LIFE AROUND A LARGER SUN


by Helen E. Davis




This article first appeared in Tightbeam 177, September 1992, and was based on an article by Neil E. Commis: "Life Around A Larger Sun" Astronomy, May 1992. The original artwork for this article has been lost, and so I have recreated it with a computer-generated image.


What if? What if Earth orbited a sun with fifty percent more mass than our Sol? What kind of life forms could survive on such a planet, Earth-like in terms of its composition and distance from the sun, but bathed in a much brighter sunlight? Could I design an intelligent lifeform which could live on that planet? Well, let's give it a try.

My first step os to design the body of the creature, which I do with a set of RNG's and the principles outlined in "How To Build A Better Martian." I came up with an eight-legged, seven-eyed, eight-eared, one-brained creature, which I will call a Heavisolarian. By editorial whim, I decree that the prototype Heavisolarian looks like this:

Drawing of Heavisolarian

All that is left is to fit the Heavisol into its environment -- which is the hard part. According to Mr. Commis the conditions on such a planet would be wicked -- at least as far as humans would be concerned. The sunlight on such a planet would be intense -- five times that of the earth -- and the gamma and UV radiation would be deadly. The average planet-wide temperature would be 150 degrees Fahrenheit, rather than the 75 degrees of Earth. Dr. Commis argues that Hevisol would be a burning desert wasteland for the most part, and that the only creatures which could survive would be those with metal encrusted skin.

Would this be true? The answer lies on Earth where, even here, the UV radiation from the sun is great enough to cause damage to unprotected tissues -- which is why most surface animals have skin coverings of non-living hair, scales, or feathers. Those animals which lack such coverings tend to stay in protected environments: under water, underground, or within other organisms.

But what about plants? Plants spend all day in the sunlight. It's true that their branches and trunks are covered by non-living bark, but what about their tender leaves? Yet -- how often do we see plants dieing of cancer? Or a tree suffering from sunburn? Plants have ways of protecting themselves, and these methods can be used to protect the plants of Hevisol.

1)On Earth, plants actually absorb light energy, then use the energy to create food. By using the light energy in this way, the energy does not build up as heat that eventually burns the plant tissue. For this reason green leaves are never hot, no matter how long they have been sitting in the sunlight. In the same way our plants of Hevisol can absorb and convert the most intense light enegies.

2)Protection of vulnerable tissues beneath bark or within sheltered buds. Whike all tissues can be burned by sunlight, the only ones which will develop cancers are those with areas of actively dividing cells. (Mitotic zones.) Leaves and flowers develop completely within their buds, and once they emerge from their buds they grow by cell enlargement, not the addition of new cells. Terminal buds cap the growth zones at the ends of the branches, and other growth takes place beneath the bark. On Hevisol this would also be true, save that the bark and buds would be impregnated with metal.

3)The ability to shed parts which have been damaged by the sun without hurting the rest of the plant. Simply put, a plant can drop its leaves and grow new ones. This would be no different on Hevisol, except that it would take place more often. Unfortunately, a too rapid turnover of leaves would soon drain the plant of energy. Therefore, the plants might have metal-covered leaves as well.

Hmmm -- real gold leaf.

The greater intensity of Heavisol's sunlight would allow the plants to grow faster and thicker, and the metal-reinforced trunks would allow higher growth. The sunlight would penetrate to a deeper depth below the canopy, and there would be plenty of water, since the higher planetary temperature would encourage higher humidty and rainfall. Therefore, instead of a desert wasteland, Heavisol would be covered by a thick, metallic jungle.

A planet where minerals are logged, not mined.

Deep in the shade of the jungle both temperature and humidity would be lower, creating a place where animals could survive. Instead of thick metal plates, they could get by with thin metal skins. Finding something to eat would be a problem, however, and the animals of Hevisol would have to either subsist intirely on roots or develope special abilities to eat and digest metal-laced plant tissue. Pure metal might be excreted as waste.

Forget logging. Mine metals with just a shovel.

Both types of creatures probably exist on Hevisol -- which path with our intelligent Hevisolarians take? The first is more feasible, and suits their body plan, but the second would give rise to an interesting culture clash when Humans arrive in their metal-skinned spaceship....

Another problem faced by our Heavisolarians is that of keeping future generations safe. DNA is highly susceptible to UV and gamma radiation, both of which are in great abundance on Heavisol. Either the Heavisolarians must suffer a high mutation rate and frequent deformities, or the genetic material must be kept highly sheltered. How? Plants might flower and seed as close to the ground as possible, deep in the shade of their metal-lined leaves and branches. In addition, seed husks would be heavily lined with metal. Pollination and seed dispersal would be difficult, as the plants would be utterly dependent upon animals to do this for them. The jungle of Heavisol would be filled with flowers, large and complex enough to attract animal pollinators, each striving to be more attractive than its neighbors, a cacaphony of color.

As for the animals, even carrying their gonads deep within their bodies might not be protection enough. They would have to spend their entire reproductive underground, or else find some way to leave their genetic material in a protected place. This is not impossible, as many insects on Earth do just that. Each Honey Bee hive has one queen and several drones, whose only purpose is to produce more honey bees. Except for the mating flight, these stay protected within the hive at all times. Likewise, on Heavisol the dominant pattern would be that the animals would live in colonies made of workers and sessile breeders.

(Story idea: If a spaceship comes to Heavisol carrying identical twins, save that one is normal and the other is quadraplegic, which one would the natives assume is the superior?)

And so it is that I argue that Heavisol, far from being a dry wilderness because of the harshness of the sunlight, would be a lush jungle planet brimming with flowers and animal life, shining brillantly in a rainbow of metallic hues.

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