[HN Gopher] Supermassive Black Hole Eruption Near Earth Spanning...
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Supermassive Black Hole Eruption Near Earth Spanning 16 Times Full
Moon
Author : wglb
Score : 41 points
Date : 2021-12-27 15:50 UTC (7 hours ago)
(HTM) web link (scitechdaily.com)
(TXT) w3m dump (scitechdaily.com)
| rbanffy wrote:
| I wonder what the radiation environment in the galaxy is. How
| bright a galactic center black hole can be before the whole
| galaxy becomes uninhabitable by something like us.
| ncmncm wrote:
| Galaxies are hazardous places to be. E.g., a minor hiccup on a
| magnetar 500 ly from Earth would sterilize it. Earth, that is.
| One might drift into range any time; Sol has probably been that
| near to one for a million years at least several times, as it
| orbits inside the Milky Way every 200 million years.
|
| Any civilization interested in longevity would get the hell
| away from any galaxy as soon as it could manage.
| arbuge wrote:
| Are the stars orbiting the Milky way all orbiting at very
| different speeds then? If not, I would think the stellar
| environment of any star would remain relatively constant over
| time.
| rbanffy wrote:
| Speeds (linear and angular) decrease the further we are
| from the center, so bodies near the center will orbit it in
| less time than us, who take less time to do a lap around
| the galaxy than stars further out.
| matt_kantor wrote:
| Actually the speeds of objects orbiting the center of
| galaxies first _increase_ then quickly flatten out the
| further you get from the center:
| https://en.wikipedia.org/wiki/Galaxy_rotation_curve
|
| This is one piece of evidence for the existence of dark
| matter.
| rbanffy wrote:
| Interesting. Thanks for the correction. So, the further
| you go towards the rim, the less the galactic year
| changes for you?
| matt_kantor wrote:
| There's some variability across different galaxies, but
| generally the curve is pretty flat if you're not right
| near the center. So the galactic year for a star at the
| outermost edge of our galaxy should be about the same as
| ours.
| ncmncm wrote:
| Stars are not, as a rule, orbiting in perfect circles. So,
| they are continually whizzing past one another as they
| trace out their respective orbits.
|
| The orbits are not even nice ellipses. Those only happen
| with point or (equivalently) spherical masses. The Milky
| Way is a quite irregular shape, and we are orbiting inside
| it. Our path bobs up and down through the galactic plane as
| we orbit, and not just once per orbit like a planet, but
| over and over.
|
| The planets like the sun that formed from the same gas
| cloud are long gone, stirred into the galactic soup.
| leephillips wrote:
| We need to get on that magnetar defense.
| rbanffy wrote:
| Let's build a Faraday cage for the Solar System!
|
| Now, on a more serious tone, we may want some contingency
| plans with underground environments and something to
| preserve some life for long enough we could be able to re-
| seed a biosphere on the surface.
|
| Useful for ice ages too.
|
| Now imagine it as the start of a story - we terraform Mars,
| or Venus, only to trigger a re-seeding of the now friendly
| environment by long buried machines left by a dead
| civilization.
| sitkack wrote:
| Who says we haven't been making our way out for awhile
| now? I also like the theory that a previous civilization
| was all soft biology based and that its tech would leave
| no trace.
|
| Speaking of underground environments, Mercury would be an
| excellent location.
|
| http://www.einstein-schrodinger.com/mercury_colony.html
| rbanffy wrote:
| An initial colony could be supplied by advancing multiple
| launches with supplies and landers before the first
| colonists arrive at sunset. They'll have 88 days to
| assemble the underground habitats or abort and come back.
|
| Are there any perpetually shaded areas? If so, the 88 day
| deadline could be extended by as much as we want just by
| sending supplies in advance.
|
| And having between 4 and 10 times as much sunshine we
| could even generate some power from the light reflected
| in the crater/canyon rim.
| geuis wrote:
| Hey mods, for the sake of scientific clarity can the title be
| edited to either remove "near Earth", or to indicate "NOT near
| Earth".
|
| It's a clickbait addition to the title by the original authors
| that is already causing confusion in the comments here.
|
| The galaxy in question is 12 million light years away. That is
| (literally) not astronomically close.
| rbanffy wrote:
| For galaxies, it pretty much is. It's about 5 times as far as
| our nearest neighbour.
|
| There aren't that many big galaxies in the radius.
| jquery wrote:
| Then the title should say near the Milky Way, not near Earth.
| The title confused the hell out of me until I read the
| article.
| rbanffy wrote:
| When the title said "supermassive black hole eruption"
| instead of "Sag A* eruption" it was pretty clear the
| supermassive black hole was not our own supermassive black
| hole, but some other galaxy's. I was curious whether it
| could be Andromeda's SMBH flaring, but very certain it
| wouldn't be our own.
| hinkley wrote:
| This shape reminds me of some simulations I've seen of a star
| falling into a black hole.
|
| Is that a coincidence, or did this SMBH eat one of those enormous
| stars that's the diameter of Venus' orbit?
| ignoramous wrote:
| > _Is that a coincidence, or did this SMBH eat one of those
| enormous stars that 's the diameter of Venus' orbit?_
|
| au contraire, enormous (in terms of mass not volume) but dying
| Neutron stars are so compressed under their own gravity, some
| are barely 12 to 25 kilometers in diameter of highly condensed
| Iron and other stable atomic arrangements, and may be spinning
| 40,000 times per minute on their own axis. Sometimes, there are
| two of those in a binary system, orbiting each other, on a
| collision course for a Kilonova, spraying out bazillion tonnes
| of star and planet making substances across a Galaxy.
|
| A blackhole gulping Neutron Stars down would make for an
| interesting event!
| ncmncm wrote:
| More probably it ate thousands if not millions of stars.
|
| It would be tricky to get it to swallow a star so big before
| that went supernova, while on the way in, on its own
| initiative. Whether the resulting black hole would then be
| swallowed up, or also be flung out at near light-speed with the
| rest of the ejecta, is an interesting question.
| mdoms wrote:
| > The emission is powered by a central black hole in the galaxy
| Centaurus A, about 12 million light years away.
|
| > As the black hole feeds on in-falling gas, it ejects material
| at near light-speed, causing 'radio bubbles' to grow over
| hundreds of millions of years.
| natch wrote:
| A black hole is ejecting stuff, is it? I suppose they mean to say
| that the black hole is ejecting stuff from its vicinity.
| LegitShady wrote:
| "science journalism" is almost always more confusion than
| enlightenment
| sliken wrote:
| Heh, well sort of, the blackhole is the engine that converts
| matter into energy, which results in the observed jets.
|
| No blackhole, no jets. Seems a bit pedantic to mention that the
| observed jets aren't crossing the event horizon.
| alok-g wrote:
| Wow! This has a size of about 1.7 million lightyears, which is
| nine times the size of the milky way, and nearing the distance to
| Andromeda which is about 2.5 million light years.
| geuis wrote:
| 12 million is much further away than 2.5.
| ncmncm wrote:
| Only when you ignore the overwhelming majority of hundreds of
| millions of galaxies, hundreds and thousands of times farther
| away than that.
|
| But yes, farther out than Andromeda.
| [deleted]
| SweetLullaby wrote:
| :DD
| saltcured wrote:
| The earlier post is comparing the size (1.7 million) to the
| distance (2.5 million) to give a sense of scale.
| Simon_O_Rourke wrote:
| Define near... Reading the headline I was thinking in terms of
| AU, not millions of light years
| sigmaprimus wrote:
| I suppose You could also measure such things in respect to
| time, considering the apparent distance of this event it also
| occurred long long ago in a galaxy far far away!
| jrootabega wrote:
| Less than 12 parsecs ago?
| bodhi_mind wrote:
| A parsec is a measure of distance, not time.
| gharman wrote:
| Not in the Kessel Sector.
| onion2k wrote:
| 12 million light years is 0.013% of the size of the observable
| universe (93 billion light years diameter). That's quite close
| on a scale relative to the size of space.
| ignoramous wrote:
| > _the size of the observable universe 93 billion light years
| diameter_
|
| While observable Universe will _always_ be 93 billion light
| years in diameter, it is worth noting that everything is
| moving away from everything faster than gravity can
| counteract. That is, the _Causally Disconnected_ (un-
| observable) Universe is _inflating_ faster, the bigger it
| gets.
| d1sxeyes wrote:
| A lot of 'citation needed' and caveats based on our current
| understanding of physics.
| lmilcin wrote:
| We only have one supermassive BH in Milky Way. Any other
| supermassive BH must live in a center of another galaxy.
|
| So a person that understands the topic should immediately
| understand we are talking about relatively close galaxy.
| tome wrote:
| > a person that understands the topic should immediately
| understand we are talking about relatively close galaxy.
|
| Sure, but a person who doesn't would receive the message more
| clearly if it were stated as "Supermassive black hole
| eruption near milky way". Otherwise I could write
| "Supermassive black hole eruption near New York" and be
| equally correct.
|
| I suspect the potential for misunderstanding was the reason
| the headline was chosen in this form, however ...
| rbanffy wrote:
| 12 million light years is around the corner in cosmic
| terms. Andromeda is our neighbour is about two million or
| so light years.
| feoren wrote:
| I fully agree that "near the White House", "near
| Washington", "near Earth", "near the solar system", and
| "near the Milky Way" all convey strongly different ideas of
| what "near" actually means. However, I think in this case
| they were basically going for "surprisingly near", or "near
| _us_ ". I think it's reasonable to say that this is
| unusually close to us.
| eitland wrote:
| Well, the headline as it currently stands includes both
| the earth and the moon which definitely primes the
| thoughts.
|
| I know research on priming has got some well deserved
| criticism, but there is no doubt basic framing works and
| this article either plays this effect for purpose or is
| scarily unaware of it.
| sliken wrote:
| Sure, but the nearest planets, stars, and galaxies to
| earth also gives an idea of the scale they are talking
| about. Sure you could say nearest the milky way, but
| sadly I suspect that a decent fraction of folks wouldn't
| not respond with "Milky Way" when asking for what galaxy
| the earth is in.
| staticassertion wrote:
| HN articles aren't for people who understand a topic. They're
| for topics that may be of interest to hackers.
| OtomotO wrote:
| So is the headline only written for a person that understands
| the topic?
|
| That explains a lot of clickbait!
| lmilcin wrote:
| There are different types of clickbait.
|
| The purpose of the title of any article is to attract
| attention, so from that point you could say every title is
| clickbait.
|
| Where I define "too far" (or actual clickbait) is when the
| title is dishonest about its contents or is purposefully
| omitting important information that makes the article much
| less interesting than the title suggests.
|
| In this case the title was actually both truthful and
| contained relatively complete description of what is
| included in the article. Could they say "near Milky Way"?
| Well... they could, but "near Earth" is also factually
| correct.
|
| And 12 million light years is actually quite close for any
| new supermassive black hole-related findings.
| skinkestek wrote:
| > Where I define "too far" (or actual clickbait) is when
| the title is dishonest about its contents or is
| purposefully omitting important information that makes
| the article much less interesting than the title
| suggests.
|
| A lot of clickbait is technically correct including many
| of the dreaded "<n> <x> that <y> - you won't guess number
| <z>".
| mdoms wrote:
| If you click the headline there's actually significantly more
| information available. This weird truck actually works with
| most headlines.
| AnimalMuppet wrote:
| Spanning 8 degrees, _12 million light years away_? That 's
| insane. A feature that's 1.67 million light years across? That's
| insane. That's a sixth of the size of the entire local cluster.
| dclowd9901 wrote:
| I was surprised that the moon only measures two degrees across
| the sky!
| ncmncm wrote:
| Half the width of your thumb held out at arm's length.
|
| Sun, likewise, of course.
|
| So these radio lobes reach out another moon-width from both
| sides of your thumb.
| shagie wrote:
| As noted, 0.5deg across... but this misconception is in part
| because 360deg or even 180deg is _really_ big when you 're
| sitting at the center of it.
|
| I believe part of this misconception comes from that when we
| _look_ at something, we 're only paying attain to +/- 15deg
| while the bifocal range is 120deg and the full field of view
| with both eyes is about 200deg. Additionally, the field of
| view of the photographs that involve the sun or moon are
| often in the 5deg to 15deg range.
|
| That narrow range photograph -
| https://www.deviantart.com/shagie/art/Crescent-
| Moonset-70823... and that has a 3.4deg field of view on the
| short axis.
|
| This is closer to the regular field of view -
| https://www.deviantart.com/shagie/art/Moon-and-
| sunset-318111... though I shot it portrait rather than
| landscape. That has a 27deg field of view on the short axis
| and a 40deg field of view on the long axis.
|
| Another aspect of the moon and its size and the sky sphere -
| it moves at a fairly good clip. The sun is easier to think of
| though, it moves through 360deg is 24h. That gives 15deg/h or
| 0.25deg/m. Every two minutes, the sun moves a solar diameter
| across the sky the moon has a similar amount of motion over a
| short period of time. This makes it difficult to take long
| exposures of the moon without a tracking mount.
| sliken wrote:
| Heh, it's easy to think these days that the moon is larger
| than you think. Especially with so many articles showing
| huge detailed pictures of the moon.
|
| Try taking a picture of the moon with a cell phone (even
| one with the best in the market camera) and be prepared to
| be disappointed.
| shagie wrote:
| My first experience with "well, that didn't work" was
| about 30 years ago. I had a 35mm point and shoot (fixed
| focus too) camera. I shot one roll at night trying to
| photograph the full moon. They didn't even cut the film.
| When looking at the negatives, all that you could see on
| a long strip of film was an occasional very small black
| dot.
|
| From this, I learned two things: (1) The moon is much
| smaller in the sky than you think it is. (2) Take a
| picture of a white wall or similar thing to expose an
| entire frame so that additional frames can be calculated
| form that first (or last or both) frame and the proper
| cuts of the film can be made.
| sliken wrote:
| I've got a Pixel 6 pro, 4x optical zoom, decent sensor,
| and a astrophotography mode. It does take some nice sky
| photos, but the moon is just too small.
| sigmaprimus wrote:
| I wonder if this is an example of an amazing event in the
| universe or an example of the amazing improvements in
| observational technologies. Will this be a much more common
| observation in six months or so when the James Webb telescope
| comes online?
| dnautics wrote:
| the relative sizes of things you have trouble seeing due to
| dimness or can't see due to wavelength is very wild to me, for
| example the andromeda galaxy (you can only, at best, see its
| nucleus even with a proper telescope or binoculars):
|
| https://slate.com/technology/2014/01/moon-and-andromeda-rela...
| Grakel wrote:
| Apparently 12 million light-years is near Earth.
|
| I know it's lame to comment on the single stupid thing in an
| article, but this is absurd.
| jessriedel wrote:
| Yea, "near Milky Way" would have been better. The closest
| galaxy (Andromeda) is 2.5 million light-years, so 12 million to
| Centaurus A is pretty close. It's also the fifth brightest
| galaxy in the sky, so "near" in that sense too.
|
| https://en.wikipedia.org/wiki/Centaurus_A
| hinkley wrote:
| "In nearby galaxy" probably got canned by the editors, who as
| we all know from many many sessions of grumbling, often pick
| the titles without much input from the author.
| ncmncm wrote:
| Also, the stuff they are calling attention to is not, in
| fact, in _any_ galaxy, and is monstrously bigger than any
| galaxy.
| sliken wrote:
| Heh, well some familiarity with cosmology is assumed. All
| (AFAIK) supermassive blackholes are in the center of galaxies.
|
| By my math 99.987% of the universe is further away than 12
| million light years. As mentioned in the article it's so big
| that from earth it's 16 times larger than the moon (as viewed
| from earth of course).
|
| Seems reasonable to consider 0.012% of the universe "near
| earth" when talking about galaxies or blackholes at the center
| of a galaxy.
| Grakel wrote:
| The nearest star is about 4 light years. So outside of the
| solar system, that should be "near." This thing is 3 million
| times that far.
| sliken wrote:
| Right, but the article isn't about stars, it's about
| supermassive blackholes. The one in the article is like #5
| or something out of trillions.
| ncmncm wrote:
| 12 million light years _is_ near to Earth, as galaxies go. The
| overwhelming majority of the _hundreds of billions_ of other
| galaxies are hundreds to thousands of times farther away.
| lifeformed wrote:
| Mentioning Earth is just weirdly specific, a mismatched
| precision. It's like saying a truck almost hit my left
| kidney, instead of just hitting me.
| hermitdev wrote:
| And the truck that almost hit you was on the other side of
| the city at the time...
| ncmncm wrote:
| Earth is a place of interest to most of us. People
| interested in the other side of the Milky Way, who might
| feel neglected, are not reading.
| leephillips wrote:
| At least they didn't say, "near the White House."
| latchkey wrote:
| I just watched "Don't look up" last night...
| lisper wrote:
| "Near" here means: 12 million light years away. So not exactly a
| day trip.
| iJohnDoe wrote:
| > a blackhole with a mass of 55 million suns.
|
| I normally don't put much emphasis or thought of our space or
| size in the galaxy or universe. However, it is very revealing how
| we are very much "a pale blue dot" within perfect distance to our
| sun and moon, and are a very special species on an amazing
| planet. We are not insignificant. Indeed, we are the exact
| opposite.
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