With many people taking a summer break during August, there is an excellent opportunity to have a late night or a broken night, while not getting too cold. I am referring to the annual Perseid meteor shower…assuming it is a clear night of course. This year, the Perseids are due to appear during the nights of 11-13 August. Although the shower originates in the constellation of Perseus, the meteors appear in all parts of the sky. The best time is after midnight, more towards the hours before dawn. One year I got up at 3am, having gone to bed early, and was rewarded by the sight of the meteors. This year, the moon will have set in the early evening during its waxing crescent stage, which means the skies will be dark. It is also possible to see them a night or so either side of the main dates. Indeed, I photographed the supermoon the day before it was at its peak – which was just as well as the evening of the main event was cloudy! Meteor showers occur every year as the Earth passes through the tail of long gone comets. Comets are a huge topic though.
This month sees spring turn to summer, during the early hours of Monday 21 June. It is when the sun is in its most northern position relative to Earth. Our northern hemisphere is pointing towards the sun, while the southern hemisphere begins its winter season. The north pole now gets its share of daylight, having emerged from round the clock darkness of winter. It is quite a feeling to be out and about in daylight at midnight! Stonehenge is well known of course for being in line with such astronomical events and recently I spent a few days in Pembrokeshire where I was fortunate enough to walk around the area from where the bluestones originated for Stonehenge. It would have taken 150 days to pull a bluestone to Wiltshire on a sled of some sort. The more recent druid type rituals at Stonehenge are not deemed to be the original purpose of the henge monument, having only occurred relatively recently in its history. An activity you can do is to photograph on 21 June, a tree with a very short shadow and then take subsequent photos a month apart to see the effect of the movement of the Earth away from the sun. It is interesting to view the photographs in a sequence to appreciate just how much movement there is.
But I digress, the summer solstice varies slightly by a day or so year on year due to the Earth’s rotation around the sun. Each summer solstice is around 6 hours later than the previous year and in a leap year, the solstice jumps backwards by a day. Remember, it takes 365 and a quarter days for the Earth to go around the sun, which is why we have an extra day every four years.
I am often asked why the sea is so cold in the summer…I went swimming in November and found the water to be much more pleasant than in August. Likewise, those people who jump into the sea on Boxing Day are less brave than those who do so at Easter when the sea has cooled down. The sea warms up with the lengthening days and takes a while to cool, hence warmer in December.
Another fun activity to enjoy during the, hopefully, warm summer days is to make a solar cooker. Full instructions are on my website, but briefly, you need a large piece of cardboard, plenty of kitchen foil and a lot of patience. No, it is quite simple to make, you are making a concave shape which will absorb a lot of heat from the sun as it is concentrated to a point in which you can put a small plate of water or a piece of bacon. And wait while the sun heats them. Be very careful not to put your hand in the line of fire so to speak. Nor look at the sun directly.
A less obvious activity to do during this somewhat fallow time for observing, is to look at a Planisphere or star atlas and familiarize yourself with the positions of the constellations during the autumn and winter so you are ready to go out in the dark, armed with the knowledge of where to look and what to look for. My book, “A stroll amongst the stars” takes you through the main stars from September to August in line with the typical observing year. At the Observatory we particularly enjoy September and October when the nights are longer but not too chilly. And take a break in July and August to enjoy the longer days. Now is the time to download free computer programmes such as Stellarium, buy my book, or take astronomy books out of the library, and sit back and learn about the subject in more detail ready for active viewing.