Mercury, the smallest and second densest planet, orbits the Sun in 88 Earth days, yet its solar day is 176 Earth days. Despite its proximity to the Sun, Mercury exhibits a significant temperature ...

The MESSENGER spacecraft has shown scientists that Mercury doesn't conform to theory. Its surface material composition differs from both those of the other terrestrial planets and expectations prior ...

You probably learned in school — or space camp — that Venus is Earth’s closest planetary neighbor. Ready to get your mind blown? A new model of the planets’ orbit shuffles things around, calculating ...

Forbes contributors publish independent expert analyses and insights. The Universe is out there, waiting for you to discover it. In the grand scheme of the Solar System, the greatest source of energy ...

In the crowded early Solar System, young planets frequently collided and reshaped each other. But Mercury stood out. It formed unusually close to the Sun. Mercury’s days are longer than its years. It ...

In this column, we'll focus on the ecliptic, the invisible "racetrack" that hosts the sun, moon and planets. Knowing how it works and where to find it can make you a master planet spotter — you'll ...

Mercury, Venus, Earth and Mars are known collectively as the rocky planets, in contrast the Solar System’s gas giants—Jupiter, Saturn, Uranus and Neptune. (Pluto is an ice dwarf, which makes it sound ...

Mercury is covered with pits that are unlike anything else in the solar system, new observations from NASA’s Messenger spacecraft show. They may have been formed by processes still active today, and ...

Recent research indicates Mercury is shrinking, with its radius decreasing by 2.7 to 5.6 kilometers due to core cooling. This contraction forms thrust faults and scarps on the surface. A new ...

Forbes contributors publish independent expert analyses and insights. An award-winning reporter writing about stargazing and the night sky. An inner planet that pings around the Sun in a mere 88 days, ...