Field of viewThe field of view (FOV) is the angular extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors, it is a solid angle through which a detector is sensitive to electromagnetic radiation. It is further relevant in photography. In the context of human and primate vision, the term "field of view" is typically only used in the sense of a restriction to what is visible by external apparatus, like when wearing spectacles or virtual reality goggles.
NavagrahaThe navagraha are nine heavenly bodies and deities that influence human life on Earth according to Hinduism and Hindu astrology. The term is derived from nava (नव "nine") and graha (ग्रह "planet, seizing, laying hold of, holding"). The nine parts of the navagraha are the Sun, Moon, planets Mercury, Venus, Mars, Jupiter and Saturn, and the two nodes of the Moon. The term planet was applied originally only to the five planets known (i.e., visible to the naked eye) and excluded the Earth.
Surface brightnessIn astronomy, surface brightness (SB) quantifies the apparent brightness or flux density per unit angular area of a spatially extended object such as a galaxy or nebula, or of the night sky background. An object's surface brightness depends on its surface luminosity density, i.e., its luminosity emitted per unit surface area. In visible and infrared astronomy, surface brightness is often quoted on a magnitude scale, in magnitudes per square arcsecond (MPSAS) in a particular filter band or photometric system.
