Astronomy - USA (2022-02)

WWW.ASTRONOMY.COM 57

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OUR GALACTIC HOME
The luminous band
of the Milky Way,
from Cassiopeia to
Scorpius, stretches
across the sky over
Panamint Valley in
Death Valley National
Park. JOHN FISANOTTI
This artist’s conception of the Milky Way is
based on data from NASA’s Spitzer Space
Telescope. Infrared images revealed that the
Milky Way’s spiral structure is dominated by two
of its four primary arms: the Perseus Arm and
the Scutum-Centaurus Arm. The Norma and
Sagittarius arms are located between them. The
newly discovered Cattail structure, reported
August 2021 by astronomers at Nanjing
University in China, may also be a spiral arm
or a very long filament of hydrogen gas.
ASTRONOMY: ROEN KELLY, AFTER NASA/JPL-CALTECH
Herschel assumed that the number of
stars in each area was a direct indication
of the stellar population in that direction.
Unaware of any relationship between
faintness and distance, or that millions of
faint stars were obscured from his view,
he produced a diagram of the Milky Way
that looks like a gigantic amoeba!
By the 1840s, Herschel’s equipment
was dwarfed by the Leviathan of
Parsonstown in Ireland. Built for William
Parsons, Earl of Rosse, this monstrous
telescope’s 72-inch mirror allowed Rosse