Definition
A unit of magnetic flux density in the centimeter-gram-second (CGS) system, equal to one maxwell of magnetic flux per square centimeter. One gauss equals 0.0001 tesla (or 100 microtesla) in the SI system.
Plain English
A measurement of how strong a magnetic field is in a given area. The smaller the number of gauss, the weaker the field; the larger the number, the stronger the field.
Context Anchor
Seen in discussions of magnetism, aircraft compasses, compass interference, and electrical equipment that may affect a compass indication.
Derivation
Named after Carl Friedrich Gauss, the 19th-century German mathematician and physicist who developed methods for measuring the Earth's magnetic field. Knowing the unit is named after a person helps explain why it is always capitalized when written as the full name and why it does not describe the thing being measured the way 'volt' or 'ohm' do not either.
Why Pilots Care
The Earth's magnetic field, which drives the magnetic compass, has a strength of roughly 0.25 to 0.65 gauss depending on location. Anything that produces a stronger local magnetic field near the compass — wiring, headsets, electronic devices — can deflect the needle and cause heading errors.
Grounding Statement
If a magnet or electrical wire is strong enough near the compass, the compass needle can be pulled away from the direction it should show.
Example Sentence 1
The Earth's magnetic field at the surface is typically less than one gauss, which is why a magnetic compass is sensitive to small disturbances from nearby electronics.
Example Sentence 2
Compass deviation checks sometimes reference gauss levels when evaluating local magnetic interference.