| Paaliaq | A moon of Saturn was discovered by the Brett Gladman in, 2000. Paaliaq also is designated as "Saturn XX" and "S/2000 S2". The moon was named after a Giant from Inuit mythology. | |
| Pan | A innermost moon of Saturn was discovered by Mark Showalter (Voyager 2) in 1990. Pan also is designated as "Saturn XVIII" and "S/1981 S13". Named for the Greek god Pan who watches over shepards and flocks. | |
| Pandora | A moon of Saturn was discovered by Steward Collins and D. Carlson (Voyager 1) in 1980. Pandora also is designated as "Saturn XVII" and "S/1980 S26". In Greek mythology, Pandora was the first woman created by Zeus to bring evil in the world tas punishment for the theft of fire. | |
| Parallax | The apparent motion of an object caused by viewing the object from different locations. | |
| Parfocal | A group of eyepieces whose focal points in the focal plane is the same so that when exchanging eyepiece re-focusing would not be required. | |
| Parsec | A measurement of distance equal to the distance of a star would shout 1 arc second of parallax or 3.26 light-years. | |
| Pascal Moon | The name of the Full Moon usually in April. Specifically the first Full Moon after Ecclesiastical Vernal Equinox (March 21). Sometimes called the "Egg Moon," the "Easter Moon" or the "Grass Moon." | |
| Pasiphae | A moon of Jupiter was discovered by Philibert Melotte on January 27, 1908. Pasiphae is also designated as "Jupiter XVIII". In Greek mythology, Pasiphae was the wife of Minos and mother of the Minotaur. | |
| Pasithee | A moon of Jupiter was discovered by Scott Sheppard and team in 2001. Pasithee is also designated as "Jupiter XXXVIII" and "S/2001 J6". In Greek mythology, Pasithea or Pasithee is the eldest of the Graces, who married Hypnos the god of sleep. | |
| Pavo | The constellation "The Peacock" | |
| Pegasus | The constellation "The Winged Horse" | |
| Perdita | A moon of Uranus was discovered by Stephen P. Synnott (Voyager 2) on January 18, 1986. Perdita is also designated as "Uranus XXV" and "S/1986 U10.". Perdita is the daughter of Leontes and Hermione in William Shakespeare's play The Winter's Tale. | |
Perihelion  Perihelion of Earth |
The Perihelion occurs when a planet is closest to the Sun during its slightly elliptical orbit. | |
| Perseus | The constellation "The Hero" | |
| Phobos | The larger and innermost of the planet Mars' two moons. Phobos was discovered by Asaph Hall on August 17, 1877. In Greek mythology, Phobos was the son of Ares (Mars) and Aphrodite (Venus) and was the personification of "Fear". | |
| Phoebe | A moon of Saturn was discovered by William Pickering on March 17, 1898. Phoebe was the first satellite to be discovered photographically. Phoebe also is designated as "Saturn IX". In Greek mythology, Phoebe was a Titan. | |
| Phoenix | The constellation "The Phoenix" | |
| Photocathode | A cathode which emits electrons when exposed to light. | |
| Photographic Plate | Photograph of the sky taken on a light-sensitive emulsion atop a piece of glass. | |
| Photomultiplier Tube | An instrument in which electrons released by photoelectric emission are multiplied in successive stages by dynodes which produce secondary emission in order to amplify an image to see smaller details. | |
| Photosphere | The luminous surface layer of the Sun. | |
| Pictor | The constellation "The Painter" | |
| Pier | A usually pemenant base for a telescope mount featuring by a single erect pillar. | |
| Piggyback Bracket | A bracket that mounts onto a telescope optical tube assembly which allows a camera or another scope to piggyback onto the telescope system. | |
| Piggyback Photography | Wide-Field astrophotography where the camera is piggybacked on top of a telescope. | |
| Pink Moon | The name of the Full Moon usually in April. Specifically the first Full Moon after Ecclesiastical Vernal Equinox (March 21). Sometimes called the "Pascal Moon," "Egg Moon," the "Easter Moon" or the "Grass Moon." | |
| Pisces | Pisces (The Fish) is a zodiacal constellation, that is, it lies across the ecliptic, an imaginary line across the sky that the Sun, Moon and all the planets except Pluto seem to move along. Pisces contains a spiral galaxy known as Messier 74 (M74). Pisces is usually represented as two fish tied together by a long string. | |
| Pisces Austrinus | The constellation "The Southern Fish" | |
| Pixel | One square of a grid into which the light-sensitive component of a CCD is divided. | |
| Planetary Filters | Color Filters used to enhance light and dark features of the moon and planets. | |
| Planisphere | A circular star chart which rotates inside a masked envelope with a oval display cut into it. By dialing the current time to the current date on the outer index of the disk the current stars and constellations for the time and date are displayed in the oval. there is some distortion in the view. | |
| Plossl | A popular, high-performance eyepiece employing two doublet lenses. | |
| Pluto | Pluto is usually the ninth planet from the Sun although it is sometimes 8th when Pluto moves within Neptune's orbit. Pluto's diameter is 2,300 km and takes 249 years to orbit the Sun. Pluto is named after the Roman god of the underworld. Pluto was discovered on February 18, 1930 by Clyde Tombaugh. | |
| Plutonian | Having to do with the planet Pluto. | |
| Polar Alignment | The alignment of an equatorial mounting's polar axis parallel with the axis of rotation of the Earth. | |
| Polar Axis | The axis of an equatorial mounting intended for alignment with the North Celestial Pole and thus with the rotational axis of the Earth, enabling a telescope to track celestial objects without rotating the field of view. | |
| Polarizing Filters | A Neutral Density Filter using polarized glass. Some polarizing filters use two polar filters that can be rotated to produce variable amounts of filtering. | |
| Polydeuces | A moon of Saturn was discovered by the Cassini Imaging Team on October 24, 2004. Polydeuces also is designated as "Saturn XXXIV" and "S/2004 S5". In Greek mythology, Polydeuces, also known as Pollux, was the twin brother Castor | |
| Porro Prism | A erecting prism system that corrects the inverted image of binoculars and refracting and catadioptric telescopes by simply rotating the field 180 degrees and leaving its left-to-right image orientation intact. | |
| Portia | A moon of Uranus was discovered by Stephen P. Synnott (Voyager 2) on January 3, 1986. Portia is also designated as "Uranus XII" and "S/1986 U1". Portia is the heroine of William Shakespeare's play The Merchant of Venice. | |
| Positive Lens Projection Photography | Projection photography in which a positive lens magnifies the image formed by the telescope objective and projects the image into the camera. Also called Eyepiece Projection Photography. | |
| Power | A measurement of magnification. Power can be calculated by dividing the focal length of a optical system (like a telescope) by the focal length of an eyepiece. | |
| Praxidike | A moon of Jupiter was discovered by Scott Sheppard and team in 2000. Praxidike is also designated as "Jupiter XXVII" and "S/2000 J7". In Greek mythology, Praxidike was the goddess of punishment. | |
| Precession | The slow, conical motion of the Earth's axis of rotation caused by the gravitational pull of the Moon and Sun on Earth's equator. | |
| Primary Mirror | The large mirror used in reflecting or catadioprtric telescope designs. | |
| Prime Focus Photography | A photographic technique that substitutes the telescope objective for the lens of the camera, focusing the image formed by the objective directly onto the film. Also called Direct Objective Photography. | |
| Prism | Wedge-shaped piece of glass used to disperse light into a spectrum. | |
| Prometheus | A moon of Saturn was discovered by Steward Collins and D. Carlson (Voyager 1) in 1980. Prometheus also is designated as "Saturn XVI" and "S/1980 S27". In Greek mythology, Prometheus was a Titan who stole fire from the gods and gave it to mortal men. | |
| Prominences | See Solar Prominences. | |
| Proper Motion | Change in the location of a star on the sky. | |
| Prospero | A moon of Uranus was discovered by Matthew J. Holman, John J. Kavelaars, Brett J. Gladman, Jean-Marc Petit, and Hans Scholl on July 18, 1999. Prospero is also designated as "Uranus XVIII" and "S/1999 U3". Prospero is the sorcerer in William Shakespeare's play The Tempest. | |
| Proteus | The second-largest, moon of Neptune was discovered by Stephen P. Synnott on June 16, 1989. Proteus is also designated as "Neptune VIII" and "S/19989 N1". In Greek mythology, Proteus was the shape-changing sea god. | |
| Psamathe | A moon of Neptune was discovered by Scott S. Sheppard, David C. Jewitt and J. Kleyna in 2003. Psamathe is also designated as "Neptune X" and "S/2003 N1". In Greek mythology, Psamathe was a nereid and was married to king Proteus of Egypt. | |
| Puck | A moon of Uranus was discovered by Stephen P. Synnott (Voyager 2) on December 30, 1985. Puck is also designated as "Uranus XV" and "S/1985 U1". Puck is a mischievous sprite who appears in Shakespeare's play A Midsummer Night's Dream. | |
| Puppis | The constellation "The Poop Deck" | |
| Pyxis | The constellation "The Compass" | |
| The "Stars and Scopes" Glossary was compiled by Peter Ue from various sources on the internet. I tried to correct and edit as much as possible, but I can make no claim or warrenty to the information here. If you find any errors just contact me and I'll try to fix it - Thanks , Peter. |
