The SR-91 Aurora is an alleged hypersonic spy plane developed in the 1980s or the 1990s, but currently there is no hard evidence to support its existence, even though many people have reported sightings.
The term "Aurora" originates from a blacked out report where "Aurora" was left available, and for which the visible content matched expectations of such a spyplane. The plane is reportedly the successor to the Lockheed SR-71 Blackbird.
The capabilities of the plane differ depending on the source. The capabilities widely vary by source, from subsonic, through hypersonic to suborbital. Photographs of the "string-of-pearls" jet trail are frequently associated with this spyplane in the aviation and military popular press. Several programs may also be conflated with the various versions of Aurora, including the putative CIA spaceplane, "Blackstar", claimed to exist by AW&ST, or TR-3A Black Manta, claimed to exist by AW&ST. The putative hypersonic Aurora is referred to as the SR-91 Aurora Alien Craft.