angular diameter

noun

, Astronomy.

1. the angle that the apparent diameter of a celestial object subtends at the eye of the observer.

Word History and Origins

Origin of angular diameter¹

First recorded in 1870–75

Example Sentences

The telescope spent 10 days of exposure time staring at a tiny patch of the sky in the Ursa Major constellation, just one-thirteenth of the moon’s angular diameter.

From Scientific American

With an angular diameter of about 0.14 degrees Phobos doesn't blot the whole Sun out - but it definitely makes a fair stab at it.

From Scientific American

It is one-fifteenth the angular diameter of the full Moon as seen from Earth.

From Literature

In the predawn sky, Mercury appears about twice the angular diameter of Uranus, so will look like a tiny half-moon that is 8 arc seconds across in a large telescope.

From Scientific American

Even with clear skies and a good telescope, turbulence smears out details smaller than about 1 arcsecond in angular diameter — good enough to look up at the Hubble telescope, which is similar in size and altitude to spy satellites, and tell that it is a cylinder, but not much else.

From Nature