The dog days of summer

Sirius rises late in the dark, liquid sky

On summer nights, star of stars,

Orion’s Dog they call it, brightest

Of all, but an evil portent, bringing heat

And fevers to suffering humanity.

— From The Iliad by Homer

This is a Sirius column. For if the dog days of summer are here, it’s not because our hounds, unleashed, plop down in the shade with long pants after short runs.

It’s because Sirius — the Dog Star — is rising. It officially crossed the eastern horizon — it’s heliacal rising — with the sun on Aug. 1

“But that’s just at sunrise. It wouldn’t be visible,” said Geoff Chester, spokesman for U.S., Naval Observatory in Washington, D.C.

But once Sirius gets unmeshed from the sun’s glare that blots it out, it will burn above the horizon at dawn.

“You can see it around Aug. 7 or so,” Chester said. It’s hard to miss. Sirius — part of the constellation Canis Major, aka the Dog — is the brightest star in our heavens. Only the planets — Mars, Venus, Jupiter, Saturn — outshine it.

It’s a nakedeye dazzler. When it’s near the horizon in the evening in winter, the atmosphere can make it look multicolored.

“It scintillates,” Chester said.

Chester said when he worked for the Albert Einstein Planetarium at the National Air and Space Museum he would routinely get calls from people swearing they’d seen a UFO over Lake Michigan. It was Sirius they were seeing.

”I would ask them “Are you from western Michigan?’’ and they would say “How did you know?” Chester said.

It’s much better known and more easily observed as a winter star. Monty Robson, the director of the John J. McCarthy Observatory in New Milford said it will reach its highest point in the sky on New Year’s Eve.

“It’s part of the winter constellations,” said Cliff Wattley, who leads sky-watching expeditions held jointly by the Discovery Center in Ridgefield and New Pond Farm in Redding. “It’s in Canis Major. It’s one of Orion’s hunting dogs.”

It’s also nearby — only 8.6 lightyears away. Chester said it’s the 7th closest star in the firmament.

“It’s the brightest star — it has the benefit of being close,’’ Wattley said.

But its rising now was once of enormous importance.

The ancient Egyptians used to predict the flooding of the Nile River and subsequent plantings and harvests — based on the first appearance of Sirius above the horizon. They called the star Sopdet and worshiped it as the goddess of fertility and pictured her as a woman with a fivepointed star upon her head

“They associated it with Osiris, their chief god,” Chester said.

“It was when they knew they could start planting their crops,” said Alan MacRobert, senior editor at Sky & Telescope Magazine.

The Greeks and Romans attributed the hottest part of summer to Sirius — its name derives from the Greek word seirios, meaning “glowing’ or ‘a scorcher.” The Greeks sacrificed to Sirius and Zeus to bring cooling breezes and believed Sirius had malign emanations. Those who suffered from the glow were ‘star struck.”

The Romans believed Sirius’ heat, added to that of the Sun, made the Empire swelter. They called the dog days ‘dies caniculares’ and Sirius, “Canicula” the little dog.

It’s always been a doggy star. The Chinese called it ‘the celestial wolf.” Native Americans called it ‘the dog that follows mountain sheep’ and ‘the coyote star.”

But the ancients were not always accurate.

MacRobert of Sky and Telescope said if your timekeeping depends on exact observations of the helical rising of a star, or the first appearance of a crescent moon in spring, there can be problems.

Stars rise of different days, depending on the latitude people are watching from. There’s atmospheric interference. There’s human error. Irregularity breeds confusion.

“We just decided to write calendars and take the moon out of them completely,” he said. “Now years, months, weeks, days are the same for everyone.”

Those old celestial ways are lost on most of us humans. When we look up at the sky now and then, we just see stars. The history, the importance of their rising and setting is long forgotten.

”People have no idea,” said Robson of the McCarthy Observatory, which is on a mission to bring some astronomical literacy to the world.. “We try our best to educate people, but very few know much before they get here. It’s rare that they understand you can tell time from the stars.”