The Moon

The Moon. An uninhabited grey ball of rock and dust. Not a very interesting place perhaps. Still, it influences our life here on earth. Rather helpfully, it can reflect light from the sun back down to the earth to help us see at night.

The moon changes its appearance night by night from a big ball of pale blue light all the way into a tiny slither of shining silver. The moon has always played an important role in life on earth. In many languages, the moon has even given a name to the first day of the week. Monday - day of the moon. And what we call a month has its roots in the length of time from one full moon to the next.

When the moon is new, it appears as if part of it is missing. But that's an illusion. It's still a ball. We just can't see all of it. The moon is orbiting around earth.

The sun shines on the moon making half of it bathe in sunlight leaving the other half in the dark. When the moon is in this position, people on earth can only see a tiny crest of the half of the moon that's lit and it's only visible right after sunset. The moon appears differently depending on where on earth you are located. In the northern hemisphere near the equator or in the southern hemisphere. As the moon keeps rotating around the earth, that lit up half of the moon becomes increasingly visible from earth.

When the moon is at a 90 degree angle to the sun, we see a half moon. When the moon is opposite to the sun, it's a full moon from earth. And then it shrinks again to be invisible for a night or two. One full revolution around earth takes the moon just over 27 days. But since earth is moving too, the moon needs another two days to catch up with it and show its full face again.

The sun, the earth and the moon are aligned so that we see a full moon every 29.5 days. On a few rare occasions, about twice a year, the moon, the earth and the sun are perfectly aligned, one casting its shadow onto the next. When the earth casts its shadow on the moon, there is a lunar eclipse. When the moon's tiny shadow hits the earth, it's a solar eclipse. Here on the screen, the moon is shown much closer to the earth than it actually is.

Otherwise, they wouldn't both fit on the screen. This is how far from each other they are shown to scale. The distance is about 30 times the earth's diameter. That makes for a very tiny shadow to pass through. Not only is the moon far away from the earth, it's also much smaller.

The moon's diameter is about one quarter of the earth's. And it has only one-eightieth of the earth's mass. And a lower mass means a weaker force of gravity. Gravity on the moon's surface is one-sixth of that on earth. Philip's mass is 70 Kilograms.

This makes his weight almost 700 Newtons on earth. On the moon, his mass is still 70 Kilograms, but his weight is only one-sixth of what it is on earth. 114 Newtons. This kind of extreme temperature is normal on the moon. The moon has no atmosphere and no water to help even out the day and night temperatures.

No atmosphere also means there is no wind. Something to consider if you have a plan to visit. Perhaps it's time to return to earth? Even here, 1000s of kilometers from the moon we are still affected by it. The sea level was much higher in the morning.

Now, the water has receded and is far away. This variation between the ebb and flow is caused by the moon's gravitational force. Because water is a liquid and easily changes shape, it moves around with the gravitational pull of the moon. The moon offers some remarkable events for us to experience: The full moon, the high tides, and occasionally, the lunar and solar eclipses. It's no wonder these things have been given mystical or religious significance in the past.

And even if we understand the science behind all of this today, they are still phenomena to marvel.