New observations of Mercury, the planet closest to the Sun, suggest it has significantly shrunk over time. Distinct “wrinkles” covering Mercury’s surface are key evidence of this contraction. Scientists believe the planet was once larger and has diminished in size. This shrinking is linked to its large metallic core cooling and contracting. These surface features offer insights into the thermal and geological history of the planet. Further study of Mercury could reveal more about the evolution of inner planets within our Solar System.