What If a Black Hole Swallowed the Sun?
Nearly every galaxy that we know of has a common feature: a supermassive black hole
lying at its centre. This black hole can be hundreds-of-thousands to billions of times
the mass of our sun. Fortunately, though, even our own - Sagittarius A-Star at the heart
of the Milky Way - is too far away to cause us any harm. But what if one appeared much
closer?
This is Unveiled and today we’re answering the extraordinary question; What if a black
hole swallowed the sun?
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To understand what would happen, we need to first look at how a black hole works. A black
hole is an extremely dense stellar object, with a large amount of mass packed into a
very small area. NASA explains it as though there’s a star that’s ten times as massive
as our sun, but it’s forced into a space about the size of New York City. This incredible
process winds up distorting spacetime and creating regions of seemingly infinite density
called singularities.
However, black holes don’t just exist forever, relentlessly growing more and more massive.
They actually lose mass faster than they gain it, via the emission of random subatomic particles
- called Hawking Radiation. Normally this wouldn’t make much sense, as nothing can
escape a black hole, but these particles can because they’re quantum particles influenced
by quantum mechanics, which means they more or less set their own rules.
When a star like our sun is devoured by a black hole, it’s called a Tidal Disruption
Event, or a TDE. TDEs are extremely bright, and can often be confused for supernovas because
of their luminosity - but this is no typical “death of a star”. Though standard “light”
can’t escape a black hole, matter from the star it consumes gathers in a glowing disc
of debris around it - the accretion disc. In fact, only around half of the star is truly
devoured at first, while the rest is flung away at nearly the speed of light, in a long,
trailing tail of dazzling particles. What we’re seeing is seriously strong magnetic
fields being twisted and broken apart, as well as what remains of the star being stretched
out under immense force through what scientists call “spaghettification”.
If this were to somehow happen to the sun (in an almost impossible turn of events),
we wouldn’t actually be aware that our now-spaghettified solar centrepiece was even changing until
a few minutes after it have already started, given the time it takes for light from the
sun to reach Earth. So, even if we could do anything to stop it (which we couldn’t)
we’d be powerless until massive damage had already been done…
Initially, we’d see the sun begin to deform as its mass is drawn away by a seemingly invisible
object. Soon, though, as the sun’s mass gathers around the accretion disc, we’d
see the black hole siphoning its power through a thin stream of light like a straw. The sun
would then be torn and stretched to its extremes, with that long tail of light stretching outwards.
It perhaps feels as though we should be quickly thrust into darkness back here on Earth, but
that wouldn’t be the case. Even though our sun would effectively be being drained of
light by the black hole, our sky would actually glow far brighter than before as it’s blasted
with energy from the accretion disc. In such an event, the light produced could even be
far more than our sun would have given in its entire lifetime! We’d actually find
ourselves bathed in such incredible brightness that even to look at the sky would now be
difficult.
At this point, it’d be safe to start the doomsday timers. The orbits of everything
in the solar system would be thrown out of balance by the immense gravitational pull,
with all of the planets inexorably drawn towards certain destruction. Here on Earth, most likely
we’d perish from the sheer radiation of it all, or the extreme heat. But, even if
we somehow managed to take cover and avoid being fried to death, then our planet would
find itself literally torn apart by a gravitational pull that’s able to best even the sun. In
the short-term, this would mean massive earthquakes and forced eruptions of super-volcanoes; a
seemingly textbook doomsday scenario. In the long term, our once life-giving world would
be nothing more than a smouldering fragment of rock still being drawn into the singularity.
Say you could somehow watch all of this happening from afar… the black hole’s destruction
of the solar system wouldn’t be instant, but it would follow a merciless pattern. First,
the spaghettification of mercury, stretching the planet closest to the now-absent sun into
a long, thin line of matter - something scientists also call “the noodle effect”. Then Venus,
Earth, Mars, the Asteroid Belt and so on. Every single planet and object pulled closer
and closer to the black hole, their particles ripped apart at the speed of light and added
to the ever-expanding accretion disc. Before long, were the black hole to be big enough,
and were it to attract enough matter, it could find itself classified as a genuine quasar
- a sprawling expanse far bigger than the solar system ever was, and one of the brightest
points in the universe. Eventually, even debris as far away as the outer edges of the Oort
Cloud would find itself pulled inwards as record of our particular star system totally
disappears.
Luckily, a black hole isn’t at all likely to form out of nowhere, so the chances of
anything like this happening are very slim. In fact, our planet will probably be (and
is actually scheduled to be) destroyed by our own sun long before a black hole wanders
our way. However, if you ever did look to the sky and wonder why the sun looks a little
out of shape… and if we ever were witness to a black hole gate-crashing our galactic
corner… then it’d mean nothing good, and there would be no escape. Over time, were
a black hole to form powerful enough to end the sun, then it’d most likely spell the
end of everything else as well - with the entire solar system dragged inwards and stripped
down to its most basic particles.
The ever-growing accretion disc would signal monumental chaos and destruction for us…
though, were our fate to be viewed through a telescope in some other far off galaxy,
it’d appear as simply a brighter-than-usual speck in the sky. And that’s what would
happen if a black hole swallowed the sun.
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