HIDING IN PLAIN SIGHT
Disney didn’t know what these clandestine objects
might be like, and he immediately wanted to follow up
with new observations, which are now taking place. In
late 2016, using the William Herschel Telescope in the
Canary Islands, he spied hints of a dozen newfound,
unmistakable dim galaxies.
These objects will increasingly have ample new
company, it seems. In a 2015 study, Pieter van Dokkum
of Yale University and colleagues announced they
had unearthed 47 never-before-seen, Milky Way-sized
yet extremely diffuse (spread out, so relatively dim)
galaxies in the Coma Cluster of galaxies, among the
most studied in astronomy. “This was a complete
surprise,” says van Dokkum.
It was not some mammoth new telescope that sussed
out these faint objects. The ever-larger telescopes
the astronomical community usually clamors for
are actually bad at revealing low-surface-brightness
objects. These telescopes typically use mirrors, which
capture more random, unwanted light, burying any
faintly emitting objects. Instead, van Dokkum found
his galaxies by grouping eight 400-millimeter lenses
into a contraption resembling an insect’s compound
eye. Indeed, the project’s name, Dragonfly, comes from
van Dokkum’s hobby of taking pictures of the insect.The novel Dragonfly telescope in New Mexico has helped researchers find dozens of previously
unknown ultra-diffuse galaxies. Its current setup groups 24 large camera lenses in a cluster
resembling a dragonfly eye. The lenses are actually commercially available 400mm telephoto lenses.