Astronomy - USA (2021-12)

or dislodge rock from a fracture,” said

study co-author Björn Davidsson of

JPL in a press release. “Our models

suggest that very small quantities of

sodium are all that’s needed to do this.”

To determine whether sodium could

indeed be the cause, the team heated

chipped samples from the Allende

meteorite — an object that fell to

Earth in 1969 and may have originated

from an asteroid like Phaethon — to

the highest temperatures Phaethon

experiences as it approaches the Sun.

After subjecting them to heat for

three hours — equivalent to a day on

fast-spinning Phaethon — the research-

ers found that while other elements

remained, the sodium in the chips had

boiled away.

More data are needed to cement this

as the reason for Phaethon’s cometlike

behavior, including repeating the test in

a vacuum to better simulate Phaethon’s

environment. And although the

researchers point out that this scenario

depends a lot on the minerals present

within a given object, they suspect

that it could be applied to other active

asteroids that have close approaches to

the Sun. This study supports a grow-

ing body of evidence that classifying

objects as either comets or asteroids

may be too simple. As study lead

author, Caltech’s Joseph Masiero, put it,

“The spectrum between asteroids and

comets [is] even more complex than we

previously realized.” — C.B.

NON-MAGNETIC MOON

The Moon likely never hosted a long-

lived global magnetic field, according to

new analysis of Apollo rock samples as

old as 3.9 billion years. With no

magnetosphere to ward off incoming

charged particles, the lunar soil may

have been enriched with resources

deposited from space, such as Helium-3.

HIDDEN SUPERNOVA

An analysis of 40 dusty galaxies

observed in infrared by the Spitzer

Space Telescope revealed five

supernovae previously undetected in

visual observations. The study’s lead

author says the results suggest optical

surveys miss up to half of all supernovae.

LAKE OR NO LAKE?

Many scientists thought Mars’ Gale

Crater, where NASA’s Curiosity rover

landed, hosted an ancient lake some

3 billion years ago. But a University of

Hong Kong team says chemical patterns

in the rocks Curiosity found suggest the

crater’s sediments were driven by winds

or volcanic activity, not carried by water.

MAUNA KEA OF THE EAST

Chinese astronomers hope to build a

world-class observing site near the

summit of Saishiteng Mountain in the

Tibetan Plateau. A three-year study

showed the site features remarkably dry,

stable air, as well as clear night skies

about 70 percent of the time.

SATURN’S HAZY HEART

Saturn’s core is a fuzzy region that

contains about 17 Earth masses of

sludgelike ice and rock, extending out to

some 60 percent of the planet’s radius.

The find comes from a new analysis of

the seismic waves, driven by pulsations

within the planet itself, that Cassini

observed in Saturn’s rings.

SWEETENING THE POT

NASA awarded nearly $250,000 to

a UC Berkeley team of chemists to help

them refine their electrochemical

process for making sugars from carbon

dioxide. By feeding these sugars to

microbes, the team hopes to produce

more complex compounds, like food or

drugs, for use by astronauts. — J.P.

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SEEING ECHOES OF LIGHT

A black hole recently gobbled up material from its companion star in the binary

system V404 Cygni, located 7,800 light-years from Earth. As the black hole’s meal

swirled around it in 2015, the matter heated up and emitted a powerful burst of X-ray

light. Like the sound waves of a yodeler echoing through the Swiss Alps, the light

waves from the black hole’s outburst are now echoing through the cosmos. This

composite image, centered on V404 Cygni, spans some 80 light-years and reveals

these so-called light echoes. Each concentric ring is formed as X-rays from the initial

burst scatter off clouds of cosmic dust, redirecting the light toward us. The larger the

ring, the closer the dust cloud that created it is to Earth. X-ray observations (blue) for

this composite image were obtained by NASA’s Chandra X-ray Observatory and Neils

Gehrels Swift Observatory, while the background star field was imaged in optical and

infrared light by the Pan-STARRS telescope in Hawaii. — JAKE PARKS

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WINTER SPECTACULAR. Geminid meteors

streak across the sky above Bill Evans Lake in

New Mexico in this long-exposure photograph.

Since first appearing in the mid-1800s, the

Geminids have become one of the most

productive meteor showers. This year, 150

meteors per hour are expected to be visible

under very dark skies. STEPHEN DORN