Which planet has the tallest volcano in the solar system?

Olympus Mons, located on the planet Mars, is the tallest volcano in the solar system. It stands at a height of 22 kilometers (14 miles) and covers an area roughly the size of the state of Arizona. To put its height into perspective, it is almost three times the height of Mount Everest, the tallest mountain on Earth. Olympus Mons is a shield volcano, which means it was formed by repeated lava flows over time, building up a broad, gently sloping mountain.

Scientists believe that the reason Olympus Mons is so much larger than any volcano on Earth is because Mars does not have tectonic plates, which means that the crust is more stable and the volcano can continue to erupt in the same spot for millions of years, building up to enormous size. In fact, some researchers believe that it is still active and could erupt again in the future.