By Ian Brand, Wharfedale Naturalists Society

AS a society we are obsessed by time. There are other rhythms to our lives, those of the natural world. I would always be aware of the tide and wind when I was a dinghy sailor, and now as a botanist, the changing seasons, and with each month the different plants in leaf, flower and fruit.

I can now add another natural rhythm, the phases of the Moon. This all started when I bought a Moon-phase clock which now hangs in our kitchen. This month is an exciting month for observing our nearest neighbour.

August is going to see two Supermoons, including a Blue Moon. What does all this mean?

Let’s start with Supermoons. The Moon orbits the Earth, every 27 days, and it is not orbiting in a circle - sometimes it is closer and sometimes further away. When it is at its closest, we call it a Supermoon. This happens roughly three to four times a year. Not to be confused with the lunar cycle when we see a New Moon, then Full Moon and back to a New Moon, that cycle is 29.5 days.

Why is there a difference of two and half days between the lunar orbit and cycle? As our Moon moves around Earth, the Earth does not stay motionless, it also moves around the Sun. Our Moon must therefore travel a little farther in its path to make up for the added distance and complete its cycle.

Usually, you have a Full Moon once every calendar month, but because the lunar cycle (29.5 days) is slightly less than the typical length of a calendar month, sometimes you get two Full Moons in one month. The second Full Moon is known as a ‘Blue Moon’, hence the expression ‘Once in a Blue Moon’ which occurs approximately every two and half years.

This month there is a combination of both Super and Blue moons at the same time. Both the Full Moons in August will be supermoons when the Moon is closest to the Earth. Now when we say “Supermoon”, it sounds as if it is going to be extra-large and bright, but in fact it is only 6 per cent bigger than normal.

This is not to be confused with the Moon illusion, which occurs when the Moon appears larger nearer the horizon than it does higher up in the sky, and it can look huge.

Confused, don’t despair, grab your binoculars go out and lie in a field, and just look up and enjoy a bit of Moon gazing.