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  2. Isotopes of helium - Wikipedia

    en.wikipedia.org/wiki/Isotopes_of_helium

    Terrestrial helium consists almost exclusively (all but ~2ppm) [16] of 4 He. 4 He's boiling point of 4.2 K is the lowest of all known substances except 3 He. When cooled further to 2.17 K, it becomes a unique superfluid with zero viscosity. It solidifies only at pressures above 25 atmospheres, where it melts at 0.95 K.

  3. Polar wind - Wikipedia

    en.wikipedia.org/wiki/Polar_wind

    The idea for the polar wind originated with the desire to solve the paradox of the terrestrial helium budget. This paradox consists of the fact that helium in the Earth's atmosphere seems to be produced (via radioactive decay of uranium and thorium) faster than it is lost by escaping from the upper atmosphere. The realization that some helium ...

  4. List of planet types - Wikipedia

    en.wikipedia.org/wiki/List_of_planet_types

    A terrestrial planet with an arid surface consistency similar to Earth's deserts. Mars: Gas dwarf: A low-mass planet composed primarily of hydrogen and helium. GJ 1214 b: Gas giant: A massive planet composed primarily of hydrogen and helium. Saturn, Jupiter, 70 Virginis b: Helium planet: A theoretical planet that may form via mass loss from a ...

  5. Helium-3 - Wikipedia

    en.wikipedia.org/wiki/Helium-3

    Helium-3 (3 He [1] [2] see also helion) is a light, stable isotope of helium with two protons and one neutron. (In contrast, the most common isotope, helium-4, has two protons and two neutrons.) Helium-3 and protium (ordinary hydrogen) are the only stable nuclides with more protons than neutrons. It was discovered in 1939.

  6. Explainer-What is helium and why is it used in rockets? - AOL

    www.aol.com/news/explainer-helium-why-used...

    Helium is inert - it does not react with other substances or combust - and its atomic number is 2, making it the second lightest element after hydrogen. Rockets need to achieve specific speeds and ...

  7. Solar System - Wikipedia

    en.wikipedia.org/wiki/Solar_System

    The remaining objects of the Solar System (including the four terrestrial planets, the dwarf planets, moons, asteroids, and comets) together comprise less than 0.002% of the Solar System's total mass. [h] The Sun is composed of roughly 98% hydrogen and helium, [41] as are Jupiter and Saturn.

  8. Geology of solar terrestrial planets - Wikipedia

    en.wikipedia.org/wiki/Geology_of_solar...

    That is why the terrestrial planets could not grow very large and could not exert a strong pull on hydrogen and helium gas. [3] Also, the faster collisions among particles close to the Sun were more destructive on average. Even if the terrestrial planets had had hydrogen and helium, the Sun would have heated the gases and caused them to escape. [3]

  9. Noble gas - Wikipedia

    en.wikipedia.org/wiki/Noble_gas

    Helium and neon are also used as refrigerants due to their low boiling points. Industrial quantities of the noble gases, except for radon, are obtained by separating them from air using the methods of liquefaction of gases and fractional distillation. Helium is also a byproduct of the mining of natural gas.

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