Shorthand for a filter that has a peak transmission at, or close to, 171 angstroms. AIA and EIT have non-identical filters that create monochromatic images around this wavelength (and so the images can appear slightly different). It is customary to assign a false color to these images in order to create a pleasing visual impression; AIA chooses yellow, and EIT chooses a blue color.
- Browse Related Terms: 171, Electromagnetic Spectrum, Faculae, Gamma Rays, Infrared, Infrared (IR) Radiation, Ionization, radiation, Radio Waves, Solar Flare, Solar Ultraviolet Irradiance, Spectrograph, spectrum, Ultraviolet, Visible Light, Wavelength, X-Rays
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With regards to physics, a discontinuity or distortion in an image produced by a lens. There is also Astronomical Aberration, which is completely unrelated, and describes the difference between the apparent position of a star to an observer on earth and the actual position of the star in the sky. This is due to the time it takes the light from the star to reach us. (In the mean time, while observers on earth are 'waiting' for the star light to reach them, the star has moved). For example, when we look up in the sky, we are seeing where the sun was 9 minutes ago, since it takes light from the sun 9 minutes to reach the earth.
- Browse Related Terms: Aberration, Big Bang, Cosmological Principle, Curvature of Spacetime, General Relativity, Hubble's Law, Milky Way, Quasar, Recede, Relativity, Spacetime, Supernova
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The spectra of electromagnetic radiation transmitted through a substance, with dark lines indicating the absorption of specific wavelengths.
- Browse Related Terms: Absorption Spectra, Black Body Spectrum, Electromagnetic Radiation, Energy Spectrum, Light, period, Scatter, Spectra, spectral line, Wavelength
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One where distance increase faster with time, in contradiction to those where the gravitational attraction of ordinary matter slows down the expansion.
- Browse Related Terms: Accelerating Universe, anomaly, Baryonic Matter, High Electron Mobility Transistor (HEMT), Homogeneous, Visible Mass
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Changing velocity. This implies that either an object's speed (rate of change of position) or direction of motion is changing.
- Browse Related Terms: Acceleration, Doppler Effect, evolution, Fluctuation, Phase Transition, Redshift, Velocity
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The smallest angular size that the instrument can resolve.
- Browse Related Terms: Angular resolution, Equilibrium, Feed, Fusion, hypothesis, initial, Kelvin, Mid-Class Explorer (MIDEX), Nucleosynthesis, Quantum Mechanics, Simultaneous
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The size of an object as viewed from the earth. For example, the moon subtends (covers) an angle of 1/2 of a degree. If the distance to an object is known, the angular size can be used to determine its diameter.
- Browse Related Terms: Angular Size, Apparent luminosities, Constant of Proportionality, Dark Matter, Flux, Heavenly Bodies, Intrinsic Luminosity, Inverse Square, Luminosity, Main Sequence Star, Observed Brightness, Parallax, Parsec, Relative Brightness, Standard Candle, Type Ia Supernova, Variable Stars
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The difference in the property of a system with changes in direction. In this case, anisotropy refers to the difference in the temperature of the cosmic microwave background radiation with direction.
Something that is anisotropic has a physical property value that varies when measured from a different direction. In cosmology, anisotropies refer to the difference in temperature of the CMB with direction.
- Browse Related Terms: Anisotropy, ERA, Frame of Reference, Isotropic, Relic, sensitivity, Stochastic, Systematic Errors
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A process in which a particle meets its corresponding antiparticle and both disappear. The energy appears in some other form, perhaps as a different particle and its antiparticle (and their energy), perhaps as many mesons, perhaps as a single neutral boson. The produced particles may be any combination allowed by conservation of energy and momentum and of all the charge types.
- Browse Related Terms: Annihilated/annihilation, Antimatter, Antiparticle/antiquark/antielectron, Coupled to Radiation, Electromagnetic Force, Electron, Ion, Ionized, Muon, Neutrino, plasma, Positron, Radiation Gas
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Something that is out of the ordinary. For example if in a set of 1000 two winged, two legged, one headed, (essentially normal) chickens, one of them had three wings, and two heads, that chicken would be an anomaly in the set.
- Browse Related Terms: Accelerating Universe, anomaly, Baryonic Matter, High Electron Mobility Transistor (HEMT), Homogeneous, Visible Mass
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Matter made up of elementary particles whose masses are identical to their normal-matter counterparts but whose other properties, such as electric charge, are reversed. The positron is the antimatter counterpart of an electron, with a positive charge instead of a negative charge. When an antimatter particle collides with its normal-matter counterpart, both particles are annihilated and energy is released.
- Browse Related Terms: Annihilated/annihilation, Antimatter, Antiparticle/antiquark/antielectron, Coupled to Radiation, Electromagnetic Force, Electron, Ion, Ionized, Muon, Neutrino, plasma, Positron, Radiation Gas
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For most particle types there is another particle type that has exactly the same mass but the opposite value of all other charges. This is called the antiparticle. For example, the antiparticle of an electron is a particle of positive electric charge called the positron.
- Browse Related Terms: Annihilated/annihilation, Antimatter, Antiparticle/antiquark/antielectron, Coupled to Radiation, Electromagnetic Force, Electron, Ion, Ionized, Muon, Neutrino, plasma, Positron, Radiation Gas
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The brightness of an object as it appears from the earth. The apparent luminosity does not take into account the distance from the earth to the object; the sun appears as the brightest object in the sky but is really dimmer (has less intrinsic luminosity) than many stars. We tend to use this interchangably with Brightness, Observed Brightness, and Flux at Earth.
- Browse Related Terms: Angular Size, Apparent luminosities, Constant of Proportionality, Dark Matter, Flux, Heavenly Bodies, Intrinsic Luminosity, Inverse Square, Luminosity, Main Sequence Star, Observed Brightness, Parallax, Parsec, Relative Brightness, Standard Candle, Type Ia Supernova, Variable Stars
an EUV Instrument onboard SDO.
- Browse Related Terms: Atmospheric Imaging Assembly (AIA), Convection, Core, Fission, Flare, Fusion, Radiative Zone
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The smallest unit of matter that possesses chemical properties. All atoms have the same basic structure: a nucleus containing positively charged protons with an equal number of negatively charged electrons orbiting around it. In addition to protons, most nuclei contain neutral neutrons whose mass is similar to that of protons. Each atom corresponds to a unique chemical element determined by the number of protons in its nucleus.
- Browse Related Terms: Atoms, Baryon, deuterium, Extrapolate, Fission, Isotopes, Neutron, Nucleon, Nucleus/Nuclei, Primordial Nucleosynthesis, Synthesis of Nuclei
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A display of colored light in the atmosphere, caused by collisions between charged particles from a planet’s magnetosphere and atmospheric gases near the planet’s magnetic poles. Auroras are visible on Earth as the aurora borealis, or northern lights, and the aurora australis, or southern lights.
Glowing, dancing curtains of light in the upper atmosphere of a planet. Auroras are caused by the interaction between the planet’s magnetic field and charged particles from Earth’s magnetosphere. Aurora Borealis are the Northern Lights and Aurora Australis are the Southern Lights.
- Browse Related Terms: AURORA, Auroral Oval, Coronal Mass Ejection (CME), Geosynchronous, Heliosphere, Magnetic Field, Magnetic Field Lines, Magnetic Storms and Substorms, Magnetosphere, Magnetotail, Radiation Belt, Solar System, Solar Wind, Space Weather
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The ring-shaped belts of auroral activity around the north and south magnetic poles. The auroral oval expands and contracts over a period of hours and days, depending on geomagnetic activity.
- Browse Related Terms: AURORA, Auroral Oval, Coronal Mass Ejection (CME), Geosynchronous, Heliosphere, Magnetic Field, Magnetic Field Lines, Magnetic Storms and Substorms, Magnetosphere, Magnetotail, Radiation Belt, Solar System, Solar Wind, Space Weather
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They are caused by streams of charged particles in the magnetotail that are accelerated to high energies and collide with atoms in the upper atmosphere surrounding Earth's poles. This interaction causes the beautiful and eerie looking aurora.
- Browse Related Terms: Auroral Substorms, Cosmic Ray, Electromagnetic Radiation, Electron, Energetic Particles, Ion, Ion, Ionize, Ionosphere, Magnetism, plasma, Proton
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Filling all space, e.g. the radiation from the early, hot universe.
- Browse Related Terms: Background Radiation, Closed Universe, COSMIC, Cosmic Microwave Backgroun (CMB), Cosmology, Flat Universe, Flatness Problem, Geocentric, Geometries, Heliocentric, Metastable Energy Density, Omega, Ω, Opaque to Radiation, Open Universe , Ω, Planck Time, Universe, Vacuum Energy
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Subatomic particles comprised of three quarks. Protons (comprised of two up quarks and one down quark) and neutrons (made up of two down quarks and one up quark) are examples of baryons.
- Browse Related Terms: Atoms, Baryon, deuterium, Extrapolate, Fission, Isotopes, Neutron, Nucleon, Nucleus/Nuclei, Primordial Nucleosynthesis, Synthesis of Nuclei