| Pleiades observatory | Canadá | Mandeville | — |
| Plessisville observatory | Canadá | Plessisville | — |
| Plomer observatory | Argentina | Buenos Aires | — |
| Plonsk observatory | Polonia | Płońsk | — |
| Plzeň observatory and planetarium | República Checa | Pilsen | 325 m |
| Po Leung Kuk observatory | República Popular China | Tuen Mun | — |
 Polaris Csillagvizsgáló | Hungría | Óbuda-Békásmegyer | — |
| Polaris observatory | Hungría | Budapest | — |
| Polino astronomical observatory | Italia | Polino | — |
| Polonia Observatory | Chile | San Pedro de Atacama | — |
| Polop observatory | España | Polop | — |
| Pommier observatory | Francia | Chapdes-Beaufort | — |
| Ponferrada observatory | España | Camponaraya | — |
| Pont-à-Mousson Observatory | Francia | Pont-à-Mousson | — |
| Ponte Uso observatory | Italia | cementerio de Sogliano al Rubicone | — |
| Popocatépetl Volcano Observatory | México | — | — |
| Popovich Observatory | Ucrania | Ivanivka | — |
| Popular Observatory in Belgrade | Serbia | Belgrado | — |
| Port Alfred Magnetic Observatory | French Southern and Antarctic Lands | — | — |
| Port Stanley Magnetic Observatory | Islas Malvinas | — | 130 m |
| Port-aux-Francais Magnetic Observatory | French Southern and Antarctic Lands | — | — |
| Portage Lake Observatory | Estados Unidos | Míchigan | — |
| Portland Bird Observatory | Reino Unido | — | — |
| Posadas Observatory | España | Posadas | — |
| Possum Observatory | Nueva Zelanda | Gisborne | — |
| Poste-de-la-Baleine Magnetic Observatory | Canadá | — | — |
| Pousada dos Anoes Observatory | Brasil | São João d'Aliança | — |
| Povegliano Veronese observatory | Italia | Povegliano Veronese | — |
| Poway Valley observatory | Estados Unidos | Poway | — |
| Powell Observatory | Estados Unidos | Kansas | — |
 Poznań Observatory | Polonia | Poznań | — |
| Prairie Grass Observatory | Estados Unidos | Mulberry | — |
| Prairie Observatory | Estados Unidos | — | — |
 Prenzlau observatory | Alemania | Prenzlau | — |
| Preston Hills observatory | Estados Unidos | Celina | — |
 PRIMA | — | — | — |
 Prince Edward Point National Wildlife Area | Canadá | Condado de Prince Edward | — |
 Principia Astronomical Observatory | Estados Unidos | Misuri | — |
| Principia observatory | España | Málaga | — |
 Prishtina Observatory | Kosovo | Pristina | — |
| Promiod observatory | Italia | Châtillon | — |
| PROMPT observatory | Australia | Coonabarabran | — |
 Provencal Baronnies Observatory | Francia | Moydans | — |
| Proyecto HATNet | — | — | — |
| Prude Ranch observatory | Estados Unidos | Texas | — |
| PSU Greenbush Observatory | Estados Unidos | Greenbush | — |
 Public Observatory Mainz | Alemania | Distrito Centro | 94 m |
 Public Observatory Mercury | Países Bajos | Dordrecht | — |