Elephants and their forebears were pushed into wipeout by waves of extreme global environmental change, rather than overhunting by early humans, according to new research.

The study, published today in Nature Ecology & Evolution, challenges claims that early human hunters slaughtered prehistoric elephants, mammoths and mastodonts to extinction over millennia. Instead, its findings indicate the extinction of the last mammoths and mastodonts at the end of the last Ice Age marked the end of progressive climate-driven global decline among elephants over millions of years.

2021 has been a great year so far for space science and astronomy. This year, we have crossed one more milestone as China's Zhurong Mars rover has become the second rover to sent back video and audio from the planet's Utopia Planitia region.

On Sunday, Zhurong descended into the planet's surface and has sent back to us the video of this amazing feat. The footage includes the deployment of its parachute and a uber-cool drive off from the Tianwen-1 landing platform. The drive off video also features sounds captured by the rover's climate station.

Here is the video of Zhurong's parachute deployment and descent.

As one of Japan's most active volcanoes, Sakurajima often dazzles with spectacular displays of volcanic lightning set against an ash-filled sky. But the volcano can also produce much smaller, invisible bursts of electrical activity that mystify and intrigue scientists.

Now, an analysis of 97 explosions at Sakurajima from June 2015 is helping to show when eruptions produce visible lightning strokes versus when they produce the mysterious, unseen surges of electrical activity, researchers report in the June 16 Geophysical Research Letters.

These invisible bursts, called vent discharges, happen early in eruptions, which could allow scientists to figure out ways to use them to warn of impending explosions.

Researchers know that volcanic lightning can form by silicate charging, which happens both when rocks break apart during an eruption and when rocks and other material flung from the volcano jostle each other in the turbulent plume (SN: 3/3/15). Tiny ash particles rub together, gaining and losing electrons, which creates positive and negative charges that tend to clump together in pockets of like charge. To neutralize this unstable electrical field, lightning zigzags between the charged clusters, says Cassandra Smith, a volcanologist at the Alaska Volcano Observatory in Anchorage.

Reports of methane detections at Mars have captivated scientists and non-scientists alike. On Earth, a significant amount of methane is produced by microbes that help most livestock digest plants. This digestion process ends with livestock exhaling or burping the gas into the air.

While there are no cattle, sheep, or goats on Mars, finding methane there is exciting because it may imply that microbes were, or are, living on the Red Planet. Methane could have nothing to do with microbes or any other biology, however; geological processes that involve the interaction of rocks, water, and heat can also produce it.

Before identifying the sources of methane on Mars, scientists must settle a question that's been gnawing at them: Why do some instruments detect the gas while others don't? NASA's Curiosity rover, for instance, has repeatedly detected methane right above the surface of Gale Crater. But ESA's (the European Space Agency) ExoMars Trace Gas Orbiter hasn't detected any methane higher in the Martian atmosphere.

American robotics company Boston Dynamics released a new robot dance video after it announced it had been acquired by Hyundai - and, like its previous effort, this one had many people terrified.

Though it announced the completion of the acquisition last week in a press release, Boston Dynamics decided to mark the occasion in style on Tuesday.

The video shows five of its dog-like 'Spot' robots dancing to the song 'IONIQ: I'm On It' by South Korean boy band BTS, and demonstrates the precision and complexity of its machines, which feature long arm-like appendages with claws.

A new class of illusion, developed by a visual artist and a psychology researcher, underscores the highly constructive nature of visual perception.

The illusion, which the creators label "Scintillating Starburst," evokes illusory rays that seem to shimmer or scintillate — like a starburst. Composed of several concentric star polygons, the images prompt viewers to see bright fleeting rays emanating from the center that are not actually there.

"The research illustrates how the brain 'connects the dots' to create a subjective reality in what we see, highlighting the constructive nature of perception," explains Pascal Wallisch, a clinical associate professor in New York University's Department of Psychology and Center for Data Science and senior author of the paper, which appears in the journal i-Perception.

"Studying illusions can be helpful in understanding visual processing because they allow us to distinguish the mere sensation of physical object properties from the perceptual experience," adds first author Michael Karlovich, founder and CEO of Recursia Studios, a multidisciplinary art and fashion production company.

A joint research team led by Prof. FU Qiaomei from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences sequenced the ancient genomes of 31 individuals from southern East Asia, thus unveiling a missing piece of human prehistory.

Prof. FU's team used DNA capture techniques to retrieve ancient DNA from Guangxi and Fujian, two provincial-level regions in southern China. They sequenced genome-wide DNA from 31 individuals dating back 11,747 to 194 years ago. Of these, two date back to more than 10,000 years ago, making them the oldest genomes sampled from southern East Asia and Southeast Asia to date.

Previous ancient DNA studies showed that ~8,000-4,000-year-old Southeast Asian Hoabinhian hunter-gatherers possessed deeply divergent Asian ancestry, whereas the first Southeast Asian farmers beginning ~4,000 years ago show a mixture of ancestry associated with Hoabinhian hunter-gatherers and present-day southern Chinese populations. In coastal southern China, ~9,000-4,000-year-old individuals from Fujian province show ancestry not as deeply divergent as the Hoabinhian.

In 2021 June 19, the circular MPEC 2021-M53 of Minor Planet Center announced the discovery of an asteroidal object by astronomers P. Bernardinelli & G. Bernstein (University of Pennsylvania) that they found in CCD exposures obtained with the 4.0-m reflector at Cerro Tololo Interamerican Observatory in the course of the "Dark Energy Survey", and which they reported as a previously unknown member of the Oort Cloud. The reported astrometry was spanning from 2014 Oct. 20 to 2018 Nov. 8. The new object was designated 2014 UN271. It was hidden among data collected by the 570-megapixel Dark Energy Camera (DECam) mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile and was announced only now because, in the words of one of the discoverers, "finding TNOs with DES is a massive computational problem (my PhD was solving this problem). The search itself took 15~20 million CPU-hours, and the catalog production from our 80,000 exposures probably took more than that!"

According to the orbit calculated using data from 2014 to 2018, this object is likely to be a comet from the outer edge of the Oort Cloud. But 2014 UN271, despite its typically cometary orbit, appeared completely stellar in these archival images when it moved from 29 to 23 AU (for comparison, Pluto is 39 au from the Sun, on average). Below a simulation (made by T. Dunn) of the orbit of comet C/2014 UN271 showing it path in the Solar System from 1985 to 2049.


A few days after the discovery announcement, 2014 UN271 has been found to show cometary appearance in new CCD images obtained by observers at station codes L81 & K93.Basically this object, that was first seen as an asteroid of magnitude ~22 by DES in 2014 at a distance of 29 AU, approaching the Sun was growing his coma and tails. As of June 2021, it was 20 AU from the Sun shining at a magnitude ~20.After the discovery of the cometary coma, the new comet has been designated C/2014 UN271 (Bernardinelli-Bernstein). This comet will reach perihelion, its closest point to the Sun, in January 2031 at about ~11 AU away from the Sun.

Astronomers may have finally discovered convincing evidence of an elusive kind of supernova, one that could explain a bright explosion that lit up the night sky on Earth nearly 1,000 years ago and birthed the beautiful Crab Nebula, a new study finds.

Supernovas are giant explosions that can occur when stars die. These outbursts can briefly outshine all of the other suns in these stars' galaxies, making them visible from halfway across the universe.

The big idea

Much of the brittle, upper crust of Venus is broken into fragments that jostle and move - and the slow churning of Venus' mantle beneath the surface might be responsible. My colleagues and I arrived at this finding using decades-old radar data to explore how the surface of Venus interacts with the interior of the planet. We describe it in a new study published in the Proceedings of the National Academy of Sciences on June 21, 2021.

Planetary scientists like me have long known that Venus has a plethora of tectonic landforms. Some of these formations are long, thin belts where the crust has been pushed together to form ridges or pulled apart to form troughs and grooves. In many of these belts there's evidence that pieces of the crust have moved side to side, too.