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When I saw this on HN, I rewatched the Cosmos episode ("The Backbone of the Night", aired on Nov 1980) where Carl Sagan is lecturing sixth graders in a Brooklyn

by Jun8 14y ago

When I saw this on HN, I rewatched the Cosmos episode ("The Backbone of the Night", aired on Nov 1980) where Carl Sagan is lecturing sixth graders in a Brooklyn school (the one he attended as a kid) on techniques to search for exoplanets and then says (from http://www.american-buddha.com/backbone.night.htm http://www.american-buddha.com/backbone.night.htm): Well, both of these methods are being used, and by the time that you people are as old as I am, we should know for all the nearest stars whether they have planets going around them or not. We might know dozens or even hundreds of other planetary systems and see if they are like our own, or very different, or no other planets going around other stars at all. That will happen in your lifetime, and it will be the first time in the history of the world that anybody found out really if there are planets around other stars. His stress on "even hundreds" shows that even he thought this figure was unlikely. Sagan was 47 at that time, so assuming the kids were about 12, he was hypothesizing into 35 years to the future, to 2015. He would have been pleasantly surprised at the progress so far, I think. I wonder if any one of those kids have looked at this page and thought of that day.

InclinedPlane 14y ago
The amazing thing is that he was more optimistic than most astronomers at the time with regards to extrasolar planets. It's a funny thing, prior to the mid-1990s there had only been extremely incomplete searches for exoplanets, and they all came up negative. But if you looked at the search space of those studies you see right away that they were really quite pitiful. I suppose this is one of those "effort trumps reason" situations, as a lot of effort were put into searches though they had almost no hope of finding planets. And yet those efforts led to a bias against the idea that planet formation could be common, and a bias against the scientific value of looking for planets. At the onset of the great exoplanet discovery breakthrough in the mid '90s only a few very meagerly funded teams working were actually searching. Once they started to find planets then the astronomical community started paying attention, and funding as well as access to the best observatories in the world started pouring in. Also, an interesting point of fact is that Sagan was actually hugely excessively optimistic. The two techniques for exoplanet discovery he describes are direct observation through occultation or deep nulling of stellar light and astrometry. As it turns out, these techniques are very, very difficult to use and we have not actually built any special-purpose spacecraft that use either method. To date only one planet has been detected through astrometry, for example. But there are methods which work rather well (doppler radial velocity and transit detection) though they were not familiar to Sagan.

by Jun8 14y ago

InclinedPlane 14y ago

The amazing thing is that he was more optimistic than most astronomers at the time with regards to extrasolar planets. It's a funny thing, prior to the mid-1990s there had only been extremely incomplete searches for exoplanets, and they all came up negative. But if you looked at the search space of those studies you see right away that they were really quite pitiful. I suppose this is one of those "effort trumps reason" situations, as a lot of effort were put into searches though they had almost no hope of finding planets. And yet those efforts led to a bias against the idea that planet formation could be common, and a bias against the scientific value of looking for planets. At the onset of the great exoplanet discovery breakthrough in the mid '90s only a few very meagerly funded teams working were actually searching. Once they started to find planets then the astronomical community started paying attention, and funding as well as access to the best observatories in the world started pouring in. Also, an interesting point of fact is that Sagan was actually hugely excessively optimistic. The two techniques for exoplanet discovery he describes are direct observation through occultation or deep nulling of stellar light and astrometry. As it turns out, these techniques are very, very difficult to use and we have not actually built any special-purpose spacecraft that use either method. To date only one planet has been detected through astrometry, for example. But there are methods which work rather well (doppler radial velocity and transit detection) though they were not familiar to Sagan.