47 Fun Facts About Betelgeuse

Betelgeuse belongs to the constellation Orion, which depicts what figure from Greek myth?

A hunter: Orion's belt lies almost on the celestial equator, which is why the figure can be seen from almost any part of the world.

What type of star is Betelgeuse?

Red supergiant: stars of this class are nearing the end of their lives and have puffed up in old age into the largest stars in the universe.

Astronomers also catalogue Betelgeuse under which Greek-letter designation?

Alpha Orionis: alpha normally marks a constellation's brightest star, yet Betelgeuse is usually only second in its own.

Which star is usually the only one in Betelgeuse's constellation that outshines it?

Rigel usually wins, but Betelgeuse's brightness swings so widely that it occasionally takes the lead for a while.

Betelgeuse usually ranks about where among the brightest stars in the night sky?

Around 10th: reference lists put Betelgeuse anywhere from ninth to eleventh, because its brightness never stays put.

At which wavelengths is Betelgeuse the brightest star in the night sky?

Near-infrared: only about 13% of Betelgeuse's energy emerges as visible light, so eyes sensitive to every wavelength would see it as the brightest star in the sky.

If Betelgeuse sat at the centre of the Solar System, its surface would lie beyond which zone?

The asteroid belt: it would swallow Mercury, Venus, Earth and Mars, and by some estimates reach as far as Jupiter's orbit.

Betelgeuse's brightness normally rises and falls over about 400 days because the star does what?

Swells and shrinks: its unstable outer layers heat and expand, then cool and contract, and the 2019 outburst was violent enough to knock that steady beat out of rhythm.

Astronomers think Betelgeuse's core has run out of hydrogen and most likely now fuses which element?

Helium: the core is thought to be forging it into carbon and oxygen, one of the last fuel stages in a massive star's short life.

Betelgeuse lies roughly how many light-years from Earth?

About 600: estimates run from under 500 to more than 700 light-years, far enough that its eventual supernova poses no danger to life on Earth.

Betelgeuse is expected to explode as a supernova most likely within how long?

100,000 years is the usual estimate, so despite the supernova headlines that follow every fade, astronomers see no sign that the blast is imminent.

When Betelgeuse finally explodes, it should for months rival what in brightness?

The Moon: estimates run from a half to a full Moon's light squeezed into a single point, enough to cast shadows at night and to be seen in full daylight.

What is expected to set off Betelgeuse's supernova?

Its core collapsing: when fusion can no longer hold the core up it caves in on itself, and the rebound tears the star apart in what astronomers class as a Type II supernova.

Though near the end of its life, Betelgeuse is only about how many million years old?

10 million years or so: massive stars race through their fuel, so Betelgeuse is already dying while the far smaller Sun is only middle-aged at nearly 5 billion years.

Betelgeuse's red colour tells astronomers that its surface is what, compared with the Sun's?

Cooler: its surface is about 3,300°C against the Sun's 5,500°C, yet the star is so vast that it still pours out thousands of times more light.

In 1920, Betelgeuse became the first star beyond the Sun to have what measured?

Its angular size: Betelgeuse was picked for the 1920 test because theory predicted it was enormous, and the disc astronomers measured was about a twentieth of an arcsecond wide.

In 1920, Michelson and Pease studied Betelgeuse with an interferometer bolted to which California observatory's 100-inch telescope?

Mount Wilson: its 100-inch Hooker telescope was then the largest in the world, and a six-metre beam of mirrors across its mouth let it act like a far wider one.

Why can't ESA's star-mapping Gaia spacecraft pin down Betelgeuse's distance?

It is too bright: Gaia was built to chart more than a billion faint stars, so the dazzling ones easiest to see by eye are largely missing from its data.

Which instrument captured the first direct image of another star's disk, Betelgeuse, in 1995?

Hubble Space Telescope: its ultraviolet picture revealed a mysterious bright spot at least 2,000 degrees hotter than the surface around it.

When Betelgeuse explodes, which particles should reach detectors on Earth before its light does?

Neutrinos: they slip out of an exploding star ahead of its light, so a network of detectors stands ready to tip off astronomers before the explosion can be seen.

What is Betelgeuse's 2019–20 episode of fading commonly called?

The Great Dimming: telescopes showed the star's southern half had gone dark, yet by April 2020 Betelgeuse was back to its normal brightness.

Astronomers traced Betelgeuse's sudden 2019–20 fade to which cause?

Dust from a surface mass ejection: the star blew off a chunk of its own surface, which cooled into a cloud that hid about a quarter of its face.

Betelgeuse will keep fusing heavier and heavier elements until it reaches which one, the end of the line?

Iron: fusing it gives back no energy, so once the star's furnace fills with iron it has nothing left to burn.

Betelgeuse's slow six-year rhythm of fading and brightening is best explained by what?

A companion star: nicknamed Betelbuddy and since named Siwarha, it is thought to plough through the supergiant's outer atmosphere about once every six years.

From which language does the name Betelgeuse come?

Arabic: the phrase most likely meant 'hand of al-Jawza', and a medieval scribe's misreading of its first letter turned the y into the b the name still carries.

Betelgeuse's name is popularly, though wrongly, said to mean which body part 'of the central one'?

Armpit: Renaissance scholars invented that reading after a copyist's slip had already turned the original 'hand' into a syllable that meant nothing.

In Beetlejuice, which actor plays the ghost whose name is actually spelled Betelgeuse, like the star?

Michael Keaton: the film's screenwriter confirmed the title comes from the star, and wherever the ghost's name is written on screen it takes the official spelling.

Which classical astronomer described Betelgeuse's colour as hypókirrhos, 'more or less orange-tawny'?

Ptolemy: his word can cover pale yellow to light red, and ancient colour records like it have led astronomers to ask whether Betelgeuse reddened within recorded history.

Which astronomer documented Betelgeuse's changing brightness in 1836?

Sir John Herschel published it in his 1849 Outlines of Astronomy, but Aboriginal Australian oral traditions appear to have recorded the star's changes long before him.

In Japanese folk tradition, red Betelgeuse is named after which clan, whose war banners were red?

The Taira (Heike): country stargazers called red Betelgeuse Heike-boshi and gave a white star nearby to the Minamoto, whose banners were white.

In a southern African star tale, Orion's Belt is three zebras; Betelgeuse is which animal, watching them?

A lion: in the Nama people's telling, a husband shot an arrow at the zebras and missed, and with the lion watching he has never dared to fetch it, so he sits there still, cold and hungry.

Which 1963 novel sends its explorers to a world circling Betelgeuse?

Planet of the Apes: Pierre Boulle's French explorers fly to Betelgeuse and find a world where apes rule, and the 1968 film that followed launched a whole franchise.

Betelgeuse could give our galaxy its first supernova visible by eye since 1604's, which bears whose name?

Johannes Kepler: his star outshone Jupiter and stayed visible without a telescope for more than a year, and the galaxy has not put on such a show since.

Together with Sirius and Procyon, Betelgeuse forms which asterism?

The Winter Triangle: Sirius is the brightest star in the night sky and Procyon the eighth, so with Betelgeuse the pattern is one of the easiest to pick out.

A line drawn from Orion's foot star through Betelgeuse points towards which pair of stars?

Castor and Pollux: the pair mark the heads of Gemini's twins, and Pollux, the beta, outshines Castor, the alpha.

Interferometry has revealed 'hotspots' on Betelgeuse thought to be caused by what?

Massive convection cells: ESO's sharpest images showed a gigantic bubble boiling on the star's surface, the kind of churning that helps it hurl gas into space.

A gas plume seen leaving Betelgeuse in 2009 stretched as far as the distance from the Sun to which planet?

Neptune: the plume showed that Betelgeuse sheds its gas unevenly rather than in all directions at once.

Roughly how many Suns could fit inside Betelgeuse?

About 400 million: the star is roughly 700 times as wide as the Sun and volume grows with the cube of width, yet all that room holds the matter of only 15 to 20 Suns.

Which bright red star in Scorpius is a dying giant of the same kind as Betelgeuse?

Antares: similar in size to Betelgeuse and also expected to end as a supernova, it has a name meaning 'rival of Mars' because its red glow resembles the planet's.

What is Betelgeuse's supernova most likely to leave behind?

A neutron star: a black hole isn't ruled out, but the likelier remnant is a ball about the size of a small town that outweighs the Sun.

Before it grew huge and turned red, Betelgeuse began life as a star of what colour?

Blue: it was born a hot O-type star, and stars that massive race through their hydrogen, which is why it has already reached red old age.

The Jesuit astronomer Angelo Secchi made Betelgeuse a model star in the 1860s when he sorted stars by what?

Their spectra: splitting starlight into its colours, he made the first survey of its kind from Rome, and his classes grew into the Harvard system astronomers use today.

Which body's Working Group on Star Names formally approved the name Betelgeuse in 2016?

The International Astronomical Union: the name had been in use for centuries, but the IAU only began an official list of star names in 2016, and Betelgeuse made the very first batch.

Who published the Uranometria star atlas in 1603, giving Betelgeuse its Greek-letter designation?

Johann Bayer: a lawyer by profession, he produced what is often called the first modern star atlas, and astronomers still use his lettering four centuries later.

Which Hitchhiker's Guide character is from 'a small planet somewhere in the vicinity of Betelgeuse'?

Ford Prefect: he breaks the news to his friend Arthur Dent over a hurried trip to the pub, minutes before the Vogons demolish Earth to make way for a hyperspace bypass.

For the Inuit, the appearance of Betelgeuse and Bellatrix high in the evening sky marked what?

The beginning of spring: in the usual telling the pair, called Akuttujuuk, stood high after sunset just as Arctic days began to lengthen, so they told people winter was ending.

Betelgeuse sits near the centre of which large seasonal star pattern?

The Winter Hexagon: south of the equator the same ring of bright stars rides the summer sky, where it is known as the summer hexagon.