National Geographic News
 An illustration of a black hole generating a jet.

Two million years ago, the supermassive black hole at the center of our galaxy was 100 million times more powerful than it is today.

Illustration courtesy Dana Berry, SkyWorks Digital/NASA

Andrew Fazekas

for National Geographic

Published September 24, 2013

For years astronomers have been puzzled as to why our Milky Way galaxy's "volcano"—a supermassive black hole (SMBH) at its core—is dormant today.

It seems the answer may simply be that we didn't catch the cosmic monster—weighing at least four million times the mass of our sun—feeding at the right time, according to a new study.

"If we had been around to see it two million years ago, the situation would have been very different," said study co-author Philip Maloney of the University of Colorado in Boulder.

"The Milky Way's black hole was maybe ten million times brighter [then]," he said. "I don't think anyone really had any expectation that SMBH might vary in luminosity by such a huge factor on such a short—relatively speaking—time scale."

(See "Monster Black Holes Gobble Binary Stars to Grow?")

Evidence: "Fossil Imprint"

Astronomers have long suspected there was an ancient outburst from the hibernating black hole, but it's only now that they believe they have found an actual "fossil imprint" of the cosmic monster's last big meal.

The international team's new theory points to a lacy filament of gas, mostly hydrogen, called the Magellanic Stream, which can be seen trailing behind our galaxy's two small companion galaxies: the Large and Small Magellanic Clouds.

Maloney believes powerful beams of energy erupting from the SMBH two million years ago hit the stream—causing its hydrogen gas to get ionized and light up, much like the glow of auroras we see here on Earth. This ionization of the Magellanic Stream has puzzled scientists since its discovery two decades ago.

"No one has been able previously to come up with a good model to explain the ionization," said Maloney.

The team now suspects that this glowing stream of extragalactic gas may be the fossil imprint of the SMBH eruption two million years ago. (See black hole photos.)

The estimated orientation and amount of energy of the original outburst, including the cooling time of the illuminated stream, fit very well with the proposed model.

Further evidence for a giant eruption sometime in the distant past has also come in the form of recently detected gamma ray and radio wave signatures of two giant, hot bubbles of gas called Fermi bubbles. Thought to have been belched out by the SMBH, the Fermi bubbles sit above and below the plane of the Milky Way.

Next Outburst Soon?

The question is not if there will be another eruption, but when, scientists say.

Infrared and x-ray satellites have been able to peer into the heart of our galaxy and detect radiation flowing out from the region around the black hole as it rips apart the small, orbiting clouds of gas falling toward it and colliding with it.

Astronomers now believe many gas clouds orbit the SMBH today, and they could trigger a future outburst—in fact, it may be just around the corner.

"They have been monitoring a cloud and predict that it will fall into the black hole at some point in the next year; however, the amount of material will be far less than the event that illuminated the stream," said co-author Greg Madsen, an astronomer at the University of Cambridge.

"It will be much fainter and will pose no threat to Earth, but several powerful telescopes will be poised and ready to watch what happens."

This research has been accepted for publication in the Astrophysical Journal.

Follow Andrew Fazekas, the Night Sky Guy, on Twitter and Facebook.

104 comments
Jay Dillon
Jay Dillon

The illustration caption reads: "Two million years ago, the supermassive black hole at the center of our galaxy was 100 million times more powerful than it is today."


The text of the article reads: "If we had been around to see it two million years ago, the situation would have been very different," said study co-author Philip Maloneyof the University of Colorado in Boulder.

"The Milky Way's black hole was maybe ten million times brighter [then]," he said. 


So, which is it? 100 million times more powerful, or 10 million times brighter, two million years ago? Or both??

Lex Manguiob
Lex Manguiob

now how can we harness that kind of energy....

prashant kumar
prashant kumar

i think that ,we live in a multi dimensional world where black hole enter midiate between two or more dimensions


Marcotte Georges
Marcotte Georges

WHITE HOLE .:. BLACK HOLE, only a small peace of the hole thing of what we call creation = manifestation  of life ...and we are part of it !

Heidi Froid
Heidi Froid

well since light takes so long to reach us from that great of a distance, could this have happened already and we just not realize it yet since the night sky we look at is more than 1,000 yrs old?

Gorgonio Esguerra
Gorgonio Esguerra

What effect will the future eruption have in our galaxy, if any? Is there need for action on the part of humans?

Peter Dawson
Peter Dawson

National Geographic science writers make the same error here that they do in all other scientific magazines and journals -- they write about black holes as though they used to exist and currently exist. In truth, no black hole ever existed and no black hole currently exists anywhere in our time frame. Why? Because of relativistic time dilation. As the material on its way to forming a black hole singularity approaches "black-hole-ness,"   its own incipient-but-not-yet-fully-formed event horizon perpetually-and-ever-more-effectively  "decelerates" black hole formation relative to distant observers  -- us -- and causes the emerging black hole to literally take forever to complete its formation relative to us. For all time, it approaches but never quite reaches the black hole state,  asymptotically, like a little school girl always stepping only one-half of the remaining distance to the school house door. Those things up there with their accretion disks and perpendicular particle jets are incipient-but-not-yet-completed black holes, and relative to  distant observers -- us -- they can never escape that state.  Relative to us, they are perpetual "prisoners" of their own incipient-but-not-yet-fully-formed event horizons.  (That is why they are called "event horizons.") This not not an illusion, but reality. I think that the error scientists make almost across the board is that they learn about relativistic time dilation in college and graduate school, they never internalize it, and then they ignore it as a hard-to-comprehend subject that is "out there" and not important.

In fact, the concept of relativistic time dilation is one-half of the basis for the Theory of Relativity. It is one-half of the reason why it is called "The Theory of Relativity."

Sharma Sandeep
Sharma Sandeep

I don't understand the evidence,,,,,Can anybody make me understand?????

Daniel Morin
Daniel Morin

This is surely the same for all galaxies.  Notice that the center of all galaxies are very bright; it is undoubtedly because supermassive black holes are at the center of all galaxies and attract with gravity so many stars that they look vrery bright.  There's still a lot to learn about black holes at the center of all galaxies and elsewhere in the Universe.  

Daniel Morin
Daniel Morin

This is surely the same for all galaxies.  Notice that the center of all galaxies are very bright; it is surely because supermassive black holes are at the center of all galaxies and attract with gravity so many stars that they look vrery bright.  There's still a lot to learn about black holes at the center of all galaxies.    

aysha bell
aysha bell

where all gonna die :P they just don't want to admit it. joking, its outburst may be much fainter like it said.

Indira Rao
Indira Rao

The Universe is still an enigma!

Reid Barnes
Reid Barnes

This article says:  "Evidence: 'Fossil Imprint'  Astronomers have long suspected there was an ancient outburst from the hibernating black hole, but it's only now that they believe they have found an actual 'fossil imprint' of the cosmic monster's last big meal. … Maloney believes powerful beams of energy erupting from the SMBH two million years ago hit the stream—causing its hydrogen gas to get IONIZED and light up, much like the GLOW OF THE AURORAS we see here on Earth." (Emphasis added.)  So we have all the elements of plasma, but they can't bring themselves to use the term.  There is even the notion of a fossil imprint of the "filament." Yet instead of considering the possibility that we may be looking at a fossil imprint of a plasma filament, the scientists are fixed to the gravitational model of a black hole, which is based on a theory that is flawed by self-contradicting non-Euclidean geometry.  Are We Ready for a Galaxy Formation Paradigm Shift? Check out this FB Note:  https://www.facebook.com/notes/reid-barnes/are-we-ready-for-a-galaxy-formation-paradigm-shiftupdated/462435587142354

Arpan Biswas
Arpan Biswas

In what form might the energy be released during the SMBH explostion?Only x-rays and gamma rays? There must be some other form in which energy is released otherwise how will the hydrogen of Magellanic stream ionize? But what is that form in which the energy is released?

Kalyani Rao
Kalyani Rao

our universe is a miracle....

so mesmerized by its beauty....


Jason Schnapp
Jason Schnapp

Wouldnt firing a gun under water help explain the theory of a black hole

Anne King
Anne King

We know so little about what goes on out there so any information like this is valuable and interesting.

Jessica C.
Jessica C.

Reading this while listening to Hans Zimmer. Sick and genius!

Ada E.
Ada E.

Space and space time are always so unpredictable, it's hard to say for sure when it will happen, and how it will affect Earth.... I'm glad we know it's out there now, at least! Who knows what else is out there that we aren't even aware of yet?

Darrell Williams
Darrell Williams

I don't want seem stupid,so why haven't we send something in there to see what it really is.

Shelmara Alexey
Shelmara Alexey

El espacio exterior... impredecible, asombroso y mágico.

Ty M.
Ty M.

Whew!  2 million years!  That's too close for comfort.

Paul Williams
Paul Williams

Fascinating article. So much to learn, always. 


Sam Arnold
Sam Arnold

hopefully planet earth wont be caught in that outburst!!!!!!!!!!!!!!

jas stellar
jas stellar

once again i'll ask, will we be able to possibly see a new point of light in the night sky or something once this event's light reaches us? or will it only be visible through powerful telescopes?

Andrew Booth
Andrew Booth

@prashant kumar 

Why? A black hole is a collapsed star so massive that it's gravity doesn't even permit light to escape- so why should it be a medium 'between two or more dimensions'?

Wayne Johnson
Wayne Johnson

@Gorgonio Esguerra I believe the more we know of the our Galaxy and even the of the smallest particle, are we able to make a better decision of our place in the Universe. At the rate we are going we will not be around much longer. Just an opinion/observation.

Ob Bop
Ob Bop

@George Mouawad   and National Geographic likes YOU!!!!


Hooray for George Mouawad!!!!!!!!!

Bruce Picken
Bruce Picken

@Darrell Williams DO you have any idea how long that would take? it's taken voyager almost 36 years travelling at about 38,000 mph to get less than 18 light hours from earth

Joey Gil
Joey Gil

@Darrell Williams For another thing, it's too far.  The Voyager 1 space probe has been travelling 32 years, and has only gotten about 0.002 light years from Earth.  A light year being the distance light travels in a year (9.5 trillion km).


The Super Massive Black Hole in the center of the galaxy is about 27,000 light years away.  So at Voyager's speed, a space probe would take about 432 million years to get there.  

Andre Coetzee
Andre Coetzee

@Darrell WilliamsBecause once you are inside, you can never get out. Not even light can escape it. Not only that, but it would take an insanely long time to even GET there.

Wayne Johnson
Wayne Johnson

@Andrew Booth @prashant kumar Well, if I might pose this additional question. Where does all that material go? Our laws of physics do not explain this phenomenon. It is therefore explained as dimensional. One to one or more dimensions. We do not have proof of this. It is only a theory.

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