John Casani spent more than half a century turning speculative ideas about distant worlds into working spacecraft that could survive the trip. His quiet influence at NASA’s Jet Propulsion Laboratory ...

Illustration comparing the planets of the Solar System and the Sun on the same scale. The planets are shown to scale relative to each other but their distances are not. From left to right the bodies ...

Simulations reveal that Jupiter’s rapid growth disrupted the early solar system, creating rings where new planetesimals formed much later than expected. These late-forming bodies match the ages and ...

For millions of years, a frozen wanderer drifted between the stars before slipping into our solar system as 3I/ATLAS—only the ...