How do Venus and Earth compare in size and mass

Venus and Earth are cosmic twins in terms of size, but their environments couldn’t be more different. Venus has a diameter of about 12,104 kilometers, while Earth measures 12,742 kilometers—only a 5% difference. In mass, Venus is about 81.5% that of Earth. Their densities are also similar, meaning both have rocky compositions and iron-rich cores. Despite these physical similarities, the differences in their surface and atmosphere make them drastically different worlds. Venus spins very slowly and in the opposite direction to most planets, taking 243 Earth days to complete one rotation. Earth’s day lasts just 24 hours. Venus also lacks a magnetic field like Earth’s, which leaves it vulnerable to solar radiation. So, while they may look alike in size and shape, Earth and Venus are a perfect example of how similar beginnings can lead to completely different destinies in planetary evolution.