A new study suggests the smallest planet in our solar system is getting even smaller. The moon-sized planet is shrinking as its insides cool down. Mercury's diameter has declined by some 9 miles, and ...

Mercury doesn't give up its secrets easily. The smallest planet in our solar system is also one of the most extreme—a sun-scorched, metal-rich world with a puzzling magnetic field and lavas unlike ...

Far smaller and closer to the Sun than it should be, Mercury has long baffled astronomers because it defies much of what we know about planet formation. A new space mission arriving in 2026 might ...

The elusive planet Mercury reaches its furthest point from the sun on Friday (Jan. 12), with this separation allowing skywatchers a chance to spot the tiny planet. The fact that Mercury is the closest ...