opposite happens on the left side as the portion lit up shrinks to nothing, known as a ‘new moon’. This process is called ‘waxing’ and takes about a fortnight. If you are in the Northern Hemisphere, the Moon’s right side grows with light from a crescent to a semicircle and then a gibbous (more than a semicircle but less than a full circle) shape until finally it becomes a glorious full moon. This means there is no dark side of the Moon, just a side facing away from the Earth.įrom Earth though, it looks like the Moon goes through different lit-up phases. And just as we have half the planet lit and the other in darkness at any one time, the Sun is always shining on half the Moon. Like the planets, we only see the Moon because it reflects the Sun’s light. To grasp why the Moon’s appearance changes, we need to bring in the Sun. As it rises at a later time, the Moon appears in a different part of the sky. This shift means Earth has to rotate a little longer to bring the Moon into view, which is why moonrise is about 50 minutes later each day. It causes the Moon to move 12–13 degrees east every day.

This movement is from the Moon’s orbit, which takes 27 days, 7 hours and 43 minutes to go full circle. By looking at where the Moon is in relation to stars in the background one night, and then comparing to where it is several hours later or on the next night you’ll notice it has moved east. The lunar orbit is slower and harder to see – but you can still spot it.

Just like the Sun and the night time stars, the Moon’s apparent rising in the east and setting in the west each day is not from the Moon’s orbit around the Earth, it’s from the Earth spinning. If we first think about the Moon in relation to the Earth, we can explain how it appears to travel across the sky over the course of a night, and why it rises and falls at different times and in different locations. Most vividly, its entire appearance changes over the course of two weeks, morphing from a bright circle to a circle sliced in half and finally fading to nothing.Īll these changes seem complicated but each one can be explained by thinking about where the Earth, Sun and Moon are in relation to one another. And from night to night it rises and falls at different times and in different parts of the sky. It moves across the sky rapidly over the course of a night. The way the Moon looks to us is continually changing. Our Moon must travel a little farther in its path to make up for the added distance and complete its phase cycle. Why? In that time, as our Moon moves around Earth, the Earth also moves around the Sun. Moon fact: The Moon’s phases repeat every 29.5 days, but it’s orbit around the Earth only takes 27. Knowing how this dance between the Moon, Earth and Sun plays out lets us understand the Moon’s constantly changing appearance. And it appears to have phases because the amount of lunar surface bathed in sunlight we can see from Earth depends on where we and the Sun are.

Does earth revolve around the sun