During This November’s supermoon the Moon will be closer to earth than it has been since 1948, making it one of the largest astronomical events of the year.
On the eve of November 14th, the moon will be 14% larger and 30% brighter than a normal full moon. An event of this magnitude won’t happen again until November 2034 so you won’t have an opportunity like this again for almost two decades.
So what causes a supermoon?
Because the moon has as an elliptical orbit, one side, which is called the perigee, is about 30,000 miles closer to Earth that the other (called the apogee).
Sometimes the Moon, Earth, and Sun line up in orbit. This event is known as a syzygy.
Occasionally this event occurs with the perigee side of the moon facing the earth, and the moon is on the opposite side of the earth to the sun, in this case we get what is known as a perigee-syzygy.
This event causes what we call a supermoon, or more exactly a perigee moon, where the moon appears larger and brighter than an average full moon.
This actually happens more often than you think though, in fact we had a supermoon last October and there is another coming on December 14th. However there has not been one of this magnitude for nearly 7 decades and it’s an event that astronomers have been looking forward to for some time.
“The full moon of November 14 is not only the closest full moon of the year, but also the closest one to date in the 21st century,” “The full moon won’t come this close to Earth again until 25 November 2034.”
Depending on where you’re viewing it from, the difference between a supermoon and a regular full moon can be stark, or difficult to tell. If the Moon is hanging high overhead, and you have no buildings or landmarks to compare it to, it can be tricky to tell that it’s larger than usual.
But if you’re viewing from a spot where the Moon is sitting closer to the horizon, it can create what’s known as ‘moon illusion’.
“When the moon is near the horizon, it can look unnaturally large when viewed through trees, buildings, or other foreground objects,” says Sources. “The effect is an optical illusion, but that fact doesn’t take away from the experience.”