The apparent diameter of a planet or other celestial object measured by the angle which it subtends at the point of observation.
〔天文〕角直径
Example sentencesExamples
Its angular diameter would be only 1.4 arc-seconds, though - less than that of Neptune as seen from Earth - so it would require serious magnification to clearly show a disk.
When the Earth is at its mean distance from the Sun, the solar orb has an apparent angular diameter of 0.533 degrees.
Its optical angular diameter is about 13 arcminutes, but viewed at radio wavelength at the frequency of neutral hydrogen, it extends considerably more than the angular diameter of the Moon.
Nevertheless it seems a staggering coincidence that the angular diameters of the Sun and the Moon are so similar.
The asteroid's maximum angular diameter is only 2 to 4 arcseconds, which means it will be a starlike point of light in all but the very largest telescopes.
It happens that the angular diameters of the Sun and the Moon as viewed from the Earth are about the same.
Both, therefore, appear to have an angular diameter of about 1/2 degree as seen from Earth.
Analysis of the contrast between the fringes revealed the angular diameter of the star to be 1.9 0.05 milliarcseconds.
He estimated that its angular diameter was as small as one minute twelve arc seconds as opposed to the four or six arc minutes suggested by Kepler and by Tycho Brahe and by others.
Definition of angular diameter in US English:
angular diameter
noun
Astronomy
The apparent diameter of a planet or other celestial object measured by the angle which it subtends at the point of observation.
〔天文〕角直径
Example sentencesExamples
Analysis of the contrast between the fringes revealed the angular diameter of the star to be 1.9 0.05 milliarcseconds.
When the Earth is at its mean distance from the Sun, the solar orb has an apparent angular diameter of 0.533 degrees.
Its angular diameter would be only 1.4 arc-seconds, though - less than that of Neptune as seen from Earth - so it would require serious magnification to clearly show a disk.
Its optical angular diameter is about 13 arcminutes, but viewed at radio wavelength at the frequency of neutral hydrogen, it extends considerably more than the angular diameter of the Moon.
The asteroid's maximum angular diameter is only 2 to 4 arcseconds, which means it will be a starlike point of light in all but the very largest telescopes.
Both, therefore, appear to have an angular diameter of about 1/2 degree as seen from Earth.
Nevertheless it seems a staggering coincidence that the angular diameters of the Sun and the Moon are so similar.
He estimated that its angular diameter was as small as one minute twelve arc seconds as opposed to the four or six arc minutes suggested by Kepler and by Tycho Brahe and by others.
It happens that the angular diameters of the Sun and the Moon as viewed from the Earth are about the same.