Restricted Vision

A very limited view of the universe. This edition published by Panther Books 1979. Cover illustration by Ken Sequin.

Our understanding of the universe is entirely dependent on the view from our planet’s surface.  We like to assume that our vision is fairly unrestricted, and so what we see is fairly clear, but it wouldn’t take much to change the view significantly, and with it our ability to assess what’s out in space.

Dust and gas clouds are common in our Galaxy and can easily obstruct the view of what lies beyond.  Writing over eighty years ago in Giant Telescopes Explore the Universe of Stars (The Telescope, July 1933), Jan Oort, then at Leiden Observatory in the Netherlands, said it was difficult to estimate the dimensions of the Milky Way due to the huge clouds of dust particles which “hinder our exploration of the stellar universe just as much as the atmospheric clouds hinder us on so many nights.”

Some are closer to the Earth than many people realise.  The Gum Nebula, probably the remains of a supernova around a million years ago, spreads over 40 degrees of the sky in the southern hemisphere, and is a mere 450 light years away at its nearest point.  That’s a vast nearby quantity of gas, though it’s actually so large and close that it’s hard to make out that it’s there at all.  But it is.

Dust clouds really close to a planet could have quite an impact on any inhabitants.  In The Feasibility of Shading the Greenhouse with Dust Clouds at the Stable Lunar Lagrange Points (JBIS, March 2007), Curtis Struck suggested how solar shades made up of dust particles could help to reduce the effects of global warming on the Earth.  But he also discussed the downside.  Not only would the meteor flux on Earth increase, but the night sky would be changed due to light scattering in the clouds – it would be much brighter, and ground-based astronomy would be devastated in many wavelengths.

Taken to extremes, intelligent aliens looking out from planets which have been surrounded by gas and dust throughout their recorded history could have an extremely limited viewpoint.  Consider the position of the inhabitants of the planet Krikkit, which features in Life, the Universe and Everything, the third part of Douglas Adams’ Hitchhiker’s Guide to the Galaxy.  Living on a planet completely enclosed in a dense dust cloud, they knew nothing of what was outside.  So, when they do discover the true immensity of the universe, they decide that “it’ll have to go” and set out to destroy it.

Other astronomical effects might equally limit the view from a planet.  In a rather more serious context, Isaac Asimov’s classic 1941 science fiction short story Nightfall describes a humanoid race on a planet in a system of six suns, where night only falls for a short period just once every couple of thousand years.  Civilization is cyclic, reaching a height and then crashing when people are unable to cope with the total darkness which has never been experienced before.  They have evolved so that they cannot even tolerate the idea of the dark, being terrified of caves and enclosed spaces.

The eternal blaze of their suns means that they are also unaware of any other planets in their system, or of any stars elsewhere, except as myths from their distant past.  It is considered the wildest speculation to suggest that there might be other suns – perhaps as many as a couple of dozen in a universe as much as eight light-years across.  That would be the weirdest science fiction.

The basic point is valid.  We have evolved on a planet which is in a relatively clear part of the Galaxy, but not all races (if they exist) will have done so.  The frequently cloudy skies of northern Europe would be nothing compared to the absolute limitation of living in a dense cloud of dust and gas.

But then, if the view out from your planet is severely restricted, any alien intelligences outside may have an equally restricted view of you.  Which may, or may not, be a blessing in disguise.

Richard Hayes, Assistant Editor (Odyssey)


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