J
| Name | Established | Location |
| Jack C. Davis Observatory | 2002 | Carson City, Nevada, USA |
| James Clerk Maxwell Telescope | 1987 | Mauna Kea, Hawaii, USA |
| James Webb Space Telescope | 2018 (planned) | Earth–Sun L2 Lagrangian point |
| James Wylie Shepherd Observatory | 2009 | Montevallo, Alabama, USA |
| Jantar Mantar | 1727 | Jaipur, Rajasthan, India |
| Jena Observatory | 1962 | Jena, Germany |
| Jewett Observatory | 1953 | Pullman, Washington, USA |
| Jodrell Bank Observatory | 1945 | Cheshire, England |
| Jones Observatory | 1936 | Chattanooga, Tennessee, USA |
| Judson B. Coit Observatory | Boston, Massachusetts, USA |
Read more about this topic: List Of Astronomical Observatories