10 DISCOVERMAGAZINE.COM
MAP: RETO STÖCKLI,
NASA EARTH OBSERVATORY.
INSETS, CLOCKWISE
FROM TOP:
GOPAL NARAYANAN;
NIMESH PATEL;
EWAN O’SULLIVAN;
DANIEL LUONG-VAN;
IZTOK BONCINA/ESO;
ALMA (ESO/NAOJ/NRAO),
C. PADILLA; SEAN GOEBEL;
JOINT ASTRONOMY CENTRE;
UNIVERSITY OF ARIZONA/
DAVID HARVEYas long as it comes not from the immediate vicinity of the black
hole, but just outside it,” Özel says. “When the light falls into the
event horizon, that part is dark.”
YEARS OF STITCHING TOGETHER DATA
The image, and resulting data, has helped astronomers learn
more about black holes in general, and this one in particular,
making that two-year wait more than worthwhile. Part of the
reason for the delay was simply the logistics of gathering so many
observations. Each observatory collects data over a narrow range
of wavelengths, resulting in massive amounts of information —
the equivalent of up to 5,000 years of mp3 music files. That’s too
much to just email someone. Researchers instead had to find ways
to physically move that data around. For instance, to transport
the information out of the South Pole Telescope in Antarctica,
scientists had to wait until spring, when planes finally started
flying out again.
Only then could researchers begin the complicated process of
stitching together data from the eight observatories, a technique
known as interferometry. The team had their work cut out for
them: Raw files from each of the observing sites came in with
different angles on the sky, in different wavelengths and at dif-
ferent observation times.
“The calibrating and working with it took many months,” ÖzelHey, Black Hole,
Say ‘Cheese’!
How do you capture a close-up of a
black hole? Start with a planet-sized
telescope: the EHT. Astronomers
at eight sites on four continents
(a ninth, in Greenland, joined in
2018) collaborated to collect data
and process it into a single image.SMA
Submillimeter Array
on Mauna Kea, HawaiiAPEX
Atacama
Pathfinder
EXperiment
on the Chajnantor
plain of ChileALMA
Atacama Large
Millimeter/
submillimeter Array
on the Chajnantor
ARO/SMT plain of Chile
Arizona Radio
Observatory’s
Submillimeter Telescope
near Safford, ArizonaLMT
Large Millimeter
Telescope “Alfonso
Serrano”
on Sierra Negra,
MexicoSMA
JCMTJCMT
James Clerk Maxwell
Telescope
on Mauna Kea, Hawaii