Compton–Getting effect
Encyclopedia
The Compton–Getting effect is an apparent anisotropy
in the intensity of radiation or particles due to the relative motion between the observer and the source. This effect was first identified in the intensity of cosmic rays by Arthur Compton
and Ivan A. Getting
in 1935 . Gleeson and Axford provide a full derivation of the equations relevant to this effect..
The original application of the Compton–Getting effect predicted that the intensity of cosmic rays should be higher coming from the direction in which Earth is moving. For the case of cosmic rays the Compton-Getting effect only applies to those that are unaffected by the Solar wind
such as extremely high energy rays. It has been calculated that the speed of the Earth within the galaxy (200 km/s) would result in a difference between the strongest and weakest cosmic ray intensities of about 0.1%. This small difference is within the capabilities of modern instruments to detect, but as of 2005 the Compton–Getting effect has not been confirmed for Cosmic Rays.
Forman (1970) derives the Compton-Getting effect anisotropy from the Lorentz invariance of the phase space distribution function. Ipavich (1974) furthers this general derivation to derive count rates with respect to the flow vector .
This Compton-Getting effect is apparent in plasma data in Earth's magnetotail. The Compton-Getting effect has also been utilized for analyzing energetic neutral atom
(ENA) data returned by the Cassini-Huygens
spacecraft at Saturn
.
Anisotropy
Anisotropy is the property of being directionally dependent, as opposed to isotropy, which implies identical properties in all directions. It can be defined as a difference, when measured along different axes, in a material's physical or mechanical properties An example of anisotropy is the light...
in the intensity of radiation or particles due to the relative motion between the observer and the source. This effect was first identified in the intensity of cosmic rays by Arthur Compton
Arthur Compton
Arthur Holly Compton was an American physicist and Nobel laureate in physics for his discovery of the Compton effect. He served as Chancellor of Washington University in St. Louis from 1945 to 1953.-Early years:...
and Ivan A. Getting
Ivan A. Getting
Ivan Alexander Getting was an American physicist and electrical engineer, credited with the development of the Global Positioning System...
in 1935 . Gleeson and Axford provide a full derivation of the equations relevant to this effect..
The original application of the Compton–Getting effect predicted that the intensity of cosmic rays should be higher coming from the direction in which Earth is moving. For the case of cosmic rays the Compton-Getting effect only applies to those that are unaffected by the Solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...
such as extremely high energy rays. It has been calculated that the speed of the Earth within the galaxy (200 km/s) would result in a difference between the strongest and weakest cosmic ray intensities of about 0.1%. This small difference is within the capabilities of modern instruments to detect, but as of 2005 the Compton–Getting effect has not been confirmed for Cosmic Rays.
Forman (1970) derives the Compton-Getting effect anisotropy from the Lorentz invariance of the phase space distribution function. Ipavich (1974) furthers this general derivation to derive count rates with respect to the flow vector .
This Compton-Getting effect is apparent in plasma data in Earth's magnetotail. The Compton-Getting effect has also been utilized for analyzing energetic neutral atom
Energetic neutral atom
Energetic neutral atom imaging, often described as "seeing with atoms", is a technology used to create global images of otherwise invisible phenomena in the magnetospheres of planets and at the boundary of the heliosphere - the far flung outer edge of the solar system.ENA images are constructed...
(ENA) data returned by the Cassini-Huygens
Cassini-Huygens
Cassini–Huygens is a joint NASA/ESA/ASI spacecraft mission studying the planet Saturn and its many natural satellites since 2004. Launched in 1997 after nearly two decades of gestation, it includes a Saturn orbiter and an atmospheric probe/lander for the moon Titan, although it has also returned...
spacecraft at Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...
.