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The flow of heat from Earth's interior to the surface is estimated at 47±2 terawatts (TW) [1] and comes from two main sources in roughly equal amounts: the radiogenic heat produced by the radioactive decay of isotopes in the mantle and crust, and the primordial heat left over from the formation of Earth. [2]
NASA scientists estimated that in 2024, Earth was about 2.65 degrees Fahrenheit (1.47 degrees Celsius) hotter than the average from the mid-19th century — a period from 1850 to 1900.
The Martian atmosphere is composed mainly of carbon dioxide and has a mean surface pressure of about 600 pascals (Pa), much lower than the Earth's 101,000 Pa. One effect of this is that Mars' atmosphere can react much more quickly to a given energy input than Earth's atmosphere. [51]
Mars has a higher scale height of 11.1 km than Earth (8.5 km) because of its weaker gravity. [5] The theoretical dry adiabatic lapse rate of Mars is 4.3 °C km −1 , [ 131 ] but the measured average lapse rate is about 2.5 °C km −1 because the suspended dust particles absorb solar radiation and heat the air. [ 2 ]
Mars, by contrast, is nearly (or perhaps totally) geologically dead and has lost much of its atmosphere. [51] Thus it would be fair to infer that the lower mass limit for habitability lies somewhere between that of Mars and that of Earth or Venus: 0.3 Earth masses has been offered as a rough dividing line for habitable planets. [52]
Total atmospheric mass is 5.1480 × 10 18 kg (1.13494 × 10 19 lb), [36] about 2.5% less than would be inferred from the average sea-level pressure and Earth's area of 51007.2 megahectares, this portion being displaced by Earth's mountainous terrain. Atmospheric pressure is the total weight of the air above unit area at the point where the ...
The distance separating the planet and its star is just 7% of the distance between Earth and the Sun, and the planet receives 1.6 times more energy from its star than Earth does from the Sun.
The study of extraterrestrial atmospheres is an active field of research, [1] both as an aspect of astronomy and to gain insight into Earth's atmosphere. [2] In addition to Earth, many of the other astronomical objects in the Solar System have atmospheres. These include all the giant planets, as well as Mars, Venus and Titan.