I recently read (well, listened to)
The Colours of Space by Marion Zimmer Bradley. You can read my proper review
over at my book blog, but here I wanted to discuss some of the science that popped up in the book.
The title of the novel —
The Colours of Space — refers to the stars
being much more brightly coloured when seen in space, as compared with
when seen from inside the Earth's atmosphere. (There's another reference
there to plot elements as well, which I won't spoil, but I read the
main reference as being to the multi-coloured stars.) The thing is, the
phenomenon, as described in the story, is not entirely real. Yes, stars
come in different colours, but those colours range from red to yellow,
white and blue. There are no green stars.
Interestingly enough, this isn't the first time I've encountered the
idea of green stars in old science fiction. I understand where the
misconception comes from — wanting to move through the optical spectrum
with increasing temperature — but that's not quite how it works. Have
you ever seen something glow "green-hot"? No. That's because green is in
the middle of the visible spectrum and when it's the peak wavelength of
a black body, the object is still emitting strongly in the neighbouring
red and blue wavelengths which, when they're all combined, appear
white. Similarly, blue stars (and red stars) aren't blue like the sky;
they look pretty white because the star is still emitting strongly in
the other visible wavelengths.
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| The Orion Nebula. Image credit: NASA/ESA |
On the other hand, it's not unreasonable to think that Earth's atmosphere would bleach out the "real" colours of objects in space. After all, hills and whatnot in the distance often look paler than up close (because of water and often pollution in the atmosphere). But we can still see distinct colours of stars even from Earth and even, if you have binoculars or a good camera, the colours of nebulae (which are entirely prettier than mere stars). The constellation of Orion is a good example. Betelgeuse is a red giant (down the bottom of Orion if you're in the
Good Southern Hemisphere), the Orion Nebula looks purplish (on the "handle" of the bit that looks like a saucepan from the south), the Horsehead Nebula (in Orion's Belt) is on the pink side, and the rest of the stars are yellow, white and blue but all look fairly white (from Earth AND space).
This reminds of another old book in which the underlying premise is based on now-outdated and hilariously erroneous science:
The Currents of Space by Isaac Asimov. In that book a rather important plot element is that supernovae are caused by clouds of gas (the titular currents) drifting around space and every now and then changing the elemental makeup of stars enough to make them explode. (I think specifically it was clouds of carbon, but I don't have the book nearby to check.) We now know that this is mostly nothing like what causes supernovae.
There are two types of supernovae: core-collapse and Type Ia. Core-collapse supernovae occur when a massive star (more than around ten times the mass of our sun) runs out of fuel in its core and can no longer maintain its size and collapses in on itself and explodes. To put it very simply. Type Ia supernovae occur when a white dwarf (the corpse of a star originally like our sun) has another star nearby feeding it matter. When the white dwarf gets too massive to maintain its fundamental (proton and electron) structure, it will collapse in on itself and explode (and become a neutron star).
Just because these books are based on science we now know not to be true, doesn't mean they're not worth reading (although I suspect it contributes to them being out of print). Have you read any other books with science that was reasonable when they were written, but doesn't stand up to the test of time and progress?
