This is a question that, rightly, comes up no matter when the Planetary Society advocates for continued or increased funding for planetary exploration and space exploration in general. It's a big question that necessitates a big answer, but we will attempt to reduce it to its essence here, with further links and background reading to provide deeper context.
The question "Why" has a unique
Exploration and the Pursuit of Knowledge
The human species, to the furthest extent we can trace back our lineage, has thrived on exploration and the pursuit of the unknown. From our early ancestors's trek out of Africa and into the undiscovered country of Europe and Asia, to crossing the land bridge at the Bering straight into the North American continent, to the disasterous voyages and future settlement of the Americas, space exploration is merely the latest incarnation of our deep desire to explore the world around us.
The Space Age, which began barely sixty years ago, has already revolutionized our understanding of the universe and our place within it. For the first time in all hundred-thousand years of human history, we have sent robotic spacecraft to directly analyse and gather data of alien worlds in our solar system. A few have been sent out beyond, towards interstellar space. Space-based astronomical observatories like the Hubble Telescope have peered billions of years back into time and given us clues to our universe's origins.
Let's Change the World
Become a member of The Planetary Society and together we will create the future of space exploration.