Observing possible free-floating planet in globular cluster
Messier 22 (artist's impression) This movie shows how the
NASA/ESA Hubble Space Telescope observes microlensing events in
the globular cluster M22. Hubble (to the left) observes a faint
background star in the Milky Way bulge (shown to the right)
through the myriad stars of M22. The movie also shows how a
possible 'free-floating' planet-sized object in M22 passes in
front of the red background star and briefly magnifies its
light. Note that the distances and sizes in this artist's
rendering have been exaggerated for the sake of clarity. Also
worth noting is that in the six actual Hubble observations the
planet-sized objects were not visible in themselves, but only
revealed their presence through their gravitational focussing of
the light from the background stars. In each of the six
microlensing events only one Hubble observation 'sampled' the
brightening of the star. This means that the estimate for the
mass of the planet-sized object will 'only' be