48 Fun Facts About Sirius

In which constellation is Sirius the brightest star?

Canis Major: it trails at the heels of Orion the hunter, and Greek stargazers often pictured it chasing Lepus, the hare, across the sky.

Which is the only star visible to the naked eye at night that lies closer to us than Sirius?

Alpha Centauri: it sits so far south that it never rises over Europe or most of North America, which makes Sirius the nearest star that skywatchers there can see without a telescope.

What is the Greek word behind the name Sirius usually said to mean?

Glowing or scorching is the usual reading of the Greek Seirios, but some scholars suspect the Greeks borrowed the star's name from an older language.

Which star is the second-brightest in the night sky, roughly half as bright as Sirius?

Canopus pours out hundreds of times more light than Sirius and only looks fainter because it lies roughly 310 light-years away, dozens of times farther off.

Roughly how far from Earth is the Sirius system?

About 8.6 light-years: only a handful of stars lie closer to the Sun, and that nearness, more than raw power, is the main reason Sirius outshines every other star at night.

What kind of object is Sirius B?

A white dwarf: it is the collapsed core of a star that used up its nuclear fuel, so with nothing left to burn it can only cool and fade.

How long do Sirius A and B take to orbit each other?

About half a century: over each orbit the hidden partner tugs Sirius A into a slightly wavy path across the sky, which gave it away before any telescope could show it.

Which astronomer deduced in 1844 that Sirius had an unseen companion?

Friedrich Bessel: he never saw his prediction confirmed, dying in 1846, sixteen years before a telescope finally revealed the faint companion.

Who first observed Sirius B, in January 1862, while testing a new telescope lens?

Alvan Graham Clark: the chance sighting during a routine lens test won the Massachusetts telescope-maker the French Academy of Sciences' Lalande Prize that same year.

The lens that first revealed Sirius B had been ordered by the University of Mississippi; which event stopped its delivery?

The American Civil War: fighting broke out before the lens left its Massachusetts makers, so it stayed in their workshop and was sold to astronomers in Chicago instead.

Sirius is one of the stars pictured on which country's national flag?

Brazil: each star stands for a state or the capital district, and together they copy the sky over Rio de Janeiro on the morning the republic was declared in 1889.

Roughly what is the diameter of Sirius B?

About that of Earth: yet it holds roughly as much matter as the whole Sun, packed so tightly that its surface gravity is hundreds of thousands of times stronger than our planet's.

Egypt's Sirius goddess Sopdet was later merged with which other goddess?

Isis: her husband Osiris was matched with neighbouring Orion, so the star and the constellation crossed the sky side by side as a divine couple.

Which annual event did the heliacal rising of Sirius herald in ancient Egypt?

The flooding of the Nile: Egyptians long believed the star itself caused the flood, and they worshipped it as a goddess who guaranteed the fertility of their land.

Sirius vanished from Egypt's sky for 70 days each year; which burial preparation traditionally took as long?

Mummification: Egyptians read the star's absence as a passage through the underworld, and one of their own sky texts likens the seventy days stars spend there to the days the dead pass in the embalming house.

In Homer's Iliad, whose gleaming bronze armour is likened to Sirius as he runs toward Troy?

Achilles: Homer calls the star the brightest of all but an evil omen that brings fever, and the charge ends with the warrior killing Troy's champion, Hector.

Romans blamed Sirius for a rust blight on which crop, sacrificing to the deity Robigo each April to protect it?

Wheat: Ovid describes a priest leading a white-robed crowd to Robigo's grove, where the offering was meant to stop the star parching the ripening fields.

The islanders of Ceos sacrificed to Sirius and which Greek god, hoping for cooling breezes?

Zeus: legend says the hero Aristaeus founded the double rite after a prophecy sent him to the island, and that it brought the Etesian winds that cool the Aegean each year.

Which season did the rising of Sirius mark for the Māori, who called it Takurua?

Winter: the same dawn rising meant high summer to the Greeks, but the seasons flip south of the equator, and the Māori word Takurua names both the star and the season.

Pacific navigators used Sirius as a latitude marker because it passes directly over which island group, near 17°S?

Fiji: a star passes straight overhead only where the latitude matches its place in the sky, so sailors who saw Sirius cross the zenith knew they were level with these islands, or with Tahiti.

In one account of the Polynesian 'Great Bird' constellation Manu, which part was Sirius?

The body: other accounts make it the head, with other bright stars as the wingtips, and navigators from Micronesia to Polynesia steered by the giant bird.

Who discovered that Sirius and other 'fixed' stars had slowly moved since antiquity?

Edmond Halley: he compared the star positions of his own day with an ancient Greek catalogue and found that Sirius had drifted about half a degree, roughly the width of the Moon.

Sirius was the first star whose speed toward or away from us was measured, using whose effect?

Christian Doppler: in 1868 William Huggins read a tiny shift in the star's spectral lines as speed, the same trick later used to show that the universe is expanding and to find planets round other stars.

Which ancient astronomer, working in Alexandria, described Sirius as reddish in his star catalogue?

Ptolemy: Roman writers such as Seneca and Cicero called it ruddy too, which led some astronomers to wonder whether the star system had changed colour within recorded history, an idea now thought very unlikely.

Which two stars join Sirius to form the seasonal triangle seen on northern cold nights?

Procyon and Betelgeuse: the neat triangle is a trick of perspective, since Procyon is a near neighbour of the Sun, as Sirius is, while Betelgeuse blazes from hundreds of light-years farther away.

Sirius is visible from almost everywhere on Earth, but it never rises in which of these places?

Svalbard: Sirius rides about 17 degrees south of the celestial equator, so it stays hidden from anywhere above roughly 73 degrees north, and these Arctic islands begin at 74.

Earth's wobbling axis will one day help turn Sirius into what?

Southern pole star: in roughly 60,000 years the wobble and the star's own drift will carry Sirius to within two degrees of the pole, a brilliant marker for southern skies that today have only barely visible Sigma Octantis.

Which star will eventually replace Sirius as the brightest in Earth's night sky?

Vega: Sirius is still edging closer and brightening, but in about 210,000 years it will have drifted away again while Vega, itself approaching the Sun, grows bright enough to take over.

Roughly how much more luminous than the Sun is Sirius A?

About 25 times: that makes it a lightweight among famous stars, since a supergiant such as Rigel gives off tens of thousands of times the Sun's light.

Which spacecraft is expected to pass within 4.3 light-years of Sirius in the far future?

Voyager 2: its power will run out long before, so the probe will drift past Sirius as a silent relic about 296,000 years from now, still carrying its golden record of Earth's sounds.

Which English poet wrote an astrolabe manual that calls Sirius 'Alhabor'?

Geoffrey Chaucer: he wrote the manual in plain English around 1391 for 'little Lewis', a ten-year-old he calls his son, because the boy's Latin was still too weak for the textbooks.

An old Icelandic name for Sirius means the 'blazing' or 'torch' of which Norse god?

Loki: the Icelandic name is Lokabrenna, and his name clung to heat elsewhere in the north too, for Danish country folk said the shimmer of hot air over the fields was Lokke herding his goats.

Which West African people were said to hold impossible knowledge of Sirius's companion?

The Dogon of Mali: French anthropologist Marcel Griaule reported the lore in the 1930s and 1940s, but a later study found no trace of it, and villagers said they had learned about the star from Griaule himself.

What playful nickname do astronomers give Sirius B, the faint companion of Sirius A?

The Pup: it is thousands of times fainter than its partner and sits so close that it hid in the glare for centuries, until a telescope-maker testing a new lens finally caught sight of it.

Lockheed named a 1929 monoplane after Sirius; its first example was built for which famous aviator?

Charles Lindbergh: he and his wife Anne flew it north to Asia and around the Atlantic to scout airline routes, and a Greenland boy named it Tingmissartoq, 'one who flies like a big bird'.

In the Harry Potter novels, what is Sirius Black to Harry?

His godfather: the star name is a clue to his secret, since he can turn at will into a great black dog, a form that earned him the school nickname Padfoot.

Sirius A is classed as an 'Am' star, a type whose spectrum shows an unusual excess of what?

Metallic elements such as iron: the surplus is probably only skin deep, because the star spins slowly enough for its own light to push such atoms up to the surface.

Seen low in the sky, Sirius often flickers through rainbow colours; what causes the flickering?

Earth's atmosphere: shifting pockets of air bend each colour of the starlight by a different amount, and Sirius shows it best because it is so bright.

Astronomers long thought Sirius drifts through space alongside most stars of which famous star pattern?

The Big Dipper: five of its seven stars travel together as the Ursa Major Moving Group, but later studies found Sirius only about half the group's age, so the shared drift looks like coincidence.

Which planet always outshines Sirius as seen from Earth?

Venus: its unbroken clouds bounce most of the sunlight that hits them back into space, so even at its faintest the planet easily beats Sirius, which Mars and Mercury manage only now and then.

Sirius reaches its highest point in the sky at about midnight on which annual celebration?

New Year's Eve: step outside as the year turns and the night's brightest star is at its peak, due south for northern watchers and high overhead for southern ones.

In Chinese astronomy, Sirius is known as the star of which 'celestial' animal?

The wolf: the Celestial Wolf was said to stand for invasion and plunder, so Chinese stargazers drew a great bow from the stars beside it, its arrow aimed straight at the beast.

In Zoroastrian and Persian mythology, Sirius appears as Tishtrya, a divinity of what?

Rain-making: in his Avestan hymn he takes the shape of a splendid white horse and fights Apaosha, the demon of drought, to set the waters free.

Which avant-garde composer wrote a piece called Sirius and claimed to come from a planet there?

Karlheinz Stockhausen: he first gave the name to his young daughter's dog, then dreamed he had studied music on the star and wrote a space-age drama in which four messengers from it visit Earth.

Olaf Stapledon's 1944 novel Sirius follows a sheepdog engineered by a scientist to have what?

Human-level intelligence: raised as a brother to the scientist's daughter, Sirius herds sheep in Wales, mixes with scholars at Cambridge and is torn between his human mind and his animal nature.

HMS Sirius was the flagship of which famous voyage in 1788?

The First Fleet to Australia: two years after the fleet landed its convicts at Sydney, its flagship was wrecked on a reef at Norfolk Island, a heavy blow to a colony already on short rations.

Sirius A's surface is close to 10,000 K, far hotter than the Sun's; what colour does that make its light?

Blue-white: among stars the everyday rule flips, so the cool ones glow red while Sirius A, at about 9,940 K and some 4,000 degrees hotter than the Sun, shines bluish white.

Sirius B is thousands of times fainter than Sirius A to the eye, but outshines it in which kind of light?

X-rays: its surface is about 25,000 degrees, hot enough to glow in X-rays, and when NASA's Chandra telescope looked in 1999 the faint companion was the bright spot and Sirius A barely showed.