Astronomers have found the stars responsible for an explosion recorded in 1437 | Hacker News Reader

Astronomers have found the stars responsible for an explosion recorded in 1437

theatlantic.com

285 pointscurtis60 comments

My first reaction was "it shone for 14 days and only Korean astronomers noticed it?" Then I googled for that nova and eventually found this interesting article https://academic.oup.com/astrogeo/article/47/1/1.29/258488/W...

It seems that Koreans were particularly keen at looking for novae. Cloudy skys, lack of fast global communications, the small number of people looking for faint new stars could explain why nobody else noticed it. For example, about the supernova of 1604 which was visible during the day:

> "On the 30th [of September], the sudden breaking of the clouds afforded one of Kepler's friends an opportunity of having a very short view of it… On the 2nd, 3rd, 4th and 6th of October, it was seen by several persons in different places. On account of cloudy weather at Prague, where Kepler resided, he did not see it until the 8th of that month."

If that's happened to a supernova, I can imagine a nova could slip away unnoticed.

This nova would also have been rather low in the sky. From Seoul's latitude, the maximum altitude of the nova would have been about 7.5 degrees above the southern horizon, and not visible at all from much of Europe.

It always saddens me to remember that with the arrival of electricity & technology we've truly lost the fascinating view of the cloudless night sky. I assume that in 15th century Korea it was much easier to notice changes in the night sky than it would be today.

(edit: typo)

There are still several dark sky preserves (https://en.wikipedia.org/wiki/Dark-sky_preserve) in the world, where the view will be just as good as 15th Century Korea.

Having spend several nights around Tekapo, which is one of the largest in the world. I would definitely say that it's worth trying to spend a night in one. The view of the night sky is stunning. You can see the Milky Way with the naked eye, and the sheer number of stars is magnificent.

In most of rural Australia you get an incredible view of the sky - particularly in the North of Western Australia and in the Northern Territory. It's an incredible view when you can see the milky way from horizon to horizon.

You don't have to go too far to find dark skies.

My wife and I rented a cottage at Sheep Dung just outside Boonville, CA, a few years ago. Ukiah was on the far side of the hills to the east, another range blocked the coast to the west, and the next closest big city was Santa Rosa -- far enough away not to cause light pollution. I got lucky because the Labor Day wildfires were east of Clear Lake and blowing smoke east toward I-5. It was the first time in my life I got to actually see the Milky Way with my own eyes.

I am in Bolinas right now, it's close to midnight, and I am going to close my laptop in a few seconds, and go out to look at the night Sky - which I did yesterday, and it was quite magnificent.

Since you posted that 20 hours ago, I'm sure you're done by now. But don't forget it can take 20 minutes to an hour to get your eyes fully adapted to the dark.

So don't go out for just a short time, plan to spend a while in the dark before fully enjoying the stars.

The night sky from the Sierra Nevada (at altitude) -- even a "crowded" place like Tuolumne Meadows -- offers amazing night skies.

Yeah lots of rural areas in the US have very dark skies. I saw lots of shooting stars one night driving acros Utah, it was pretty incredible.

Seeing one an hour is average, seeing many _while driving_ sounds like it was a meteor shower. Did that happen to be around August 12, which is when the strongest shower of the year peaks?

Pretty close. End of July, 8 years ago. It was definitely more than one an hour, but not like what Is imagine a shower to be like. Maybe more like one every 15 minutes

The Perseids peak at around 60/hour, but I guess it's a lot less a couple weeks before.

The Blackrock Desert in Northern Nevada is a wonderful place to see the night sky (except maybe this week)

> The view of the night sky is stunning. You can see the Milky Way with the naked eye, and the sheer number of stars is magnificent

Note that you can see the Milky Way with naked eyes also outside of reservates. Maybe most people forget this when living in a city, but all you need for a stunning sky view is to go to the next grassland on the countryside around your city. (And you need non-cloudy weather, of course.)

It might not be as perfect as in the preservates, but compared to what you see within a city, it is a huge difference. You see at least 10 times as many stars. And of course you see the Milky Way clearly.

(But beware that a beginner might mistake large, thin clouds for the Milky Way. Also, note that beginners might be confused by the sheer amount of stars, being unable to identify even basic star signs. The trick here is to visit the grassland on sunset, then wait for the dusk, and watch as more and more stars appear on the sky. The first seen (i.e. brightest) stars are usually easy to identify, then you see the brighter star signs, and finally have enough orientation to recognize the rest of the sky as it appears.)

I second the 'get to the observation point before sundown' advice. In some really dark places, there are so many stars that I even have a hard time picking out bright stars like Vega or easy constellations such as Cygnus, Orion, or the Big Dipper. Watching the stars come out makes this much easier, and as a bonus the planets really awe at dusk.

Yep, as long as you're remote enough you can get a truly fascinating view.

Last summer I camped in Zion National Park and it was the first time I've seen the night sky with such clarity. I couldn't look away - I laid outside of the tent and just stared for hours.

The fact that we're in the midst of a big explosion is quite striking.

Also to note, make sure you go when it is a New Moon i.e., no moon in the sky.

40 years ago my father worked in Mongolia. He never seen stars like there even in rural or very remote areas of Russia. The reason for that is elevation (over 2 km at place where he worked) and very dry air (it was on edge of Gobi desert).

Maybe the OP just means generally?

I used to live in Amsterdam and the light pollution was so bad [1] the night sky just looked like a dull grey, I remember how grateful I was to move away and get to view the night sky more frequently. Light pollution such as that found in Rotterdam is almost suffocating I find.

Sure travelling is an option, for kids? Not really.

[1] https://www.lightpollutionmap.info/#zoom=9&lat=6819816&lon=5...

One of the things I really liked about living in NYC was that I actually got pretty familiar with the planets (because you can't really see anything else).

You don't even have to go that far. One of the nice things about hiking outdoors is you get far enough away from civilization to reduce or eliminate city glow. On the off chance you ever get tired of looking at all the stars and the milky way, you can also spot satellites flying overhead, especially just after sunset.

Not just lost the view through light pollution but found loads of other bright things to stare at once the sun is down. I agree it's quite sad.

Humans have been staring at fire at night for our entire evolution.

True, but the spectrum and intensity a fire is much lower than today's incandescent light bulbs, fluorescences, LEDs, and screens.

And I was speaking more from the perspective of screen addiction, lured to watch TV and trawl social media. Not that staring into a fire is much more productive.

The western US has some large areas with almost no lights. Northern Nevada and Eastern Oregon are almost empty. North of Winnemucca, when starting to head west on highway 140, there is a sign, "Next gas 179 miles".

South Dakota too! Camped at the Badlands a few weeks ago and other than a little light pollution from nearby Wall, you could see everything. It was spectacular.

>we've truly lost the fascinating view of the cloudless night sky

We haven't truly lost anything, unless you're unwilling to travel for an hour or two away from light pollution. The sky is still there and you can still see it.

Ten days ago, weather gave us an excellent clear night, and the Milky Way was visible from my front door, in the middle of the neighborhood, even though we have old street lights and live in town.

I try to practice spotting the Milky Way in the midst of light pollution. Nothing like a real dark sky, but use an app on your phone to show you where to look, and with practice you can appreciate the skies from where you are.

(Every time I show someone the International Space Station, they think it is an airplane. It gets very bright, and apparent speed changes as it climbs towards zenith and back down again.)

I got to say I am always astonished at astronomical discoveries. Finding a wrecked ship in ocean is really really difficult, but correlate and finding what is out there in the open space, hundreds or even more light years away is like finding a dust particle in the open sea. Let's pause for a moment and appreicate these discoveries....

And yet the average investment banker or lawyer gets 10x the salary. Priorities...

Astonishment factor is not worth much in terms of money.

"Michael Shara and his researcher colleagues have spent the last nearly 30 years looking for the star responsible for this nova." that's what you call dedication :D

This headline is a little funny if you choose to read it as a legal verdict.

Good eye 11

Lock 'em up!

It's grating to see a major publication quote a date as "1437 AD". It's either "1437 CE" or "AD 1437".

It may be a house style, and/or it may not be as important as you think.

For example, the Wikipedia house style, at https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style/Date... , "says: AD may appear before or after a year (AD 106, 106 AD); the other abbreviations appear only after (106 CE, 3700 BCE, 3700 BC)."

The Atlantic is at least consistent.

"Pre-Islamic Iranian history is believed to range from about 4000 BC to 651 AD." - https://www.theatlantic.com/international/archive/2012/04/ir...

"But earlier sand blows found underground have been dated—thanks in part to the native pottery shards and charcoal that sandwich them—to 1450 AD, 900 AD and 2350 BC." - https://www.theatlantic.com/science/archive/2016/06/the-grea...

"The dawn of the "Neolithic revolution" around 8,000 BC marks man's transition from hunter-gatherer to food producer. Life" - https://www.theatlantic.com/health/archive/2013/01/the-iron-...

"...which killed about 50 million people in Europe and the Byzantine Empire between 600 and 800 A.D..." - https://www.theatlantic.com/health/archive/2015/09/disease-p...

The one exception I found (I only looked at the first few matches) is due to a book titled "EUROPE BETWEEN THE OCEANS: 9000 BC to AD 1000 " - https://www.theatlantic.com/magazine/archive/2008/12/books-o...

I was way more concerned with a modern photo being labelled as if it were taken in 1437 AD.

I'm left wondering if that's the nova now, supposedly created in 1437, is it an artistic rendering of how it is supposed to have looked (in negative, b&w, through a telescope), or what?

"One the one hand" - do these publications proofread their stuff?

Did you get a refund?

I did not, but I did swallow the ads they sent me so maybe I should.

So keep your adblocker and scriptblockers running.

Except for the subjectively well written articles of course

What? No. Well-written or not, if they try to put ads and javascript in my face, I block it.

This is a perfectly acceptable phrase where I'm from

They obviously meant to write "On the one hand" Those if you downvoting me -- grammer is sexy.

I completely mis-read the first "one" - oops. Guess that's why I was downvoted to 0 :-D

>"According to their calculations, the star was right in the center of the nova shell on the day the Koreans saw a mystery star, which means it caused the cosmic explosion."

Hmm, or it was in a different plane and is many light years from the nova and some other star, which died, or is too faint to see, or isn't charted, was the cause of that particular nova.

Isn't this classic "correlation is not causation" stuff?

I was expecting to find how they showed the Koreans recorded the position so accurately it could be matched - to the day - with a projected location of a star for which we have 3 data points?

The conclusion (in the abstract) sounds more like a postulate. It seems perfectly reasonable, but does it really follow logically from this single instance?

Presumably, if the conclusion is sound, there are enough records of novae that one can now draw _many_ star trajectories through groups of novae each caused by a single star?

Isn't this classic "correlation is not causation" stuff?

It isn't. There are only a few dozen intragalactic novas per year. They've been looking for this one for a while and so far this is the only candidate anyone's found.

one can now draw _many_ star trajectories through groups of novae each caused by a single star?

That's a bit like saying you can draw many trajectories of cars that could have been in a crash while the smoldering wreckage is sitting by the side of the road.

We're looking at 600 years back, so are you saying there's 18000 novas to examine (30 per year) across that period?

Their conclusion in the OP was AIUI that _many_ stars produce novae serially. So we should surely be able to match series of novae (along a stars trajectory).

Do you know are English language details of the historic Korean record available (are they in the paper)?

http://www.cbat.eps.harvard.edu/nova_list.html shows very few recorded novae, is this a listing including the dozens per annum you mention?

https://arxiv.org/abs/astro-ph/0501331 includes a table (as far as I know, exhaustive) of historical Korean nova records.

Fascinating, I was expecting it to be in hanguls rather than Chinese characters - never really considered astronomy as having an overlap with history quite so much as this before. Thanks for the link.

Their conclusion in the OP was AIUI that _many_ stars produce novae serially. So we should surely be able to match series of novae (along a stars trajectory).

The time between classical nova outbursts is estimated to be on the order of 10,000 years, so the previous outburst of this particular nova was probably long before the development of writing.

In addition, it likely takes only a couple of thousand years for the expanding shell of gas to fade from visibility, so it's probably not possible to find the traces of previous outbursts along the trajectory (although that would be cool).

Binary systems that produce classical novae (like this one) don't "die". Moreover, the star that they identified is a confirmed binary system with an evolved late-type star and a white dwarf, which is precisely the kind of system that you need to produce a classical nova. (Part of the paper is data demonstrating this, including the orbital period -- about half a day -- of the system). In addition, it has produced minor ("dwarf nova") outbursts several times in the last century, which is what you'd predict for a system in the "hibernation" period between classical nova outbursts.

So it's not just the spatial match-up -- there's a lot of additional supporting evidence that this binary system is in fact the one what done the deed.

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