Shine on Harvest Moon! Explaining the phases of the Moon

Alan Willison, chairman of Hertford Astronomy Group. (Image: Alan Willison)

Last month we agreed that the Earth orbits the Sun and that the Moon orbits the Earth.

This month we will have a look at why the amount of the Moon that we see changes.

Like Earth, the Moon has a day side and a night side which, like the Earth, is illuminated by the Sun.

As the Moon orbits the Earth the amount of the day side that we can see changes – these are the phases.

Steve Heliczer's photo of the Moon with an aeroplane fly across the image. (Image: Steve Heliczer)

When the Moon’s night side is facing us then we can’t see any of it and this is called 'New Moon'.

Gradually, day by day as the Moon orbits the Earth, more of the Moon is revealed. This is called waxing.

After approximately 14 days we reach the Full Moon phase when the whole of the day side of the Moon is facing us.

From then on the Moon begins to get apparently smaller as its night side starts to come back towards Earth. This is called waning.

This diagram shows the full cycle:

A diagram showing the full cycle of the Moon phases. (Image: NASA)

There’s a great website where you can learn more about these phases at https://moon.nasa.gov/moon-in-motion/moon-phases/

By the way, many people are surprised to learn that the Moon is visible during the daytime.

All the phases, except New Moon, are technically visible although it will be sometimes difficult to find as it will appear faint against the bright blue sky.

Each Full Moon also has a name associated with it:

• Wolf Moon – January
• Snow Moon – February
• Worm Moon – March
• Pink Moon – April
• Flower Moon – May
• Strawberry Moon – June
• Buck Moon – July
• Sturgeon Moon – August
• Harvest Moon – September or October
• Full Corn Moon (Harvest) – September
• Hunter's Moon (Harvest) – October
• Beaver Moon – November
• Cold Moon – December

Some of these names are obvious in meaning but you can have some fun finding out about how these names came about – something to do when it is cloudy and making stargazing impossible.

Photos of the Month

We have been hearing in the news about the first photos coming back from the James Webb Space Telescope (JWST).

Stephan’s Quintet taken by the James Webb Space Telescope. (Image: NASA, ESA, CSA and STSci)

Here’s the Stephan’s Quintet one taken with $10 billion worth of telescope, and next to it is the same area taken from the back garden in Cuffley by our own Steve Heliczer for considerably less cost.

Stephan’s Quintet taken from the back garden in Cuffley by Steve Heliczer. (Image: Steve Heliczer)

Another Photo of the Month

The Veil Nebula supernova taken by Martin Weston from his back garden in Wheathampstead. (Image: Martin Weston)

When a star comes to the end of its life its final moments can be quite dramatic often resulting in a huge explosion called a supernova.

This image was taken last month by Martin Weston from his back garden in Wheathampstead.

The Veil Nebula supernova remnant is located 2,100 light years away in the Cygnus constellation that spans 110 light years across.

A supernova remnant is the remains of a star that has ended its life in an explosion known as a supernova.

In the case of the Veil Nebula, the star in question was 20 times the mass of the Sun and exploded about 8,000 years ago.

Want to learn more? Consider joining the Hertford Astronomy Group where all ages (9-99) and capabilities are welcomed. Visit www.hertsastro.org.uk