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.

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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.

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

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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.

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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.

Read more on Nature