Astronomy & Space
Intermediate

Angular Size

Apparent angular size of an object (small-angle).

Formula

θ=dD\theta = \frac{d}{D}

Variables

dActual size
DDistance

Example

Sun and Moon look equal in size

Did You Know?

By pure coincidence the Sun and Moon have nearly the same angular size, which is why total eclipses are so perfect.

observation

Share this formula

More in Astronomy & Space

View all

Escape Velocity

Intermediate

Minimum speed to escape a body's gravity.

Orbital Velocity

Intermediate

Speed of a circular orbit.

Kepler's Third Law

Advanced

Relates orbital period to semi-major axis.

Schwarzschild Radius

Advanced

Event horizon radius of a black hole.

Hubble's Law

Advanced

Recession velocity of galaxies with distance.

Stefan–Boltzmann Law

Advanced

Luminosity of a star from radius and temperature.