In laboratories on Earth, Bose-Einstein condensates are created by cooling a cloud of atoms to billionths of a kelvin. The atoms lose their individuality and merge into a single quantum wave that behaves as one entity. But in space, such conditions are not needed: gravity itself creates deep wells where matter compresses and cools into a state of quantum fog.

This fog condenses in a variety of places. Inside a neutron star, where density reaches nuclear levels, short-lived kaon particles could form a condensate that softens the matter and reduces the maximum stellar mass from 2.16 to 1.97 solar masses. Around rotating black holes, superradiance, the amplification of waves by rotational energy, can grow a boson cloud that emits continuous gravitational waves. And in the centers of dwarf galaxies, ultralight axions, dark matter candidates, form a stable quantum clump with a radius of about 160 parsecs.

Gravity is not just a backdrop but an active player. It suppresses condensation: the critical temperature shifts by an amount of order GM/rc², which is noticeable near compact objects. For axionic dark matter, a solitonic core emerges that naturally smooths the steep density rise toward galactic centers, the 'core-cusp' problem unresolved in the standard cold dark matter model. This turns BECs from an exotic curiosity into a working tool for astrophysics.

The prospects are broad. Numerical simulations of neutron star mergers with condensate cores could provide templates for next-generation gravitational wave detectors. The nonlinear dynamics of condensates in turbulent dark matter flows and many-body effects near black holes remain open questions. The quantum fog condensing in the gravitational wells of the Universe is only beginning to reveal its secrets.