Venus
Venus is the second closest planet to the sun and the third brightest thing in Earth's sky. It is sometimes referred to as the "sister planet" to Earth because their size and mass are about the same. It's also the closest planet to Earth. Venus got its name from the Roman goddess, Venus.
Mercury
Mercury and Venus are very different. For example, Mercury can't be seen, except sometimes during twilight. Whereas Venus is one of the brightest things in the sky. Also, Mercury is much smaller than Earth. And since Earth and Venus are about the same size, both Earth and Venus are much bigger than Mercury, which is the smallest planet in the solar system and the closest planet to the sun.
