For a wrong word,
underline the wrong word and write the correct one in the
blank provided at the end of the
line. For a missing word,
mark the position of the missing word with a "∧" sign and
write the word you believe to be missing in
the blank
provided at the end of
the line. For an unnecessary word,
cross the unnecessary word with a slash "—" and put the word
in the blank provided at the end of the
line.
Among her fellow astronomers, Vera Rubin is known as an
expert observer of the night sky, one of the best. Her reputation derives
from the project she has doggedly pursued through most of her career:
measuring how (1) ______ fast spiral galaxies are
spinning, from their luminous cores out of the faint (2)
______ wisps of light at their fringes. Such a task may sound tedious; even
her colleagues thought so when she started the project 20 years ago. But for
her (3) ______ painstaking measurements Rubin has learned
something important about galaxies: they spin so fast they have to fly apart.
Since galaxies do not seem (4) ______ to be shedding stars the way
like a rotating lawn sprinkler shed water; (5)
______ moreover, something must be holding the stars in. That something has
to be (6) ______ gravity, no other force is powerful
enough on a galactic scale. And where (7)
______ there is gravity, there is mass. Rubin realized that a huge reservoir
Of extra materials, invisible to her telescope, must be tucked away somewhere
in each (8) ______ galaxy. We cannot see this matter—it is
invisible to all our detectors. But this "dark matter" seems to make up at
least 90 percent of the mass of the universe, Large because
of Rubia’s work, dark matter has become the buzzword in
(9) ______ Astronomy. Her work has stirred Such ferment that observers
are desperate to (10) ______ find some way of seeing dark matter
and theorists are desperate to find an explanation of what it is—swarms of
unknown elementary particles, for instance, hidden armadas of Jupiter-like
planets.