The Jiangmen Underground Neutrino Observatory (JUNO) is a medium-baseline reactor neutrino experiment under construction in China. It will be the largest ever built liquid scintillator detector for neutrino physics. It will be sensitive to various astrophysical neutrino sources, including solar neutrinos, the diffuse supernova neutrino background, pre-supernova neutrinos and the all-flavor neutrino flux from a Galactic core-collapse supernova (CCSN) with high statistics. For maximizing the physics reach of JUNO as a neutrino telescope, two trigger systems will operate to search for a transient astrophysical signal in real time: a dedicated multi-messenger trigger system and a Prompt CCSN monitor, the latter embedded in the global trigger system. This talk will report the expected performance of JUNO for the detection of the different neutrino fluxes from the mentioned sources, describing its dedicated trigger schemes and highlighting the unique contributions it will bring to the understanding of the various astrophysical phenomena.