Mercury's surface features indicate a reduction in size over time. This planet, the smallest in our solar system, orbits the sun at an average distance of 36 million miles. Its formation occurred around 4.5 billion years ago from gas and dust.

The early solar system was marked by collisions between space rocks, generating significant heat in newly formed planets. As this heat escapes, the planet's interior changes.

Further information about Mercury's shrinking size and its implications can be found through additional sources, including NASA's findings on the planet's orbit and formation.