New NASA eBook Reveals Insights of Earth Seen at Night from Space

Earth has many stories to tell, even in the dark of night. Earth at Night, NASA’s new 200-page ebook, is now available online and includes more than 150 images of our planet in darkness as captured from space by Earth-observing satellites and astronauts on the International Space Station over the past 25 years.


The year in reviews: Books and more that stood out in 2019



The increasing pace of modern life — and how we can adapt | Kathryn Bouskill

Why does modern technology promise efficiency, but leave us constantly feeling pressed for time? Anthropologist Kathryn Bouskill explores the paradoxes of living in a fast-paced society and explains why we need to reconsider the importance of slowing down in a world that demands go, go, go.

Why Rembrandt and da Vinci may have painted themselves with skewed eyes


A strongly dominant eye, not
an eye disorder, may explain why Leonardo da Vinci and Rembrandt van Rijn painted
themselves with misaligned eyes.

Previous research suggested
that the famous artists may have had a literal artist’s eye —
an eye disorder called exotropia in which one eye turns outward. Exotropia
makes it harder for the brain to use input from both eyes to see in 3-D, so it
must rely on 2-D cues to see depth. This gives people with the disorder a
“flattened” view of the world, which could give artists who work on flat
surfaces like canvas an advantage.

But using trigonometry and
photographs of people looking into a mirror, David Guyton, an ophthalmologist
at Johns Hopkins University, and his colleague Ahmed Shakarchi, conclude that the artists could have had eyes that faced straight ahead
after all
. The researchers published
their analysis November 27 in JAMA

The brains of people who have
a strongly dominant eye will favor whatever that eye sees. So when people with
a strongly dominant eye look closely in a mirror — like, say, artists leaning in to get details needed
to paint a self-portrait —
they could perceive that they have exotropia even if that’s not true, Guyton

For instance, a person with
a strongly dominant eye and eyes six centimeters apart who was sitting 16.5
centimeters from a mirror would wrongly perceive that the weaker eye is turned
outward at a 10.3-degree angle, the researchers found. That angle is consistent
with the eye angle portrayed in some artworks painted by or modeled after da Vinci.

“It is a clever idea,” says
Christopher Tyler, a visual neuroscientist at the City University of London
whose previous analysis of six pieces of art — some by da Vinci himself and some for which it’s
suspected he was the model —
suggested that da Vinci had exotropia (SN: 10/22/18).
In many of those works, the eyes appear misaligned.

For the geometry of the
strong eye explanation to work, Tyler says, the artist would have to sit
“unrealistically close” to the mirror, especially for some of Rembrandt’s half-length,
self-portraits or for the painting Salvator
, which da Vinci may have partially modeled after himself. And it
doesn’t fully explain why statues that were sculpted in da Vinci’s likeness by
other artists also show apparent exotropia, Tyler says.

Bevil Conway, a
neurobiologist at the National Institutes of Health in Bethesda, Md., says both
explanations are plausible. A common trick among artists is to shut one eye and
hold out a thumb to get a sense of how a three-dimensional world looks in 2-D. Both
exotropia and a strongly dominant eye could have a similar “flattening” effect,
which could have helped da Vinci and Rembrandt bring a 3-D world to life on flat

“The debate is still open,
and the answer is that we can never know,” Conway says.

Stealthy robots with microphones could improve maps of ocean noise


slowly and stealthily through the Pacific Ocean, a robotic glider with a
microphone captured a cacophony of sounds from ships, whales and underwater

glider’s journey, across 458 kilometers off the Washington and Oregon coast and
down to 650 meters, demonstrates that gliders could be effective tools to help map ocean noise levels, researchers report November 20 in PLOS ONE. Separate audio recordings from
nearby microphones dangled from the water’s surface confirmed the accuracy of
the glider’s 18 days of recordings in July and August 2012.

Stationary microphones can’t catch the full array of sounds throughout large swathes of sea or at various depths in the water column the way a glider can, though, the researchers say. Ocean noise is “something we need to measure and try to better understand why that’s happening, where it’s happening, and what the impacts are” to wildlife and marine ecosystems, says oceanographer Joe Haxel, at Oregon State University’s coastal campus in Newport. For example, previous research has shown that Navy sonar (SN: 3/25/11) and passing ships can create noise pollution that harms marine animals (SN: 2/13/18), impacting social behaviors and foraging habits.

scientists eavesdrop underwater with hydrophones, waterproof microphones that
are moored or dangled from the surface, or mounted on large ships that can drown
out other sounds and scare away marine life.

glider’s slow speed —
just over 1 kilometer per hour —
and quiet movement allow it to sneak through the water picking up ambient
noises. A pump moves oil in and out of the glider’s bladder, affecting its buoyancy
and causing it to float up or sink down in the water column. Those depth
changes propelled the glider forward on a slow, meandering path.

glider is good because it’s noninvasive,” says Haxel. “It’s coming in on
stealth mode.”