No, howsoever tall Mount Everest stands, it doesn’t stand a chance on this count. The highest as well the largest known mountain in the Solar System is Olympus Mons, on the planet Mars. (See photo) It rises about 79,000 feet (24,000 meters) above the surrounding plains. The Mount Everest, on the other hand is only 29,028 feet above sea level. It has about 100 times the volume of our terrestrial champion. The base of Olympus Mons is 600 kilometers across. The volcanic crater at the summit is over 64 kilometers across, large enough to accommodate about eight cities like Mumbai. If Edmund Hillary had set out to climb Olympus Mons at the same pace as he climbed Everest, it would take him 130 days – almost three times as long as Everest.
On the Earth’s surface, about 35,000 feet (10,670 meters) is the upper limit of a mountain’s height. The limit is set by the Earth’s gravity, which would tend to pull down the mass that exceeds the limit. Mars has gravity which is only 38% as strong as that of the Earth. Consequently, volcanic mountains there could attain greater heights than their counterparts on the Earth.