 Perrott's Folly | Reino Unido | Birmingham | — |
 Perth Observatory | Australia | City of Kalamunda | 428 m |
| Peschiera del Garda observatory | Italia | Peschiera del Garda | — |
| PESCOPE observatory | Sudáfrica | Puerto Elizabeth | — |
 Peterberg Observatory | Alemania | Nohfelden | 576 m |
| Petit Jean Mountain observatory | Estados Unidos | Petit Jean Mountain | — |
| Petit Sant Feliu observatory | España | San Feliú de Llobregat | — |
| Peverell observatory | Reino Unido | City of Plymouth | — |
| PGC observatory | España | Fregenal de la Sierra | — |
 Philippine Institute of Volcanology and Seismology | Filipinas | — | — |
| Phillips Academy Observatory | Estados Unidos | Andover | — |
| Phoebe Waterman Haas Public Observatory | Estados Unidos | Washington D. C. | — |
| Phuthuy Magnetic Observatory | Vietnam | — | — |
| Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center | Suiza | Davos | — |
| Piazzano Observatory | Italia | Empoli | — |
 Pic du Midi Observatory | Francia | Bagnères-de-Bigorre | 2.877 m |
| Picard observatory | Austria | — | — |
 Pico dos Dias Observatory | Brasil | Brasópolis | 1.864 m |
| Piconcillo observatory | España | Piconcillo | — |
| Picoto Observatory | Portugal | Freguesia de Carreira | — |
| Piera Observatory | España | Piera | — |
 Pierre Kauffman Radio Observatory | Brasil | São Paulo | 819 m |
| Pieta observatory | Malta | Pietà | — |
| Pieterse Planetarium | — | — | — |
| Pilar Magnetic Observatory | Argentina | — | — |
| Pin Oak Observatory | Estados Unidos | Fort Madison | — |
 Pine Mountain Observatory | Estados Unidos | Oregón | — |
| Pineapple Observatory | Estados Unidos | Frederick | — |
| Pinsoro Observatory | España | Pinsoro | — |
| Pinto Valley observatory | Estados Unidos | San Bernardino County | — |
 Piombino Observatory | Italia | Piombino | 55 m |
| Plana Geodetic Observatory | Bulgaria | Plana | 1.300 m |
 Planck | — | — | — |
| Planetario de Serón-Almería | España | Serón | — |
| Planetarium de Vaulx-en-Velin Observatory | Francia | Vaulx-en-Velin | — |
 Planetarium Halle-Kanena | Alemania | Halle | — |
 Planetarium Negara | Malasia | Kuala Lumpur | — |
 Planetarium České Budějovice | República Checa | České Budějovice 7 | — |
 Planetary astronomical observatory of Anzi | Italia | Anzi | — |
 Planetology and Astrophysics Institute of Grenoble | Francia | Grenoble | — |
 Planetron | Países Bajos | Westerveld | — |
| Platanus Observatory | Polonia | Lusówko | — |
| Plateau Observatory | — | Región del Tratado Antártico | — |
 PLATO | — | — | — |
| Platteville Atmospheric Observatory | Estados Unidos | Colorado | — |
| Pleasant Groves Observatory | Estados Unidos | Pleasant Groves | — |
| Pleasanton observatory | Estados Unidos | Pleasanton | — |
| Pleiade Observatory | Italia | Pescantina | 90 m |