Is the Earth the Best of All Possible Worlds?

The search for exoplanets continues, with some very interesting recent discoveries, including 11.2 billion year old planets (though the Hubble space telescope identified a 13 billion year old planet back in 2003) and planetary ring systems that is 200 times the size of Saturn's ring system.

Now Rene Heller, in a Scientific American magazine article titled "Better Than Earth," asks whether planets elsewhere may be better homes for life than our Earth.  In fact, her article notes that Earth is "poised near the inner edge of the sun's habitable zone and will become too hot to harbor liquid water in some 1.75 billion years."  This may sound like a long time, but M and K dwarf stars would have offered habitable zones that could last tens of billions of years. 

The article notes that the best time to be on Earth may have been 300 million years ago when Earth was warmer, wetter, and more oxygen-rich.  We live on a much less habitable Earth, and it may not get any better.  We would be even better on an Earth about twice the size of our current planet since it would have more inner heat, allowing the planet to last longer and benefit from a longer-lasting sun.

Hence, the galaxy offers us many options, some of which may be even better than our current situation.  And we still have 1.75 billion years to figure out how to relocate to these new worlds.  That should give us a good start. 

Great Accomplishments in 2012

Before we get too far into 2012, I wanted to highlight some of the great space-related achievements from last year.  While there were many noteworthy events, a few come to mind as setting the stage for years to come.  Here are four that I have selected.

-- SpaceX:  The company's successful resupply mission to the International Space Station has created a new relationship between the U.S. space program and the private sector.  Today private companies are in a position to replace NASA for routine missions.  The question now is whether they someday supplant NASA.

-- Higgs Bosom:  The discovery of this mysterious particle explaining most of the universe will keep scientists busy for years.  Brian Cox, the English professor and particle physicist, stated in The Guardian:

The hubristic nature of daring to imagine it, of daring to say: "This is how I think the universe works", is truly brilliant. It's difficult for anyone to get their head around – it's only a century ago that Rutherford discovered the atomic nucleus. We didn't even know that atoms existed 150 years ago. This will speed up our understanding of the universe rapidly.

-- Voyager Exiting the Solar System:  The two Voyager spacecraft are crossing the border between home and the unknown as they exited our solar system and began a new journey.  They are still part of the protecting heliosphere of our system, but not for much longer. What is amazing beyond this feat is that we can still communicate with both spacecraft 35 years after their launch. According to NASA, the signal from Voyager 1 takes approximately 17 hours to travel to Earth. The durability of these craft and ingenuity of our space program is pretty amazing. 

-- Curiosity on Mars:  The successful landing of the Curiosity rover on Mars was a solid accomplishment for NASA and mankind.  With its cluster of sophisticated instruments, we have a chance to learn much more about the Red Planet and its origins.  With the success of Curiosity, NASA is planning a second rover.  Nothing breeds optimism (and duplication) like success. 

Update:  Scientific American released its own list of Top 10 Science Stories of 2012.  We certainly agree on many topics.