Earth Similarity And Planetary Habitability Indexes Show Best Vacation Spots In The Universe

We are all suckers for top ten lists, so after discovering over 700 alien planets we needed a way to determine which were the best.  So scientists have devised a scale to tell how wonderful a planet is.  Earth, of course is simply the best, so everything else is compared to it’s scientific ranking of number 1 on both Indexes.  The Earth Similarity Index is based on factors such as size, density and distance from it’s star. It's a good way to judge a planet when specific factors about the planet are not yet known.  The Planetary Habitability Index looks closer at a planetary body to see whether it has a rocky or ice surface, how much atmosphere it has, and if it has a magnetic field that will keep out deadly radiation.  It also considers how much energy is available to a life-form through sunlight or tidal flexing.  Another important aspect takes into account the particular chemistry of the planet and whether is has liquid solvents like water in which the building blocks of life can come together.

So where are the best vacation spots in the universe?  Well, we haven’t found anywhere better than Earth yet but that doesn’t mean that we won’t.  The rankings for the Earth Similarity Index (ESI) and Planetary Habitability Index (PHI) are: 

ESI                                              PHI
*  Earth  -  1.00                           *  Earth  -  1.00
Gliese 581g  -  0.89                *  Titan  -  0.64
Gliese 581d  -  0.74                *  Mars  -  0.59
Gliese 581c  -  0.41               *  Europa  - 0.49
Mars  -   0.70                 *  Gliese 581g  -  0.45
Mercury  -  0.60          *  Gliese 581d  -  0.43
HD 69830 d  -  0.60   *  Gliese 581c  -  0.41
55 Cancri c  -  0.56           *  Jupiter  -  0.37
*  Moon  -  0.56                           *  Saturn  -  0.37
Gliese 581e  -  0.53                 *  Venus  -  0.37

Well, there we have it.  Gliese 581 is about 20 light years away, which would take several hundred years with today’s technology – so if you want to vacation there you might want to book a flight right away.  Titan isn’t much better with it’s lakes of methane and very chilly temperatures, but to see Saturn rise at Sunset might make it worthwhile.  Mars would be the next choice vacation spot.  We currently have several robots testing out what SPF sunblock we will need while they also look for the pool.  While the only place that we have actually managed to vacation at is the Moon, it is low on the rankings which should mean even more fun and possibly alien life on many of the higher ranked possibilities. 

With this ranking, we have to keep in mind that we have only found 700+ of the suspected billions of planets just in our galaxy.  Thousands more have already been found, but are awaiting confirmation by independent sources.  Though no planets with an index greater than 1 have been found, it’s quite possible that a planet with even better qualities than Earth could be found.  With the creation of these indexes we can do our best to calculate exactly where the best vacation spots in the universe are and how likely it is that the beach will be crowded with another type of life.

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