Not long ago, the center of the Milky Way exploded | Hacker News Reader

Not long ago, the center of the Milky Way exploded

phys.org

235 pointsdnetesn120 comments

When this was first noticed (2013) I recall statements (possibly speculative) that the irradiated part of the Magellanic Stream might have glowed brightly enough to be visible in the night sky. If so, it would have subtended about half a degree, about the same width as the moon and the sun.

And here we are stuck with just a sun and moon!

I guess that's why we won't be hearing radio signals from the Magellanic clouds...

Now, seriously, what would be a safe distance for an Earth like planet to be from such an unlucky event?

Paper: http://www.physics.usyd.edu.au/~jbh/share/Papers/JBH-Ionizat...

Given that we're able to aim telescopes at things that are billions of light years away, I wonder how close we are to being able to see the reflection of such a thing when it actually happens on some celestial body 3.5 million light years away.

You might be interested in the examples section of https://en.wikipedia.org/wiki/Light_echo

I remember as a child thinking I had fixed time travel (in a very limited sense) when I wondered why we didn't just stick a bunch of mirrors far far away, and then aim them back at the earth and use telescopes to look back at the dinosaurs etc.

While that wouldn't work for heaps of reasons, I like your idea. I guess the issue would be discerning 'when' such a thing happened, and finding the right item to look back at, which would be a difficult challenge...

I had the same idea. I forgot about it before I was old enough to reason about it. At the time I thought the size of the mirrors would be the biggest issue. I guess I thought faster-than-light travel was easy.

I have a distant childhood memory of a book based on this concept, in which the protagonist is projected back in time through light beams bounced off of distant mirrors. I think I stopped reading because I could tell the science was completely impossible, and ultimately just an excuse to write an historical fiction book which I didn't feel like reading. Perhaps I judged it too harshly?

Ignoring the problems with resolution, the big issue with this is you would need FTL travel to position the mirrors ahead of the light.

And this in turn is one of the big reasons why FTL is probably impossible: It is in essence time travel.

You need natural mirrors, because as others have pointed out, they have to already be there, you can't get ahead of the light to put them there.

It has been suggested that black holes could provide this mirror, but it requires resolving not just something the size of Earth, but something much smaller, at a distance of 30 million light years +. Unfortunately you actually start hitting up against the limits of spacetime's resolution itself fairly quickly. But at least in principle, it is possible that some lucky photon has bounced off a dinosaur, and has traveled all the way out there, and all the way back to Earth, just now, that if you knew where to look in the sky, perhaps such a photon might even enter your eye now. Or perhaps there is some human out there who really has "seen" the dinosaurs. But you'd never really know.

What are these "limits of spacetime's resolution" you speak of?

Beyond speculation, I'm not aware of anything showing spacetime to be discrete.

> What are these "limits of spacetime's resolution" you speak of?

> Beyond speculation, I'm not aware of anything showing spacetime to be discrete.

It is a prediction of loop quantum gravity [1]:

In 1988, Carlo Rovelli, Lee Smolin, and Abhay Ashtekar introduced a theory of quantum gravity called loop quantum gravity. In 1995, Rovelli and Smolin obtained a basis of states of quantum gravity, labelled by Penrose's spin networks, and using this basis they were able to show that the theory predicts that area and volume are quantized. This result indicates the existence of a discrete structure of space at very small scale.

[1] https://en.wikipedia.org/wiki/Carlo_Rovelli#Loop_quantum_gra...

It's a prediction of other things, too. Even just sheer every-day quantum mechanics sets a limit, too; eventually you're asking to nail down a photon's origin with so much precision that you lose the frequency or something, things you don't normally think about even in the most extreme astronomy today, but become relevant when discussing bouncing photons around a black hole 30 million light years away.

Modern QM formalization doesn't predict a discrete spacetime. Or, if it does, nobody has been able to demonstrate this, to my knowledge.

Eventually you will get so far away from something that you cannot resolve it even at the plank distance.

How does that necessitate a discrete spacetime?

:) https://news.ycombinator.com/item?id=9161967

Bit turnoff is, we couldn't even take photograph of human size on moon, things far away are mind blowing huge. Every data is blurred out.

We already have: Clavel et al. (2013) Echoes of multiple outbursts of Sagittarius A[star] revealed by Chandra.[0] Here's the abstract:

> The relatively rapid spatial and temporal variability of the X-ray radiation from some molecular clouds near the Galactic center shows that this emission component is due to the reflection of X-rays generated by a source that was luminous in the past, most likely the central supermassive black hole, Sagittarius A[star]. Studying the evolution of the molecular cloud reflection features is therefore a key element to reconstruct Sgr A[star]'s past activity. The aim of the present work is to study this emission on small angular scales in order to characterize the source outburst on short time scales. We use Chandra high-resolution data collected from 1999 to 2011 to study the most rapid variations detected so far, those of clouds between 5' and 20' from Sgr A[star] towards positive longitudes. Our systematic spectral-imaging analysis of the reflection emission, notably of the Fe Kalpha line at 6.4 keV and its associated 4-8 keV continuum, allows us to characterize the variations down to 15" angular scale and 1-year time scale. We reveal for the first time abrupt variations of few years only and in particular a short peaked emission, with a factor of 10 increase followed by a comparable decrease, that propagates along the dense filaments of the Bridge cloud. This 2-year peaked feature contrasts with the slower 10-year linear variations we reveal in all the other molecular structures of the region. Based on column density constraints, we argue that these two different behaviors are unlikely to be due to the same illuminating event. The variations are likely due to a highly variable active phase of Sgr A[star] sometime within the past few hundred years, characterized by at least two luminous outbursts of a few-year time scale and during which the Sgr A[star] luminosity went up to at least 10^39 erg/s.

0) https://arxiv.org/abs/1307.3954

Edit: Older image: https://www.chandra.harvard.edu/photo/2007/gcle/

WOWWW...that's super cool. If you could find multiple reflections of the same source [edit: after a second look, that's actually what they did which is even more amazing], you could start piecing together a sequence.

But, darn it, now we're going to have to map the cosmic background light pollution. :)

They have some sort of sequence worked out. There was a paper cited in previous discussion here of this flareup. Maybe a month or so ago. I've gotta deal with stuff now, or I'd find it.

I am guessing this would lead to solar system-scale destruction? Putting a base on Mars doesn’t seem like it would do much to counter such an event if it headed our way?

My opinion is that the idea of a base on Mars is not to somehow secure humanity's position in the Solar System, but to give us something to aim for so we have a reason to pump money into space exploration and aerospace research

Don't you think two self-sufficient instances of a civilization separated by a ~dozen light-minutes decreases the risk of species extinction events?

I find it very hard to imagine a human civilization on Mars being self-sufficient. Getting there is not the hard part. The ecology of self-sufficiency is not something we understand currently, even on Earth.

Indeed. If we were serious about colonizing mars we should first colonize portions of the earth that are currently uninhabitable (self-sufficiently). They all are much easier to get to and have significantly more favorable conditions than Mars, but for some reason no one tries to make the Arctic self-sustaining or wants to build a deep ocean colony.

Why, though?

It seems to me that the long term payoff of colonizing Mars is huge.

The long term payoff of colonizing remote and inhospitable areas on earth is many, many orders of magnitude lower.

I can maybe rationalize that effort if we simply assume that those areas are similar enough to Mars that the experience and technology developed while doing it could be applied effectively.

But I'm not really convinced that most of that experience will transfer - The requirements to make a self-sustaining ocean colony or artic colony are wildly different from the tools and experience we'll need for Mars. At best we gain some general insights, but we'd still have to spend enormous resources developing the right tech and tools for Mars.

The payoff for Mars is, I think, overrated. The payoff of learning how to colonize all kinds of different environments is more valuable, and it is easier to start with the ones close by than the one's so far away we've only ever sent probes.

Doing these things are still ludicrously ambitious projects, and yet colonizing Mars is at least an order of magnitude more ambitious.

Experiments on Mars cost way more, and small mistakes are likely to destroy the whole colony. Anything we can learn on Earth is much easier to learn here.

> Anything we can learn on Earth is much easier to learn here.

Not true for "is/was there life on other planets in the solar system".

We already have experiments being performed on ocean floor labs and arctic outposts. Building habitats on remote places on earth and building them in space are not mutually exclusive, in fact the former is part of the space program today. (Astronauts are trained on the ocean floor before being sent to the ISS).

There are specific reasons for the things you're talking about.

For Antarctica (which is not the Arctic, but I assume what you meant - Scandinavia is quite self sustaining!) you have the Antarctic Treaty System. [1] The TL/DR there is that pretty much every form of development in Antarctica is illegal, and you're not allowed to leave any waste whatsoever. When an antarctic researcher is on a mission, they're required to bottle up their feces/urine and bring it back to base. The urine is processed and then returned to the sea. Feces are generally returned to the host nation for local removal. Mining and other industry is expressly prohibited.

But something even more interesting is comparing Antarctica to Mars, even ignoring the treaty system. Mars has two big things going against it: radiation, and a negligible atmosphere. That means you need to limit your exposure outside, and when you do go outside it needs to be with appropriate equipment and clothing. Of course the exact same requirements also hold true of Antarctica, though to a lesser degree.

But it also has quite a lot of things going for it. Mars day/night cycle is identical to Earth and it even has near identical seasons owing to a near identical tilt. Antarctica, by contrast, has what is basically a 6 month long day/night cycle. And the weather is absolutely vicious. There are genuinely violent snowstorms, as well as temperatures that average -30F, and much lower on the inner areas away from the coasts. By contrast temperatures on Mars (depending on what part of the planet you're on, and when) can get right balmy. Summer on the equator? It gets up to about 70F, though the nights are still extremely cold owing to no atmosphere.

But the snow storm part is one of the more interesting comparisons. Maybe the biggest thing is "The Martian." The key plot event there was a terrible sand storm on Mars ravaged their base and setup the plot for the rest of the film/movie. The Martian itself is a hard sci-fi book. This is one of the very few things that was intentionally faked. The worst sandstorm on Mars would feel like a slight breeze owing to the negligible atmospheric pressure. Think about that - a hard sci-fi book had to resort to fantasy to create a meaningful disaster!

There's a lot more to say/compare as well, but this is already getting a bit too long. Suffice to say, these issues are extremely counter-intuitive, but also extremely interesting to explore!

[1] - https://en.wikipedia.org/wiki/Antarctic_Treaty_System

The other things that was fakes was the ability to live in tents on the surface and travel on the surface for long periods of time. The radiation would kill you pretty quickly.

Absolutely agree. The idea that we are anywhere close to being able to recreate a perfectly self-sustaining closed-loop ecosystem - do better than billions of years of evolution - is a little far fetched.

I think of Biosphere 2, where trees fell down because we didn't know that we didn't know that wind is required to make trees strong enough to support their own weight. I'm sure there's a lot more we dont know that we dont know.

But I mean more of a self-propagating civilization, a group of people learning to draw on the resources throughout the solar system to stay alive and raise the next generation. More about building a dynamic growing system than a perfectly balanced one. To raise a solar-system sized super-organism of humans. The space termite mound.

I don't think a civilization anywhere other than Earth will be able to outlast any Earth catastrophe until we develop much, much more sophisticated types of technology, so it's all moot

Self-sufficiency is a bit of a sliding scale. You can be self sufficient as a band of hunter gatherers at only a dozen people but technological civilization certainly takes a lot more than that, there's more total knowledge involved so it has to be spread out over many heads and spread redundantly so that a single death doesn't remove a technology.

One can imagine a Mars that's been terraformed and grown to a population of 1 billion people in the very distant future. But at that point I expect most of the mechanism of technological civilization to live inside AIs rather than human heads.

If you imagine a colony of just 1 million people on Mars that's pretty doable in the medium term. But it's only a very narrow range of disasters that would reduce Earth's population to less than a million and not also spill over to wipe out Mars's more fragile civilization as well.

A Mars base would do a lot to prevent extinction of human life because of an "unlikely" but "it's just a matter of when, not if" situation where we get hit by a massive rock.

Actually there's only a period in time where we're vulnerable to such things. Eventually we'll know of all the potential threats with enough advanced warning and have the capabilities to deflect them. Maybe we're vulnerable for another hundred years, but not likely still vulnerable in a thousand. Given the rarity of such events, we should be fine.

> we should be fine

Every time somebody says that, I remember of this:

https://xkcd.com/1159/

> Eventually we'll know of all the potential threats with enough advanced warning

We have no idea what Type II or III adversarial civilization will be able to do to us, and how fast.

From my understanding, something that can wipe out the entire solar system at once is highly unlikely.

Huge bursts of concentrated energy coming out of black holes are usually tight beams of high energy particles and light (x-rays, gamma rays) moving very fast and aligned with the object's poles. The focused beam of energy is what is deadly to life. If it's not tight and focused and moving fast, the energy dissipates out into space.

The solar system is huge and extends in three dimensions. A burst of energy that hit earth directly could miss Mars (or the moon, or the space around the earth and the moon) entirely. To sterilize a specific planet, the event has to be close (within like 10,000 light years I seem to remember reading) and the poles of the object undergoing the event have to be pointing at the planet.

If the black hole was only 1,000 light years away, and the angle of divergence of the beam was only 0.1 degrees, by the time the beam hit our solar system it would be about 2 light years across, or 126,000 AU.

Compared to interstellar distances, our solar system is tiny.

intensity is proportional to the inverse square of the distance, anything exploding that far away will be but a pinpoint in the sky by the time it gets here, even if it was a cataclysm when it occurred.

For those of us who read Larry Niven's sci-fi novels, this headline is… both amusing and somewhat scary.

And for those of us who do not, can you elaborate as to why exactly?

I believe the story referenced is "At The Core", where stars at the core of the galaxy have gone supernova and thereby started a supernova chain reaction expanding outward from the core into the surrounding stars of the galaxy.

https://en.wikipedia.org/wiki/At_the_Core

The galactic core exploding is a major plot point driving the Known Space series.

In one of Niven's short stories an alien corporation hires a Human pilot to fly to the galactic core. It's a publicity stunt to demonstrate the speed and range of a new FTL drive. When he gets close to the core, his ship is almost fried by the radiation wave front coming from a chain reaction explosion of suns in the galactic core. This drives events in many of Niven's later stories.

The devastation won't reach 'Known Space' for thousands of years, but the alien Puppeteers that funded the trip are paranoid herbivores. They immediately start a mass exodus of their whole species out of the galaxy, causing a massive economic crash along with many effects on other plot lines.

Niven's Known Space future (and past) history is an amazing and incredibly influential achievement. Highly recommended. Most of it consists of collections of short stories and novellas written over decades, so it's very digestible.

While these books sound interesting, “amazing and incredibly influential achievement” sounds more like something someone might say about a President than a sci-fi author.

Larry Niven is still relevant while Millard Fillmore is not.

And yet few have ever heard this Larry while Millard Fillmore maintains the distinction of being the president with the coolest name.

If only Spiro T. Agnew would have made it.

Larry Niven's most famous work Ringworld, inspired both of the massively popular games Magic the Gathering, and Halo: Combat Evolved.

I suspect that Niven and Fillmore have roughly equal name recognition, though, simply by the nature that Niven is still alive, and appears to be more consequential long term.

Magic? What is the link there?

Nevinyrral's Disk, at a minimum.

https://gatherer.wizards.com/Pages/Card/Details.aspx?multive...

The entire concept of mana being generated from land.

While Larry Niven is most famous for his hard science fiction, in the traditional sense of the term, he also has a fantasy universe, with a decent introduction at https://en.wikipedia.org/wiki/The_Magic_Goes_Away In this universe, magic is a finite quantity, which gets used up. The modern world is mundane not because magic is impossible, but because it was all used up.

(It would be interesting if he ever wrote the story set in this universe, after the modern times, in which humanity gets out to space, and, uh, hey guyz, magic kinda... works out here... what the heck? It wouldn't necessarily take long to figure out what the deal is with Earth being a dead zone, but it would cause some interesting political upheaval as suddenly the sparse space colonies that nobody thought were worth anything and barely even worth the effort became industrial powerhouses as the only place where magic works... and not just the tame, dying magic of Niven's stories, but the original wild, abundant magic the stories claimed Earth initially had.)

I have heard of Larry Niven and never heard of Millard Fillmore.

Being outside the US I never covered past US presidents in school.

Even if the US, he isn't someone who would be covered.

Probably fewer than 10% of Harvard graduates could tell you anything substantive about Millard Fillmore’s presidency. He isn’t covered here either.

I'm possibly only aware of Millard Fillmore because of the Infocom game "Bureaucracy" and oddly enough:

"Jerry Pournelle named Bureaucracy as his game of the month for October 1987, stating that he and Larry Niven became "engrossed""

I've never heard of Millard Fillmore before.

Likely more people (inside the US and outside too) are more familiar with Fillmore St. in San Francisco[1], which is named for President Fillmore, and its famous theater / music venue of the same name.

1: https://en.wikipedia.org/wiki/Fillmore_District,_San_Francis...

I can only speak for myself, but Larry Niven's wonderfully imaginative stories have influenced my thinking more than any president ever did.

There another short story by Niven where someone gazing at the moon sees it get as bright as the sun. They quickly come to the conclusion that some horrific event will end life on earth as soon as the earth rotates towards whatever made the moon so bright.

It's a fun little romp.

Does 3.5M years ago count as “not long ago” in astronomy time scales?

According to the article, yes.

I would say so, it's even short on Earth time scale.

Whenever timespans like this come up, it always reminds me of the opening from Now and Then, Here and There: Because ten billion years’ time is so fragile, so ephemeral… it arouses such as a bittersweet, almost heartbreaking fondness.

I think 3.5M years aren’t even that long ago in geological time scales.

According to https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_h..., that's when "Blue whales grew to their modern sizes". So it's fairly recent not just in astronomy scales.

In cosmological terms, it's more like "earlier today". Our ancestors were already walking around, talking to black monoliths and crushing skulls by then.

I hate that movie.

I'm sorry about that. I love it. :-)

Which movie?

2001: A Space Odyssey.

“2001, a space odyssey”. post above is making a reference to the opening scene

2001, specifically

https://youtu.be/ypEaGQb6dJk

I've never seen it.

You should get that fixed.

Forget the movie. I didn't like it either. Read the book. It's fantastic.

The book? I read a book long time ago that was a "novellization" of the movie. I was young, in my early teens, and clearly remember that I wasn't sure what the end meant. Later I watched the movie and realized that it was even less clear. And later learned that the movie was based on a short story (Rendezvous with Rama) that I haven't read.

It's actually based on "The Sentinel". The short story is more or less the starting point for 2001.

Rendezvous with Rama would be an AMAZING movie. I only hope SyFy doesn't get to do to it what it did with Childhood's End.

I have to strongly disagree with that. 2001 is a master class of storytelling. Everything, from audio-only prologue, the triviality of the dialog, the stiffness of the acting, the awkwardness in zero G, the looooong scenes, to the breathing in the spacesuits is there for a reason. Even the Douglas Trumbull acid trip is there maybe to remind you humans are not supposed to understand everything any more than the monkeys did in the start of the movie.

The book is good, of course, but it doesn't approach the brilliance of the movie.

Oof. Harsh, HN, harsh, downvoted for disliking a (albeit very loved) movie.

The Krell, on the other hand, were near the peak of their development.

Their Great Machine is a metaphor for social networking. I'm quite sure it'll kill us all.

I say we take off and nuke the entire site from orbit. It's the only way to be sure.

It's very nearly 3.5 days in terms of a middle aged person's lifetime, which is an interesting rule of thumb I think I've just discovered.

so ... wild guess

37 years * 365 days = 13,500 days

universe has existed for 13.5 billion years

So each day in a middle aged life is 1 million of the universe's years.

I like it ! :-)

* This flare: Last Friday

* Dinosaur extinction: 3rd of August

* Pangea breaks apart: about Valentines day

* Earth formed: June 2007

* Universe Born: 1982

Of course this means the Universe would have listened to Flock Of Seagulls as a kid, and loved Knight Rider.

Dammit, I'm older than the universe. There's a happy thought.

"When I was born, time didn't exist."

https://old.reddit.com/r/programming/comments/2b4kpg/conspir...

The puzzling thing is that first life appeared around Xmas 2009, just days after the lava cooled down. (probably)

Knight Rider! Oh my sweet childhood. :D

Best I read all day

* The Great Pyramids: 6 minutes and 37 seconds ago.

* 1982: 3.2 seconds ago.

That surprisingly shows just how old the pyramids are - very cool. This idea from from @hanoz really has legs :-)

The Milky Way is ~150,000 - 250,000 light years across, and rotates -- call it a galactic year -- once every 240 million years. At that scale, 3.5 million years would be like about 5 days relative to Earth's year.

So: earlier this week, more or less.

They said it would have been a massive event, but what would our ancestors have seen?

They said the flare lasted 300,000 years, but how quickly does something like this start? How fast does it go from "nothing" to "full strength"?

Also if there was any form of life orbiting a star in the path of this flair, is it safe to assume that said life is no longer alive? At least if that life resembles us in its tolerance (or lack thereof) for radiation.

> Also if there was any form of life orbiting a star in the path of this flair...

Based upon a couple other articles I read [1] [2], it sounds unlikely there were other galaxies or smaller structures in the path of this flare. I only see references to a very directional cone at the poles of the Milky Way, and the cone only intersects a trail of gases left behind by the Magellanic Stream.

Were there somehow orphaned planets, solar systems or smaller galaxies in the path of those cones not mentioned in the articles however, then the gamma rays, X-rays and highly ionizing gases in those cones of energy would certainly strip away most if not all of the atmosphere of any Earth-like planet, and kill all forms of life as we know it unless it was in some kind of weird, tidally-locked configuration that kept one side always facing the originating, ejecting side of the cone.

These flares would make a great plot device setup for a story in the Xeelee Sequence or /r/HFY. We find out the flares are deployed as weapons, used as a kind of galactic-scale sawed-off shotgun against another galaxy. Or the flares are galactic-grade energy reactor experiments gone horribly awry, and are the cause of one Great Filter at the Kardashev Type-III scale.

[1] https://www.sciencealert.com/something-in-the-centre-of-our-...

[2] https://earthsky.org/space/explosion-milky-way-center-seyfer...

Is there a name for some kind of inverted Kardashev scale, where higher civilizations decide to slow down and go miniature, conserving as much energy and information as possible?

Possibly as a) some kind of bet to hide from other civilizations and b) to delay the heat death as long as possible.

The most advanced civilizations hide in black holes. :)

My go-to entry point for exploring those kinds of questions was Isaac Arthur. He goes into the Kardashev scale [1], dying Earth [2], dying stars [3], farming black holes [4], and going past iron stars [5]. A Boltzmann Brain's description bears remarkable similarity to the Judeo-Christian concept of God before time begins, and has been fertile ground for ruminations [6], though none with any verifiable claims backing them in our current knowledge of physics [7].

Now if we could only restructure our implementation of capitalism to be pinned to advancements towards resolving physics questions to survive those kinds of timescales and challenges instead of locked down to a single planet's worth of baryonic matter and cognitive capacity...

[1] https://www.youtube.com/channel/UCZFipeZtQM5CKUjx6grh54g

[2] https://www.youtube.com/watch?v=p58yFf7aZsM

[3] https://www.youtube.com/watch?v=GpYGMIZ9Bow

[4] https://www.youtube.com/watch?v=Qam5BkXIEhQ

[5] https://www.youtube.com/watch?v=Pld8wTa16Jk

[6] https://turingchurch.net/does-god-emerge-from-boltzmann-brai...

[7] https://www.reddit.com/r/AskPhysics/comments/6btjud/what_if_...

Great list! I'm bookmarking this.

There very likely were thousands of stars in the paths of the jets as they passed through the galactic bulge at the center of the galaxy. Our galaxy gets thicker in the galactic center and the bulge is 3000+ light years thick and contains an estimated 10 million stars.

They probably would've mentioned this in the article were it the case, but I wonder if it was visible at all in the night sky? We can see part of the Milky Way, after all. I guess there wouldn't have been writing yet but could such a thing have made it into oral history? Was there even oral history yet?

Dust and gas surrounding the galactic center blocks almost all visible light. Sadly most events simple wouldn't be visible.

No oral history, sorry. 3.5MYA, we were still Austropithecenes, basically as smart as a modern day chimp or gorilla, but bipedal. The little numbers in the tree here show divergence time:

https://en.wikipedia.org/wiki/Australopithecus#Phylogeny

No mention of what observations they made to come to this conclusion. Not in the press release I guess.

They said the flare lasted 300,000 years, but how quickly does something like this start? How fast does it go from "nothing" to "full strength"?

So for laymen as us, how far is the center from us in light years?

26,490 ± 100 light years or 8,122 ± 31 parsecs

https://en.wikipedia.org/wiki/Galactic_Center

https://en.wikipedia.org/wiki/Sagittarius_A%2a

26000 light years

Give the (Monty) Python headline on today's HN, let me add that it's worth learning to sing https://youtu.be/buqtdpuZxvk I find.

The exact numbers are not quite exact, although they are usually in the right ballpark. "We are 30,000 light-years from Galactic central point." But I found it so useful knowing that song over the years.

So basically we are not on the way of bursts exploding from the poles of the center, we are perpendicular to the bursts trajectory?

normally

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