The hottest temperature ever recorded on Earth’s surface is 2370 degree Celsius (4298 degree Fahrenheit). It occurred when a space rock crashed into earth nearly 40 million years ago in what is now Canada, creating hellishly hot temperature in the collision zone for a brief period of time. According to New Scientist, the resulting shock waves vaporised both the meteorites and the surface rocks, and it even altered earth’s atmosphere and crust, and affected its habitability.
Researchers say the revelation was made by an unexpected source: gemstones. The clues left behind in the Mistastin Lake crater in Labrador, Canada, which is 28 kilometres across, show just how hot the impact site became. They found that the crater was once hot enough to transform the mineral zircon (found in the impact rocks of the crater) into gem-like cubic zirconia. The zircon acts as a thermometer, because the minimum temperature necessary for this transformation is 2370 °C.
“Nobody has even considered using zirconia as a recorder of temperatures of impact melts before,” says Nicholas Timms of Curtin University in Perth, Australia. “This is the first time that we have an indication that real rocks can get that hot.”
“These new results underscore just how extreme conditions can be in the seconds to minutes after asteroids strike a planet,” says Benjamin Black of the University of California, Berkeley. “Understanding the upper limits of temperatures during these impacts might improve our picture of the conditions on Earth’s surface over 4 billion years ago, when the newly formed planet was repeatedly bombarded from space.
Frequent and larger impacts could have baked Earth’s crust, keeping hydrogen, carbon and sulphur in the atmosphere. These elements are considered essential for life,because without hydrogen and oxygen there can be no water. But too much could have affected the planet’s climate and chemistry, making it less habitable, researchers say.
The study, entitled “Cubic zirconia in >2370 °C impact melt records Earth’s hottest crust” has been published in Earth and Planetary Science Letters
Source: New Scientist