In 2006, the International Astronomical Union (IAU) voted on the definition of a planet. Famously, Pluto no longer met the criteria and was demoted to a dwarf planet. Things have been a bit of a mess ...

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The debate over the definition of planethood has been simmering for years – and it bubbled up again this week, thanks to new research into free-floating planemos, or planetary-mass objects. It turns ...

Dear Mr. Tyson, I think Pluto is a planet. Why do you think Pluto is no longer a planet? I do not like your anser!!! Pluto is my faveret planet!!! You are going to have to take all of the books away ...

The main problem with transits like Moon square Pluto is that they inspire us to find the worst in others. As if that's such a chore anyway. We're always looking for the worst traits in other people; ...