The milliarcsecond is a highly precise unit of angular resolution used to measure tiny apparent distances on the celestial sphere. It equals 1/3,600,000 of a degree. Astronomers use it to quantify stellar parallax, proper motion, and the resolving power of space telescopes or very-long-baseline interferometry arrays.
Heard on the job
The astrometry data shows a parallax shift of just three milliarcseconds over the six-month observation window.
Insider tip
A milliarcsecond is roughly equivalent to the apparent width of a dime sitting on top of the Eiffel Tower as seen from New York.
Also heard as
- mas