Angular Size Calculator
Calculate the angular size of celestial objects
About this calculator
An Angular Size Calculator determines how large celestial objects appear from Earth by calculating their angular diameter in degrees, arcminutes, or arcseconds. This tool is essential for astronomers, astrophotographers, and stargazers who need to understand the apparent size of planets, stars, galaxies, and other cosmic objects. By inputting the object's actual diameter and distance from Earth, you can calculate its angular size, which helps in telescope selection, observation planning, and understanding the scale of astronomical phenomena in our night sky.
How to use
Enter the actual diameter of the celestial object you want to observe (in kilometers or miles). Input the distance from Earth to that object (in astronomical units, light-years, or kilometers). Select your preferred units for the result (degrees, arcminutes, or arcseconds). The calculator will instantly display the angular size, showing how large the object appears from Earth.
Frequently asked questions
What is angular size in astronomy?
Angular size is the apparent diameter of a celestial object as seen from Earth, measured in degrees, arcminutes, or arcseconds rather than actual physical dimensions.
Why does the Moon appear larger than distant stars?
The Moon appears larger because angular size depends on both actual size and distance. The Moon is much closer to Earth than stars.
What units are commonly used for angular measurements?
Angular size is measured in degrees (°), arcminutes ('), and arcseconds ("). One degree equals 60 arcminutes, and one arcminute equals 60 arcseconds.