parallax

The parallax of a star, the apparent change of its position during the year, can be used to find the star's distance from the Earth. The star appears to change its position because it is viewed at a different angle in July and January. By measuring the angle of parallax, and knowing the diameter of the Earth's orbit, simple geometry can be used to calculate the distance to the star.

The parallax of a star, the apparent change of its position during the year, can be used to find the star's distance from the Earth. The star appears to change its position because it is viewed at a different angle in July and January. By measuring the angle of parallax, and knowing the diameter of the Earth's orbit, simple geometry can be used to calculate the distance to the star. The technique was developed by the German astronomer Friedrich Bessel.

Change in the apparent position of an object against its background when viewed from two different positions. In astronomy, nearby stars show a shift owing to parallax when viewed from different positions on the Earth's orbit around the Sun. A star's parallax is used to deduce its distance from the Earth.

Nearer bodies such as the Moon, Sun, and planets also show a parallax caused by the motion of the Earth.

parallax

In virtual reality, the distance between the viewer's left and right eyes in the virtual world.

This difference is what creates the impression of depth. Right and left images of distant objects look the same; but left and right images of nearby objects look markedly different owing to the difference of perspective. Manipulating this variable in a virtual world helps make objects look large or small.