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The Moon's surface contains helium-3 at concentrations on the order of 10 ppb, much higher than the approximately 5 ppt found in the Earth's atmosphere. [ 117 ] [ 118 ] A number of people, starting with Gerald Kulcinski in 1986, [ 119 ] have proposed to explore the Moon, mine lunar regolith, and use the helium-3 for fusion .
The partial pressure of helium in the Earth's atmosphere is about 0.52 pascals (7.5 × 10 −5 psi), and thus helium accounts for 5.2 parts per million of the total pressure (101325 Pa) in the Earth's atmosphere, and 3 He thus accounts for 7.2 parts per trillion of the atmosphere.
The Sun is an active star, and Earth is located within its atmosphere, so there is a dynamic interaction.The Sun' light influences all life and processes on Earth; it is an energy provider that allows and sustains life on Earth.
The reason is that there is no primordial helium in the atmosphere; due to the small mass of the atom, helium cannot be retained by the Earth's gravitational field. [71] Helium on Earth comes from the alpha decay of heavy elements such as uranium and thorium found in the Earth's crust , and tends to accumulate in natural gas deposits . [ 71 ]
The heliosphere is the magnetosphere, astrosphere, and outermost atmospheric layer of the Sun.It takes the shape of a vast, tailed bubble-like region of space.In plasma physics terms, it is the cavity formed by the Sun in the surrounding interstellar medium.
In Earth's atmosphere, the ratio of 3 He to 4 He is 1.343(13) × 10 −6. [5] However, the isotopic abundance of helium varies greatly depending on its origin. In the Local Interstellar Cloud, the proportion of 3 He to 4 He is 1.62(29) × 10 −4, [6] which is ~121 times higher than in Earth's atmosphere.
The Fraunhofer lines are typical spectral absorption lines. Absorption lines are narrow regions of decreased intensity in a spectrum, which are the result of photons being absorbed as light passes from the source to the detector. In the Sun, Fraunhofer lines are a result of gas in the Sun's atmosphere and outer photosphere. These regions have ...
For example, since the Sun formed, some of the helium and heavy elements have settled out of the photosphere by diffusion. As a result, the Solar photosphere now contains about 87% as much helium and heavy elements as the protostellar photosphere had; the protostellar Solar photosphere was 71.1% hydrogen, 27.4% helium, and 1.5% metals. [2]