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Small BodiesStories, updates, insights, and original analysis from The Planetary Society.
How do you define a planet?
As our ability to study space has improved, our definitions of planets have evolved.
Why do some planets have rings and others don't?
The giant planets of our Solar System all have rings, as do some dwarf planets and even asteroids. So why don’t Mercury, Venus, Earth, or Mars?
What is a "planetary alignment"?
What to expect when multiple planets appear in the sky together.
The Artemis II mission: What to expect
NASA is preparing to send humans back to the Moon for the first time in over 50 years. The Artemis II mission will send a crew of four astronauts on a 10-day mission around the Moon and back to Earth. Here’s what to expect from the upcoming mission.
Rogue worlds and the boundaries of planethood
Exploring rogue planets, how they form, and how they expand our conception of what counts as a planet.
The year in pictures 2025
The most memorable and impactful images from space exploration in 2025.
The Planetary Society's Best of 2025 Winners
The official results of The Planetary Society's Best of 2025 voting campaign.
“We’re made of starstuff.” What does that mean?
Carl Sagan's famous quote is more than just poetic — it's true.
What is comet 3I/ATLAS?
A roundup of key facts and surprising discoveries about the third known interstellar object.
The pale blue dot 35 years later
On its 35th anniversary, a reflection on what the pale blue dot means to us.
A test bed in the search for life
Updates from a Planetary Society STEP Grant-funded project.
When space rocks get too close for comfort
Some of the best-documented encounters Earthlings have had with asteroids and meteorites.
Scientists behind threatened NASA missions explain what’s at stake
Here is what they have to say, in their own words.
It's not magic; it's magnetic!
The magnetism behind spectacular phenomena.
Not too hot to handle
How a spacecraft is able to touch the Sun.
The Fermi Paradox: Where are all the aliens?
The conditions for intelligent life to arise don't seem uncommon in the Cosmos. So where is everybody?
The Voyager Golden Records: A cosmic love letter
How a message to aliens captured the human spirit.
Are we alone in the universe? AI may help us find out
A Planetary Society-funded project uses machine learning to search for intelligent alien life.
Computing in space exploration history
Before artificial intelligence, there was human ingenuity.
EELS and the future of exploration
How artificial intelligence could traverse other worlds