Co-founded by Carl Sagan in 1980, The Planetary Society is a member-funded nonprofit organization dedicated to advancing space science and exploration through three core enterprises.

We connect with planetary exploration experts from around the world to strengthen our work and support international exploration efforts. Our 50,000+ international membership makes us the largest, …

They established The Planetary Society to give anyone from anywhere in the world an active role in advancing space exploration. Today, The Planetary Society continues this work, under the …

What is a Planet? It's right there in our name: The Planetary Society. But what is a planet? This seemingly simple question is the subject of much debate. Learn More

The latest stories from The Planetary Society, featuring humanity's quest to explore worlds, find life, and defend Earth.

Together with our members and supporters, we’re on a mission to explore worlds, find life off Earth, and protect our planet from dangerous asteroids. Join us at planetary.org.

What’s up in the night sky: January 2026 Our monthly feature focuses on easy and fun things to see in the night sky, including eclipses, supermoons, meteor showers, planetary conjunctions, and more.

Planetary Radio looks back at the biggest space exploration stories of 2025, from stunning images and major missions to hard lessons about how science moves forward.

The Planetary Science Caucus, now in its second year, is officially reorganized and has hit the ground running; organizing against the devastating proposed cuts and rallying bipartisan congressional …

For over 4 decades, our members have made strides in advancing planetary exploration, planetary defense, and the search for life beyond Earth. We have delivered tens of thousands of petitions to …