Heliophysics (from the prefix " helio", from

Attic Greek Attic Greek is the Greek language, Greek dialect of the regions of ancient Greece, ancient region of Attica, including the ''polis'' of classical Athens, Athens. Often called Classical Greek, it was the prestige (sociolinguistics), prestige diale ...

''hḗlios'', meaning Sun, and the noun "

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

": the science of matter and energy and their interactions) is the physics of the Sun and its connection with the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

defines heliophysics as "(1) the comprehensive new term for the science of the Sun - Solar System Connection, (2) the exploration, discovery, and understanding of Earth's space environment, and (3) the system science that unites all of the linked phenomena in the region of the cosmos influenced by a star like our Sun." Heliophysics is broader than

Solar physics Solar physics is the branch of astrophysics that specializes in the study of the Sun. It intersects with many disciplines of pure physics and astrophysics. Because the Sun is uniquely situated for close-range observing (other stars cannot be re ...

, that studies the Sun itself, including its interior, atmosphere, and magnetic fields. It concentrates on the Sun's effects on

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

and other bodies within the Solar System, as well as the changing conditions in space. It is primarily concerned with the

magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...

ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...

thermosphere The thermosphere is the layer in the Earth's atmosphere directly above the mesosphere and below the exosphere. Within this layer of the atmosphere, ultraviolet radiation causes photoionization/photodissociation of molecules, creating ions; the ...

mesosphere The mesosphere (; ) is the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature decreases as altitude increases. This characteristic is used to define limits: it be ...

, and

upper atmosphere Upper atmosphere is a collective term that refers to various layers of the atmosphere of the Earth above the troposphere and corresponding regions of the atmospheres of other planets, and includes: * The mesosphere, which on Earth lies between th ...

of the Earth and other

planet A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...

s. Heliophysics combines the science of the Sun,

corona Corona (from the Latin for 'crown') most commonly refers to: * Stellar corona, the outer atmosphere of the Sun or another star * Corona (beer), a Mexican beer * Corona, informal term for the coronavirus or disease responsible for the COVID-19 ...

heliosphere 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 ...

and geospace, and encompasses a wide variety of astronomical phenomena, including "

cosmic rays Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar ...

and

particle acceleration In acoustics, particle acceleration is the acceleration (rate of change in speed and direction) of particles in a sound transmission medium. When sound passes through a medium it causes particle displacement and as such causes changes in their ac ...

space weather Space weather is a branch of space physics and aeronomy, or heliophysics, concerned with the varying conditions within the Solar System and its heliosphere. This includes the effects of the solar wind, especially on the Earth's magnetosphere, ion ...

and

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes: * ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...

dust Dust is made of particle size, fine particles of solid matter. On Earth, it generally consists of particles in the atmosphere that come from various sources such as soil lifted by wind (an aeolian processes, aeolian process), Types of volcan ...

and

magnetic reconnection Magnetic reconnection is a physical process occurring in electrically conducting Plasma (physics), plasmas, in which the magnetic topology is rearranged and magnetic energy is converted to kinetic energy, thermal energy, and particle accelerati ...

, nuclear energy generation and internal solar dynamics,

solar activity Solar phenomena are natural phenomena which occur within the Stellar atmosphere, atmosphere of the Sun. They take many forms, including solar wind, Solar radio emission, radio wave flux, solar flares, coronal mass ejections, Stellar corona#Coron ...

and

stellar magnetic field A stellar magnetic field is a magnetic field generated by the motion of conductive plasma inside a star. This motion is created through convection, which is a form of energy transport involving the physical movement of material. A localized mag ...

aeronomy Aeronomy is the scientific study of the upper atmosphere of the Earth and corresponding regions of the atmospheres of other planets. It is a branch of both atmospheric chemistry and atmospheric physics. Scientists specializing in aeronomy, know ...

and

space plasma The interplanetary medium (IPM) or interplanetary space consists of the mass and energy which fills the Solar System, and through which all the larger Solar System bodies, such as planets, dwarf planets, asteroids, and comets, move. The IPM sto ...

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

s and

global change Global change in broad sense refers to planetary-scale changes in the Earth system. It is most commonly used to encompass the variety of changes connected to the rapid increase in human activities which started around mid-20th century, i.e., the G ...

", and the interactions of the Solar System with the

Milky Way Galaxy The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galaxy, which are ...

History and etymology

Term "heliophysics" () was widely used in

Russian-language Russian is an East Slavic language belonging to the Balto-Slavic branch of the Indo-European language family. It is one of the four extant East Slavic languages, and is the native language of the Russians. It was the ''de facto'' and ''de j ...

scientific literature Scientific literature encompasses a vast body of academic papers that spans various disciplines within the natural and social sciences. It primarily consists of academic papers that present original empirical research and theoretical ...

. The

Great Soviet Encyclopedia The ''Great Soviet Encyclopedia'' (GSE; , ''BSE'') is one of the largest Russian-language encyclopedias, published in the Soviet Union from 1926 to 1990. After 2002, the encyclopedia's data was partially included into the later ''Great Russian Enc ...

third edition (1969–1978) defines "Heliophysics" as " ��a division of

astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the ...

that studies physics of the Sun". In 1990, the

Higher Attestation Commission Higher Attestation Commission (, , abbreviated Cyrillic: ВАК, Latin: VAK) is a name of a national government agency in Russia, Ukraine and some other post-Soviet states that oversees awarding of advanced academic degrees. Due to translation diff ...

, responsible for the advanced academic degrees in

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

and later in

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

and the

Former Soviet Union The post-Soviet states, also referred to as the former Soviet Union or the former Soviet republics, are the independent sovereign states that emerged/re-emerged from the dissolution of the Soviet Union in 1991. Prior to their independence, they ...

, established a new specialty “Heliophysics and physics of solar system”. In

English-language English is a West Germanic language that developed in early medieval England and has since become a English as a lingua franca, global lingua franca. The namesake of the language is the Angles (tribe), Angles, one of the Germanic peoples th ...

scientific literature prior to about 2001, the term heliophysics was sporadically used to describe the study of the "physics of the Sun". As such it was a direct translation from the French "héliophysique" and the Russian "гелиофизика". In 2001, Joseph M. Davila, Nat Gopalswamy and Barbara J. Thompson at NASA's

Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C., in Greenbelt, Maryland, United States. Established on May 1, 1959, as NASA's first space flight center, GSFC ...

adopted the term in their preparations of what became known as the International Heliophysical Year (2007–2008), following 50 years after the

International Geophysical Year The International Geophysical Year (IGY; ), also referred to as the third International Polar Year, was an international scientific project that lasted from 1 July 1957 to 31 December 1958. It marked the end of a long period during the Cold War w ...

; in adopting the term for this purpose, they expanded its meaning to encompass the entire domain of influence of the Sun (the

). As an early advocate of the newly expanded meaning,

George Siscoe George L. Siscoe (June13, 1937April9, 2022) was an American physicist and professor emeritus of space physics at Boston University. He made major contributions to the understanding of the Earth's magnetosphere and the heliosphere, particularly in ...

offered the following characterization:

"Heliophysics ncompassesenvironmental science, a unique hybrid between
meteorology Meteorology is the scientific study of the Earth's atmosphere and short-term atmospheric phenomena (i.e. weather), with a focus on weather forecasting. It has applications in the military, aviation, energy production, transport, agricultur ...
and
astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the ...
, comprising a body of data and a set of paradigms (general laws—perhaps mostly still undiscovered) specific to magnetized plasmas and neutrals in the heliosphere interacting with themselves and with gravitating bodies and their atmospheres."

Around mid-2006, Richard R. Fisher, then Director of the Sun-Earth Connections Division of NASA's

Science Mission Directorate The Science Mission Directorate (SMD) of the National Aeronautics and Space Administration (NASA) is one of the six directorates that constitute NASA. Its responsibility is to define and direct research into scientific questions of interest, shari ...

, was challenged by the NASA administrator to come up with a concise new name for his division that "had better end on 'physics'".Richard Fisher speaking just after the 1h30m mark i
this youtube movie
/ref> He proposed " Heliophysics Science Division", which has been in use since then. The Heliophysics Science Division uses the term "heliophysics" to denote the study of the heliosphere and the objects that interact with it – most notably planetary atmospheres and magnetospheres, the solar corona, and the

interstellar medium The interstellar medium (ISM) is the matter and radiation that exists in the outer space, space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as cosmic dust, dust and cosmic rays. It f ...

. Heliophysical research connects directly to a broader web of physical processes that naturally expand its reach beyond NASA's narrower view that limits it to the Solar System: heliophysics reaches from

solar physics Solar physics is the branch of astrophysics that specializes in the study of the Sun. It intersects with many disciplines of pure physics and astrophysics. Because the Sun is uniquely situated for close-range observing (other stars cannot be re ...

out to

stellar physics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the ...

in general, and involves several branches of

nuclear physics Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter. Nuclear physics should not be confused with atomic physics, which studies th ...

plasma physics Plasma () is a state of matter characterized by the presence of a significant portion of charged particles in any combination of ions or electrons. It is the most abundant form of ordinary matter in the universe, mostly in stars (including th ...

space physics Space physics, also known as space plasma physics, is the study of naturally occurring plasmas within Earth's upper atmosphere and the rest of the Solar System. It includes the topics of aeronomy, aurorae, planetary ionospheres and magnetospheres, ...

and magnetospheric physics. The science of heliophysics lies at the foundation of the study of

, and is also directly involved in understanding

planetary habitability Planetary habitability is the measure of a planet's or a natural satellite's potential to Abiogenesis, develop and sustain an environment hospitable to life. Life may be abiogenesis, generated directly on a planet or satellite endogenously. Res ...

Background

The Sun is an active

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

, and Earth is located within its

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

, 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 Life, also known as biota, refers to matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes. It is defined descriptively by the capacity for homeostasis, Structure#Biological, organisation, met ...

on Earth. However, the Sun also produces streams of high energy particles known as the

solar wind The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...

, and radiation that can harm life or alter its evolution. Under the protective shield of

Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from structure of Earth, Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from ...

and its atmosphere, Earth can be seen as an island in the universe where life has developed and flourished. The intertwined response of the Earth and

are studied because the planet is immersed in this unseen environment. Above the protective cocoon of Earth's lower atmosphere is a plasma soup composed of electrified and magnetized matter entwined with penetrating radiation and energetic particles. Modern technologies are susceptible to the extremes of

— severe disturbances of the upper atmosphere and of the near-Earth space environment that are driven by the magnetic activity of the Sun. Strong electrical currents driven in the Earth's surface during auroral events can disrupt and damage modern electric power grids and may contribute to the corrosion of oil and gas pipelines.

Heliophysics research program

Heliophysics System Observatory satellites - 201707

Methods have been developed to see into the internal workings of the Sun and understand how the

Earth's magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...

responds to

. Further studies are concerned with exploring the full system of complex interactions that characterize the relationship of the Sun with the

. There are three primary objectives that define the multi-decadal studies: * To understand the changing flow of energy and matter throughout the Sun, heliosphere, and planetary environments. * To explore the fundamental physical processes of space plasma systems. * To define the origins and societal impacts of variability in the Earth-Sun system.

Heliosphere

Plasmas and their embedded magnetic fields affect the formation and evolution of planets and planetary systems. The heliosphere shields the Solar System from galactic cosmic radiation. Earth is shielded by its

, protecting it from solar and cosmic particle radiation and from erosion of the atmosphere by the

. Planets without a shielding magnetic field, such as

Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...

and

Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...

, are exposed to those processes and evolve differently. On

, the magnetic field changes strength and configuration during its occasional polarity reversals, altering the shielding of the planet from external radiation sources.

Magnetospheres

Determine changes in the

, ionosphere, and upper atmosphere in order to enable specification, prediction, and mitigation of their effects. Heliophysics seeks to develop an understanding of the response of the near-Earth plasma regions to

. This complex, highly coupled system protects Earth from the worst solar disturbances while redistributing energy and mass throughout.

References

External links

NASA HeliophysicsHeliophysics Integrated Observatory
*NASA video
Understanding The Sun – The Heliophysics Program
*NASA video
Introduction to Heliophysics
*American Geophysical Union video
Heliophysics and the Weather in Space''Principles Of Heliophysics: a textbook on the universal processes behind planetary habitability'' by Karel Schrijver et alNASA Heliophysics textbooksNASA-funded Summer Schools
{{Authority control Sun Space science Space weather Astrophysics Space plasmas