The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between 0.5 and 10 keV. The composition of the solar wind plasma also includes a mixture of materials found in the solar plasma: trace amounts of heavy ions and atomic nuclei of elements such as C, N, O, Ne, Mg, Si, S, and Fe. There are also rarer traces of some other nuclei and isotopes such as P, Ti, Cr, 54Fe and 56Fe, and 58Ni, 60Ni, and 62Ni. Superimposed with the solar-wind plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field. The boundary separating the corona from the solar wind is called the Alfvén surface.
Voyager 1 is a space probe launched by NASA on September 5, 1977, as part of the Voyager program to study the outer Solar System and interstellar space beyond the Sun's heliosphere. Launched 16 days after its twin Voyager 2, Voyager 1 has been operating for 45 years, 11 months and 13 days as of August 19, 2023 UTC [refresh]. It communicates through NASA's Deep Space Network to receive routine commands and to transmit data to Earth. Real-time distance and velocity data is provided by NASA and JPL. At a distance of 160.221 AU from Earth as of August 2, 2023, it is the most distant human-made object from Earth.
In astronomy, the interstellar medium (ISM) is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space. The energy that occupies the same volume, in the form of electromagnetic radiation, is the interstellar radiation field. Although the density of atoms in the ISM is usually far below that in the best laboratory vacuums, the mean free path between collisions is short compared to typical interstellar lengths, so on these scales the ISM behaves as a gas (more precisely, as a plasma: it is everywhere at least slightly ionized), responding to pressure forces, and not as a collection of non-interacting particles.
Advanced Composition Explorer is a NASA Explorer program satellite and space exploration mission to study matter comprising energetic particles from the solar wind, the interplanetary medium, and other sources.
In astrophysics, a bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby flowing ambient plasma such as the solar wind. For Earth and other magnetized planets, it is the boundary at which the speed of the stellar wind abruptly drops as a result of its approach to the magnetopause. For stars, this boundary is typically the edge of the astrosphere, where the stellar wind meets the interstellar medium.
The heliosphere is the magnetosphere, astrosphere, and outermost atmospheric layer of the Sun. It takes the shape of a vast, bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding interstellar medium. The "bubble" of the heliosphere is continuously "inflated" by plasma originating from the Sun, known as the solar wind. Outside the heliosphere, this solar plasma gives way to the interstellar plasma permeating the Milky Way. As part of the interplanetary magnetic field, the heliosphere shields the Solar System from significant amounts of cosmic ionizing radiation; uncharged gamma rays are, however, not affected. Its name was likely coined by Alexander J. Dessler, who is credited with the first use of the word in the scientific literature in 1967. The scientific study of the heliosphere is heliophysics, which includes space weather and space climate.
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 stops at the heliopause, outside of which the interstellar medium begins. Before 1950, interplanetary space was widely considered to either be an empty vacuum, or consisting of "aether".
The magnetosphere of Saturn is the cavity created in the flow of the solar wind by the planet's internally generated magnetic field. Discovered in 1979 by the Pioneer 11 spacecraft, Saturn's magnetosphere is the second largest of any planet in the Solar System after Jupiter. The magnetopause, the boundary between Saturn's magnetosphere and the solar wind, is located at a distance of about 20 Saturn radii from the planet's center, while its magnetotail stretches hundreds of Saturn radii behind it.
Cluster II is a space mission of the European Space Agency, with NASA participation, to study the Earth's magnetosphere over the course of nearly two solar cycles. The mission is composed of four identical spacecraft flying in a tetrahedral formation. As a replacement for the original Cluster spacecraft which were lost in a launch failure in 1996, the four Cluster II spacecraft were successfully launched in pairs in July and August 2000 onboard two Soyuz-Fregat rockets from Baikonur, Kazakhstan. In February 2011, Cluster II celebrated 10 years of successful scientific operations in space. As of March 2023, its mission has been extended until September 2024. The China National Space Administration/ESA Double Star mission operated alongside Cluster II from 2004 to 2007.
A Forbush decrease is a rapid decrease in the observed galactic cosmic ray intensity following a coronal mass ejection (CME). It occurs due to the magnetic field of the plasma solar wind sweeping some of the galactic cosmic rays away from Earth. The term Forbush decrease was named after the American physicist Scott E. Forbush, who studied cosmic rays in the 1930s and 1940s.
The heliospheric current sheet, or interplanetary current sheet, is a surface separating regions of the heliosphere where the interplanetary magnetic field points toward and away from the Sun. A small electrical current with a current density of about 10−10 A/m2 flows within this surface, forming a current sheet confined to this surface. The shape of the current sheet results from the influence of the Sun's rotating magnetic field on the plasma in the interplanetary medium. The thickness of the current sheet is about 10,000 km (6,200 mi) near the orbit of the Earth.
Interstellar Boundary Explorer is a NASA satellite in Earth orbit that uses energetic neutral atoms (ENAs) to image the interaction region between the Solar System and interstellar space. The mission is part of NASA's Small Explorer program and was launched with a Pegasus-XL launch vehicle on 19 October 2008.
Adolfo Figueroa-Viñas is the first Puerto Rican astrophysicist at the National Aeronautics and Space Administration (NASA) and is an expert in solar and space plasma physics at the Heliophysics Science Division. As a staff scientist his research interests include studying plasma kinetic physics and magnetohydrodynamics of the solar wind, heliosphere, shock waves, MHD and kinetic simulation of plasma instabilities, and turbulent processes associated with space, solar and astrophysical plasmas.
Energetic Neutral Atom (ENA) 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 throughout the heliosphere.
The Heliophysics Science Division of the Goddard Space Flight Center (NASA) conducts research on the Sun, its extended Solar System environment, and interactions of Earth, other planets, small bodies, and interstellar gas with the heliosphere. Division research also encompasses geospace—Earth's uppermost atmosphere, the ionosphere, and the magnetosphere—and the changing environmental conditions throughout the coupled heliosphere.
Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a planned joint venture mission between the European Space Agency and the Chinese Academy of Sciences. SMILE will image for the first time the magnetosphere of the Sun in soft X-rays and UV during up to 40 hours per orbit, improving our understanding of the dynamic interaction between the solar wind and Earth's magnetosphere. The prime science questions of the SMILE mission are
The Interstellar Mapping and Acceleration Probe(IMAP) is a heliophysics mission that will simultaneously investigate two important and coupled science topics in the heliosphere: the acceleration of energetic particles and interaction of the solar wind with the local interstellar medium. These science topics are coupled because particles accelerated in the inner heliosphere play crucial roles in the outer heliospheric interaction. In 2018, NASA selected a team led by David J. McComas of Princeton University to implement the mission, which is currently planned to launch in February 2025. IMAP will be a Sun-tracking spin-stabilized satellite in orbit about the Sun–Earth L1 Lagrange point with a science payload of ten instruments. IMAP will also continuously broadcast real-time in-situ data that can be used for space weather prediction.
Nancy U. Crooker is an American physicist and professor emerita of space physics at Boston University, Massachusetts. She has made major contributions to the understanding of geomagnetism in the Earth's magnetosphere and the heliosphere, particularly through the study of interplanetary electrons and magnetic reconnection.
Lynn Kistler is a physicist known for her research on the magnetosphere that protects Earth from radiation from space.
Antoinette (Toni) Galvin is space physicist at the University of New Hampshire. She is known for her research on the solar wind.
