VERY
January, as though cheered by the completion of the Earth's latest
jaunt around the sun, the field of astronomy explodes like a supernova
spewing barrages of celestial news. The year 2002 has been no different,
with arresting tales of effervescing "bubbles" light-years across
a kind of cosmic burp and a towering fountain of gas erupting
from a galaxy like a slow-motion volcano. The assortment of new planets
has expanded once again, including a stillborn star called a brown
dwarf orbiting its own sun.
The timing of the announcements is actually coincidental. January
is when the American Astronomical Society holds the first of its two
yearly meetings the most recent was earlier this month in
Washington giving members a chance to reveal what they have been
working on. Another burst of revelations comes every June at the
summer meeting, the two events circling each other as rhythmically
as binary stars.
For astronomy fans, the excitement eclipses the Super Bowl, with
one report after another conjuring up visions of vast luminescent
turmoil. But don't try to look too closely. To take in the whole
show one would need not only a powerful telescope but eyes sensitive
to a spectrum far wider than the narrow little rainbow people call
visible light.
Every year, as satellites and electronic sensors further extend
the visual range, more and more of the astronomical drama takes
place on invisible stages. The familiar image of a laboratory prism
casting its gradations of red, orange, yellow, green, blue, indigo
and violet is so deeply ingrained that we forget that color or,
more precisely, electromagnetic radiation stretches way beyond
both edges of the scale.
To directly experience the thrill of the galactic fountain,
observed by Dr. Edward M. Murphy, an astronomer at the University of
Virginia, one would have to see far beyond blue with eyes that
registered ultraviolet. Spewing from supernovae exploding stars
these geysers of extremely hot gas vault into the galactic sky like
Old Faithful before cooling and falling back down. Dr. Murphy was
able to register the event, in the nearby Whale Galaxy (NGC 4631),
using the Far Ultraviolet Spectroscopic Explorer, a satellite
launched in June 1999 to study this small window of light.
Ultraviolet, with a frequency slightly higher than visible light,
lies just beyond the eye's grasp. To see the gargantuan bubbles
reported by Dr. Brian McNamara of Ohio University in Athens, one
would literally have to have X-ray vision the ability to register
extremely high-pitched electromagnetic waves. Instead Dr. McNamara
relied on the orbiting Chandra X-ray Observatory. What he found was
evidence, in a cluster of galaxies called Abell 2597, of huge voids,
or "ghost cavities," foaming through the surrounding gas the
aftershocks of ancient explosions ignited perhaps by matter falling
into a black hole.
With its penetrating sensors, Chandra can also see through the
stellar muck to the center of the Milky Way, revealing the black
holes, neutron stars and other astronomical exotica lurking at its
core. At the meeting, Dr. Q. Daniel Wang of the University of
Massachusetts showed off stunning images a pyrotechnical wonder of
reds, greens, yellows and blues. (To make them pretty, his team took
a bit of artistic license, substituting the familiar colors for
various frequencies of X-rays.)
OTHER sessions of the meeting focused on sightings made with
gamma-rays, the highest treble notes on the scale. Others
concentrated on the bass notes at the opposite end: low- frequency
radio and infrared emissions that provide their own points of
view.
These days astronomers often find themselves pondering ways to
map the universe without using light at all. Future Januarys may be
filled with results from projects like LIGO (Laser Interferometer
Gravitational- Wave Observatory), which aim to measure the faint
waves of gravity emitted by collapsing stars, colliding black holes
and other calamities. To make the delicate measurements, laser beams
will be sent ricocheting between mirrors 2 1/2 miles apart, a
distance that should subtly fluctuate as the Earth is buffeted by
claps of gravity. By precisely measuring changes in the length of
the beams, astronomers hope to listen in on the rumbling.
ACTUALLY, much of what scientists are learning about the universe
already comes from studying gravity. The new planets often reported
in January and June cannot actually be seen, even by the orbiting
Hubble Space Telescope. Their existence is inferred from the way
they cause their mother stars to wobble.
Thus one of the most satisfying finds revealed this month was a
distant planet that could actually be observed by its light and
even the visible kind. Sixty-five times as massive as Jupiter, the
orbiting body technically qualifies as a brown dwarf bigger than a
planet but not quite heavy enough to collapse in on itself, igniting
the nuclear furnace that powers stars. Dr. Michael Liu of the
University of Hawaii found the system, 58 light-years from Earth,
using the Gemini North and Keck optical telescopes on Mauna Kea.
They were rigged with computerized "adaptive optics": by
compensating for atmospheric turbulence, they allow for sharper
images of distant objects.
In the end there is still nothing more pleasing than good
old-fashioned light. In fact, two Johns Hopkins University
astronomers, Dr. Ivan Baldry and Dr. Karl Glazebrook, stole the show
by demonstrating that the universe is pale green, somewhere between
aquamarine and turquoise. This is a little strange considering that
there are no green stars. Old ones are reddish and new ones are
bluish. But when the light of all the stars is mixed together, the
result is predominantly green.
It's a pleasing thought. If one could step outside the universe
and view it from afar it would glow like a swimming pool at night.
Now if only it were possible to see all those other
colors.