Podcaster: Richard Drumm
Title: How to Hide a Planet
Organization: 365 Days Of Astronomy
Link : astrosphere.org ; http://unawe.org/kids/unawe1149/
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:
How to Hide a Planet
For over 100 years, we’ve been searching the skies for signs of life beyond our little planet. Although we haven’t found any aliens yet, space is an enormous place and there are still an effectively endless number of places to check.
But the search for aliens raises an interesting question — what if aliens are searching for us, too? Do we want them to find us?
While we’d like to imagine all aliens are like E.T. or Dr. Who, our extra-terrestrial neighbors might be more like the Evil Emperor Zurg than Buzz Lightyear. If they had the advanced technology needed to travel through space, they could wreak havoc on our world!
So, we must decide: do we continue to broadcast our existence to the Universe, or hide and stay safe? Hiding an entire planet is not an easy task, but 2 scientists have thought of a way to do it using powerful lasers.
Planets orbiting other stars are so far away that they mostly appear much too small and dark to photograph directly. At least with our current technology. Instead, we have to look for them using clever tricks, like watching to see if a star becomes dimmer when a planet transits the star. That’s when the planet passes in front of its parent star.
Venus transited our Sun a couple years ago and Mercury is going to transit the Sun on May 9th, 2016, just a couple weeks after this podcast is first published. There may well be an astronomy club with solar filter-equipped telescopes near you that’s planning an event.
You’ll need more than eclipse shades to see the tiny dot of the planet, so link up with your local astronomers for this one. Don’t try to use a department store telescope or binoculars to view the transit, you’ll cook your eyeballs and be blind! Ouch!
The graphic in today’s album artwork is not an example of us zapping aliens, but it is a photograph of a laser in action. In this case it’s a laser being used to help compensate for our shaky atmosphere with what’s called adaptive optics.
The laser creates a star-like dot in the night sky that the telescope can use to remove most of the twinkling effect that we see in starlight. It makes the pictures that the telescope can make much, much sharper.
The transit method is the most successful way we have for finding exoplanets. A total of almost 2,000 planets have been found beyond our Solar System, and more than half of them were detected using this method.
The other exoplanet finding method is the radial velocity method. The planet tugs very slightly on the parent star and moves it a tiny bit as it orbits around it. This stellar movement is detected with spectrographs as a slight cyclical motion of the star.
But back to transits…
If we wanted to, we could stop aliens from seeing the Sun become dimmer when the Earth passes in front of it by shining a very powerful laser at them to make up for the sunlight lost by having the Earth in the way.
But there are a few problems.
If we were trying to hide, we’d have to know where the bad aliens are so that we could aim the laser. Added to that is the problem that lasers are monochromatic. This means they emit just one single wavelength or color.
The Sun’s light that the laser would be standing in for has a broad spectrum of colors, though. So that’s another way it gets more complicated. You’d need lots & lots of lasers of different colors!
And we know nothing about the ostensible aliens and their capabilities. It’s almost certain that our laser wouldn’t fool them for a second if they were sufficiently technologically advanced.
To successfully hide the Earth, we’d need to turn on a powerful laser for only 10 hours, once a year (that’s how long it takes Earth to cross the Sun).
The energy needed to do this is about the same as all the energy collected by the International Space Station in a year! So that energy would have to be stored for a year, then used up with that 10 hour burst.
Now all of this only applies to exoplanets that are very near the ecliptic plane, the plane that Earth orbits the Sun. Those everywhere else don’t see Earth transit the Sun, so we don’t have to laser cloak ourselves in that case.
The 2 researchers who wrote the paper, Dr. David Kipping & grad student Alex Teachey, both of Columbia University, also propose that it just might be that it’s the aliens who’d want to hide from us.
In this case they would be laser cloaking themselves so they’d be harder for us to spot them. They could be in any direction from us too, not confined to our ecliptic. It’s us who’d be on their ecliptic,
However, if we decide we want to risk communication with the aliens after all, we can put the lasers to a different use. We could use them to send information to aliens and alert them (if they’re there at all) to our presence.
Of course you wouldn’t necessarily be constrained to exoplanet systems near our ecliptic in that case too. But you would want to do a very detailed survey to determine where the most likely advanced alien civilization would be. Gotta know where to point the big gun!
So, what do you think — should we try to communicate with aliens or hide from them?
Hey, Here’s A Cool Fact:
The simpler laser system would only be able to shine in visible light. A blast that shines in all the other types of light (from radio to gamma rays) would need 8 times as much power!
Though the power running through each of the lasers in the various colors would be less, making cooling the individual lasers less of an issue.
There is another use we might have for space-based lasers that has nothing to do with aliens, hostile or friendly. We could use the laser to slowly deflect potentially deadly Earth-crossing asteroids. That gets MY vote!
Thank you for listening to 365 Days of Astronomy!
End of podcast:
365 Days of Astronomy
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The 365 Days of Astronomy Podcast is produced by Astrosphere New Media. Audio post-production by Richard Drumm. Bandwidth donated by libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. This year we will celebrate more discoveries and stories from the universe. Join us and share your story. Until tomorrow! Goodbye!