Supermoons and red grass

This week has seen the appearance of a super blood blue Moon in our skies.  There's been a lot of excitement about it, with people marvelling over how large the Moon looks in our skies, and how red it has appeared in some places.  For many people, this has been one of the rare events when they pay any attention to the natural world they're a part of.

But a science fiction writer writing about another world has to invent everything about that planet.  Instead of a supermoon, the planet might have two Moons orbiting it, like Tatooine.  Or a huge gas giant might have dozens of moons.  And the planet's star might be a different colour from our familiar Sun.  Stars come in several colours; red, blue, white, and yellow, and in big, medium, and small sizes too.

Here on Earth grass is green, and most of our plants are too, because their tissues contain chlorophyll.  This absorbs the red and blue from our atmosphere, but it reflects the green.  This relationship came about through evolution's constantly adaptive mechanisms.  It became the most efficient mechanism for plants to extract energy from sunlight.

But not all chlorophyll is green.  Some is yellow, some is brown, and some is red.  So the plants it powers can be different colours too.  Take a walk around any garden centre and you will see mahogany-brown grasses, scarlet-leaved plants, and some with golden leaves too.   You can have fun with this as a science fiction writer.  The vegetation on a world is finely-tuned to the star it gets its energy from.  So if you change the colour of a star a planet orbits you might end up with vegetation that is predominantly black, red, or even oermanently-brilliant Autumn colours.

It can be fun forcing characters to adapt to red-grass prairies, or having them coping with the complicated shadows of a planet that orbits two Suns.  And I can't even begin to imagine how complicated the tides would be on a planet with multiple moons close by.  Would the world end up with four tides a day?  Would there be spectacular (and frightening) huge tidal bores racing along that world's major rivers every day?  How would that affect the growth of civilisations?  Most major human cities are by rivers or the ocean.  Would people with tidal bores fear the water?

Supermoons encourage us to look up and connect with our world, and remind SF writers that what is normal here won't be on other worlds.