Final answer:
Stratovolcanoes like the Hawaiian volcanoes can be vast, stretching over 100 kilometers in diameter, with Mauna Kea used as a significant astronomy site. Venus houses Sif Mons, a vast volcano with long lava flows, while Mars boasts the towering Olympus Mons, vastly exceeding the height of volcanoes on Earth or Venus.
Step-by-step explanation:
The average height or slope of a stratovolcano, such as those found in the Hawaiian Islands and on other celestial bodies like Venus and Mars, can vary greatly. Stratovolcanoes on Earth, like the Hawaiian volcanoes, can be enormous, with some more than 100 kilometers in diameter and rising approximately 9 kilometers above the ocean floor. The dormant Mauna Kea, for instance, is not only a significant mountain on Earth but also a prominent location for astronomy due to its height. The size of stratovolcanoes on other planets, like Venus, can differ, with Sif Mons stretching approximately 500 kilometers across and about 3 kilometers high, featuring a large caldera and long lava flows. On Mars, Olympus Mons stands out as an impressive volcano, towering over 20 kilometers above its surroundings and almost 30 kilometers above the lowest areas on the planet.
Comparing these stratovolcanoes allows for a better understanding of their scale and the geologic processes at play. For example, the Hawaiian hotspot has been active for at least 100 million years, leading to a chain of volcanic islands stretching 3500 kilometers long. Other planets also display distinct volcanic features; Mars' Olympus Mons, for example, is significantly taller than the volcanoes found on Earth or Venus.