Broadcast 3450 Dr. Jeffrey Coughlin

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Guest:  Dr. Jeff Coughlin; Topics: Exoplanets, the search for life, five exoplanet detection methods, exoplanet atmosphere biosignature detection and more.

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We welcomed back to the program Dr. Jeff Coughlin for a wide ranging exoplanet discussion.  Note that there were streaming and recording issues (my fault this time) brought to my attention very early in the show so I restarted the program about ten minutes late.  I apologize for the confusion.  We then proceeded to have an uneventful but very informative and interesting one segment 75 minute discussion with Dr. Coughlin. 

Our discussion started with my asking our guest about a line I read in his bio suggesting that Earth was common.  I asked him why Earth was seen as being common given no other place in the universe (so far) has life on it, especially advanced life.  Don't miss how our guest answered this but for a hint, common refers to size, water, and being a rocky planet.  That said, you will want to hear his full explanation of why Earth is considered a common planet.  Next, I asked our guest to start us out by outline the exoplanet detection methods used today to find exoplanets.

Dr. Coughlin said there were five exoplanet detection methods.  He provided us with a detailed explanation for each method and then later in our discussion, he referenced a specific method if it was used for a certain search or the finding of a specific exoplanet.  While most of us were familiar with one or two of the methods such as the transit method, you might be surprised by the others which included a method called microlensing and another known as direct imaging.  Don't miss his detailed explanation of how each of the five methods finds exoplanets. 
Dr. Coughlin discussed TESS and the exciting discovery of exoplanet TOI 700 which he described in some detail. You can check it out here:  www.space.com/nasa-tess-exoplanet-habitable-zone-discovery-milestone.html.  In talking about it orbiting a small red dwarf star, he compared that to Earth orbiting our sun which as he explained was quite different.  Our guest talked about detecting biosignatures in the atmosphere of the newly found exoplanet in the near future.  In addition, Dr. Coughlin spoke about the JWST capabilities which would be 6.5 times greater than Hubble in studying exoplanet atmospheres.  He then explained why it would be much easier to detect atmospheric and biosignatures in larger exoplanets before our being able to do it with smaller exoplanet discoveries. 

Listener Karen sent in an email asking how many biosignatures were probably needed to confirm or at least strongly suggest life.  Our guest thought that water might be the most important so maybe only one biosignature would be sufficient to strongly suggest life but not prove it.  Our guest than talked about detecting both O2 and methane but said they could also originate form non-biological methods.  He explained this, especially with O2.  In the end, he suggested we might want to see 4-6 biosignatures from an exoplanet.  Regarding the JWST, he said it would detect multiples but there would be limitations.  A Neptune size planet would be far easier to see than an Earth size planet.  Before taking our next call, our guest went back to the newly discovered exoplanet TOI 700  to discuss the star and what an ET might see if they detected Earth as an exoplanet around our sun.  Be sure to hear what he said given the size of Earth and the type of sun we have.

Marshall called to discuss several topics with our guest so don't miss his call.  After Marshall's call, we went into the latter part of our program with a conversation about the past 25 years of exoplanet searching and how things have evolved over the years.  As part of this discussion, Ben sent in an email asking if amateurs could now detect exoplanets.  The answer was yes and our guest provided examples, including very recent examples.  One example highlighted a car mechanic in Australia who recently discovered a three planet system.  Our guest then suggested a few websites for us to check out.  Look for www.planethunters.com and www.zooniverse.org

Our guest mentioned exoplanet moons so a listener sent in a note asking if an exoplanet moon had been discovered.  He said not yet but said there was one good candidate which he described.   This was a Kepler discovery which he explained.  He also told us why finding exomoons was so hard, especially when I said that if there were trillions of planets out there as he mentioned early in the show, why have we not found moons.  Don't miss his response to my question.  Our guest then raised some interesting research questions focusing on the part a moon might play in there being life on a planet.  One of his surprising comments was that if we spotted Jupiter as an exoplanet, we would not be able to see any of the Jupiter moons with our existing technology.

We fielded several more listener emails, then Ft. Worth John called the show for an extended conversation.  John started out asking aboutO2 in the atmosphere.  Don't miss this discussion.  With John on the phone, I asked our guest if SETI using radio telescopes was a better method for searching for life or was searching for exoplanets the better method.  Our guest said that the SETI organization does both but then listen to what he actually had to say about both methods. 

As we were nearing the end of our discussion, I asked our guest if as an astronomer, he was concerned about light and other pollution due to the very large LEO and MEO satellite constellation planned for and being launched by various companies.  Don't miss what he said about this potential issue.  In addition, don't miss what he said about detecting Earth from a distance were we elsewhere in the universe out looking for exoplanets.

Before concluding our program, I asked our guest what was likely to unfold in the exoplanet world for 2020.  He said we would continue getting more information from Kepler/K2 and certainly more from TESS.  Before ending, George sent in an email asking if we could detect it or not if an ET sent a probe to orbit and get information about Earth.  Don't miss how Jeff responded to this question.  Our guest offered us concluding comments and then said that a binary star would go supernova around 2083, Star V Sagittae.  For those around to see it, he explained just how bright the explosion would be looking out from Earth.

Please post your comments/questions for Dr. Coughlin on our blog for this show.  You can reach our guest through me or his NASA JPL website.

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21 Jan 2020 Dr. Jeffrey Coughlin
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