SkyMatters: It will look like a bite has been taken out of the Moon this October

It’s the brightest object in the evening sky not because it’s the closest planet but because its vast size – you would fit an incredible 1,300 earths inside Jupiter – turns it into a huge solar reflector.

In the morning sky, again looking towards the east, the planet Venus has slowly been brightening and gaining altitude and is now a brilliant spectacle easily visible even as the rising sun brings in the dawn. 

While Jupiter is the largest of the planets in our solar system, Venus is the hottest, so we have two record-holders that can easily be observed this month at times that suit adults and children alike.

On Saturday 28, there will be a partial eclipse of the Moon. Such eclipses occur when the Earth and Moon align “just right” and the Moon passes through the Earth’s shadow. 

The relative motion of the Earth, Moon and Sun is a little complicated and so some eclipses are “full” (when the Moon is fully within the Earth’s shadow) whilst others are partial. How much of the Moon is cast into shadow in a partial eclipse varies, as does the timing. 

This month we’re fortunate that the timing is good, with the eclipse starting at 20:40 and ending at 21:45 (and maximum at 21:10).

However, the depth of the eclipse is not as large as at some other times and at maximum it will look like a modest, but visible bite has been taken out of the lower part of the Moon.

If the weather is good, and even if there is a light cloud, this will still be a partial lunar eclipse worth watching.

With the bright planet Jupiter to the left of the Moon, it will make for a memorable observing opportunity.

The eclipse can be viewed with the unaided eye or perhaps enjoyed even more with binoculars or a small telescope. 

The Moon will be bright enough and high enough in the sky to be visible from a city garden unless your southern horizon is completely blocked.

And since the event lasts a couple of hours from start to finish, there’s plenty of time to pass around the binoculars or give everyone a go with the telescope without the need for “argy-bargy in the lineout”.

And as a final sweetener, if such is needed, the clocks go back on Sunday 29th, so not only do we not have to get up for school or work, but we get an extra hour in bed to recover from eclipse excitement!

Prior to the eclipse, on the evening of 21st October we are graced with the annual Orionid meteor shower.

The best time to observe meteors is after midnight, and with the Moon setting around then this month it will leave the skies dark - perfect for seeing fainter meteors.

The Orionids are interesting because they come from dust in the tail of the most famous of all comets, Comet Halley.

As our skies become more and more crowded with satellites, the need to distinguish between a satellite and a meteor is ever more relevant. In reality, it’s very easy.

Meteors last around 1 second, move very quickly, and brighten and dim all in that brief moment of glory. 

Satellites move much more slowly and generally don’t change brightness quickly, although they do slowly fade as they pass into the Earth’s shadow – the same shadow that is responsible for October’s lunar eclipse.

Most visible satellites orbit at a height of 300-600km, whilst most meteors burn up in the atmosphere at a height of 50km or less.

As always in astronomy, the story behind faint points of light which might appear similar on a casual glance can be so different.