Late September can bring some of the best early evening experiences for those who enjoy looking upwards.

Visibility is likely to fluctuate a bit, but it looks as though we may get some of the best stargazing weather of the year over the next few nights. It promises to be warm enough to enjoy long spells outside, but without the crazily late sunsets of midsummer.

I’ll point out a few of the things worth looking for in a minute, but first just a few words about this weather.

On my courses I encourage people to take note of shifts in wind direction and how this relates to changes in weather patterns. If the weather is unseasonably warm or cold, we should expect some deviation from the prevailing wind direction, southwest.

The image above shows the UK (at lunchtime tomorrow) sandwiched neatly between a high pressure system over the continent and a couple out in the Atlantic. Winds rotate clockwise around a high pressure system and anti-clockwise round a low pressure. The net effect for us will be winds that will be coming from the south and southeast. Southerly winds tend to bring warmer air, and southeasterly winds from over the continent bring drier air than the moist southwesterly winds from over the Atlantic. Hence the warm and dry conditions.

On to the night sky…

As the sun sets the brightest stars will start to show their face. The bright yellow and orange Arcturus will appear low in the west not long after sunset.

In the south there will be three bright white stars worth looking for. Search for a large triangle that occupies the high southern sky. This triangle is made up of the three brightest stars, Altair, Deneb and Vega, from the constellations Aquila, Cygnus and Lyra. It is not surprising that sailors have learned to abbreviate this family to the nickname ‘The Summer Triangle’ or ‘The Navigator’s Triangle’.

The star of the show will undoubtedly be Jupiter, rising at about 8pm just north of east, he will be ruling the eastern sky with pomp by 9.30pm.

Many, many people will accuse this majestically bright white object of being Venus, Sirius or the North Star.

In reverse order, it can’t be the North Star as that is not a particularly bright star (and, as you may well have deduced, is in the north not the east) and it couldn’t be Sirius as Orion is nowhere to be seen. There is no way that it could be Venus, as Venus lives near the sun. If the sun has set then it is well to the west of us and we are looking east.

If you are up early in the mornings, Orion will be on watch over the southern sky, with Sirius burning brightly not far below him.

Enjoy.

Take a really keen interest in the sky whenever bad weather is forecast after a good spell. Don’t wait for the change to become obvious though, the interesting higher clouds: the wispy cirrus, mares’ tails, mackerel skies etc. will all be found just before most people notice that the weather is changing, so you need to remain aware.

It works the other way round too of course, if you don’t have access to forecasts, or prefer to do your own, then this sort of sky after settled weather is a strong sign that a big change is on its way. More tips on weather lore here.

(There should be a great opportunity to see some moonlit cloudscapes tonight hopefully too.)

Will write more about them tomorrow if I get the chance, but wanted to get the photo up while I could.

The two pictures above show two sides of the same bridleway signpost on the South Downs Way. The arrows both point east and there is a clue to this in the photos. It is not in the lichen growth, which unusually is quite similar on both sides, but in the colour of the arrows themselves. The blue of the south-facing (but east-pointing!) arrow has been bleached more by the sun. The three main weathering clues are sun, wind and rain. The first will usually be greatest on the southern side, but wind and rain will usually leave their marks more prominently on the southwestern side.