As many of you will already know, the full moon is coinciding with Halloween this year, a pretty fun and rare event, as it only happens about once every 19 years. In celebration, we thought we'd put together some interesting facts about the Moon.
First of all, let's talk about what some media are calling a blue moon —it won't actually be blue in colour. While it sounds fancy, or mysterious, its definition is just "the second full moon in any given month". So, if there was a full moon on March 1 the second one on March 30 would be called a blue moon. Full moons happen every 29.5 days so blue moons are relatively rare. This also means that if Halloween is going to host a full moon, it will always be called a “blue moon” as it will always be the second full moon of October!
Here are some other fun moon facts we think you'll enjoy:
Did you know: The Moon is slowly drifting away from the Earth at a rate of 3.8 cm per year - this is slightly less than the rate at which our fingernails grow!
Where did the Moon come from? Scientists think that about 4.5 billion years ago, a roughly Mars-sized planet (named Theia) collided with a very young Earth. The impact was powerful enough to completely destroy Theia and its debris, as well as debris from Earth, started orbiting the Earth. The Moon is thought to have formed from this material!
During the Apollo missions, astronauts placed seismometers on the Moon’s surface. From these instruments we learned that the Moon experiences “moonquakes” which are likely caused by factors such as tidal forces between the Earth and Moon and the cooling/shrinking of the Moon.
The Moon has quite a collection of craters on its surface! Using data collected by orbiting lunar spacecraft, scientists have identified tens of thousands of craters wider than 5 km!
Only one side of the Moon is visible from Earth because the Moon rotates on its axis at the same rate that the Moon orbits the Earth. This means one “Moon day” lasts as long as 29.5 Earth days.
The “far side” of the Moon is not always dark; when we see a “new moon” on Earth this half is fully illuminated by the Sun!
At the furthest point in its orbit, the Moon is about 400,000 km from Earth. Within this space between the Earth and the Moon you could just about fit the rest of the planets in the Solar system, all lined up!
Tidal friction from the Moon is gradually slowing the Earth’s rotation. Although this process is quite slow, every 100 years, one Earth day gets about 0.001 seconds longer.
Just as we see Moon phases from Earth, an observer on the Moon sees “Earth phases”! This phase cycle is ~2 weeks out of sync. For example, when we see a “new Moon”, someone on the Moon would see a “full Earth”.
Perspective matters! Due to the spherical shape of our planet, the Moon’s features appear “flipped” depending on whether you’re observing from the Northern or Southern Hemisphere!