The angular diameter, angular size, apparent diameter, or apparent size is an angular separation (in units of angle) describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is the angular aperture (of a lens).

角直径是以 角度 做测量单位时，从一个特定的位置上观察一个物体所得到的"视直径"。 视直径只是被观测的物体在垂直观测者视线方向中心的平面上产生的透视投影的直径。 由于它是在观测者的角度下按比例的缩影，因此与物体真实的直径会有所不同。 因此，从1 pc的距离看，地球绕太阳轨道的角直径是2“，因为1 AU是地球轨道的平均半径。 从一 光年 的距离，太阳的角直径为0.03“，而 地球 的角直径为0.0003”。 角直径是以角度做测量单位时，从一个特定的位置上观察一个物体 …

May 21, 2024 · The angular diameter of an object refers to the size that it appears to be. Usually defined as an angle, it is usually in proportion to an object’s actual size divided by its distance. The angular distance from one side of something to another is often used to measure the size of objects in the night sky.

Angular diameter is the apparent size or width of an object in the sky, as measured by the angle it subtends at the observer's eye. It is a fundamental concept in astronomy that relates the physical size of an object to its distance from the observer.

Angular diameter, sometimes also called angular size, apparent size or apparent diameter is an angular measurement that describes how large a circle appears. In astronomy, it is usually used to describe the sizes of objects in the sky as seen from an observer on Earth and is typically used for the Moon, the planets and other extended objects ...

The apparent size or angular diameter refers to an object’s size as viewed from a specified place. It is the object’s visual diameter as determined from an angle. This is known as a visual angle. It is the visual diameter perspective projection diameter of an object.

The angular diameter is proportional to the actual diameter divided by its distance. If any two of these quantities are known, the third can be determined. For example if an object is observed to have an apparent diameter of 1 arc second and is known to be at a distance of 5000 light years, it can be determined that the actual diameter is .02 ...

Angular diameter is a measure of how large something "appears to be". An object's angular diameter α is proportional to its size (linear diameter) and inversely proportional to how far away it is (distance). An object with linear diameter of 2 units and a distance of 40 units has an angular diameter of 10313.3 arcsec (which is almost 3°).

The angular diameter, angular size, apparent diameter, or apparent size is an angular measurement describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is the angular aperture (of a lens).

The angular diameter of an object as seen from a given position is the diameter measured as an angle. It satisfies the formula δ = arctan ⁡ ( d i a m e t e r / d i s t a n c e ) {\displaystyle \delta = \arctan (diameter/ distance)} .