Acronyms and abbreviations

Acronyms and abbreviations are a common sight in space weather bulletins and they can be confusing if you aren't familiar with them. On this page you will find a list of the most commonly used terms along with a short description.

ShortLongDescription
ACEAdvanced Composition ExplorerSolar and space exploration spacecraft located at the Sun-Earth L1 point. Was the primary source of real time space weather data until DSCOVR took over in 2016.
AIAAtmospheric Imaging AssemblyInstrument on the SDO spacecraft. Provides continuous full-disk observations of the solar chromosphere and corona in seven extreme ultraviolet channels.
ARActive RegionGroups of sunspots indicated with a number. Also known as a sunspot region.
BBSOBig Bear Solar ObservatorySolar observatory located in the USA that has telescopes and instruments specifically used for studying the activities and phenomena of the Sun.
CHCoronal holeArea on the Sun where magnetic field lines arch away from the Sun. This enables the solar wind to escape at a high speed and cause dark holes in the corona as seen on solar images.
CIRCo-rotating Interaction RegionTerm for the compressed boundary between the fast and slow solar wind in a high speed solar wind stream from persistent coronal holes over multiple solar rotations.
CMECoronal mass ejectionLarge cloud of solar plasma released into space due to an event on the Sun.
DSCOVRDeep Space Climate ObservatoryAn earth observation and space weather spacecraft operated by NOAA located at the Sun-Earth L1 point. It is the primary source of real time solar wind and IMF data.
DSFDisappearing Solar FilamentThe disappearance of a solar filament channel often due to a collapse or eruption.
DstDisturbance storm time indexIndicates the strength of the ring current around Earth caused by solar protons and electrons. A negative Dst value means that Earth's magnetic field is weakened. Values of -50nT and lower are generally considered as geomagnetic storm conditions.
EITExtreme ultraviolet Imaging TelescopeInstrument on the SOHO spacecraft. Provides solar imagery in four different wavelengths.
EPAMElectron, Proton, and Alpha MonitorInstrument on the ACE spacecraft. Measures a broad range of energetic particles.
ESAEuropean Space AgencyEuropean organisation dedicated to the exploration of space.
EUVExtreme ultravioletElectromagnetic radiation spanning from 124 nanometre down to 10 nanometre in the electromagnetic spectrum.
EVEExtreme Ultraviolet Variability ExperimentInstrument package on the SDO spacecraft.
GFZGeoForschungsZentrumGFZ German Research Centre for Geoscience is the national research center for Earth Sciences in Germany.
GOESGeostationary Operational Environmental SatelliteSeries of satellites in a geostationary orbit around Earth.
HFHigh frequencyTerm used to describe radio waves with a wavelength between 3 and 30 MHz.
HMIHelioseismic and Magnetic ImagerInstrument on the SDO spacecraft.
HSSHigh Speed StreamStream of solar wind at a higher than average speed. Often used to define solar wind coming from a coronal hole.
IMFInterplanetary Magnetic FieldSolar magnetic field carried by the solar wind among the planets of the Solar System.
IRISInterface Region Imaging SpectrographNASA solar observation spacecraft.
L1Lagrangian point 1Point in space between two celestial objects where the gravitational pull from the two objects is equal. Several space weather related satellites orbit the Sun-Earth L1 point.
LASCOLarge Angle and Spectrometric CoronagraphInstrument on the SOHO spacecraft used to detect and study coronal mass ejections.
LMSALLockheed Martin Solar and Astrophysics LaboratoryPart of Lockheed Martin which design, build, and operate solar and astrophysical observing instruments.
MDIMichelson Doppler ImagerInstrument on the SOHO spacecraft. It is no longer in use.
MLSOMauna Loa Solar ObservatoryA solar observatory located on the island of Hawaii in the United States of America.
NASANational Aeronautics and Space AdministrationAmerican agency responsible for the civilian space program as well as aeronautics and aerospace research.
NOAANational Oceanic and Atmospheric AdministrationAmerican scientific agency. The SWPC Forecast Center is jointly operated by NOAA and the USAF.
nTnanoTeslaA unit of measurement of the strength of a magnetic field often used in space weather.
PFUParticle flux unitA unit of flux intensity. Number of particles registered per second, per square centimeter and per steradian.
PlasMagPlasma Magnetometer Solar Weather InstrumentThree instruments on the DSCOVR spacecraft which measures the solar wind for space weather predictions.
PROBA2PRoject for OnBoard Autonomy 2ESA spacecraft that has two scientific instruments to observe the Sun.
SDOSolar Dynamics ObservatorySolar observation spacecraft operated by NASA in a geosynchronous orbit around Earth.
SISudden ImpulseA sudden impulse occurs when a coronal mass ejection from the Sun collides with Earth’s magnetosphere. This causes the ring current and the horizontal component of the magnetic field to increase. This increase appears as a sudden spike on terrestrial magnetometers.
SIDCSolar Influences Data Analysis CenterEuropean space weather services provider based in Belgium.
SIRStream Interaction RegionTerm for the compressed boundary between the fast and slow solar wind in a high speed solar wind stream.
SOHOSolar and Heliospheric ObservatorySolar observation spacecraft at the Sun-Earth L1 point.
SPESolar proton eventAlso known as a proton storm. If the intensity of protons having an energy of at least 10 MeV is at least 10 pfu at geosynchronous altitudes, then it is categorized as a SPE.
SSNSmoothed Sunspot NumberAveraged sunspot number over a specific period.
STASTEREO AheadSolar observation spacecraft operated by NASA in an orbit around the Sun. It orbits slightly faster around the Sun than Earth does.
STBSTEREO BehindSolar observation spacecraft operated by NASA in an orbit around the Sun. It orbits slightly slower around the Sun than Earth does.
SUVISolar Ultraviolet ImagerInstrument on the GOES-16 satellite. This instrument observes the Sun in six different wavelengths in extreme ultraviolet.
SWPCSpace Weather Prediction CenterService center that continually monitors and forecasts Earth's space environment. It is the official source of space weather alerts and warnings for the United States.
USAFUnited States Air ForceService branch of the United States Armed Forces. The SWPC Forecast Center is jointly operated by NOAA and the USAF.
UTCCoordinated Universal TimePrimary time standard by which the world regulates clocks and time.
XRSSolar X-ray SensorInstrument on the GOES satellites used to measure X-ray output of the Sun.
ÅÅngströmCommonly used unit of length for wavelengths of electromagnetic radiation. 1 Ångström equals 10-10 metres, 0.1 nanometres or 100 picometres.
Current data suggest that it is not possible to see aurora now at middle latitudes

Latest news

Today's space weather

Auroral activity Minor Severe
High latitude 20% 15%
Middle latitude 5% 1%
Predicted Kp max 3
Solar activity
M-class solar flare 1%
X-class solar flare 1%
Moon phase
Waning Crescent

Support SpaceWeatherLive.com!

A lot of people come to SpaceWeatherLive to follow the Sun's activity or if there is aurora to be seen, but with more traffic comes higher server costs. Consider a donation if you enjoy SpaceWeatherLive so we can keep the website online!

100%

Get instant alerts!

Space weather facts

Last X-flare:2017/09/10X8.2
Last M-flare:2017/10/20M1.0
Last geomagnetic storm:2017/12/05Kp5 (G1)
Number of spotless days in 2017:94
Current stretch spotless days:2

This day in history*

Solar flares
12006X1.5
22001M4.4
32001M3.5
42014M1.6
52014C8.6
ApG
1200647G4
2200327G1
3201520G1
4201016
5201314
*since 1994