The Atacama Large Millimeter/submillimeter
Array (ALMA) probes the sky for radio waves
from the Milky Way (shown here) and beyond.
But even ALMA can’t see the supermassive
black hole shrouded in ionized gas at our
galaxy’s center, Sagittarius A*. “Any images
we make are fuzzy, as though you’re looking
at a small light through frosted glass,” says
Shep Doeleman of the Harvard-Smithsonian
Center for Astrophysics. So astronomers are
linking 11 telescopes around the world into
one Event Horizon Telescope (EHT), named
for the spacetime boundary where the black
hole’s gravity prevents the escape of light
and matter. When an upgraded ALMA joins
in 2015, it should make EHT 10 times more
sensitive and may help bring Sagittarius A*’s
shadowy edge into focus. ALEXANDRA OSSOLA
