Our planet probably experienced its hottest temperatures in its earliest days, when it was still colliding with other rocky debris (planetesimals) careening around the solar system. The heat of these collisions would have kept Earth molten, with top-of-the-atmosphere temperatures upward of 3,600° Fahrenheit.
Even after those first scorching millennia, however, the planet has sometimes been much warmer than it is now. One of the warmest times was during the geologic period known as the Neoproterozoic, between 600 and 800 million years ago. Another “warm age” is a period geologists call the Paleocene-Eocene Thermal Maximum, which occurred about 56 million years ago.
History of hot
Temperature records from thermometers and weather stations exist only for a tiny portion of our planet's 4.54-billion-year-long life. By studying indirect clues—the chemical and structural signatures of rocks, fossils, and crystals, ocean sediments, fossilized reefs, tree rings, and ice cores—however, scientists can infer past temperatures.
None of that helps with the very early Earth, however. During the time known as the Hadean (yes, because it was like Hades), Earth’s collisions with other large planetesimals in our young solar system—including a Mars-sized one whose impact with Earth is thought to have created the Moon—would have melted and vaporized most rock at the surface. Because no rocks on Earth have survived from so long ago, scientists have estimated early Earth conditions based on observations of the Moon and on astronomical models. Following the collision that spawned the Moon, the planet was estimated to have been around 2,300 Kelvin (3,680°F).
No comments:
Post a Comment