Aliens that weren't aliens

[This is a transcript of the video embedded below.]


The interstellar object ‘Oumuamua travelled through our solar system in 2017. Soon after it was spotted, the astrophysicist Avi Loeb claimed it was alien technology. Now it looks like it was just a big chunk of nitrogen.

This wasn’t the first time scientists yelled aliens mistakenly and it certainly won’t be the last. So, in this video we’ll look at the history of supposed alien discoveries. What did astronomers see, what did they think it was, what did it turn out to be in the end? And what are we to make of these claims? That’s what we’ll talk about today.

Let’s then talk about all the times when aliens weren’t aliens. In 1877, the Italian astronomer Giovanni Shiaparelli studied the surface of our neighbor planet Mars. He saw a network of long, nearly straight lines. At that time, astronomers didn’t have the ability take photographs of their observation and the usual procedure was to make drawings and write down what they saw. Schiaparelli called the structures “canali” in Italian, a word which leaves their origin unspecified. In the English translation, however, the “canali” became “canals” which strongly suggested an artificial origin. The better word would have been “channels”.

This translation blunder made scientific history. Even though the resolution of telescopes at the time wasn’t good enough to identify surface structures on Mars, a couple of other astronomers quickly reported they also saw canals. Around the turn of the 19th to the 20th century, the American Astronomer Percival Lowell published three books in which he presented the hypothesis that the canals were an irrigation system built by an intelligent civilization.

The idea that there had once been, or maybe still was, intelligent life on Mars persisted until 1965. In this year, the American space mission Mariner 5 flew by Mars and sent back the first photos of Mars’s surface to Earth. The photos showed craters but nothing resembling canals. The canals turned out to have been imaging artifacts, supported by vivid imagination. And even though the scientific community laid the idea of canals on Mars to rest in 1965, it took much longer for the public to get over the idea of life on Mars. I recall my grandmother was still telling me about the canals in the 1980s.

But in any case the friends of ET didn’t have to wait long for renewed hope. In 1967, the Irish Astrophysicist Jocelyn Bell Burnell noticed that the radio telescope in Cambridge which she worked on at the time recorded a recurring signal that pulsed with a period of somewhat more than a second. She noted down “LGM” on the printout of the measurement curve, short for „little green men”.

The little green men were a joke, of course. But at the time, astrophysicists didn’t know any natural process that could explain Bell Burnell’s observations, so they couldn’t entirely exclude that it was a signal stemming from alien technology. However, a few years after the signal was first recorded it became clear that its origin was not aliens, but a rotating neutron star.

Rotating neutron stars can build up strong magnetic fields and then emit a steady, but directed beam of electromagnetic radiation. And since the neutron star rotates, we only see this beam if it happens to point into our direction. This is why the signal appears to be pulsed. Such objects are now called “Pulsars”.

Then in 1996, life on Mars had a brief comeback. That year, a group of Americans found a meteorite in Antarctica which seemed to carry traces of bacteria. This rock was probably flung into the direction of our planet when a heavier meteorite crashed into the surface of Mars. Indeed, other scientists confirmed that the Antarctic meteorite most likely came from mars. However, they concluded that the structures in the rock are too small to be of bacterial origin.

That wasn’t it with alien sightings. In 2015, the Kepler telescope found a star with irregular changes in its brightness. Officially the star has the catchy name KIC8462852, but unofficially it’s been called WTF. That stands, as you certainly know for Where’s the flux? The name which stuck in the end though was “Tabby’s star,” after the first name of its discoverer, Tabetha Boyajian.

At first astrophysicists didn’t have a good explanation for the odd behavior of Tabby’s star. And so, it didn’t take long until a group of researchers from the University of Pennsylvania proposed aliens are building a megastructure around their star.

Indeed, the physicist freeman Dyson had argued already in the 1960s, that advanced extraterrestrial civilizations would try to capture energy from their sun as directly as possible. To this end, Dyson speculated, they’d build a sphere around the star. It’s remained unclear how such a sphere would be constructed or remain stable, but, well, they are advanced, these civilizations, so presumably they’ve figured it out. And they’re covering up their star to catch its energy, that can quite plausibly lead to a signal like the one observed from Tabby’s star.

Several radio telescopes scanned the area around Tabby’s star on the lookout for signs of intelligent life, but didn’t find anything. Further observations now seem to support the hypothesis that the star is surrounded by debris from a destroyed moon or other large rocks.

Then, in 2017, the Canadian astronomer Robert Weryk made a surprising discovery when he analyzed data from the Pan-STARRS telescope in Hawaii. He saw an object that passed closely by our planet, but it looked neither like a comet nor like an asteroid.

When Weryk traced back its path, the object turned out to have come from outside our solar system. “‘Oumuamua” the astronomers named it, Hawaiian for “messenger from afar arriving first”.

‘Oumuamua gave astronomers and physicists quite something to think. It entered our solar system on a path that agreed with the laws of gravity, with no hints at any further propulsion. But as it got closer to the sun, it began to emit particles of some sort that gave it an acceleration.

This particle emission didn’t fit that usually observed from comets. Also, the shape of ‘Oumuamua, is rather untypical for asteroids or comets. The shape which fits the data best is that of a disk, about 6-8 times as wide as high.

When ‘Oumuamua was first observed, no one had any good idea what it was, what it was made of, or what happened when it got close to the sun. The Astrophysicist Avi Loeb used the situation to claim that ‘Oumuamua is technology of an alien civilization. “[T]he simplest, most direct line from an object with all of ‘Oumuamua’s observed qualities to an explanation for them is that it was manufactured.”

According to a new study it now looks like ‘Oumuamua is a piece of frozen nitrogen that was split off a nitrogen planet in another solar system. It remained frozen until it got close to our sun, when it began to partly evaporate. Though we will never know exactly because the object has left our solar system for good and the data we have now is all the data we will ever have.

And just a few weeks ago, we talked about what happened to the idea that there’s life on Venus. Check out my earlier video for more about that.

So, what do we learn from that? When new discoveries are made it takes some time until scientists have collected and analyzed all the data, formulated hypotheses, and evaluated which hypothesis explains the data best. Before that is done, the only thing that can reliably be said is “we don’t know”.

But “we don’t know” is boring and doesn’t make headlines. Which is why some scientists use the situation to put forward highly speculative ideas before anyone else can show they’re wrong. This is why headlines about possible signs of extraterrestrial life are certainly entertaining but usually, after a few years, disappear.

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