This
story was updated at 11:33 a.m. EST.
Astronomers
have continued to cast their eyes to the heavens, with bigger and better
telescopes and as much passion as ever this year, but some of the coolest
findings of 2008 were right in our own backyard, or at least looked like they
were.
From worlds
nearby like Mercury and Mars to those beyond our solar system, planetary
science saw a boon. As for extrasolar
planets, astronomers bagged at least 50 newbies this year.
"It's
been a very exciting year for exoplanet discoveries," said Michael Liu, an
astronomer at the University of Hawaii.
What's
responsible for the surge of exoplanet detections?
"The
big picture is that a wide variety of new technologies, both instruments on
existing telescopes and new dedicated telescopes, are really allowing
astronomers to do much more sensitive measurements, and thus leading to a real
bonanza of discoveries," Liu told SPACE.com.
And there's
more. Here are five favorite findings in astronomy for 2008:
1. Alien
worlds
With the
extrasolar planet tally now well above 300, astronomers seem to be on track for
spotting another Earth (the astronomical jackpot) before long. Along the way
this year, a jaw-dropping
announcement came in November when two teams of astronomers reported they
had snapped direct images of exoplanets.
Geoffrey
Marcy of the University of California, Berkeley, calls the images "the
most spectacular thing in 2008."
"In my
own professional opinion this is by far the most definitive picture of a planet
ever taken," Marcy said during a telephone interview, referring to the
direct image by the Hubble Space Telescope of the planet called Fomalhaut b.
The gold
rush of exoplanet discoveries this year boils down to new techniques and
observatories as well as energetic astronomers involved, Marcy said.
Some other
highlights include: the least-massive planet, weighing in at just three times
the mass of Earth; the hottest planet, with temperatures reaching about 4,000
degrees Fahrenheit (2,200 degrees Celsius); and three so-called super-Earths
orbiting a star.
Astronomers
like Marcy predict the upcoming year will bring us even closer to detecting
Earth's twin. For instance, NASA's Kepler mission is scheduled to launch in
March with the goal of finding rocky planets about the size of Earth that orbit
within the habitable zone of their host stars where liquid water and life might
exist. Stay tuned.
2.
Martian life?
The red
planet has gotten celebrity treatment this past year, with the touchdown of
NASA's Phoenix Mars Lander in May, the continuing presence of the Mars
Exploration Rover twins (Spirit and Opportunity) and NASA's Mars Reconnaissance
Orbiter (which has imaged nearly 40 percent of the planet).
A major
goal of such missions has been to find signs of past or present liquid water,
the main ingredient for life. That's why Phoenix snagged a star-studded
headline when the lander collected
water ice near Mars' north pole this year.
Earlier in
the year, Spirit found deposits of silica in Gusev Crater, suggesting,
scientists said, that hot water once flowed through the Martian soil in hydrothermal
vents. As on Earth, these hydrothermal vents may have once harbored life. The
discovered silica could preserve fossils of such ancient life if it did indeed
exist there.
And just in
from MRO — evidence of carbonates on the Martian surface. Since carbonates
can't survive in acidic, harsh conditions, the mineral finding suggests any microbes
crawling around when Mars was wet could've enjoyed a cushy existence.
3. Dark energy
Scientists
were hot on the trail this year of a mysterious "force" called dark
energy that has been expanding the universe at an increasing pace and was only
discovered about 10 years ago.
Though,
admittedly, scientists say they are more than a few years away from solving the
puzzler of what dark energy is, a new method this year confirmed its existence,
suggesting the force is stifling
the growth of galaxies in the universe. Basically, in an expanding universe
dominated by dark energy, galaxies fly away from one another rather than mingle
and merge.
These
results also suggest dark energy takes the form of what Einstein called the
cosmological constant — a term in Einstein's theory of general relativity that
represents the possibility of empty space having a density and pressure associated with it.
4. Black
hole antics
Black holes
are so dense that nothing, not even light, can escape their gravitational
grips. Though invisible, astronomers have inferred the presence of the dark
behemoths from their effects on nearby objects. And this year, it seems, all
the crazies came out of their cosmic closets.
Take the
fastest spinning black hole, found to whirl around at speeds approaching the
speed of light.
And when it
comes to obesity, one
black hole could've gobbled up 18 billion suns. This giant would dwarf the
smallest black hole found this year, weighing in at about 3.8 times the mass of
our sun and spanning just 15 miles (24 km) in diameter.
Researchers
also found this year that some supermassive black holes, which reside at the
centers of many or all galaxies, spew out giant bubbles from the tips of their
jets. (As material falls into the gravitational clutches of a black hole, the
energy can be spit out as jets of radiation and high-speed particles.) The
bubbles ultimately pop, spilling their gaseous guts. Turns out, the hot gas
keeps the black hole and its galaxy from ballooning to mega sizes.
Black holes
can also take the form of "masked fugitive." Computer simulations
revealed that when two black holes merge, the energy produced can kick the
newly merged black hole clear out of its galaxy.
Also, for
the first time this year, scientists detected such a
rogue black hole racing along at 5,900,000 mph (2,650 kilometers per
second).
5. Solving
Mercury mysteries
More than
half of our solar system's smallest planet (Pluto once took this honor),
Mercury, had remained a mystery until this year. On Jan. 14, NASA's MESSENGER
probe made its first flyby of Mercury, beginning a mission to image the entire
planet.
From the
get-go, the probe sent back intriguing images, including clear evidence for
volcanoes. Images of the Caloris basin showed hints of lava flows and the
presence of a shield volcano larger than the state of Delaware, with gently
sloping sides.
And Mercury
is indeed shrinking as its iron-rich core slowly cools. Scientists had
speculated this much from images taken during the Mariner 10 mission in 1974.
But MESSENGER images showed more faults than did Mariner 10, suggesting the
strain from the planet's contraction was at least one-third greater than originally
thought.
More to
come: The thousands of images and other data collected by MESSENGER could also
shed light on other
Mercury mysteries, including the planet's relatively giant core, which
makes up about two-thirds of the planet's mass. One idea is that huge impacts
hundreds of millions of years ago might have stripped the innermost planet of
its original surface.
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