Madness and heat of dog days

The Milky Way and summer triangle: Vega is at the top
The Milky Way and summer triangle: Vega is at the top

by Heather Elvidge

This is the period called the dog days, the hottest part of the year. It’s named after Sirius, the brilliant Dog-star that follows at the heels of Orion the hunter.

Sirius is the brightest star in our winter sky, but in summer it rises and sets along with the sun. In ancient Rome this combination was thought to produce so much heat that people were driven mad; hence, the dog days.

While we’re enjoying warmer days, migrant birds are planning for winter. Those that breed in the Arctic’s short summer start to filter back into Britain, while the visitors that breed here begin to leave for warmer climes.

Once its eggs are tucked in other birds’ nests, the cuckoo’s work here is done. So after some time spent feeding, the adults set off for Africa.

Most of the males have left now; already some have reached their wintering places. The females linger a bit - after all, they’ve had more to do. Their youngsters won’t go before September, when they will make the long journey without any adult help.

While they’re here, those young cuckoos won’t sing - they don’t want to attract any attention. Neither do our garden birds, for a different reason. This is the month they begin to moult.

Moulting birds look out of sorts. Noisy birds become quiet; bold ones, such as male robins, become uncharacteristically shy. Perhaps feather-shedding feels uncomfortable. Certainly birds are vulnerable without their flight feathers so these are lost in ones or twos, allowing the bird to keep flying.

While this is going on they keep quiet. But if you do hear birdsong it’s probably a wren. These little birds can still be nesting and the males need to keep rivals away.

No birds seem bothered by all the mawkins, mammets and tattie-bogles that appear in villages at this time of year. They may not scare the crows, but they certainly attract armies of fans. Join them at Muston Scarecrow Festival, from July 26 to August 3.

Night sky

This is a good month to begin looking at the stars. In July, nights are growing longer - a development welcomed by stargazers - and they’re also relatively warm.

A dark rural sky reveals the full glory of the Milky Way, yet even in well-lit towns there are places to enjoy the brighter stars.

As twilight ends, the first star to become visible appears almost overhead. This is bright Vega, one of three stars in the “summer triangle”.

Next to show is Deneb, the head of a cross of stars that form Cygnus the swan, also known as the Northern Cross.

The third star in the triangle is Altair, lying further down the sky. Its constellation is also cross-like, although Aquila is not as obvious as Cygnus.

The summer triangle bounds a dark patch in the Milky Way, a band of cosmic dust that hides the more distant stars. Some cultures saw this as a mysterious part of the sky, a fork in the glowing route to the afterlife.

The cross of Cygnus was a great bird, flying along the shining path of souls.