Astronomie - Traumhaft Falsch: Warum der Kerl, der Uranus entdeckte, dachte, es hat Leben auf der Sonne


You can’t live on the sun. Well, you can try if you want. I’m not your mother.  NASA
There are a whole lot of places in the universe that aren’t exactly conducive to the proliferation of life: the vacuum of space, for instance, or the poisonous, boiling atmosphere of Venus, or anywhere Chuck NORRIS goes. But surely the most brutal are the unimaginably hot surfaces of stars like our sun, furnaces so powerful that they fling energy billions of miles.
Sure, we know that now. But in 1795, prominent astronomer William Herschel, who had discovered Uranus 14 years previous, took the opposite view. In the essay “On the Nature and Construction of the Sun and Fixed Stars,” he argued that the sun is simply an enormous planet, and because all other planets in our SOLAR SYSTEM contain life (a popular opinion in his day), so too must our star. It sounds mad, but he put forth sophisticated arguments to bolster his theory.
But first, a bit of background on the years leading up to Herschel’s bold claim. The telescope was invented in the early 1600s, and was first turned skyward not by its inventors, who were concerned with more terrestrial APPLICATIONS (“seeing faraway things as though nearby,” as one patent application read), but by Galileo. Observations of the sun began almost immediately, and what followed was a sort of stargazing gold rush, as inventors developed ever more powerful devices, while of course remaining cautious not to burn their eyeballs out of their heads.
William Herschel, the discoverer of Uranus, believer of life on the sun, disapprover of paragraphs above and to the left of his person.
By the 1700s, astronomers observing sunspots hit upon an idea: The sun was a regular old terrestrial planet like ours that just happened to be covered with a luminous atmosphere. One Englishman figured that such sunspots were volcanoes BELCHING smoke through glowing gas, while another reckoned they were towering mountains peeking through, according to Steven Kawaler and J. Veverka in their essay “The Habitable Sun: One of William Herschel’s Stranger Ideas.” Another figured the bright, hot matter wasn’t an atmosphere but an ocean, and that sunspots were instead mountains exposed by ebbing tides.
In reality, sunspots are areas where the star’s magnetic field becomes highly concentrated, inhibiting convective motion and therefore the transport of heat, dropping the temperature inside to thousands of degrees cooler than the rest of the surface. It’s still quite bright (if you could pull one out of the sun it’d glow brighter than a full moon), but in contrast to the surrounding hotter areas it appears dark. And that apparent ebbing tide exposing and enveloping mountains? It’s actually the sun’s shifting magnetic field opening up and closing new spots willy-nilly.
Anyway, along comes Herschel, who subscribes to the idea that sunspots can be either openings in the atmosphere exposing land or mountains rising above the luminosity. Scaling up the potential size of mountains on the sun using a mountain on Earth with a height of 3 miles, he gets a potential height of 334 miles, adding that “there can be no doubt but that a mountain much higher would stand very firmly”—unlike his theory as a whole, appropriately enough.
Sunspots utilize the time-tested buddy system, opening up in pairs as the sun’s magnetic field comes out of one and dives back into another.  NASA
As to how the atmosphere formed in the first place, Herschel invokes the formation of clouds on Earth, “but with this difference, that the continual and very extensive decompositions of the elastic fluids of the sun, are of a phosphoric nature, and attended with lucid appearances, by giving out light.” But why hasn’t the sun exhausted its supply of “elastic fluids” that throw so much energy into space? Just as clouds rain water back down to Earth, “in decomposition of phosphoric fluids every other ingredient but light may also return to the body of the sun.” I mean, could you imagine it raining light? That’d just be silly.
According to Kawaler and Veverka in their essay, “it is clear that what especially attracted Herschel to this model of the sun were its philosophical implications,” since it brought the sun in league with other planetary bodies. “Clearly,” they add, “it is a product of Herschel’s prejudice that all planets are inhabited.”
It’s Getting Hot in Here, So Take Off All Your Preconceived Notions of Where Life Can Potentially Exist
It was prejudice that of course came with problems, both scientifically and existentially. While Herschel believed the sun to be inhabited “by beings whose organs are adapted to the peculiar circumstances of that vast globe,” at the same time he pointed out that “angry moralists” thought the star to be “a fit place for the punishment of the wicked,” while “fanciful poets” reckoned it was home to blessed spirits. Clearly not all parties could inhabit the same world without stepping on each other’s toes.
And then there was the question of how the luminous atmosphere wouldn’t simply cook any life on the sun. Herschel argued that “heat is produced by the sun’s rays only when they act upon a calorific medium.” Substances that can be heated, you see, contain the “matter of fire,” as a flint can ignite gunpowder that already contains such fire. If light alone could cause heat, he reasoned, then you’d expect the top of our highest mountains, where light’s course is the least interrupted, to be quite hot indeed, when in fact they’re frigid. And because the sun emits such an incredible amount of light, it stands to reason that little of it is acting upon such a “calorific medium” to produce heat on the surface. There must be something chemically different about the surface and atmosphere of the sun.
According to Kawaler and Veverka, six years after he proposed this theory, Herschel returned with another reasoning of how life on the sun would keep from bursting into flames. The sun must have not just a luminous atmosphere, but an underlying layer of clouds so opaque that they bounce the light into space, protecting the inhabitants below.
The scientific community, however, wasn’t buying it. The polymath Thomas Young reckoned that not only would the CLOUD layer be totally worthless at reflecting heat, no matter how dense it was, but there also was the rather glaring problem of gravity. Living beings on such a large body would be flattened like Wile E. Coyote beneath an anvil—my words, not his. And in 1821, David Brewster, also a polymath (Europe was lousy with them back then), instead attacked the very core of Herschel’s reasoning: He’d based his theory on the assumption that the sun was like any other planet and would therefore harbor life, when the sun was in fact unique in our SOLAR SYSTEM.
And in 1801, the collapse of a building in Germany led humanity to see the sun in a totally new light. Joseph von Fraunhofer, an orphan and decidedly not a polymath, was trapped when the mirror and glass shop he apprenticed in crumbled. The crowd that gathered to witness the ensuing rescue included Prince Elector Maximilian Joseph IV, who took pity on von Fraunhofer, providing him cash and books to further his studies. Von Fraunhofer eventually made huge advances in lens-making and, more importantly for astronomy, invented the spectroscope, which was later used to determine the chemical MAKEUP of the sun by analyzing its light.
What we then began to understand is that instead of featuring a surface for life to amble around upon, the sun is in fact comprised of HYDROGEN and helium gas. And later on in the early 20th century, scientists finally solved the mystery of the sun’s power: It is, as They Might Be Giants noted, a gigantic nuclear furnace. Specifically, it’s a nuclear FUSION furnace, in which hydrogen atoms collide to produce not only helium, but astounding amounts of energy and sunburns on Earth.
Joseph von Fraunhofer shows off his fancy spectroscope to—if you can believe it—old white men.
So our sun never has been and never will be home to life. But Herschel’s rather far-fetched theorizing ignited a debate that furthered our understanding of the star. And his kind of thinking—imagining what it would take for beings to proliferate on other worlds—echoes today in our quest to find life elsewhere in our SOLAR SYSTEM and beyond. While not as fanciful as Herschel’s thinking, scientists have proposed, for instance, that methane-based life could find a home on a planetary body like Saturn’s moon Titan.
There’s also vast clouds of alcohol in space, by the way. Could life be floating around drunk in there? We’ll never know until someone foots the bill for putting me in a rocket to go and investigate. So please. Please someone put me in a rocket so I can go investigate.
Herschel, W. (1795) On the Nature and Construction of the Sun and Fixed Stars. Philosophical Transactions of the Royal Society of LONDON. 1795-01-01. 85:46–72
Kawaler, S. and Veverka, J. (1981) The Habitable Sun: One of William Herschel’s Stranger Ideas. Journal of the Royal Astronomical Society of Canada. Vol. 75, P. 46
Quelle: WIRED