宇宙で最も大きな火山
The biggest volcano in the solar system is Olympus Mons on Mars. This volcano is about 22 km tall, which is about 2.5 times higher than Mount Everest on Earth (about 8.8 km). Also, Olympus Mons has a diameter of about 600 km, which is half the size of Japan. This volcano is very old and is believed to be inactive now, but its size is truly amazing.
