# What would happen if someone had a telescope and watched Betelgeuse when it goes supernova?

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Would that person go blind?

Neutrino detectors and the abundance of Neutrinos would detect the upcoming visible show about 3 hours before any visible signs, so there would be time to point certain telescopes that could handle the brightness towards it.

I'm curious if an individual with a telescope pointed in that direction would have an unpleasant surprise. Would the scientific community be wise to not announce the massive stellar explosion until after it's visible to avoid potential negative effects from over-eager amateur astronomers.

I realize this is a kind of silly question and it might depend too much on the telescope, but I'm curious.

No, it would not be a problem. Supernovae are not at all like flashbulbs - they brighten over a period of many days and dim again even more slowly. Here are a number of different light curves taken from Wikipedia:

The rise is fast on an astronomical scale - several orders of magnitude over a period of roughly ten days - but very slow on a human scale. An amateur looking at it would not notice any significant change in brightness, but if the same person came back a few hours later or the next night, the change would be very evident.

As far as we can tell, the reason is that the light at peak brightness is caused by emissions from material blown off by the explosion. For example, in Type 1a SNe, most of the light is from the radioactive decay of the huge mass of ejected nickel-56 (half life 6 days).

The Wikipedia article on supernovae is quite good and covers this all in more detail.

Brightness varies inversely with the square of the distance. Betelgeuse is about 642.5 light years away and has an apparent magnitude of 0.42. My grasp of apparent magnitude concepts is a bit wobbly, but I believe if it grew a million times as bright, it might have an apparent magnitude of -14.5 or so, which is a lot more like the brightness of the moon than the sun.

Given the great distance, the decrease in brightness due to distance, and the countless amounts of dust & gas between earth and Betelgeuse, I think you'd probably be fine. You might be dazzled by its brightness -- a bit like looking at a light bulb, I imagine -- but I doubt it would cause any physical harm.

EDIT: I hope a real astronomer sounds off here. I'm not sure what kind of supernova we might expect from Betelgeuse, but apparently supernovas (supernovae?) can achieve a theoretical brightness equal to 5 trillion suns!

If you insist on observing the exploding Betelgeuse at peak brightness, you could potentially damage your eye. The complete answer enters the realm of physiology. Here I'll discuss the astronomical parts:

Betelgeuse will explode as a type II supernova, the typical brightness of which is around $$M sim -17$$. With a distance of $$dsimeq200,mathrm{pc}$$, its distance modulus is $$mu = 5log(d/mathrm{pc}) - 5 simeq 6.5,$$ so its apparent magnitude will be $$m = M + mu simeq -10.5.$$

For these calculations I assume that the Sun is the threshold for damaging your eye (a brief look at the Sun is okay, a longer look will cause permanent damage. But… physiology… ). The Sun has an apparent magnitude of $$m_odot = -26.7$$, i.e. it is $$Delta m = 16.2$$ magnitudes brighter. In other words, Betelgeuse will be $$f = 10^{Delta m/2.5} simeq 3 imes10^6$$ times dimmer than the Sun.

However, the Sun is an extended source, spanning an angle of roughly $$heta_mathrm{Sun} = 32$$ arcminutes across. In contrast, Betelgeuse is a point source, which when transferred through the atmosphere and the telescope, is spread out over $$heta_mathrm{Bet} sim$$ a few square arcseconds. Thus its light will be more concentrated; i.e. it will be much brighter, but it will hit a much smaller area of your retina. However, your eye will also move around, smearing out the light. Not being a physiologist, for the sake of this calculation I assume that the light is smeared out over a disk 1 arcminute across (about the size of a planet seen from Earth).

Thus, the factor $$f$$ will itself be a factor $$( heta_mathrm{Sun} / heta_mathrm{Bet})^2 simeq 1000$$ times larger - that is, Betelgeuse is only $$sim 3,000$$ times dimmer than the Sun.

Hence, for our assumptions your eye will be damaged if you observe exploding Betelgeuse through a telescope with an area $$sim 3,000$$ larger - or roughly 55 times wider - than your pupil. In bright light, the pupil contracts to roughly 3 mm in diameter, so if observing through a telescope of 16 cm or larger, you could damage your eye.

Based on evolutionary models of Betelgeuse, Dolan et al. (2016) estimate an apparent magnitude of $$m=-12.4$$, i.e. roughly 6 times brighter than our estimate. This would mean that you only need a 7 cm telescope to damage your eye.

However, as Mark writes in his answer, supernovae don't increase to their peak brightness in matters of seconds, but rather in matters days (roughly half a mag per day), so you have plenty of time to look away.

From Wikipedia: The visual light curves of the different supernova types all depend at late times on radioactive heating, but they vary in shape and amplitude because of the underlying mechanisms, the way that visible radiation is produced, the epoch of its observation, and the transparency of the ejected material. The light curves can be significantly different at other wavelengths. For example, at ultraviolet wavelengths there is an early extremely luminous peak lasting only a few hours corresponding to the breakout of the shock launched by the initial event, but that breakout is hardly detectable optically.

I'm not sure I'd want to be looking at Betelgeuse through a large telescope when this happens. Visible light is not what damages your eye. UV is.

## Apa yang akan terjadi jika seseorang memiliki teleskop dan menyaksikan Betelgeuse ketika menggunakan supernova?

Detektor Neutrino dan kelimpahan Neutrino akan mendeteksi pertunjukan yang akan datang sekitar 3 jam sebelum tanda-tanda yang terlihat, sehingga akan ada waktu untuk mengarahkan teleskop tertentu yang dapat menangani kecerahan ke arah itu.

Saya ingin tahu apakah seseorang dengan teleskop yang menunjuk ke arah itu akan memiliki kejutan yang tidak menyenangkan. Apakah komunitas ilmiah bijaksana untuk tidak mengumumkan ledakan bintang besar sampai setelah itu terlihat untuk menghindari efek negatif potensial dari para astronom amatir yang terlalu bersemangat.

Saya menyadari ini adalah pertanyaan konyol dan mungkin terlalu bergantung pada teleskop, tapi saya penasaran.

Tidak, itu tidak akan menjadi masalah. Supernova sama sekali tidak seperti bola lampu - mereka mencerahkan selama beberapa hari dan redup lagi bahkan lebih lambat. Berikut sejumlah kurva cahaya berbeda yang diambil dari Wikipedia:

Peningkatannya cepat pada skala astronomi - beberapa urutan besarnya selama sekitar sepuluh hari - tetapi sangat lambat pada skala manusia. Seorang amatir yang melihatnya tidak akan melihat perubahan signifikan dalam kecerahan, tetapi jika orang yang sama kembali beberapa jam kemudian atau malam berikutnya, perubahan itu akan sangat jelas.

Sejauh yang bisa kita katakan, alasannya adalah bahwa cahaya pada kecerahan puncak disebabkan oleh emisi dari material yang meledak oleh ledakan. Sebagai contoh, dalam Tipe 1a SNe, sebagian besar cahaya berasal dari peluruhan radioaktif dari massa besar nikel-56 yang dikeluarkan (waktu paruh 6 hari).

The artikel Wikipedia pada supernova cukup baik dan mencakup semua ini secara lebih rinci.

Jika Anda bersikeras mengamati Betelgeuse yang meledak pada kecerahan puncak, Anda berpotensi merusak mata Anda. Jawaban lengkap memasuki ranah fisiologi. Di sini saya akan membahas bagian astronomi:

Betelgeuse akan meledak sebagai supernova tipe II, kecerahan tipikal adalah sekitar . Dengan jarak , modulus jaraknya adalah jadi besarnya yang terlihat adalah M ∼ − 17 d ≃ 200 p c

Untuk perhitungan ini saya berasumsi bahwa Matahari adalah ambang untuk merusak mata Anda (pandangan singkat pada Matahari tidak apa-apa, pandangan yang lebih lama akan menyebabkan kerusakan permanen. Tapi . fisiologi . ). Matahari memiliki magnitudo , yaitu magnitudo lebih terang. Dengan kata lain, Betelgeuse akan menjadi kali lebih redup daripada Matahari. m ⊙ = − 26.7 Δ m = 16.2

Namun, Matahari adalah sumber yang diperluas, mencakup sudut kira-kira arcminutes. Sebaliknya, Betelgeuse adalah sumber titik, yang ketika ditransfer melalui atmosfer dan teleskop, tersebar di beberapa arcsecond persegi. Dengan demikian cahayanya akan lebih terkonsentrasi yaitu akan jauh lebih terang, tetapi akan mengenai area retina yang jauh lebih kecil. Namun, mata Anda juga akan bergerak, mengoleskan cahaya. Bukan menjadi ahli fisiologi, demi perhitungan ini saya berasumsi bahwa cahaya dioleskan di atas cakram 1 melintas 1 (sekitar ukuran planet dilihat dari Bumi). θ S u n = 32 θ B e t ∼

Dengan demikian, faktor itu sendiri akan menjadi faktor kali lebih besar - yaitu, Betelgeuse hanya kali lebih redup daripada matahari. f ( θ S u n / θ B e t ) 2 ≃ 1000 ∼ 3 000

Oleh karena itu, untuk asumsi kami mata Anda akan rusak jika Anda mengamati Betelgeuse yang meledak melalui teleskop dengan area lebih besar - atau kira-kira 55 kali lebih luas - dari murid Anda. Dalam cahaya terang, pupil berkontraksi dengan diameter sekitar 3 mm, jadi jika mengamati melalui teleskop 16 cm atau lebih besar, Anda dapat merusak mata Anda. ∼ 3 000

Berdasarkan model evolusi Betelgeuse, Dolan et al. (2016) memperkirakan besarnya , yaitu sekitar 6 kali lebih terang dari perkiraan kami. Ini berarti Anda hanya perlu teleskop 7 cm untuk merusak mata Anda. m = − 12.4

Namun, seperti yang ditulis Mark dalam jawabannya, supernova tidak meningkatkan kecerahan puncaknya dalam hitungan detik, tetapi dalam hitungan hari (kira-kira setengah mag per hari), jadi Anda punya banyak waktu untuk berpaling.

## How Long Does the Once-dimming Star Betelgeuse Have Left?

It's been called one of the most famous stars of all time: Betelgeuse (pronounced "Beetlejuice," like the movie) is part of the well-known Orion constellation and is usually the 10th-brightest star in the heavens, visible even to the naked eye.

"Betelgeuse over time has been more famous than Mickey Mouse, or any human alive today," says Andy Howell, staff astronomer at the Las Cumbres Observatory and a physicist at the University of California, Santa Barbara in an email interview. "That's because over hundreds of thousands of years, our human nighttime entertainment was looking at the night sky."

But in October 2019, Betelgeuse's star mysteriously began to dim. Its drop in brilliance was apparent even to casual observers. Astronomers were bewildered by its sudden shift in mood. Some suspected that Betelgeuse was running out of fuel, perhaps going supernova. Stars that go supernova create the most powerful explosions that occur in space.

However, more recent research indicates that Betelgeuse isn't necessarily on the verge of death. It may simply have produced a debris field of sorts that temporarily blocked its incredible brightness.

"Betelgeuse is a red supergiant star, about 12 times the mass of the sun, but a whopping 900 times the diameter," says Howell. "That means that if Betelgeuse were where the sun is, it would easily swallow Earth and extend out to beyond the orbit of Jupiter."

He adds that red supergiants are stars at the end of their lives, after they have fused all the hydrogen to helium in their cores. As they burn heavier and heavier elements, their cores contract and their outer layers puff up to extraordinary dimensions.

Betelgeuse has always been known for its variable brightness. Generally, those fluctuations occur semi-regularly and in only modest amounts. Howell says this happens because it pulsates as the stellar atmosphere churns like a pot of boiling water, throwing up huge blobs of material.

"But last year it started to dim noticeably to the naked eye and got quite dim for a long time in a way that had not been seen in more than a century," he says. "It was a mystery until observations revealed that there was a huge dust cloud covering a large fraction of the star."

"The cause of the dimming is under discussion and argument," emails Edward Guinan, an astrophysics and planetary science professor at Villanova. "The dimming could be due to the ejection of gas that cooled to dust and blocked the star's light. On the other hand the recent dimming (called the 'great dimming' or 'great fainting') occurred at the time expected on the 430-day periodicity so in this case would be related to a cooling caused by pulsation or the presence of a super-large convection cell."

Guinan adds that he and his colleagues think the dimming was caused by an extra-energetic pulse or the upwelling of giant convection cell and not new dust. "Continuing observations should answer this question soon," he says.

## Betelgeuse: Dying star sparks hope for ‘moon’-sized supernova over Earth

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Betelgeuse, the normally bright red star in the constellation Orion, might be dying — and its supernova will one day rival the moon in the sky above Earth. One day.

Betelgeuse is currently in its red supergiant phase, which is the geriatric stage of a star’s life when it gets bright and bloated before it dies. The next phase is full-blown supernova, when the star will collapse in on itself in a massive explosion.

The explosion is expected to happen “sometime in the next 100,000 years,” according to NASA. When it does happen, it’s expected to light up the sky over Earth in a spectacular display that will last for weeks.

Many skywatchers are hoping that “sometime” will be “sometime soon” after observing an obvious decline in Betelgeuse’s light over the last several months. Betelgeuse’s brightness faded by more than half in the latter part of 2019, making it dimmer than it’s ever been in recorded history. It’s still visible in the “armpit” of Orion, but it’s not nearly as bright as it used to be.

NASA says Betelgeuse is “likely” just running through its variable cycles, which make it look brighter or dimmer from time to time. It’s a coughing, cranky old star, and there are bound to be hiccups as it nears the end.

3:09 NASA discovers first potentially habitable Earth-size planet

A recent burst of gravitational waves has stoked speculation that the end might be near for Betelgeuse, though astronomer Andy Howell says the two situations are probably not related.

Howell admitted to stepping outside to see if Betelgeuse had blown up Tuesday, although he compared that to “buying a lottery ticket” in terms of the slim chance that it might occur.

“Betelgeuse blowing up would be far more exciting than winning the lottery,” Howell tweeted. “Lottery winners happen every day. It has been 400 years since humans have seen a supernova in our galaxy, and I’m one of the best prepared people on the planet for it.”

Supernova expert J. Craig Wheeler says it’s highly unlikely that Betelgeuse is about to explode.

“My money all along has been that Betelgeuse is going through a somewhat extreme, but otherwise normal quasi-periodic change in brightness,” he told The New York Times from the University of Texas at Austin.

Nevertheless, some skywatchers say they’re ready to start the Betelgeuse death watch. Just in case.

Just a guy, with a telescope, hoping Betelgeuse goes boom.

&mdash Mark Benson (@WaysideWriter) January 14, 2020

Betelgeuse is approximately 640 light-years from Earth. That means it’s close enough that we could watch it die without a telescope, while being far enough away that it won’t hurt us when it goes, NASA says. And it will absolutely go sometime in the next 100,000 years, in what astronomers say will be a truly spectacular display.

When Betelgeuse blows up, the supernova will be about as bright as a quarter-moon in the Earth’s sky, according to a 2015 article on the subject by Jillian Scudder, a U.K.-based astrophysicist. The supernova would show up clearly in the night sky, and would even be visible during the day if you know where to look.

1:59 Magnificence of ‘Super Wolf Blood Moon’ captured in time lapse video

Scudder said a dying Betelgeuse would be about 16 times brighter than the most well-documented supernova, which caused a stir among many ancient civilizations in 1006.

“It was said that the supernova in 1006 was bright enough to cast a shadow at night,” Scudder wrote. “Betelgeuse, being significantly brighter, would likely also cast shadows.”

One simulation suggests it would look like a bright streetlight hanging in the sky for several weeks before it fades away, leaving one less star in the Orion constellation.

Popular astronomer Neil deGrasse Tyson echoed Scudder’s words in a lengthy Twitter thread about Betegeuse’s death earlier this month.

“No need to panic, but if it exploded, the flash would be visible in the daytime, and rival the brightness of the moon for weeks,” Tyson wrote.

Tyson also pointed out that Betelgeuse “may have already exploded,” since it would take about 640 years for its light to reach Earth. That would make it a ghost or a “dead star walking,” as Tyson put it.

In fact, there might be many “dead stars” in the night sky right now, although we wouldn’t know it for millennia because of how long it takes for light to travel through space.

As writer Alan Moore once put it: “All we ever see of stars are their old photographs.”

And Betelgeuse’s next photograph might be a crazy one — though it might take a few millennia for it to reach us.

## Betelgeuse is smaller, closer, and won’t explode any time soon

Betelgeuse as seen in sub-millimeter wavelengths by the ALMA telescope in Chile. The “bump” on the left side is hot gas slightly protruding from the red supergiant star’s extended atmosphere. Image via ALMA (ESO/ NAOJ/ NRAO)/ E. O’Gorman/ P. Kervella/ ASU.

Betelgeuse is a red supergiant star in the famous constellation Orion the Hunter and one of the brightest stars in our night sky. Last year, this beloved bright star began dimming dramatically, which prompted speculation as to whether it might finally be nearing its end in a fiery explosion – a supernova – as is expected to happen sometime in the future. Many asked, could this be it? It was very exciting. But now a new study from researchers at Australian National University – announced on October 16, 2020 – suggests we might have to wait another 100,000 years before Betelgeuse’s explosive finale. The findings also show that Betelgeuse is smaller and closer than scientists had thought.

The researchers published their conclusions in a new peer-reviewed paper in The Astrophysical Journal on October 13, 2020.

This comparison image shows the star Betelgeuse before and after its unprecedented dimming, which started in late 2019. The observations – taken with the SPHERE instrument of the Very Large Telescope (VLT) in January and December 2019 – show how much the star faded and how its apparent shape changed. Image via ESO/ M. Montargès et al.

Meridith Joyce at ANU, who led the study, stated:

It’s normally one of the brightest stars in the sky, but we’ve observed two drops in the brightness of Betelgeuse since late 2019. This prompted speculation it could be about to explode. But our study offers a different explanation. We know the first dimming event involved a dust cloud. We found the second smaller event was likely due to the pulsations of the star.

If indeed the second dimming of the star was due to natural pulsations, that would be significant in terms of what will happen to Betelgeuse in the near and long-term future. Using hydrodynamic and seismic modeling, the researchers were able to determine that pressure waves were the cause of the pulsations. This means that the star is still burning helium, and therefore it shouldn’t explode anytime soon. Co-author Shing-Chi Leung from the University of Tokyo said the study:

… confirmed that pressure waves – essentially, sound waves – were the cause of Betelgeuse’s pulsation.

This image, obtained with the VISIR instrument on ESO’s Very Large Telescope, shows the infrared light being emitted by the dust surrounding Betelgeuse in December 2019. The clouds of dust, which resemble flames in this dramatic image, are formed when the star sheds its material back into space. The black disk obscures the star’s center and much of its surroundings, which are very bright and must be masked to allow the fainter dust plumes to be seen. The orange dot in the middle is the SPHERE image of Betelgeuse’s surface, which has a size close to that of Jupiter’s orbit. Image via ESO/ P. Kervella/ M. Montargès et al.

It’s burning helium in its core at the moment, which means it’s nowhere near exploding. We could be looking at around 100,000 years before an explosion happens.

The study also provided other surprising details about Betelgeuse: it’s smaller and closer to our solar system than previously thought. It’s still a red supergiant star, hundreds of times larger than our sun, but with a slightly smaller radius. According to co-author László Molnár from the Konkoly Observatory in Budapest:

The actual physical size of Betelgeuse has been a bit of a mystery earlier studies suggested it could be bigger than the orbit of Jupiter. Our results say Betelgeuse only extends out to 2/3 of that, with a radius 750 times the radius of the sun.

Once we had the physical size of the star, we were able to determine the distance from Earth. Our results show it’s a mere 530 light-years from us, 25% closer than previous thought.

Meridith Joyce at ANU, lead author of the new study. Image via ANU.

That’s significantly closer than the previously estimated distance of 724 light-years, but still plenty far away safety-wise. Whenever Betelgeuse does eventually explode, it is still distant enough that the explosion won’t have much, if any, effect on Earth. That’s a comforting thought, although if the scientists are right, none of us alive right now will be around to see it. But for any other scientists at the time, it will be a unique chance to witness a supernova that is relatively close by. Joyce said:

It’s still a really big deal when a supernova goes off. And this is our closest candidate. It gives us a rare opportunity to study what happens to stars like this before they explode.

Last August, scientists using the Hubble Space Telescope (HST) reported that a large cloud of dust most likely caused the star’s first major dimming, starting in late 2019. The dust cloud is thought to have formed from dense hot gas moving through Betelgeuse’s extended atmosphere.

This 3-paneled artist’s concept illustrates new research, explaining why the bright red supergiant star Betelgeuse suddenly became fainter for several months during late 2019 and early 2020. In panel 1, a bright, hot blob of plasma is ejected from the star. In panel 2, outflowing expelled gas rapidly expands outward and cools to form an enormous cloud of obscuring dust. In panel 3, the huge dust cloud partially blocks Betelgeuse’s light. Image via NASA/ ESA/ E. Wheatley (STScI)/ CfA.

The star later started returning to normal brightness until between late June and early August 2020, when it began dimming once again. As explained in this new study, the second, shallower dimming was likely caused by normal pulsations in the star itself. This isn’t too surprising, since Betelgeuse is a variable star and goes through brightness cycles that last about 420 days.

The new results support other assertions from scientists that Betelgeuse most likely won’t go supernova anytime soon. Plus, having more accurate measurements of the star’s size and distance will help researchers better understand its behavior and how and why these giant stars eventually face such fiery deaths.

Bottom line: The red supergiant star Betelgeuse may not explode for another 100,000 years, and is also smaller and closer than first thought, according to a new study.

## SN1987A remnant

All this talk of Betelgeuse's hundred year minimum has people excited about the possibility of the big red star going boom in a spectacular supernova. While a Betelgeuse supernova will be visible for weeks if not months to the naked eye, eventually it'll fade away.

How long before we can expect to pick the remnant up visually with an amateur-class telescope?

Remember SN1054 is now M1, first observed

SN 1572 (Tycho's Supernova) was first observed in the 60s using one of the Mt Palomar telescopes - sounds like it's invisible to amateur telescopes.

SN 1604 (Kepler's Supernova) - status not clear.

Is it possible to see the original star and the remnant within a lifetime?

### #2 Space Ant

All this talk of Betelgeuse's hundred year minimum has people excited about the possibility of the big red star going boom in a spectacular supernova. While a Betelgeuse supernova will be visible for weeks if not months to the naked eye, eventually it'll fade away.

How long before we can expect to pick the remnant up visually with an amateur-class telescope?

Remember SN1054 is now M1, first observed

700-800 years later.

SN 1572 (Tycho's Supernova) was first observed in the 60s using one of the Mt Palomar telescopes - sounds like it's invisible to amateur telescopes.

SN 1604 (Kepler's Supernova) - status not clear.

Is it possible to see the original star and the remnant within a lifetime?

The remnant of 1987a has already been imaged by Hubble and/or some larger observatories, iirc. However, I doubt most amateur equipment is capable of observing/imaging it.

### #3 Sleep Deprived

Remember SN1054 is now M1, first observed

700-800 years later.

SN 1572 (Tycho's Supernova) was first observed in the 60s using one of the Mt Palomar telescopes - sounds like it's invisible to amateur telescopes.

SN 1604 (Kepler's Supernova) - status not clear.

Each of the supernovae mentioned above are relatively distant when compared to Betelgeuse. Although there is lots of uncertainty, approximate distances are 6,000/8,000/20,000 light years, but Betelgeuse is 700-ish LY distant.

When it goes, Betelgeuse's supernova will be spectacular. If it were to happen tomorrow, I would expect that the expanding remnant would be visible pretty quickly after the glare of the supernova abates, even in amateur scopes. 1987A is visible in large scopes, but is many (many!!) times farther away than Betelgeuse, I suspect 'something' would always be visible - the glare of the SN at first, then the dimming white dwarf, then the expanding remnant as the white dwarf dims.

There was an article on CNN today, about exactly this, and it said stars like Betelgeuse (they were talking about Betelgeuse, specifically) can be expected to live

9MY. It went on to say that a supernova, although the exact timing is unpredictable, is probably 100,000's of years off. I have no idea about these timespans - I am just passing along what I read. What will amateur astronomy be like in 100,000 years. Amateur astronomy 100,000 years from now may well be exactly what it was 100,000 years AGO, so that when the 'visitor star' dims below the threshold of unaided human vision, it may never be seen again.

Apes, on the other hand, may be able to follow the progression laid out above, with their amateur scopes!! At least when the hulking remains of the Statue of Liberty don't block their view. LOL.

### #4 B l a k S t a r

Ha. Dark skies in the forbidden zone though.

### #5 Allan Wade

In 1987 I was contemplating professional astronomy, and would spend every night outside. I was panning around the LMC and saw a very bright star on the edge of the Tarantula that wasn’t there the night before. I phoned my physics teacher straight away and he casually said, it’s probably a supernova. What I would give to have had internet back then.

With that connection in mind, it was a thrill in April this year when I got to see for the first time the remnants of SN1987A in the 32”. I had never considered it before, but I guess it wouldn’t be too common for someone to see both the supernova and it’s remnant. In my case, the observations were separated by just over 32 years.

### #6 Araguaia

Here is a question: what happens if you are observing a nearby star with decent aperture when it explodes? Do you go blind?

### #7 AstroVPK

Each of the supernovae mentioned above are relatively distant when compared to Betelgeuse. Although there is lots of uncertainty, approximate distances are 6,000/8,000/20,000 light years, but Betelgeuse is 700-ish LY distant.

When it goes, Betelgeuse's supernova will be spectacular. If it were to happen tomorrow, I would expect that the expanding remnant would be visible pretty quickly after the glare of the supernova abates, even in amateur scopes. 1987A is visible in large scopes, but is many (many!!) times farther away than Betelgeuse, I suspect 'something' would always be visible - the glare of the SN at first, then the dimming white dwarf, then the expanding remnant as the white dwarf dims.

There was an article on CNN today, about exactly this, and it said stars like Betelgeuse (they were talking about Betelgeuse, specifically) can be expected to live

9MY. It went on to say that a supernova, although the exact timing is unpredictable, is probably 100,000's of years off. I have no idea about these timespans - I am just passing along what I read. What will amateur astronomy be like in 100,000 years. Amateur astronomy 100,000 years from now may well be exactly what it was 100,000 years AGO, so that when the 'visitor star' dims below the threshold of unaided human vision, it may never be seen again.

Apes, on the other hand, may be able to follow the progression laid out above, with their amateur scopes!! At least when the hulking remains of the Statue of Liberty don't block their view. LOL.

The distance does make any remnant ten times larger in angular size at a given true physical size - that's a great point. Allan Wade commented in the post above that he's seen the SN1987A remnant in a 32" scope. It's been 32 years since 1987, so it sounds like if Betelgeuse does go supernova, it'll be possible to have seen it as a star, supernova, and remnant within a lifespan. That's pretty cool.

## What happens if Betelgeuse explodes?

As a star nears the end of its life, it runs out of fuel and essentially collapses under its own gravity. The death of a giant star results in a massive explosion witnessed across galaxies, a supernova.

Astronomers have only been able to observe supernovae faint stars in distant galaxies. Because of the distance, these supernovae are only detected long after the star has exploded. But Betelgeuse is right here in our neck of cosmic woods — being this close to the star means that scientists could observe the entire process from start to finish in unprecedented detail.

“We’ll have a front-row seat observation to what happens when a star becomes a supernova,” Guinan says.

The problem is knowing when that might happen. Astronomers aren’t exactly sure what happens before a star goes supernova, so it’s hard to predict whether Betelgeuse will explode tomorrow -- or 100,000 years from now. When Betelgeuse explodes remain a cosmic mystery.

“No one has ever really seen a star before it became supernova, or measured it for weeks or months before it happened,” Guinan says. “There’s no precedence, there are no clues.”

Scientists still aren't sure whether this is part of the star’s irregular behavior or if Betelgeuse is about to give us the show of a lifetime.

“There’s a very, very, very low chance that it would blow up, but if it does -- then it would completely change my life,” Andy Howell, staff scientist at Las Cumbres Observatory Global Telescope Network, tells Inverse. “It’s like a lottery ticket . very low probability but life-changing.”

If Betelgeuse were to explode, the star will appear super bright once more— in fact, it's going to appear brighter than it's ever been.

The exploding star would reach peak brightness after a week or so, becoming as bright as the full Moon in the night sky and casting a shadow on Earth.

The detonation would also be visible during the daytime, similar to how Venus looks in twilight. Its light would last for a few months, before it plateauing and eventually completely fading from our vision over the course of a year or two.

Aside from the awe-inspiring sight of a star visible during the day, it would be an incredible learning opportunity for scientists around the world. An astronomical event of this size would make everyone hyper-aware of astronomy and the intricate science behind our stars, Howell says.

Observing a supernova in real time would also provide insight into some of the still-unexplored physics behind the stellar explosions, he says.

“People have been trying to simulate supernova for decades,” Howell says. “But in the simulators, they haven’t been blowing up.”

Because our knowledge of these events is incomplete, astronomers think they are likely still missing a piece of the puzzle behind what causes a star to explode.

## Betelgeuse went dark, but didn’t go supernova. What happened?

What look like dramatic flames are actually clouds of dust surrounding the red supergiant star Betelgeuse, as photographed in infrared light by the Very Large Telescope in Chile. The black disk blocks the star’s bright light to allow the dust plumes to show. Betelgeuse itself, photographed by the SPHERE instrument in Chile, is superimposed in the center of the black disk.

ESO, Pierre Kervella, M. Montargès et al

November 29, 2020 at 6:00 am

Astrophysicist Miguel Montargès has a clear memory of the moment the stars became real places to him. He was 7 or 8 years old, looking up from the garden of his parents’ apartment in the south of France. A huge, red star winked in the night. The young space fan connected the star to a map he had studied in an astronomy magazine and realized he knew its name: Betelgeuse.

Something shifted for him. That star was no longer an anonymous speck floating in a vast uncharted sea. It was a destination, with a name.

“I thought, wow, for the first time … I can name a star,” he says. The realization was life-changing.

Since then, Montargès, now at the Paris Observatory, has written his Ph.D. thesis and about a dozen papers about Betelgeuse. He considers the star an old friend, observing it many times a year, for work and for fun. He says good-bye every May when the star slips behind the sun from the perspective of Earth, and says hello again in August when the star comes back.

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So in late 2019, when the bright star suddenly dimmed for no apparent reason, Montargès was a little alarmed. Some people speculated that Betelgeuse was about to explode in a brilliant supernova that would outshine the full moon. Astronomers know the star is old and its days are numbered, but Montargès wasn’t ready to see it go.

“It’s my favorite star,” he says. “I don’t want it to die.”

Other researchers, though, were eager to watch Betelgeuse explode in real time. Supernovas mark the violent deaths of stars that are at least eight times as massive as the sun (SN: 11/7/20, p. 20). But astronomers still don’t know what would signal that one is about to blow. The outbursts sprinkle interstellar space with elements that ultimately form the bulk of planets and people — carbon, oxygen, iron (SN: 2/18/17, p. 24). So the question of how supernovas occur is a question of our own origins.

### A bit dim

The SPHERE instrument in Chile took images of Betelgeuse in January (top) and December (bottom) 2019. The December image shows a dark splotch, a dimming, over Betelgeuse’s southern hemisphere.

###### January 2019

ESO, M. Montargès et al
###### December 2019

ESO, M. Montargès et al

But the explosions are rare — astronomers estimate that one occurs in our galaxy just a few times a century. The last one spotted nearby, SN 1987A, was more than 33 years ago in a neighboring galaxy (SN: 2/18/17, p. 20). Betelgeuse is just one of the many aging, massive stars — called red supergiants — that could go supernova at any moment. But as one of the closest and brightest, Betelgeuse is the one that space enthusiasts know best.

So when the star started acting strangely at the end of last year, Montargès and a small band of Betelgeuse diehards aimed every telescope they could at the dimming giant. Over the following months, the star returned to its usual brightness, and the excitement over an imminent supernova faded. But the flurry of data collected in the rush to figure out what was happening might help answer a different long-standing question: How do massive, old stars send their planet-building star stuff into the cosmos even before they explode?

#### Orion’s shoulder

If you’ve looked up at the stars during winter in the Northern Hemisphere, you’ve probably seen Betelgeuse, whether you realized it or not. The star is the second brightest in the constellation Orion, marking the hunter’s left shoulder from our perspective.

And it’s huge. Estimates for Betelgeuse’s vital statistics vary, but if it sat at the center of our solar system, the star would fill much of the space between the sun and Jupiter. At about 15 to 20 times as massive as the sun, somewhere between 750 and 1,000 times its diameter and just about 550 light-years from Earth, Betelgeuse is typically between the sixth- and seventh-brightest star in the sky.

Betelgeuse’s brightness varies, even under normal circumstances. Its outer layers are a bubbling cauldron of hot gas and plasma. As hot material rises to the surface, the star brightens as material falls toward the core, the star dims. That convection cycle puts Betelgeuse on a semiregular dimmer switch that fluctuates roughly every 400 days or so. The star’s brightness also varies about every six years, though astronomers don’t know why.

### Big deal

Betelgeuse is the left shoulder of the Orion constellation (left). The star’s first portrait, made with the Hubble Space Telescope in 1996, took some doing. Hubble’s operators worried that the bright star would fry the telescope’s detectors. So astrophysicist Andrea Dupree had to use every filter Hubble had — “like wearing four sets of sunglasses,” she says. “There was nothing. Black. No light got through.” Only by taking off the sunglasses could she finally see the massive star, with a diameter that rivals the width of Jupiter’s orbit.

What they do know is that Betelgeuse is running out of time. It’s less than 10 million years old, a youngster compared with the roughly 4.6-billion–year-old sun. But because Betelgeuse is so massive and burns through its fuel so quickly, it’s already in the final life stage of a red supergiant. Someday in the not too distant future, the star won’t be able to support its own weight — it will collapse in on itself and rebound in a supernova.

“We know one day it’s going to die and explode,” says Emily Levesque, an astrophysicist at the University of Washington in Seattle. But no one knows when. “In astronomical terms, ‘one day’ means sometime in the next 200,000 years.”

In October 2019, Betelgeuse started dimming, which wasn’t too strange in and of itself. The change fit within the normal 400ish-day cycle, says astronomer Edward Guinan of Villanova University in Pennsylvania, who has been tracking Betelgeuse’s cycles of brightness since the 1980s.

But by Christmas, Betelgeuse was the dimmest it had been in the 100-plus years that astronomers have measured it. And the dimming continued all the way through February.

Guinan was one of the first to sound the alarm. On December 7, and again on December 23, he and colleagues posted a bulletin on The Astronomer’s Telegram website announcing the star’s “fainting” and encouraging fellow astronomers to take a look.

There was no reason to think that the dimming was a harbinger of a supernova. “I never said it was going to be one,” Guinan says. But because these explosions are so rare, astronomers don’t know what the signals of an imminent supernova are. Dimming could be one of them.

That report of odd behavior was all astronomers and amateur space enthusiasts needed to hear. Online, the story caught fire.

“On Twitter, it was hysterical,” says Andrea Dupree, an astrophysicist at the Harvard & Smithsonian’s Center for Astrophysics in Cambridge, Mass. She recalls seeing one tweet suggesting that the explosion was going to happen that night, with the hashtag #HIDE. “Where am I going to hide? Under my desk?” (When Betelgeuse finally explodes, it probably won’t hurt life on Earth — it’s a safe distance away.)

### Living large

After millions of years, stars that are between eight and 30 times the sun’s mass evolve into yellow supergiants, spend a few thousand years as such, then become red supergiants like Betelgeuse. Ultimately these stars explode violently as supernovas. The images above are not to scale.

C. ChangSources: Kathryn Neugent/Univ. of Washington S. Ekstrӧm et al/Astronomy & Astrophysics 2012

C. ChangSources: Kathryn Neugent/Univ. of Washington S. Ekstrӧm et al/Astronomy & Astrophysics 2012

Most astronomers didn’t really believe that Betelgeuse’s end was nigh, even as they rushed to schedule telescope time. But some got caught up in the excitement.

“I don’t expect it to blow,” Guinan recalls thinking. “But I don’t want to blink.” He signed up for phone alerts from telescopes that detect invisible particles called neutrinos and ripples in spacetime called gravitational waves. A detection of either one might be an early sign of a supernova. He found himself outside at 1 a.m. in January after a report of gravitational waves from the direction of Orion. “It was cloudy, but I thought I might see a brightening,” he says. “I’ve gotten crazy about it.”

Others were believers too, until their data cast doubt on the notion.

“I thought it might,” says astrophysicist Thavisha Dharmawardena of the Max Planck Institute for Astronomy in Heidelberg, Germany. “We knew there were other explanations, and we might have to look into it. But we know Betelgeuse is an old star, close to the end of its life. It was exciting.”

#### Two camps

Once the star started returning to its usual brightness in mid-February, talk of an imminent supernova faded. A paper published in the Oct. 10 Astrophysical Journal boosted confidence in Betelgeuse’s longevity, suggesting that the star is just at the beginning of its old age and has at least 100,000 years to go before it explodes. But what was it up to, if it was not on the verge of exploding?

As results from telescopes all over the world and in space flooded in, most astronomers have fallen into two camps. One says Betelgeuse’s dimming was caused by a cloud of dust coughed out by the star itself, blocking its glow. The other camp isn’t sure what the explanation is, but says “no” to the dust speculation.

One explanation for why Betelgeuse went dark in 2019 is that the star sneezed out a burst of gas and dust (illustrated, left), which condensed into a dark cloud. That cloud blocked the star’s face from the perspective of Earth (right). NASA, ESA, E. Wheatley/STScI

If the dust theory proves true, it could have profound implications for the origins of complex chemistry, planets and even life in the universe. Red supergiants are surrounded by diffuse clouds of gas and dust that are full of elements that are forged only in stars — and those clouds form before the star explodes. Even before they die, supergiants seem to bequeath material to the next generation of stars.

“The carbon, oxygen in our body, it’s coming from there — from the supernova and from the clouds around dying stars,” Montargès says. But it’s not clear how those elements escape the stars in the first place. “We have no idea,” he says.

Montargès hoped studying Betelgeuse’s dimming would let scientists see that process in action.

In December 2019, he and colleagues took an image of Betelgeuse in visible light with the SPHERE instrument on the Very Large Telescope in Chile. That image showed that, yes, Betelgeuse was much dimmer than it had been 11 months earlier — but only the star’s bottom half. Perhaps an asymmetrical dust cloud was to blame.

Observations from February 15, 2020, seem to support that idea (SN: 4/11/20, p. 6). Levesque and Philip Massey of the Lowell Observatory in Flagstaff, Ariz., compared the February observations with similar ones from 2004. The star’s temperature hadn’t dropped as much as would be expected if the dimming was from something intrinsic to the star, like its convection cycles, the pair reported in the March 10 Astrophysical Journal Letters.

That left dust as a reasonable explanation. “We know Betelgeuse sheds mass and produces dust around itself,” Levesque says. “Dust could have come toward us, cooled and temporarily blocked the light.”

#### Dark cloud

A strong vote for dust came from Dupree, who was watching Betelgeuse with the Hubble Space Telescope. Like Guinan, she has a decades-long relationship with Betelgeuse. In 1996, she and colleague Ronald Gilliland looked at Betelgeuse with Hubble to make the first real image of any star other than the sun. Most stars are too far and too faint to show up as anything but a point. Betelgeuse is one of the few stars whose surface can be seen as a two-dimensional disk — a real place.

By the end of 2019, Dupree was observing Betelgeuse with Hubble several times a year. She had assembled an international team of researchers she calls the MOB, for Months of Betelgeuse, to observe the star frequently in a variety of wavelengths of light.

In late 2019, Betelgeuse started dimming (V curve, right) more than its normal up and down (V curve, left). The blue and green dots are brightness measurements from ground-based observatories.

###### Betelgeuse brightness measurements, 2019-2020

A.K. Dupree et al/Astrophysical Journal 2020

A.K. Dupree et al/Astrophysical Journal 2020

The goal was the same as Montargès’: to answer fundamental questions about how Betelgeuse, and perhaps other red supergiants, lose material. The MOB had baseline observations from before the dimming and already had Hubble time scheduled to track the star’s brightness cycles.

Those observations showed that in January and March 2019, Betelgeuse looked “perfectly normal,” Dupree says. But from September through November, just before the dimming event, the star gave out more ultraviolet light — up to four or five times its usual UV brightness — over its southern hemisphere.

The temperature and electron density in that region went up, too. And material seemed to be moving outward, away from the star and toward Earth.

Dupree and colleagues’ theory of what happened, reported in the Aug. 10 Astrophysical Journal, is that one of the giant bubbles of hot plasma always churning in the star’s outer layers rose to the edge of the star’s atmosphere and escaped, sending huge amounts of material flowing into interstellar space. That could be one way that red supergiants shed material before exploding.

Once it had fled the star, that hot stuff cooled, condensed into dust and floated in front of Betelgeuse for several months. As the dust cleared, Betelgeuse appeared brighter again.

“It seems to us that what we saw with the ultraviolet is kind of the smoking gun,” Dupree says. “This material moved on out, condensed and formed this dark, dark dust cloud.”

Paul Hertz, director of NASA’s astrophysics division, shared the Hubble results in a NASA online town hall meeting on September 10 as if it were the final answer. “Mystery solved,” he said. “Not gonna supernova anytime soon.”

#### Cycles and spots

Maybe not — but that doesn’t mean dust explains the dimming.

In the July 1 Astrophysical Journal Letters, Dharmawardena and colleagues published observations of Betelgeuse that ran counter to the dust explanation. Her team used the James Clerk Maxwell Telescope in Hawaii in January, February and March to look at Betelgeuse in submillimeter wavelengths of light. “If we think it’s a dust cloud, the submillimeter is the perfect wavelength to look at,” she says.

Dust should have made Betelgeuse look brighter in those wavelengths, as floating grains absorbed and reemitted starlight. But it didn’t. If anything, the star dimmed slightly. “Our first thought was that we’d done something wrong — everyone in the community expected it to be dust,” she says. But “the fact that it didn’t increase or stay constant in the submillimeter was pretty much a dead giveaway that it’s not dust.”

Infrared observations with the airborne SOFIA telescope should have found the glowing signature of dust too, if it existed. “It never showed up,” Guinan says. “I don’t think it’s dust.”

Instead, Guinan thinks the dimming may have been part of Betelgeuse’s natural convection cycle. The star’s outer atmosphere constantly pulsates and “breathes” in and out as enormous bubbles of hot plasma rise to the surface and sink down again. “It’s driven by the internal core of the star,” he says. “You have hot blobs rising up, they cool, they get more dense, they fall back.”

Multiple cycles syncing up could explain why the 2019 dimming was so extreme. Guinan and colleagues analyzed about 180 years of observations of Betelgeuse, dating back to astronomer John Herschel’s 1839 discovery that the star’s brightness varies. Guinan’s group found that, in addition to the roughly six-year and 400-day cycles, Betelgeuse might have a third, smaller cycle of about 187 days. It looks like all three cycles might have hit their brightness nadirs at the same time in late 2019, Guinan says.

Or maybe the darkness in the southern hemisphere that Montargès’ team saw with SPHERE was an enormous star spot, Dharmawardena offers. In the sun’s case, those dark splotches, called sunspots, mark the sites of magnetic activity on the surface. Betelgeuse is one of a handful of stars on which star spots have been directly seen.

But to cause Betelgeuse’s dimming, a star spot would have to be enormous. Typical star spots cover about 20 to 30 percent of a star’s surface, Dharmawardena says. This one would need to cover at least half, maybe up to 70 percent.

“That’s rare,” Dharmawardena admits. “But so is this kind of dimming.”

#### Pandemic disruptions

Analyses are still coming in. But just as Betelgeuse was returning to its normal brightness, the COVID-19 pandemic hit.

“We were hoping to have a lot more data,” Dharmawardena says.

A few observations came in right under the wire. The SOFIA observations were made on one of the last flights before the pandemic grounded the plane that carries the telescope. And Montargès took another look with SPHERE just days before its observatory shut down in mid-March.

In mid-July 2020, astronomers announced that STEREO, a sun-watching spacecraft, had seen signs that the star Betelgeuse was beginning to dim yet again. HI/Stereo/NASA

In mid-July 2020, astronomers announced that STEREO, a sun-watching spacecraft, had seen signs that the star Betelgeuse was beginning to dim yet again. HI/Stereo/NASA

But one of Montargès’ most hoped-for results may never come. Eager to solve the dust versus not-dust mystery, his plan was to combine two kinds of observations: making a 2-D picture of the whole star’s disk, like Dupree did with Hubble in the ’90s, but in longer wavelengths such as infrared or submillimeter, like Dharmawardena’s images from early 2020. That way, you could differentiate the dust from the star, he reasoned.

Only one observatory can do both at once: the Atacama Large Millimeter/submillimeter Array, or ALMA, in Chile. Montargès had planned to ask to observe Betelgeuse with ALMA in June and July, when the winter skies in the Southern Hemisphere are most free of turbulence. But ALMA closed in March and was still closed in September.

“When I realized ALMA will not get the time in June, I thought … we are never going to solve it,” he says. “We may never be completely certain, because of COVID.”

#### Any other star

Montargès and his colleagues have submitted their analysis of the SPHERE pictures from March for publication. Though he’s not yet willing to share the results, he thinks they could pull the two camps together.

Ultimately, if Betelgeuse did cough out a cloud of dust last year, it could teach us about the origins of life in the universe, Montargès says. If the dust camp is even partially right, Betelgeuse’s dimming may have been the first time humans have watched the seeds of life being launched into the cosmos.

In the meantime, he’s relieved to see his favorite star shining bright again. “I must admit that since [last] December, since this whole stuff started, every time I see it, I am like, phew, it’s still there,” he says.

People keep asking him if he would like ​Betelgeuse to go supernova so he can study it. “I would like another star to go supernova,” he says. “Antares, I don’t care about it it can explode anytime. But not Betelgeuse.”

Questions or comments on this article? E-mail us at [email protected]

A version of this article appears in the December 5, 2020 issue of Science News.

## Astroquizzical: What happens when Betelgeuse explodes?

It’s one of the nearest red supergiants to us, and a supernova is only a matter of time. What are we in for when it happens?

Question: If Betelgeuse explodes right now, could we see it with naked eye? It is over 400 light years away, so you might think that people would see it long after it actually happens?

Betelgeuse is already one of the brightest stars in the night sky, sitting somewhere around the 8th or 9th brightest star in the night sky. (These lists don’t include the Sun, which is somewhat obviously always the brightest object in the sky.) It sits in the constellation Orion, along with a number of other bright stars, and makes up the left hand shoulder of the warrior. It looks visibly orange in the night sky, and is classified as a red supergiant star, in the later stages of its life. It’s also one of the few stars that’s close enough for us to resolve in more detail than a point source, and the pictures are pretty fun.

If Betelgeuse were to go supernova right now — as in, if you could break physics and travel to the star instantaneously to check on it — you’re absolutely correct to think that it would take us quite a while to notice. Betelgeuse is about 600 light years away from our solar system, so the light traveling from Betelgeuse has about 600 years of travel before it will reach us. If the star had physically exploded in 2015, we wouldn’t spot the light from that explosion until 2615. We’re constantly observing this star (and pretty much everything in the Universe) as it was, a significant period of time ago. This is also why astronomers say that in studying the night sky, we study the past. The more distant the object, the further in the past we observe. 600 light years, in the grand scheme of things, is pretty close we’re still dealing with our local neighborhood inside our own galaxy.

Supernovae are incredibly bright phenomena. At the brightest point of the explosion, a supernova can outshine the whole galaxy it lives in. A single star has managed to, for a short time, be a brighter source of light than the several billion other stars in its galaxy combined. This is tremendously bright. Supernovae do have a “rising time” of about a week, when the star is increasing in brightness — it stays at its peak brightness for a few days, and then slowly declines into obscurity over a period of a couple of weeks.

But how bright would Betelgeuse specifically be? We can do some math to work this out, making the assumption that Betelgeuse explodes as a Type II supernova. The exact style of supernova is still up for a bit of debate, depending on the exact rotation speed and mass loss of the star over the next hundred thousand years. Regardless of the exact method of its explosion, all the supernovae options for this star have a peak brightness of approximately the same value, so for a quick calculation that’s good enough to determine what we’d see with the naked eye.

There are two ways of measuring brightness in the astronomy world the first is absolute magnitude, which is the brightness of the star, as it would be measured from a fixed distance. (It’s arbitrary, but the fixed distance chosen is 10 parsecs, or about 33 light years.) This is trying to get to a measure of intrinsic brightness — as though we could line up everything in the sky at equal distance from us, and compare them to each other that way. We can’t actually measure the brightness of a star this way, but we can apply some corrections based on the distance to the star to get to it. The absolute magnitude of a Type II supernova is around -17. Because astronomers have the worst conventions in the world (for largely “historical reasons”), negative numbers mean brighter objects. The sun has an absolute magnitude of 4.83, which, once we translate out of “magnitudes”, means that the sun is 500 million times fainter than the supernova, when measured at the same distance. This huge difference in relative brightness is why a supernova can outshine an entire galaxy.

The other method of measuring brightness is a bit more straightforward. It’s the apparent brightness — i.e., how bright does it appear to us as viewed from the Earth. In this frame of reference, more distant objects will always appear fainter, regardless of how intrinsically bright they are. Because Betelgeuse is still fairly distant from us, the apparent brightness would be significantly less than the absolute magnitude. Based on the distance to Betelgeuse, we can work out that the apparent magnitude of the peak of the explosion would be -10. The sun, in apparent magnitude, is the brightest thing in our sky, and is checking in at an apparent magnitude of -26.74. Once again translated out of magnitudes, this means that the Sun as seen from the Earth is a whopping

5 million times brighter than Betelgeuse’s explosion, so our supernova certainly won’t be anywhere near as bright as our sun in the daytime. That’s not to say you wouldn’t be able to see it — it would definitely be bright enough to see during the daytime, as long as you were looking in the right direction. (After all, you can still see Venus in the daytime, if you know where to look!)

Nighttime will be a different story. The brightness of Betelgeuse’s supernova is about the same as the quarter moon. It would also be about 16 times brighter than the brightest supernova known to have been seen from earth, which occurred in 1006, and was recorded by a number of early civilizations. (An image of what remains of that supernova is shown below.)

It was said that the supernova in 1006 was bright enough to cast a shadow at night. Betelgeuse, being significantly brighter, would likely also cast shadows — which, if you think about the brightness of a quarter moon, would make sense!

All that said, Betelgeuse isn’t expected to explode for another 100,000 years or so. We do expect a few supernova in our galaxy every few hundred years, so there are a number of stars that are nearing the ends of their lifetimes within our galaxy. It’s hard to predict exactly when a star will transition from “close to the end of its life” to “exploding in the next week”, so while we expect that none of these will be exploding in the next little while, it’s difficult to predict which one of the stars will be the first to go. In the mean time, we can take wonderful pictures of the more nearby stars, like the one below taken by Hubble, and watch them cast off their outer layers at an incredible rate.

If you have your own questions you’d like Astroquizzical to cover, you can submit them at Astroquizzical’s ask page!

## RELATED ARTICLES

Astronomer and BBC Sky at Night presenter Chris Lintott says the star's light is variable, which means it's not likely to go supernova in the near future.

'Lots of people are either excited or scared that Betelgeuse is about to go supernova. The fact it’s dimming is amazing - so weird that Orion looks different - but it’s no more likely to go bang in a dip like this than before.

'Betelgeuse just does this from time to time. It’s hard being a constant brightness when you’re big enough to engulf the inner solar system.'

If it were at the centre of the Solar System in place of the Sun its surface would engulf the inner planets from Mercury to Mars and possibly even Jupiter

If it does go supernova, as some scientists predict, it will appear much brighter than Venus when looked at by the naked eye - says data scientist Jason Baumgartne.

'Venus has an apparent magnitude of -4.4. Betelgeuse going super nova would probably get to around -12.4 apparent magnitude.

'Imagine looking at Venus in the sky but it was over 1,500 times brighter. That's how bright Betelgeuse would appear.'

Science writer and astronomy imaging specialist Jason Major says speculating about a supernova is like imagining what you'd do if you won the lottery

Sky at Night presenter Chris Lintott is among a number of astronomers explaining that Betelgeuse is a variable star that dips in brightness regularly

Betelgeuse is a Red Super Giant star and is one of the largest in the Milky Way Galaxy.

• It has a diameter of about 700 million miles
• It's brightness is 7,500 times greater than the Sun
• It can be seen from Earth on the shoulder of the Orion constellation
• It can be easily found in the night sky through most of the year
• It is is estimated to have a maximum mass of around 20 to 30 times that of the sun
• It's surface temperature is thought to be about 6,000 F
• It is about 100,000 times more bright than the Sun
• It's about 640 light years from the Earth
• When it explodes it will appear as bright as the moon in the night sky for several weeks

It takes about 642 years for the star's light to get to Earth so any sign that it might be going supernova that we are seeing now, actually happened in 1377.

'If Betelgeuse goes supernova, the blast will take 20,000-100,000 years to reach us, and the Sun's magnetic bubble will shield us', says science writer Corey S Powell.

'It would be as bright as the full moon, concentrated into a point. Easily visible during the day, and possibly painful to look at directly at night!'

Mr Eagle said that when it does pop it will be 'as bright as the full moon' but the light would be contained with a tiny point of light - making Orion strange to look at.

'After many weeks outshining all the other stars in the sky, the supernova’s light will start to fade.

'From then on our view of Orion will change forever, The Mighty Hunter effectively losing his right shoulder.'

What is not known is whether Betelgeuse will turn into a neutron star or a black hole after its end of life explosion.

To become a black hole it has to leave behind material equalling more than three times the mass of the Sun. Under that and it becomes a neutron star.

### SUPERNOVAE OCCUR WHEN A GIANT STAR EXPLODES

A supernova occurs when a star explodes, shooting debris and particles into space.

A supernova burns for only a short period of time, but it can tell scientists a lot about how the universe began.

One kind of supernova has shown scientists that we live in an expanding universe, one that is growing at an ever increasing rate.

Scientists have also determined that supernovas play a key role in distributing elements throughout the universe.

In 1987, astronomers spotted a ‘titanic supernova’ in a nearby galaxy blazing with the power of over 100 million suns (pictured)

There are two known types of supernova.

The first type occurs in binary star systems when one of the two stars, a carbon-oxygen white dwarf, steals matter from its companion star.

Eventually, the white dwarf accumulates too much matter, causing the star to explode, resulting in a supernova.

The second type of supernova occurs at the end of a single star's lifetime.

As the star runs out of nuclear fuel, some of its mass flows into its core.

Eventually, the core is so heavy it can't stand its own gravitational force and the core collapses, resulting in another giant explosion.

Many elements found on Earth are made in the core of stars and these elements travel on to form new stars, planets and everything else in the universe.