The inner planets are "probably rocky and may have thin atmospheres," NASA said, while the five outer planets are expected to have thick atmospheres. Artist's concept of Kepler-385, ...

Our best simulations so far capture only the general picture of the inner planets' formation, a roughly 100 million-year-long period in which small planetesimals collided to form the planets we ...

Astronomers have gotten a sneak peek at what could be Earth's ultimate fate in about 5 billion years when the sun reaches the end of its life and engulfs the solar system's inner planets ...

These inner planets are now believed to be the youngest, taking at least 100 million years—and possibly more—to fully form. While a 90-million-year age gap might sound massive, ...

Are planets in the solar system that are closer to the Sun older than the ones further away? ... The inner planets, including Earth, took at least 100 million years, maybe more.

Astronomers have discovered six planets orbiting a bright star in perfect resonance. The star system, 100 light-years from Earth, was described on Wednesday in a paper published in the journal ...

Scientists have determined that Mercury, the closest planet to the sun, may contain a 10-mile thick mantle layer of diamonds based on data from NASA’s MESSENGER space probe, Space.com reported.

But our inner planets seem to have formed with little of the element or lost it early in their history. But a look at exoplanets suggests that this isn't an inevitable fate.