  Photonic lanterns (PLs) are tapered waveguides that gradually transition from
a multi-mode fiber geometry to a bundle of single-mode fibers. In astronomical
applications, PLs can efficiently couple multi-mode telescope light into a
multi-mode fiber entrance and convert it into multiple single-mode beams. The
output beams are highly stable and suitable for feeding into high-resolution
spectrographs or photonic chip beam combiners. For instance, by using relative
intensities in the output cores as a function of wavelength, PLs can enable
spectroastrometry. In addition, by interfering beams in the output cores with a
beam combiner in the backend, PLs can be used for high-throughput
interferometric imaging. When used on an Extremely Large Telescope (ELT), with
its increased sensitivity and angular resolution, the imaging and
spectroastrometric capabilities of PLs will be extended to higher contrast and
smaller angular scales. We study the potential spectroastrometry and imaging
science cases of PLs on ELTs, including study of exomoons, broad-line regions
of quasars, and inner circumstellar disks.
