Arcsecond | COSMOS - Centre For Astrophysics And Supercomputing

Home » What Is An Arc Second » Arcsecond | COSMOS - Centre For Astrophysics And Supercomputing

Maybe your like

Cosmos

  • Swinburne
  • Centre for Astrophysics and Supercomputing
  • Swinburne Astronomy Online
Search

Index

ABCDE
FGHIJ
KLMNO
PQRST
UVWXY
ZAll

COSMOS - The SAO Encyclopedia of Astronomy › A

Arcsecond

An arcsecond (denoted by the symbol “) is an anglular measurement equal to 1/3600 of a degree or 1/60 of an arcminute. There are also 206,264.5” in a radian, so that 1” = 4.848 ×10-6 radians.

For observations from the Earth’s surface, turbulence in the Earth’s atmosphere causes point sources (such as stars) to be smeared out and twinkle. This is known as seeing. Under the best atmospheric conditions, point sources will be smeared out to an angular diameter of about 0.5”.

The trigonometric parallax of an object at a distance of 1 parsec is 1”, however, there are no known stars beyond the Solar System with parallaxes greater than 1”. The nearest star to the Sun, Alpha Centauri (actually a triple star system), is about 1.3 parsec away with a parallax of 0.75”.

A milliarcsecond is 10-3 arcseconds.

A microarcsecond (μas) is 10-6 arcseconds.

Study Astronomy Online at Swinburne University All material is © Swinburne University of Technology except where indicated.

Tag » What Is An Arc Second