Our definition of a planet has changed over the years — causing a bit of confusion. | Credit: wasan prunglampoo/Getty Images Over the past 250 years, the number of "planets" in our solar system has ...
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Human colonies in the solar system
The future of humanity in the solar system is explored through a speculative look at what colonization could mean for life beyond Earth. Mars independence, an Earth-Moon alliance, the asteroid belt, ...
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