Looks can be deceiving
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PrECisiON MOtiON CONtrOller
T
he Final Frontier,
Looking
as Star Trek fans
christened the realms
For ET
beyond Earth, appears as a
vast, quiescent, landscape.
Sure, solar system bodies –the
frequent targets of amateur
astronomers – slide around the
sky. But only slowly. You can
watch the moons of Jupiter
orbit their gassy master, but it
takes an hour or more
by Seth
The slow-motion to see much change
Shostak
gait of the heavens in position. And yes,
during a solar eclipse
led our ancestors or a stellar occultation, it’s possible
to assume that to witness in real time the relentless
of the moon around our planet.
the universe was parade
But again, it’s poky.
unchanging, an idea The slow-motion gait of the heavens
that was probably led our ancestors to assume that the
universe was unchanging, an idea that
bolstered by the was probably bolstered by the fact that
fact that the night the night sky is silent. We instinctively
that if there’s no noise, there’s no
sky is silent. We sense
action.
instinctively sense But it’s all an illusion, of course. The
that if there’s no universe is no more static than the
continents. Everyone who’s ever taken
noise, there’s no an astronomy course knows there’s
action. But it’s all an plenty of systematic change, as space
expands and galaxies appear to recede.
illusion, of course. Important, but slow.
However, in the limited confines of
stellar systems, sudden and violent dramas can
occur. And occasionally do.
In October 1604, a new star (or nova) appeared
in the constellation Ophiuchus. This was the
topic of polite dinner conversation in Europe for
weeks, as no one had either expectation of, nor
explanation for, this strange light in the sky. It
was as wondrous as a new comet.
However, even a nova – a star that dramatically
brightens – takes many hours to do its thing.
Today, we know there is far faster action above
our heads. For example, black holes not only
form, but occasionally collide. Such exotic
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head-ons seem to be the cause of the several
gravitational wave events detected by the Laser
Interferometer Gravitational-Wave Observatory.
The time it takes black-hole pairs to merge
is no more than an eye blink – a few tenths
of a second. The impact ripples space, and
eventually, after billions of years, shakes the
mirrors of LIGO.
An entirely new type of transient object, Fast
Radio Bursters (FRBs), was found by radio
astronomers only a decade ago. They belch
powerful radio blasts into space and last less
than a second. While no one knows for sure
what causes these brief eruptions, they too could
be manifestations of colliding neutron stars or
black holes.
We are often surprised by such celestial
“bumps in the night.” This is probably because
we don’t expect anything that’s big – and much
of the stuff in the cosmos is big – to change very
quickly. It’s also true that historically, a lot of
observational astronomy has had to deal with
the faintness of stars and nebulae by means of
time exposures. If your camera shutt