40 Fun Facts About Canis Major

Canis Major and Canis Minor are traditionally drawn as dogs trailing which constellation across the winter sky?

Orion is the hunter both dogs trail, though the earliest Greek writers gave him only one dog. The smaller second dog had joined the picture by Roman times.

Sirius, nicknamed the Dog Star, has a faint companion star that astronomers affectionately call by which name?

The Pup was first spotted in 1862 by American telescope-maker Alvan Graham Clark, who was testing a new lens when a faint dot appeared beside Sirius.

The yearly dawn return of Sirius warned ancient farmers that which great river was about to flood?

The Nile flood began soon after the star's dawn return each year, so the Egyptians worshipped Sirius as the goddess Sopdet, bringer of the flood.

Sirius is the brightest star in the night sky, almost twice as bright as which runner-up star?

Canopus is in truth far more luminous than Sirius. It only looks fainter because it lies much farther away, while Sirius is one of the Sun's nearest neighbours.

Which book series features Sirius Black, a wizard named after the Dog Star who can turn into a huge black dog?

Harry Potter's Black family names its children after stars and constellations, which is why Sirius has cousins called Bellatrix and Andromeda.

The dog days are named for the dawn return of Sirius, which the ancient Greeks watched for in which season?

Summer heat was blamed on the star itself: the Greeks feared that its dawn appearance made plants wilt and men weaken.

Chinese astronomers saw Sirius not as a dog but as which other animal, a sign of invasion and plunder?

A wolf prowled the Chinese sky: Sirius was the Celestial Wolf, and a nearby pattern of stars formed a bow and arrow aimed straight at it.

NGC 2359, a glowing gas bubble in Canis Major blown by a single hot star, is better known by which nickname?

Thor's Helmet spans about 30 light-years, and the star at its centre is thought to be in a brief stage just before it explodes.

Which country's flag shows Sirius and other Canis Major stars among 27 stars for its states and federal district?

Brazil gives Sirius to the state of Mato Grosso, and each star on the flag is sized by how bright the real one looks in the sky.

Sirius B, the faint companion of Sirius, packs the Sun's mass into a ball roughly the size of which planet?

Earth is about the right size, yet Sirius B weighs as much as the Sun. It is the collapsed remains of a star that was once about five times the Sun's mass.

Which bright star has a Greek name meaning before the dog, because it rises shortly ahead of Sirius?

Procyon is the brightest star of Canis Minor, the Little Dog. About five light-years from Sirius, it is also that star's closest large neighbour in space.

Sirius forms the Winter Triangle with the brightest star of Canis Minor and which red supergiant?

Betelgeuse lies hundreds of light-years away, dozens of times farther than Sirius, so the three corners of the triangle only look like neighbours.

Canis Major is often pictured chasing which small neighbouring constellation, whose Latin name means hare?

Lepus crouches just west of Canis Major, and although it has been charted since antiquity the hare stands for no particular figure in Greek myth.

In one Greek myth Canis Major is Laelaps, a hound that always caught its prey; which uncatchable animal did it chase?

A fox fated never to be caught met a dog fated never to miss. In this telling Zeus ended the paradox by turning both to stone and setting them among the stars.

Canis Major was among 48 constellations listed in the second century by which author of the Almagest?

Ptolemy's list has lasted: Canis Major is still one of the 88 constellations that astronomers officially recognise.

Sirius B was once the heavier of the two stars in the Sirius system; what kind of stellar remnant is it now?

White dwarf is the answer, and Sirius B is the nearest one to us. It swelled into a red giant, shed its outer layers and left only its hot, dense core.

A clump of stars found in Canis Major in 2003 was hailed as the closest small companion of which galaxy?

Milky Way gravity may be tearing the clump of stars apart, though other astronomers argue it was never a separate galaxy, just part of our own galaxy's disc.

Which space probe, launched to study the four giant planets, should drift past Sirius in roughly 296,000 years?

Voyager 2 will still miss by a wide margin, coming no closer to Sirius than about four light-years.

The Egyptians worshipped Sirius as the goddess Sopdet, who was later merged with which far better-known goddess?

Isis absorbed her almost completely in later centuries, just as Sopdet's husband Sah, the hunter constellation next door, was merged with Osiris.

Star cluster M41, just south of Sirius, may have been noted around 325 BC by which Greek philosopher?

Aristotle may have beaten its official discoverer by almost 2,000 years: Giovanni Battista Hodierna catalogued the cluster before 1654.

If the hypergiant VY Canis Majoris replaced the Sun, its surface would swallow every planet out to which one?

Jupiter would orbit inside the star, which is so vast that a beam of light would need about six hours to travel once around its surface.

Sirius looks so bright partly because it is a close neighbour of the Sun; about how far away is it?

8.6 light-years is next door in galactic terms, while the other bright stars of Canis Major lie hundreds of light-years away.

Which German astronomer deduced from a wobble in the motion of Sirius that the star had an unseen companion?

Friedrich Bessel made the call in 1844, and it took another 18 years before a telescope was good enough to show the companion.

Which English astronomer found that Sirius had moved since ancient star catalogues, showing that stars are not fixed?

Edmond Halley compared the sky of his own day with positions recorded in the second century and found that Sirius, Arcturus and Aldebaran had all drifted.

Mirzam, a bright star of Canis Major, rises just before Sirius; what does its Arabic name mean?

The herald once outshone its master: Mirzam is thought to have been the brightest star in the whole sky about 4.4 million years ago.

Adhara, the second-brightest star in Canis Major, is the night sky's brightest source of which kind of light?

Extreme ultraviolet light from Adhara is strong enough to shape the thin gas between the stars near the Sun, stripping electrons from its hydrogen.

Which holy book mentions Sirius by name in a chapter titled The Star, calling God the lord of Sirius?

The Quran names the star because some Arab tribes had worshipped Sirius before Islam, and the verse places God above it.

In Scandinavia, Sirius was traditionally known as the torch of which god of Norse myth?

Loki gave the star its Scandinavian name, Lokabrenna, which can also be read as the burning done by him.

Which French writer's tale Micromégas follows a giant from a planet circling Sirius on a visit to our world?

Voltaire made his visitor almost 39 kilometres tall, an outsider through whose eyes he could comment on Western culture.

The Lockheed Sirius, a monoplane named after the star, was built at the request of which American aviator?

Charles Lindbergh bought the first one and flew it to the Far East with his wife Anne, who wrote a book about the journey.

A star cluster in Canis Major, NGC 2360, is nicknamed after which comet-hunting astronomer who discovered it?

Caroline Herschel logged the cluster in 1783, but her notes were overlooked until her brother William credited her in his own catalogue.

NGC 2207 and IC 2163, seen in Canis Major but vastly more distant than its stars, are a colliding pair of what?

Spiral galaxies in mid-collision: the two brushed past each other about 40 million years ago, and the larger is expected to swallow the smaller in the end.

Canis Major is best placed for evening viewing, at about 9 pm, during which month of the year?

February suits it because Canis Major belongs to the northern winter sky, and it can be seen from everywhere south of 60 degrees north.

Which faint constellation, lying between Canis Major and Canis Minor, is drawn as a unicorn?

Monoceros is a newcomer beside the ancient dogs: it was only defined in the 17th century, by the mapmaker Petrus Plancius.

The Dogon, said by some researchers to have known of Sirius B without telescopes, live in which West African country?

Mali is home to the Dogon, but the claim is doubted: an anthropologist reported in 1991 that they disagreed about which star was even meant.

The name Sirius comes from a Greek word, Seirios, that is usually translated as glowing or as what?

Scorching fits the star's old reputation: Greek writers called it burning or flaming, and anyone thought harmed by it was said to be star-struck.

A North American company renamed itself Sirius in 1999, after the brightest star, to sell which new service?

Satellite radio had not yet gone on air when the firm, until then called CD Radio, took the star's name. In 2008 it merged with its rival XM.

HMS Sirius, flagship of the First Fleet that left Portsmouth in 1787, helped found a European colony in which country?

Australia's first European colony soon lost its flagship: HMS Sirius was wrecked off Norfolk Island in 1790.

Egypt's 365-day calendar fell back into step with the rising of Sirius every 1,460 years, a span known as what?

The Sothic cycle exists because Egypt's calendar had no leap day, so it slipped about a quarter of a day against the star every year.

On Johann Bayer's star atlas, the brilliant Sirius marks which part of the Great Dog's body?

Its mouth holds the Dog Star on Bayer's chart, while Adhara, the constellation's second-brightest star, marks the right thigh.