The great planet debate: Pluto's redefinition is still controversial 15 years later
What is a planet? More importantly, why is it that something that seems so academic is the subject of such scrutiny and controversy? As it turns out, the struggle to define what constitutes a planet is closely tied to our understanding of the Universe, which has evolved considerably in the past twenty years. It also demonstrates that the scientific community is not entirely devoid of politics and divisiveness. But first, a little background!
Green Launch's hydrogen impulse launcher could fire payloads to orbit in 10 minutes at 20 times the speed of sound.