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12 ASTRONOMY • FEBRUARY 2018

HIGH ABOVE. University of Bern researchers used NASA’s SOFIA jet to witness the transit of the super-Earth

exoplanet GJ 1214b across its home star.

BRIEFCASE

METHANE MONSOONS

Thanks to the Cassini-Huygens mission, we know that

Saturn’s largest moon, Titan, has some pretty bizarre

features, including lakes and seas of liquid methane and

ethane. Astronomers published a study October 9 in

Nature Geoscience showing that Titan also experiences

surprisingly intense methane storms that can dump up

to a foot of rain a day. As the deluge flows over Titan’s

surface, it deposits sediment into the lowlands, forming

cone-shaped features called alluvial fans. By studying

how rainfall influences planetary surfaces, researchers

hope to better understand how various weather

patterns can affect a planet’s climate and habitability.

• NOBEL PRIZE
  Gravitational waves have dominated headlines for the
  past year because for thousands of years, astronomers
  could only study the cosmos using light. On October 3,
  three American physicists were awarded the 2017 Nobel
  Prize in Physics for their “decisive contribution to the
  LIGO detector and the observation of gravitational
  waves.” Half of the prize went to Rainer Weiss from MIT,
  while the other half was split between Kip Thorne and
  Barry Barish from Caltech. With the recent detections of
  gravitational waves, astronomers now have an entirely
  new way to study the universe.


• 
  

  PLANET EATER
  The Sun-like star Kronos, about 350 light-years away, is
  named after the mythological Greek titan who ate his
  own children. On September 15, Princeton astronomers
  posted a paper online supporting this name by showing
  that Kronos likely devoured over a dozen of its rocky
  inner planets during its 4 billion-year lifetime. Although
  the exact process that led to the planetary feast is not
  known, the astronomers suggest that Kronos once flew
  too close to another star, catapulting its outer planets
  through the inner solar system, in turn sending the
  rocky inner planets into a death spiral. — J.P.

  
  

T

he fact that we can’t see the Milky

Way face-on really annoys astrono-

mers. It’s akin to a cartographer who

wants to make a map of the neigh-

borhood, but is stuck in a house.

In a study published October 13 in

Science, a team of researchers directly

measured the distance to a star-forming

region called G007.47+00.05 on the far

side of the Milky Way using the National

Science Foundation’s Very Long Baseline

Array (VLBA). This shattered the previ-

ous record for a direct distance measure-

ment within our galaxy.

“This means that, using the VLBA, we

now can accurately map the whole extent

of our galaxy,” said the study’s lead author,

Alberto Sanna of the Max Planck Institute

for Radio Astronomy.

Previous attempts to accurately map the

opposite side of the Milky Way have failed,

mostly because interloping interstellar dust

in the galactic plane blocks optical light

from reaching us. But radio waves can pass

straight through the dust, which is why the

researchers turned to the VLBA to take

observations in radio wavelengths.

Between 2014 and 2015, the team used

the VLBA and an observing technique

called trigonometric parallax to measure

a distance of just over 66,500 light-years to

G007.47+00.05. The previous record for a

parallax measurement was about 36,

light-years.

Despite this record-breaking distance

measurement, it will still take time for

astronomers to gather enough data to cre-

ate a comprehensive map of the Milky

Way. “Within the next 10 years, we should

have a fairly complete picture,” said Mark

Reid of the Harvard-Smithsonian Center

for Astrophysics.

Ten years seems like a long time, but

just think how long it took explorers to

accurately chart the Americas. And that

was just an ocean away. — J.P.

A BETTER MAP OF THE MILKY WAY

Hubble spots farthest

active comet

FAR SIDE.

Astronomers

measured the

distance to a

star-forming region

with the catchy

name G007.47+00.05,

about 66,

light-years away

in the Scutum-

Centaurus spiral

arm. NRAO/AUI/NSF;

ROBERT HURT, NASA

UNTIL NEXT TIME. Astronomers caught Comet

PANSTARRS (C/2017 K2) as it traveled between the

orbits of Saturn and Uranus, making it the most

distant active comet sighting ever. When spotted,

it was a whopping 1.5 billion miles from the Sun,

and researchers believe it may have come from

as far out as 46,000 times the distance of the Sun

to Earth. The comet is currently on course for an

ASTRONOMY encounter with Mars in 2022. — John Wenz

: ROEN KELLY

URANUS BLAZES A TRAIL

FAST

FAC T

Uranus’ orbit tilts just enough

to the ecliptic plane that it cuts

across a corner of the non-zodiacal

constellation Cetus.

SLOW MOTION. It takes the

seventh planet 84 years to circle

the Sun, so it typically spends a

lot of time in each constellation.

In early 2018, it ends a nearly

eight-year-long run through

Pisces when it crosses the border

into Aries. But its longest stretch

comes in Virgo, where it resides

for more than nine years. The

chart shows what percentage of

time Uranus will spend in each

constellation from the beginning

of 2018 until it returns to the

same position in 2101.

— Richard Talcott

NASA/ESA/D. JEWITT

Earth 66,500 light-years

Star-forming region