Nothing to do with the Ramblers really but I think this may be of interest. Let’s hope for a clear night.
There will be a full Moon on Sunday 10th August and it will appear to be much bigger than normal in the sky.
The Moon does not orbit the Earth in a perfect circle so its distance from us varies. When the Moon is at its closest it is known as perigee and this can occur at any point in the Moon’s cycle. When perigee coincides with a full Moon it is known as a ‘super-Moon’ and one is due in a few weeks. At 7.00pm on 10th August the Moon will be at its closest point this year a mere 356, 896Km away and this closest approach will occur 9 minutes before the full Moon. At that time the Moon will still be below the horizon (in this country) but when it does rise about an hour later it will look particularly large.
Although the Moon will be slightly bigger in the sky than normal due to its closeness, when viewed against the horizon it will appear inordinately large. This is due to an optical illusion and is very impressive. We perceive the sky as shaped like the interior of a flattened dome. A flattened dome of this shape would have its horizon a great distance away and as we see all celestial objects as being fixed to this dome the Moon is perceived as being much further away than it really is so our brains subconsciously think it must be a huge object in order to assume its apparent size. (Conversely, when the Moon is overhead we perceive it as much closer and therefore smaller in actual size).
This affect is heightened when the rising Moon is seen against a distant horizon especially if the horizon contains recognisable objects – e.g. buildings.
So look out for the rising full Moon on the evening of Sunday 10th August to see an impressive site – and a good photo opportunity.
According to http://www.timeanddate.com/moon/uk/sheffield moonrise for Sheffield will be at 8:09 p.m. bearing 109 ESE