Australian_Science_Illustrated_Issue_52_2017

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clusters of solar power
plants of different sizes
and paths pass between
the star and Earth. The
civilisation could even be
so sophisticated that the
flying solar power plants
do not only convert the
starlight, but also the
heat of the solar panels
into power. That could
explain the low levels of
thermal radiation when
compared to similar stars.
Astronomers admit that the
theory sounds far-fetched,
but a construction boom near
the star cannot be ruled out.
So, the theory is now being
scrutinised by astronomers,
who have pointed radio
telescopes at the star to see, if
any civilisation is communicating by
radio signals, like we do on Earth.
Recently, another astronomer
introduced a theory, which has
attracted much attention. The theory
involves that within the past 10,000 years
,Tabby’s Star swallowed a planet. This is rare,
but a collision with an asteroid or a large
comet could have sent the planet into the
burning hell of the star. If so, the star’s
brightness would increase, only to be
gradually reduced to the normal level. The
scenario could explain the dimming over the
past century. If the planet were a gas giant,
it might have been surrounded by large
moons, which were not swallowed, but rather
sent into orbit close to the star. If they
melted, they would produce the large clouds
of dust and gas, which could explain the
sudden dimmings captured by Kepler.

TELESCOPES TO SOLVE MYSTERY
Astronomers want to record the spectrum
of light during the next dimming. They'll use
a global network of coordinated telescopes
known as the Las Cumbres Observatory. A
detailed spectrum could indicate what is
blocking out the light of the star. A dust
cloud would reduce the light of the blue and
red wavelengths only. Rarer elements will
absorb other colours. And if huge clusters of
solar power plants are in the way, the light
will be equally reduced at all wavelengths.
None of the theories have been proved
yet, but hopefully, the telescopes will
provide the new knowledge required to
solve the mystery.

5 Theories (1 Aliens)

Comets, solar power stations, or a nebula? Astronomers have five

theories, which each explain the apparently random dimmings.

COMETS PASS IN FRONT OF STAR

1

Clusters of comets – and their very long

tails – could block out the light of the star

at irregular intervals. The comets must

orbit far away from the star, as the water vapour of

the tails would otherwise be heated and emit

infrared heat radiation.

PROBLEM: The theory does not explain the general

dimming of the star's light over the past 100 years.

THE LIGHT PASSES THE DISC

SURROUNDING A BLACK HOLE

3

Black holes are surrounded by a disc of dust

and gases, which is spinning around the

hole. Such a disc of varying thickness could

dim the light from the star at irregular intervals.

PROBLEM: The disc must be larger than any disc

ever observed to have dimmed the light for 100 years.

STAR SWALLOWED A PLANET

5

In the past 10,000 years, the star might

have swallowed a planet, first increasing

brightness, which would secondly be

reduced to the normal level. If the planet had

moons which came close to the star, they could melt

into clouds of dust and gas to dim the light.

PROBLEM: Both planet remains and clouds

should emit infrared heat radiation, but none have

been detected.

A NEBULA DIMS THE LIGHT

2

A dark nebula of dust and gas, which is

located in empty space between Earth and

the star, could dim the light of the star at

irregular intervals. The turbulent motions in the

nebula would compress the dust and the gases in

different places of the nebula.

PROBLEM: A dark nebula would also dim the light

of the neighbouring stars, and that is not the case.

SOLAR POWER PLANTS SURROUND STAR

4

According to some scientists, the

reduction of the star's brightness over the

past 100 years and the irregular dimmings

could be due to alien civilisations constructing huge

clusters of solar power plants around the star.

PROBLEM: This would be the first alien civilisation

ever discovered. It seems hard to believe.

EXPLANATIONS

HENNING DALHOFF

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