Solar System

Data from the Juno probe found that Jupiter's core is less dense and more spread out than expected. Now, astronomers believe they have an answer – a huge ancient planet, with 10 times the mass of Earth, crashed into the gas giant in the early days of the solar system.

When scientists need to learn about something, recreating it in the lab is often one of the best ways – and now that even applies to the Sun itself. Physicists from the University of Wisconsin-Madison have built a mini-Sun in the lab, and used it to probe the secrets of the real thing.

The Japanese spacecraft Hayabusa 2 has successfully pulled off a second touchdown on the surface of the distant asteroid Ryugu. The risky dive saw the probe collect material that had been exposed during the creation of an artificial crater on April 5.

Saturn sports an impressive ring system, but Uranus also has some, although they’re usually too faint to see without a powerful telescope. Striking new images shows these rings in very clear detail thanks to thermal imaging, allowing astronomers to measure their temperature for the first time.

An international team of physicists has finally found proof of circumplanetary disks, adding substantial weight to current theoretical models of planet formation. These disks of gas surrounded by dust have eluded detection, until now.

New research suggests some asteroids could actually be alien, captured during close flybys with other star systems. These close encounters could also explain objects like Oumuamua and might even provide an alternative to the “Planet Nine” hypothesis.

According to research by planetologists at the University of Münster, the collision with a Mars-sized planetoid that formed the Moon 4.4 billion years ago brought with it almost all the water that makes our planet habitable.

Meteorites can tell us stories of ancient stars and long-lost planets. One of these stories has now been uncovered in a piece of space rock retrieved from Antarctica, containing grains from a stellar explosion that predates the Sun.

Scientists have discovered a tiny fragment of a comet in a meteorite. The bulk of the rock itself was once an asteroid, but when the team cracked it open and analyzed the inside, they found that the growing asteroid must have swept up the seed of a comet billions of years ago.

Metallic asteroids​ in the early days of the solar system may have had volcanoes spewing molten iron instead of lava. Based on models of how metallic asteroids form and cool, a new study by planetary scientists at UC Santa Cruz opens the window on such a spectacular possibility.

As the largest planet in the solar system by a wide margin, Jupiter has a lot of sway, but its history is still a bit of a mystery. Now astronomers have put forward a new theory, suggesting that the gas giant formed much farther away from the Sun and then migrated into its current position.

Roughly 4.6 billion years ago, all the planets in our solar system began to form in a huge disk of dust and gas that swirled around the Sun. Now astronomers have spotted the same kind of thing happening around a nearby young star, which could give us a better understanding of planet formation.