Podcaster: Richard Drumm
Title: Space Scoop: Alien Invasion Not Likely
Organization: 365 Days Of Astronomy
Link : astrosphere.org ; http://unawe.org/kids/unawe1543/
Description: Space scoop, news for children.
Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.
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Transcript:
This is 365 Days of Astronomy. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
Today’s story is:
Alien Invasion Not Likely
Despite all our advances in astronomy, we have yet to make contact with an alien civilization. In fact, we still have no idea if aliens even exist. But given what we know about the Universe, the history of life on Earth and our own civilization, we are still able to make some intelligent guesses about what they could be like.
In the 1960s, the Russian astronomer Nikolai Kardashev began to wonder whether some alien civilizations might be much more advanced than us. Not just thousands, but millions or billions of years ahead of us. He came up with a system to describe possible alien civilizations based on how much energy they could harness.
The scale goes from 1 to 3. A Type 1 civilization would be most similar to life on Earth. This type of civilization is able to gather energy from their planet including the weather, earthquakes and even volcanoes. And they take advantage of every inch of space, even building cities on the oceans.
The next step, Type 2, is a civilization that can capture all the energy from its sun. With all this energy, an advanced civilization could use it to power supercomputers and fuel space travel.
One hypothetical way to do this energy capture is to construct a “Dyson Sphere” that completely surrounds the star to capture all its solar output, light, high energy particles, everything.
This leads to the Kardashev Type 3: the super-civilization. This civilization would be so advanced that it could harness the energy not just of their sun, but their entire galaxy! Life would have settled in every inch of the galaxy and would be using energy from every one of its billions of stars.
From the perspective of an outside observer, a galaxy occupied by a Type 3 civilization would appear almost completely invisible. The one thing we would expect to detect is heat. Infrared light.
A new study by a team of astronomers led by Dr. Jason Wright of Penn State University shows that Type 3 civilizations don’t exist close to the Milky Way, as we can see the stars in nearby galaxies shining brightly in visible light and there aren’t any infrared-only galaxies detected either.
There was infrared mixed in with visible light, but the IR was of the type that can be made by natural processes like warm dust around the star. The light from the stars in the several hundred target galaxies that were studied, isn’t being harnessed in its entirety by putative hyper-advanced civilizations.
So much for Type 3 civilizations.
But maybe there are type 1 and type 2 civilizations out there waiting to be found.
Then this month, October 2015, a team of 29 astronomers led by Dr. Tabitha Boyajian of Yale University published a paper on the strange light variations of a 12th magnitude star in the constellation Cygnus, a star 1,480 light years away called KIC 8462852. This star was observed by NASA’s Kepler Space Observatory for over 4 years.
When a star has a planet orbiting it and the Earth is fortuitously positioned, we here on Earth get to see a dip in the light output of the star. But the dips come at a regular interval, an interval of several weeks, months or years, like clockwork.
This star, though, has a very irregular light output graph and a couple of the dips in intensity are huge, one is 15% and another is 22%. A typical exoplanet transit creates a dip of less than 1%.
The detection of this irregular light output, or flux, happened quite by accident. The Zooniverse citizen science network’s Planet Hunter Project volunteers spotted it literally by eye. An automated search would have ignored it precisely because it was so darned irregular.
The astronomers first ruled out the possibility that the star has sunspots or starspots or any internal pulsations that could cause the variation in brightness. No such luck. It’s a fairly normal main-sequence F3 class star, although it does spin a bit fast, once every 21.1 hours.
The team also looked for infrared light of the type that dust produces but didn’t find any significant excess of it. So that rules out big clouds of planet-forming dust or debris from an asteroid or planet collision.
The team also ruled out statistical or instrumental variations that might’ve created the dips in light intensity. The dips in flux are indeed astrophysical in origin. They’re real.
Another possibility is that there might be dozens of comets around that star that are passing at irregular intervals in front of the star, causing the dips in the light. The comets would all have to pass in front of the star and the observed light intensity curves have a shape that doesn’t fit this scenario well.
The team wisely did not put the Dyson Sphere theory into the scientific paper, that would have doomed publication in the peer review process, but off-the-record they cannot rule out the possibility completely.
At least not yet. More visible light ground-based observations are happening even as we speak that will help astronomers figure this out. The team decided that the breakup of an exocomet is the most compelling explanation as it requires the least IR output.
Don’t hold your breath waiting for it to be aliens, I’m just sayin’!
Hey, Here’s A Cool Fact:
We’re Type 0 on the Kardashev scale. We do use energy from Earth, such as fossil fuels like coal & oil, and some solar, wind and hydroelectric, but we don’t use all the Earth’s energy just yet.
Depending on how fast our technology advances and how quickly the population of Earth grows we could become Type 1 in a few hundred years! Or not…
Thank you for listening to 365 Days of Astronomy!
End of podcast:
365 Days of Astronomy
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