  CubeSats are small satellites built in standard sizes and form factors, which
have been growing in popularity but have thus far been largely ignored within
the field of astronomy. When deployed as space-based telescopes, they enable
science experiments not possible with existing or planned large space missions,
filling several key gaps in astronomical research. Unlike expensive and highly
sought-after space telescopes like the Hubble Space Telescope (HST), whose time
must be shared among many instruments and science programs, CubeSats can
monitor sources for weeks or months at time, and at wavelengths not accessible
from the ground such as the ultraviolet (UV), far-infrared (far-IR) and
low-frequency radio. Science cases for CubeSats being developed now include a
wide variety of astrophysical experiments, including exoplanets, stars, black
holes and radio transients. Achieving high-impact astronomical research with
CubeSats is becoming increasingly feasible with advances in technologies such
as precision pointing, compact sensitive detectors, and the miniaturisation of
propulsion systems if needed. CubeSats may also pair with the large space- and
ground-based telescopes to provide complementary data to better explain the
physical processes observed.
