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[Music throughout]

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Gamma-ray bursts or

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GRBs are the most energetic events
in the universe.

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They are hundreds of times more powerful
than a supernova, typically last

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about a minute, and briefly outshine
the rest of the gamma-ray universe.

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GRBs are divided into two categories:
long and short.

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Long GRBs
last from several seconds to many minutes

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and are caused
by the deaths of massive stars.

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Short GRBs last less than 2
seconds, down to milliseconds.

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They are thought to result
from mergers of compact, ultradense

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objects like neutron stars and black holes.

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Long GRBs make up most of the observed
gamma-ray bursts.

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When a star born with more than 30 times
our Sun's mass runs out of fuel,

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the core quickly
collapses into a black hole.

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As surrounding material falls
toward the black hole,

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some of it forms narrow,
intense jets of particles

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that drive through the star 
at 99.9% the speed of light.

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The jets burst through the star on
opposite sides and keep speeding into space

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These jets produce gamma rays
when they first emerge and light

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across the spectrum as they interact
with gas and dust surrounding the star.

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If a jet is pointed in our direction,
spacecraft instruments

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can spot the bright gamma-ray flash.

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Other telescopes
that detect different kinds of light

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can then follow up
by observing the burst’s long afterglow.

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from X-rays to radio waves.
With each type of light

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giving astronomers
different information about the burst.

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Short gamma-ray bursts
likewise produce narrow particle

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jets following the abrupt formation
of a black hole.

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In this case, however, the black
hole forms when two city-size objects,

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each weighing more than the Sun, spiral
toward each other and merge.

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These objects can either be neutron stars
or black holes,

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both the ultradense
remnants of supernovae.

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These brief events are also followed

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by a long, fading afterglow
and other phenomena.

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The systems that create short gamma-ray
bursts also produce gravitational waves.

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In 2017, such waves were detected

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1.7 seconds before a short GRB
appeared in the same direction, a first

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that conclusively proved that neutron
star mergers can generate short GRBs.

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But some events

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share characteristics
with both short and long gamma-ray bursts,

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one of the many mysteries
scientists are still trying to solve.

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Despite being the brightest events
in the gamma-ray sky

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— occasionally even temporarily
blinding satellites —

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all the GRBs ever detected erupted over

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100 million light-years away.

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These bursts emit more energy 
than our Sun will

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produce over its 10-billion-year life.

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They truly are
the biggest light shows in the universe.

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[NASA]