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just love that," Ghez reflects, smiling broadly.
did she do it?
no small feat to find a black hole, those infinitely dense phantoms
created, scientists postulate, from the remnants of collapsed stars
(so-called "stellar black holes") or from an aggregate of stellar
holes ( "supermassive black holes," such as Ghez revealed). Whatever
its origin, the mass of a black hole is so dense, that nothing --
not even light -- can escape its grasp. Yet, when one is in your
neighborhood, there are signs. Outside the ominously titled "Event
Horizon" -- about 10 million miles wide -- gravity from a black
hole rises to Looney Toon effect, grabbing the near side of a passing
star and stretching it away from the backside like the neck of a
rubber chicken. In our eeriest sci-fi imaginings -- not an approach
to which Ghez nor most other astronomers would ascribe, but which
serves nicely as illustration -- we might envision a black hole,
as described by New Zealand astronomer Roy Kerr, as a "magic ring"
of infinitely forceful spin, like the eye of a hurricane, through
which an astronaut could, POOF!, pass through to an alternate universe.
the farther reaches of the Milky Way, there is about one star flickering
within each three cubic light years of space. Near the middle, where
the black hole is supposed to be, the population is a million times
that. In a slow pan of the galaxy, the black hole's glowing "accretion
disk" is so inconspicuous it had been compared by one astronomer
to "finding a Coke machine in the desert."
find that Coke machine, Ghez in 1995, using the Keck I telescope,
started to track the movement of 100 stars near the galactic core.
Over the course of three years of observation from the mountain
top, she found that these stars showed the telling signs of influence
by extreme gravitational forces.
that grouping, Ghez found that a nucleus of 20 stars were spiraling
around the black hole at speeds up to 3 million miles per hour,
about 10 times the speed at which stars typically move. In order
to account for their speed, Ghez determined that an object 2.6 million
times more massive than our sun must be concentrated into a single
our first year, we could only collect the data, and we didn't really
know that we could see the faint sources because we hadn't worked
out all the analytical codes," Ghez says. "But the second year,
when we knew we'd gotten the measurements, there was actual cheering.
We were ecstatic."