Reference articles on history, science, culture and more
Surprise meSurprise meSubscribe
Encyclopedia

Sun sensor

Spacecraft instrument that senses the direction to the Sun

Wikipedia contributorsAdapted for Fathomly · View authors
1 min read
Source updated August 11, 2026
Image credit is listed at the end of this article.

A Sun sensor is a navigational instrument used by spacecraft to detect the position of the Sun. Sun sensors are used for attitude control, solar array pointing, gyro updating, and fail-safe recovery.

In addition to spacecraft, Sun sensors find use in ground-based weather stations and Sun-tracking systems, and aerial vehicles including balloons and UAVs.

01Mechanism

There are various types of Sun sensors, which differ in their technology and performance characteristics. Sun presence sensors provide a binary output, indicating when the Sun is within the sensor's field of view. Analog and digital Sun sensors, in contrast, indicate the angle of the Sun by continuous and discrete signal outputs, respectively.

In typical Sun sensors, a thin slit at the top of a rectangular chamber allows a line of light to fall on an array of photodetector cells at the bottom of the chamber. A voltage is induced in these cells, which is registered electronically. By orienting two sensors perpendicular to each other, the direction of the Sun can be fully determined.

Often, multiple sensors will share processing electronics.

02Criteria

There are a number of design and performance criteria which dictate the selection of a Sun sensor model:

Watch videos about Sun sensorExplainers and documentaries on YouTube (opens in a new tab)

Sources and credits

This article is adapted from the Wikipedia article “Sun sensor”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

Images, from Wikimedia Commons:

Fathomly is not affiliated with or endorsed by the Wikimedia Foundation. Spotted a problem? Tell us.

Continue exploring

Related topics

Celestial navigation

Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the surface of the Earth without relying solely on estimated positional calculations, commonly known as dead reckoning. Celestial navigation is performed without using satellite navigation or other similar modern electronic or digital positioning means.

Spacecraft attitude determination and control

In astronautics, spacecraft attitude control is the process of controlling the orientation of a spacecraft with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle attitude requires actuators to apply the torques needed to orient the vehicle to a desired attitude, and algorithms to command the actuators based on the current attitude and specification of a desired attitude.

Star tracker

A star tracker is an optical device that measures the positions of stars using photocells or a camera. As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may be used to determine the orientation of the spacecraft with respect to the stars.