Small Angles

Calculation of very small angles, such as those encountered in astronomy and nuclear physics when observing objects. The angular size depends on the size of the object being observed and its distance from the observer. For very small objects or at great distances, the resulting angle becomes extremely small. We cannot see atoms and most molecules because they are too small. Nevertheless, they do have a physical size and thus subtend a certain angular size. Planets and stars, on the other hand, are very large, but unless they are within our solar system, they are so distant that their angular size and apparent size are also are tiny.
Please select the appropriate units for the true size (the diameter measured perpendicular to the line of sight) and the distance, or specify an application area to select the suitable units. The result is displayed as a decimal fraction of a degree and of an arcsecond (the latter being one 3600th of a degree), rounded to up to 15 decimal places.

Very small angles

True size:		fmpma0ÅnmμmmmcmmkmmilesMoon-⌀Earth-⌀Sun-⌀AUlypc
Distance:		fmpma0ÅnmμmmmcmmkmmilesMoon-⌀Earth-⌀Sun-⌀AUlypc
Angular size:	°
in arc seconds:	″

 

Standard units:
  |         |  

Examples: 1. The star Sirius has a diameter of approximately 1.7 times that of the Sun and is 8.6 light-years away from us. This gives it an angular size of 0.006 arcseconds.
2. A water molecule has a size of 150 picometers (pm) or 1.5 Ångströms. Its angular size from a distance of one meter is therefore 0.00003 arcseconds.

In addition to the SI unit of length, the meter (m) and its derivatives ranging from the femtometer (fm) to the kilometer (km), the following units of length are also available:
a₀: Bohr radius; corresponds roughly to the radius of the electron's orbit in the Bohr model of the hydrogen atom
Å: one ten-millionth of a millimeter, a typical scale for atoms and chemical bonds
miles: international mile (statute mile); 1609.344 meters
Moon-⌀: average Moon diameter; 3474.8 kilometers
Earth-⌀: average Earth diameter; 12742 kilometers
Sun-⌀:: average Sun diameter; 1392679 kilometers
AU: astronomical units; average distance from Earth to the Sun; 149597870.7 km
ly: light-years; distance light travels in a vacuum in one year; 9460730472580.8 km
pc: parsec (parallax-seconds); distance at which one astronomical unit subtends an angle of 1 arcsecond; 3.26156 ly

Zuletzt aktualisiert am 23.07.2026. Autor: Jürgen Kummer

Rechner für Sichtbarkeit | Alle Angaben ohne Gewähr

© Jumk.de Webprojekte | Rechneronline | Impressum & Datenschutz | English: Angular Diameter

---