Today's Image of the Day from the European Space Agency features UGC 5460, a spiral galaxy that is located about 60 million light-years away in the constellation Ursa Major.&nbsp;



“This image combines four different wavelengths of light to reveal UGC 5460’s central bar of stars, winding spiral arms and bright blue star clusters. Also captured in the upper left-hand corner of this image is a far closer object: a star just 577 light-years away in our own galaxy,” said <a href="https://www.esa.int/ESA_Multimedia/Images" target="_blank" rel="noreferrer noopener">ESA</a>.



“UGC 5460 has hosted two recent supernovae named SN 2011ht and SN 2015as. It’s because of these two stellar explosions that Hubble targeted this galaxy, collecting data for three observing programmes that aim to study various kinds of supernovae.”&nbsp;



<h2 class="wp-block-heading" id="h-a-core-collapse-supernova-nbsp">A core-collapse supernova&nbsp;</h2>



SN 2015as is an example of a core-collapse supernova. This type of <a href="https://www.earth.com/news/supernova-explosions-could-damage-distant-planets/" target="_blank" rel="noreferrer noopener">supernova</a> occurs when the core of a massive star - typically with more than 8 times the mass of the sun - can no longer support its own gravity after exhausting its nuclear fuel. 



This causes the core to collapse under its own weight, leading to an extremely violent explosion. The collapse triggers the release of an enormous amount of energy, expelling the outer layers of the star into space.



In the aftermath of the explosion, a dense <a href="https://www.earth.com/news/shockingly-bright-carbon-monoxide-detected-in-supernova-remnant/" target="_blank" rel="noreferrer noopener">remnant</a> is created. This is often a neutron star or black hole, depending on the mass of the original star. Core-collapse supernovae are some of the most powerful events in the universe.



According to ESA, Hubble observations of SN 2015as will help researchers understand what happens when the expanding shockwave of a <a href="https://www.earth.com/news/supernova-dandelion-year-1181-leaves-behind-zombie-star-defying-death/" target="_blank" rel="noreferrer noopener">supernova</a> collides with the gas that surrounds the exploded star.



<h2 class="wp-block-heading" id="h-rare-stars-with-large-eruptions-nbsp">Rare stars with large eruptions&nbsp;</h2>



“SN 2011ht might have been a core-collapse supernova as well, but it could also be an impostor called a luminous blue variable. Luminous blue variables are rare stars that experience eruptions so large that they can mimic supernovae,” noted ESA.



“Crucially, luminous blue variables emerge from these eruptions unscathed, while stars that go supernova do not. Hubble will search for a stellar survivor at SN 2011ht’s location, and the explosion’s identity may be revealed at last.”



<h2 class="wp-block-heading" id="h-what-is-a-spiral-galaxy">What is a spiral galaxy?</h2>



Spiral galaxies are some of the most recognizable and beautiful structures in the universe. They are known for their distinctive arms that spiral outward from a central bulge.&nbsp;



These galaxies are typically composed of stars, gas, dust, and dark matter. The arms are often sites of intense <a href="https://www.earth.com/news/fluffy-molecular-clouds-may-change-our-understanding-of-star-formation/" target="_blank" rel="noreferrer noopener">star formation</a>, where clouds of gas collapse to form new stars. 



In the center of a spiral galaxy lies a dense concentration of older stars and, often, a supermassive black hole.



<h2 class="wp-block-heading" id="h-structure-of-a-spiral-galaxy-nbsp">Structure of a spiral galaxy&nbsp;</h2>



The structure of a spiral galaxy is generally divided into three main components: the disk, the bulge, and the halo.&nbsp;



The disk is where the spiral arms are located and contains most of the galaxy's visible stars and interstellar medium.&nbsp;



The bulge is a tightly packed region of older stars at the core, and the halo consists of a sparse collection of stars and globular clusters that surround the galaxy.&nbsp;



Spiral galaxies can be classified into different types based on the tightness and number of their spiral arms, as well as the size of their central bulge.



<h2 class="wp-block-heading" id="h-the-milky-way-galaxy">The Milky Way galaxy</h2>



Our solar system is located within a large spiral galaxy known as the Milky Way. The name refers to its appearance as a dim, milky band of light stretching across the night sky.&nbsp;



The term "Milky Way" comes from ancient Greek mythology, where it was associated the goddess Hera's milk spilling into the sky. In Greek, it was called "Galaxias Kyklos," meaning "milky circle."&nbsp;



Spanning about 100,000 light-years in diameter, the Milky Way is composed of stars, gas, dust, and dark matter. The galaxy has a distinct disk shape with spiral arms that wind outward from a central bulge, which houses a supermassive <a href="https://www.earth.com/news/milky-ways-black-hole-unleashes-mysterious-flares/" target="_blank" rel="noreferrer noopener">black hole</a>. 



Our sun is located in one of the spiral arms - known as the Orion Arm - positioned roughly halfway from the center to the outer edge.&nbsp;



The Milky Way is part of a small group of galaxies called the Local Group, which includes the Andromeda Galaxy and several smaller galaxies.



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Hubble views a spiral galaxy with stellar explosions

Today's Image of the Day from the European Space Agency...

Today's Image of the Day from NASA features the spiral galaxy NGC 2566, which is located 76 million light-years away in the constellation Puppis. The image was captured by the NASA/ESA Hubble Space Telescope.



“A prominent bar of stars stretches across the center of this galaxy, and spiral arms emerge from each end of the bar. Because NGC 2566 appears tilted from our perspective, its disk takes on an almond shape, giving the galaxy the appearance of a cosmic eye,” said <a href="https://phys.org/news/2024-12-hubble-spies-spiral-galaxy-ngc.html" target="_blank" rel="noreferrer noopener">NASA</a>.



“As NGC 2566 appears to gaze at us, astronomers gaze right back, using Hubble to survey the galaxy's star clusters and star-forming regions.”



<h2 class="wp-block-heading" id="h-complex-appearance-of-ngc-2566">Complex appearance of NGC 2566</h2>



NGC 2566 lies at a considerable distance from Earth, making it a challenging object for amateur astronomers to observe in detail without powerful telescopes.&nbsp;



It can be seen in the Southern Hemisphere sky and is better observed from locations with minimal <a href="https://www.earth.com/news/how-light-pollution-influences-interest-in-astronomy/" target="_blank" rel="noreferrer noopener">light pollution</a>.&nbsp;



The galaxy's arms are populated with young, bright stars, regions of active star formation, and interstellar gas and dust - giving it a dynamic and complex appearance.



<h2 class="wp-block-heading" id="h-measuring-the-ages-of-stars">Measuring the ages of stars</h2>



According to NASA, data from Hubble is especially valuable for studying stars that are just a few million years old. “These stars are bright at the ultraviolet and visible wavelengths to which Hubble is sensitive.”



“Using these data, researchers can measure the ages of NGC 2566's stars, which helps piece together the timeline of the galaxy's star formation and the exchange of gas between star-forming clouds and the stars themselves.”



<h2 class="wp-block-heading" id="h-star-formation-in-galaxies">Star formation in galaxies</h2>



Star formation in <a href="https://www.earth.com/news/shapes-of-one-million-galaxies-hint-at-the-universes-origins/" target="_blank" rel="noreferrer noopener">galaxies</a> is a fascinating and complex process that unfolds over millions of years. It begins in vast clouds of gas and dust, known as molecular clouds, which are often found in the spiral arms of galaxies or in regions of irregular or starburst galaxies.&nbsp;



These clouds provide the raw material for star formation, consisting primarily of hydrogen and helium, with trace amounts of heavier elements.



As the molecular clouds collapse under their own gravity, regions within them begin to condense and fragment, forming dense clumps. Within these clumps, protostars emerge. Their formation is driven by the gravitational pull drawing in surrounding gas.&nbsp;



During this process, the gas heats up due to increasing pressure, eventually igniting nuclear fusion in the core, signaling the birth of a new star.



<h2 class="wp-block-heading" id="h-rate-of-star-formation-nbsp-across-galaxies">Rate of star formation&nbsp;across galaxies</h2>



The rate of star formation varies across galaxies is influenced by numerous factors. In spiral galaxies like the Milky Way, star formation is most active in the spiral arms, where density waves compress gas and dust, triggering the collapse of molecular clouds.&nbsp;



Elliptical galaxies, which often have little cold gas and dust, typically exhibit low rates of star formation or none at all.



Starburst galaxies, on the other hand, experience episodes of exceptionally high star formation, often triggered by <a href="https://www.earth.com/news/webb-captures-a-galaxy-collision-with-a-radiant-smile/">galactic collisions</a> or interactions. 



These events can funnel large amounts of gas into central regions, leading to intense star-forming activity. However, such bursts are usually short-lived on cosmic timescales, exhausting the available gas quickly.



The environment within a galaxy also plays a significant role. Stellar winds and supernova explosions from existing stars can both inhibit and promote star formation. They may disperse gas, preventing further collapse, or compress nearby clouds, triggering new star formation.&nbsp;



Over time, as galaxies evolve, the availability of gas diminishes, leading to a gradual decline in star formation activity.



<h2 class="wp-block-heading" id="h-the-puppis-constellation-nbsp">The Puppis constellation&nbsp;</h2>



The Puppis constellation in the southern sky represents the stern of a ship. It was once part of a larger constellation known as Argo Navis, which depicted the mythical ship of Jason and the Argonauts.&nbsp;



However, Argo Navis was later divided into three separate constellations: Puppis, Carina (the keel), and Vela (the sails). Puppis is the largest of these three and contains many notable celestial objects.



This constellation is home to several bright stars, including Naos (Zeta Puppis), a hot, massive star that emits intense ultraviolet radiation. Puppis also hosts a wide variety of deep-sky objects, such as open <a href="https://www.earth.com/news/stunning-star-clusters-captured-in-the-extreme-outskirts-of-the-milky-way/" target="_blank" rel="noreferrer noopener">star clusters</a> and nebulae.&nbsp;



Among these, Messier 46 and Messier 47 stand out. Both are beautiful star clusters that are visible through binoculars or small telescopes. The region is dense with stars because it lies along the <a href="https://www.earth.com/news/milky-way-collision-may-change-everything-we-know-about-our-galaxy/" target="_blank" rel="noreferrer noopener">Milky Way</a>, making it a prime area for stargazing and astrophotography. 



Image Credit: NASA



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A cosmic eye in the Puppis constellation

Today's Image of the Day from NASA features the spiral...

Today's Image of the Day from NASA Earth Observatory features a satellite view of retreating glaciers in Alaska, where meltwater is rapidly expanding glacial lakes. 



“In parts of Alaska, water is replacing ice. As glaciers thin and <a href="https://www.earth.com/news/satellite-images-reveal-hidden-retreat-of-arctic-glaciers/" target="_blank" rel="noreferrer noopener">retreat</a>, meltwater collects at their fronts, forming proglacial lakes. According to an analysis by Mauri Pelto, a glaciologist at Nichols College, three such lakes in the southeastern part of the state have grown rapidly in recent decades,” said <a href="https://earthobservatory.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA</a>.



<h2 class="wp-block-heading" id="h-retreating-glaciers-in-alaska">Retreating glaciers in Alaska</h2>



“A trio of glaciers - Yakutat, Alsek, and Grand Plateau - descend from inland mountains and flow onto the coastal plain southeast of Yakutat borough, ending at Harlequin Lake, Alsek Lake, and Grand Plateau Lake,” noted NASA.&nbsp;



The retreat of the glaciers, as well as the growth of the lakes, are visible in the image. When compared to an <a href="https://eoimages.gsfc.nasa.gov/images/imagerecords/153000/153638/fastestlake_tm5_19840705_lrg.jpg" target="_blank" rel="noreferrer noopener">image</a> captured by Landsat 5 in the summer of 1984, the changes are even more evident.



NASA elaborated on the extent of the glacier retreat from 1984 to 2024. “During this period, Yakutat Glacier’s main arm retreated 4.3 miles, while Alsek Glacier’s northern and southern arms retreated 3.3 miles and 3.4 miles, respectively. Grand Plateau Glacier’s northern arm lost the most, retreating 4.8 miles.”



<h2 class="wp-block-heading" id="h-glacial-lakes-doubled-in-size-nbsp">Glacial lakes doubled in size&nbsp;</h2>



“Collectively, the three lakes more than doubled in size over 40 years. In 1984, they covered about 50 square miles. By 2024, they spanned 90 square miles. That’s an area larger than Seneca Lake (67 square miles) - one of the Finger Lakes in New York, which also have a glacial origin,” said NASA.



Pelto noted that the lakes forming in this region are immense - starting at the mountains and spreading toward the coast - making this a new lake district that is unique in our nation.



“Millions of other lakes, named and unnamed, dot the state. But this system has grown fast, so much so that Pelto thinks it might represent the fastest lake growth in the United States this century,” said NASA.



<h2 class="wp-block-heading" id="h-understanding-glacier-retreat-nbsp">Understanding glacier retreat&nbsp;</h2>



Glacier retreat is a significant phenomenon driven primarily by global warming the results from rising greenhouse gas <a href="https://www.earth.com/news/global-carbon-dioxide-emissions-hit-a-record-high-in-2023/" target="_blank" rel="noreferrer noopener">emissions</a>.&nbsp;



As temperatures rise, glaciers lose more ice during the summer melt than they can regain in winter snowfall, causing them to shrink over time. This process has profound implications for ecosystems, water resources, and global sea levels.



<h3 class="wp-block-heading" id="h-glacial-lakes">Glacial lakes</h3>



When glaciers retreat, they often leave behind depressions in the landscape that can fill with meltwater, forming glacial lakes. These lakes are typically bounded by natural dams made of rock, ice, or moraine - accumulations of debris left behind by the glacier's movement.&nbsp;



Over the past century, the number and size of glacial lakes worldwide have increased significantly due to the accelerating pace of <a href="https://www.earth.com/news/tropical-glaciers-offer-a-glimpse-of-our-harsh-climate-reality/" target="_blank" rel="noreferrer noopener">glacier</a> retreat. This trend is especially evident in high-altitude regions like the Himalayas, the Andes, and the Alps, as well as in polar areas such as Alaska and Greenland.



<h3 class="wp-block-heading" id="h-positive-and-negative-impacts-nbsp">Positive and negative impacts&nbsp;</h3>



Glacial lakes can have both positive and negative impacts. They provide critical water sources for downstream communities, support biodiversity, and sometimes offer opportunities for hydropower development or tourism.&nbsp;



However, they also pose serious risks. The dams holding back these lakes can fail suddenly, causing glacial lake outburst floods (GLOFs). These catastrophic events can devastate downstream areas, destroying infrastructure, agricultural lands, and habitats while endangering human lives.



<h3 class="wp-block-heading" id="h-monitoring-changes">Monitoring changes</h3>



Understanding glacier retreat and glacial lake formation requires a multidisciplinary approach, combining climate science, hydrology, and geology.&nbsp;



Monitoring these changes is essential to mitigate associated risks and adapt to the evolving landscape shaped by a <a href="https://search.app?link=https%3A%2F%2Fwww.earth.com%2Fnews%2Fperu-has-lost-over-half-of-its-glaciers-in-six-decades%2F&amp;utm_campaign=aga&amp;utm_source=agsadl2%2Csh%2Fx%2Fgs%2Fm2%2F4" target="_blank" rel="noreferrer noopener">warming planet</a>.



<h2 class="wp-block-heading" id="h-glacier-retreat-worldwide">Glacier retreat worldwide</h2>



Studies and satellite observations show that most glaciers in almost all regions of the world are shrinking.&nbsp;



Melting glaciers contribute significantly to global <a href="https://www.earth.com/news/emergency-meeting-reveals-the-alarming-extent-of-antarcticas-ice-loss/" target="_blank" rel="noreferrer noopener">sea level rise</a>, which threatens coastal communities and ecosystems.



The retreat of glaciers is considered one of the clearest indicators of climate change.&nbsp;Some glaciers are retreating at unprecedented rates, indicating accelerating climate impacts.



The image was captured on August 4, 2024 by the Landsat 8 satellite.



Image Credit: NASA Earth Observatory



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Retreating glaciers and expanding meltwater lakes in Alaska

Today's Image of the Day from NASA Earth Observatory features...

Today's Image of the Day from NASA Earth Observatory features the Costa Atlántica Reserve stretching along the Atlantic coast in Argentina.



“At the far southern reaches of South America, a stretch of tidal flats, shoals, and beaches serves as a refuge for migratory shorebirds and copious aquatic life,” said <a href="https://earthobservatory.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA</a>.



“The Costa Atlántica Reserve in Argentina extends for 220 kilometers (140 miles) along the eastern shore of Tierra del Fuego. The area was designated a Ramsar site in 1995 and a provincial nature reserve in 1998." 



According to NASA, the reserve is the southernmost site both on the Ramsar list and in the Western Hemisphere Shorebird Reserve Network.



<h2 class="wp-block-heading" id="h-significance-of-the-costa-atlantica-reserve">Significance of the Costa Atlántica Reserve</h2>



The Costa Atlántica Reserve is an important conservation site that signifies Argentina's commitment to preserving its rich <a href="https://www.earth.com/news/human-induced-changes-in-ocean-salinity-threaten-biodiversity-and-marine-ecosystems/" target="_blank" rel="noreferrer noopener">coastal biodiversity</a>.&nbsp;



This vast expanse of protected area serves as a sanctuary for many species, ranging from migratory birds to marine mammals and diverse plant life.



“Tidal habitats along the coast support some 135 species of birds, while crustaceans, mollusks, fish, and cetaceans feed in the productive coastal waters,” said NASA.&nbsp;



“The topography inland of Costa Atlántica, stretching into Chile to the west, is blanketed in shrubs and grassland vegetation adapted to dry conditions - part of a semiarid ecosystem known as the Fuegian steppe.”



<h2 class="wp-block-heading" id="h-maintaining-ecological-balance-nbsp">Maintaining ecological balance&nbsp;</h2>



Established to safeguard the delicate ecosystems of dunes, estuaries, and <a href="https://www.earth.com/news/coastal-lagoons-have-high-loads-of-microplastics/" target="_blank" rel="noreferrer noopener">coastal lagoons</a>, the reserve plays a crucial role in maintaining ecological balance.&nbsp;



The Costa Atlántica Reserve provides critical habitats for numerous threatened species, including the <a href="https://www.earth.com/news/southern-right-whales-have-shifted-their-foraging-grounds/">Southern Right Whale</a>, which finds refuge in these waters during its breeding season. 



The reserve’s sheltered bays and nutrient-rich waters create an ideal environment for mothers to nurse their calves before embarking on long migrations. 



In addition to whales, the reserve supports populations of sea lions and Magellanic penguins. Its protection is vital for the long-term survival of these species in the face of climate change and human activity.



<h2 class="wp-block-heading" id="h-costa-atlantica-reserve-a-living-laboratory-nbsp">Costa Atlántica Reserve: A living laboratory&nbsp;</h2>



The Costa Atlántica Reserve is not only a refuge for wildlife but also a living laboratory for scientific research. 



Conservationists and researchers work within its bounds to monitor ecosystems, study species behaviors, and develop strategies for sustainable management. 



This ongoing research is pivotal in understanding the impacts of climate change on <a href="https://www.earth.com/news/coastal-river-deltas-face-major-threats-beyond-climate-change/" target="_blank" rel="noreferrer noopener">coastal environments</a> and in devising measures to mitigate these effects.



Furthermore, the reserve illustrates the importance of community involvement in conservation efforts. Local communities are engaged in sustainable tourism and educational programs.&nbsp;



Through <a href="https://www.earth.com/news/how-bird-photographers-improve-nesting-success/" target="_blank" rel="noreferrer noopener">eco-tourism</a> initiatives, visitors can experience the natural beauty of the reserve while contributing to its preservation.



<h2 class="wp-block-heading" id="h-tierra-del-fuego-archipelago">Tierra del Fuego archipelago</h2>



According to NASA, the broader landscape of the Tierra del Fuego archipelago was shaped by glaciers.&nbsp;



“Ice advanced over the mountains and lowlands during cold climatic periods between the mid-Pleistocene, about 1 million years ago, and the Last Glacial Maximum, about 20,000 years ago. San Sebastián Bay formed in a tectonic depression that was deepened by glacial erosion," noted NASA.&nbsp;



“Further evidence of glaciation, including hummocky moraines and fields of glacial erratics, appears around the bay, though it is too small to be visible in this image.”



“Partially enclosed by a long, sandy peninsula, San Sebastián Bay attracts copious migratory birds, some of which shuttle seasonally between the Northern and Southern Hemispheres.”



“Large populations of the Hudsonian godwit, white-rumped sandpiper, and other long-distance flyers congregate in the vast intertidal zones. This part of the reserve, however, is vulnerable to the impact of oil and gas extraction from onshore and offshore deposits.”



The image was captured on February 20, 2024 by the <a href="https://landsat.gsfc.nasa.gov/satellites/landsat-9/landsat-9-instruments/oli-2-design/" target="_blank" rel="noreferrer noopener">OLI-2</a> (Operational Land Imager-2) on Landsat 9.



Image Credit: NASA Earth Observatory&nbsp;



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Costa Atlántica Reserve in Argentina

Today's Image of the Day from NASA Earth Observatory features an explosive eruption of Mount Etna, the most active volcano in Europe. The photo was captured on February 13 by the OLI (Operational Land Imager) on the Landsat 8 satellite.



<a href="https://earthobservatory.nasa.gov/images/153962/river-of-fire-on-mount-etna" target="_blank" rel="noreferrer noopener">NASA</a> noted that the natural-color scene is overlaid with an infrared signal to distinguish the lava’s heat signature on the mountain's snowy slopes.



<h2 class="wp-block-heading" id="h-signs-of-unrest">Signs of unrest</h2>



“On February 8, 2025, Italy’s National Institute of Geophysics and Volcanology (INGV) reported that Mount Etna had begun exhibiting ‘signs of unrest above its background level,’”&nbsp;said NASA.



“That’s unsurprising for the frequently unruly Sicilian peak, one of the most active stratovolcanoes in the world. But the fiery explosions, disruptive ash clouds, and long lava flows that ensued stood out as being unusually spectacular to many Etna watchers.”



<h2 class="wp-block-heading" id="h-intensifying-eruptions-on-mount-etna">Intensifying eruptions on Mount Etna </h2>



The activity intensified on February 10th, with lava flowing from the Bocca Nuova crater at an altitude of approximately 3,000 meters above sea level.&nbsp;



According to news reports, the eruption created a striking visual as molten lava traversed the snow-covered slopes, producing rivers of lava up to 3 kilometers long and emitting ash plumes visible from several kilometers away.



The <a href="https://www.earth.com/news/new-research-enhances-predictions-on-volcanic-eruptions/" target="_blank" rel="noreferrer noopener">volcanic activity</a> attracted thousands of tourists eager to witness the spectacle. However, the influx of visitors led to traffic congestion, obstructing emergency services and prompting warnings from local authorities about the potential dangers of approaching the active volcano.



<h2 class="wp-block-heading" id="h-impacts-of-mount-etna-eruptions">Impacts of Mount Etna eruptions </h2>



Despite the dramatic displays, there were no reports of injuries or significant property damage, though experts continue to closely monitor the situation.



Satellite imagery has provided detailed views of the active lava flow cutting through the snow-covered slopes, with ash plumes dispersing from the summit.



“The presence of ash prompted authorities to raise the aviation color code to orange on February 13. On other days during this eruption, it was elevated to red, the highest level of concern. The airport in nearby Catania diverted flights amid hazardous conditions, according to news reports,” said NASA.



“Since Etna stirred to life this time around, crowds of hikers and even some skiers flocked to its slopes to witness the fiery displays and lava flows melting through snow. The eruption was ongoing as of February 18, with weak ash emissions and decreasing explosive activity.”



<h2 class="wp-block-heading" id="h-a-volcano-with-a-long-history">A volcano with a long history </h2>



Mount Etna has a history stretching back hundreds of thousands of years. Located on the east coast of Sicily, near Catania, the volcano has shaped the landscape and influenced human civilization.



The volcano’s activity dates back at least 500,000 years, with its earliest eruptions occurring beneath the sea before the landmass emerged. Over time, lava flows, <a href="https://www.earth.com/news/yellowstone-supervolcano-eruption-study-sparks-new-debate-on-where-and-when-it-will-erupt/" target="_blank" rel="noreferrer noopener">eruptions</a>, and collapses have sculpted the towering stratovolcano seen today.



Ancient civilizations were well aware of Etna’s power. Greek mythology depicted it as the forge of Hephaestus, the god of fire, while the poet Pindar described its violent eruptions. The philosopher Empedocles was even said to have perished in its fiery depths.&nbsp;



Etna’s eruptions were documented throughout Roman history, including a major event in 122 BC that devastated Catania.



During the Middle Ages and Renaissance periods, Etna continued its eruptions, frequently altering its landscape and affecting nearby settlements.&nbsp;



<h2 class="wp-block-heading" id="h-monitoring-the-activity-of-mount-etna">Monitoring the activity of Mount Etna </h2>



One of the most devastating eruptions occurred in 1669, when lava flows destroyed several villages and overwhelmed parts of Catania’s city walls. Despite these dangers, people continued to live and farm on Etna’s fertile slopes, taking advantage of its rich volcanic soil.



Scientific study of Mount Etna began in the 19th and 20th centuries, as researchers sought to understand its behavior and mitigate its risks. Advances in monitoring technology have since helped track its activity, though eruptions remain unpredictable.&nbsp;



In modern times, Etna continues to be one of the most closely watched <a href="https://www.earth.com/news/axial-seamount-large-underwater-volcano-off-us-coast-will-likely-erupt-in-2025/" target="_blank" rel="noreferrer noopener">volcanoes</a> in the world, with frequent eruptions, ash clouds, and lava flows affecting air travel and local communities.



Mount Etna was designated a UNESCO World Heritage Site in 2013 due to its geological significance and cultural history.&nbsp;



Today, the <a href="https://www.earth.com/news/earths-next-big-volcano-eruption-will-cause-global-chaos-climate-impact/" target="_blank" rel="noreferrer noopener">volcano</a> attracts tourists, scientists, and locals alike, serving as both a reminder of nature’s power and a source of economic and scientific interest.



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Fiery eruption of Mount Etna captured from space

Birds and feathers are closely tied together - feathers enable flight, provide insulation, and make courtship displays possible. Yet the origin of these remarkable structures predates birds.



Feathered dinosaurs were first reported in the 1990s, but many mysteries remain about how and when feathers emerged. Did all dinosaurs share a feathered ancestor, or did feathers appear multiple times in different lineages?&nbsp;



A new study co-authored by Paul Barrett and Xu Xing from the <a href="https://www.nhm.ac.uk/" target="_blank" rel="noreferrer noopener">Natural History Museum</a> attempts to consolidate the latest knowledge and move us closer to an answer.



<h2 class="wp-block-heading" id="h-feathers-of-the-distant-past">Feathers of the distant past</h2>



Fossil evidence has revealed that <a href="https://www.earth.com/news/modern-bird-feathers-contain-traces-of-dinosaur-feathers/" target="_blank" rel="noreferrer noopener">feathers</a> are not exclusive to modern birds and their immediate relatives. Dinosaurs with feathers existed in the distant past, showing that these structures are much more ancient than once believed.&nbsp;



However, broad questions endure: Are feathers found only in meat-eating <a href="https://www.earth.com/news/large-theropod-dinosaurs-thrived-in-polar-environments/" target="_blank" rel="noreferrer noopener">theropods</a> close to birds, or could they have been more widespread across the dinosaur family tree?



“While dozens of feathered dinosaurs have been identified since Sinosauropteryx was first unveiled in the 1990s, they’re mainly meat-eaters that are close relatives of birds,” Barrett explained. “Everyone agrees that these dinosaurs had feathers, but there’s little consensus beyond that.”



“To settle these disagreements, we need more fossils and to define what a feather is. If we can sort this out, it could reveal where feathers first came from and whether they predate the dinosaurs themselves.”



<h2 class="wp-block-heading" id="h-conflicting-theories-on-feather-origins">Conflicting theories on feather origins</h2>



Some scientists propose that feathers originated in a common ancestor of dinosaurs and pterosaurs, suggesting all later descendants inherited the potential to grow feathers - though some lost it over time.&nbsp;



Others argue that pterosaurs did not have true feathers, meaning the structures observed on them might be something else. A third viewpoint holds that feathers emerged solely within theropods, the group that includes well-known predators like Velociraptor and <a href="https://www.earth.com/news/t-rex-may-have-had-brains-and-brawn/" target="_blank" rel="noreferrer noopener">Tyrannosaurus</a>.



To resolve these debates, better fossil evidence from earlier time periods is essential. Most known feathered dinosaur fossils date to the Cretaceous, yet feathers may have evolved well before then.&nbsp;



Finding older specimens could clarify whether feathers appeared at the dawn of dinosaur evolution or surfaced in only one branch of the family tree.



<h2 class="wp-block-heading" id="h-did-early-dinosaurs-have-feathers">Did early dinosaurs have feathers?</h2>



Professor Barrett emphasized the importance of discovering prehistoric remains from much earlier geological periods.&nbsp;



“We need to find new sites with fossilized feathers, particularly from the Jurassic and the Triassic,” he said. “The Triassic is especially important, as finding feathered dinosaurs at this early time in dinosaur evolution would suggest that all dinosaurs had an ancestor with feathers.”



“If feathered dinosaurs aren’t found among early <a href="https://www.earth.com/news/dinosaurs-evolved-feathers-for-much-more-than-just-flying/" target="_blank" rel="noreferrer noopener">dinosaurs</a>, then it makes it more likely feathers were an innovation among later groups.”



Such discoveries could shift perceptions of the entire dinosaur lineage. Were feathers a universal trait that some species shed over time, or did they evolve independently in separate groups?



<h2 class="wp-block-heading" id="h-defining-a-true-feather">Defining a "true feather"</h2>



Another challenge paleontologists face involves the definition of a “true feather.” Modern bird feathers have distinct chemical and structural characteristics, including growth from a follicle in the skin. Ancient dinosaur feathers may have looked different, reflecting earlier evolutionary stages.



“To identify a true feather from a living bird, we’d look to see what it’s made out of, and its structure,” Barrett explained. “One of the characteristics we have to identify is that the feather grows out of a follicle in the skin.”



“It’s possible, however, that follicles and other modern characteristics might not have been present in all dinosaur feathers. Detailed anatomical work at a microscopic level to compare preserved skin and feathers with examples from living birds could help to resolve this.”



Fossilized skin can also offer important clues. Some specimens display bird-like tissues, hinting that the common ancestor of certain dinosaurs and birds shared these traits.&nbsp;



But other dinosaurs show more reptilian textures, indicating the possibility that feathers evolved separately in multiple lineages.



<h2 class="wp-block-heading" id="h-unraveling-the-history-of-feathers">Unraveling the history of feathers</h2>



For the moment, experts remain divided on how feathers took hold in dinosaur evolution. The challenge lies in discovering enough well-preserved fossils from the right time periods and reaching a clear consensus on what counts as a feather.&nbsp;



From tantalizing glimpses in existing fossils to ongoing searches in promising new sites, researchers continue to piece together this ancient puzzle.



Ultimately, answers about the origins of feathers may transform how scientists understand dinosaur evolution - and the emergence of <a href="https://www.earth.com/news/bird-evolution-timeline-pushed-back-20-million-years-by-baminornis-zhenghensis-discovery/" target="_blank" rel="noreferrer noopener">birds</a>.&nbsp;



Until then, paleontologists will continue to search the world for the fossils which can finally settle this decades-old debate. Each new find has the potential to reshape our perception of the prehistoric world and the ancestors of the birds we see in our skies today.



The study is published in the journal <a href="https://dx.doi.org/10.1098/rsbl.2024.0517" target="_blank" rel="noreferrer noopener">Biology Letters</a>.



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From dinosaurs to birds: The mysterious origin of feathers

Birds and feathers are closely tied together - feathers enable...

Memory plays a critical role in learning and survival across species. Particularly in primates, social interaction significantly shapes how memory develops and functions. 



Primates, from monkeys to great apes, spend substantial time in social environments, making it crucial for them to observe and learn from others effectively.



<h2 class="wp-block-heading" id="h-social-interactions-among-primates">Social interactions among primates</h2>



Primates live closely together in groups. They rely heavily on noticing social signals from others, like facial expressions and gestures.



From birth, primates naturally focus more on interacting with each other than with objects or things.



This strong preference for social interaction helps them develop important skills, especially in how they learn and remember information. 



Paying attention to others is crucial for their brain development and memory formation, influencing how primates learn and adapt throughout life.



<h2 class="wp-block-heading" id="h-social-interactions-boost-ape-memory">Social interactions boost ape memory</h2>



A team of researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, examined how social interactions affect memory in great apes.



They presented both young and adult apes with videos showing a human hand (social model) or a mechanical claw (non-social model) constructing a tower.



"We found that apes better remembered a tower when they saw a hand building it rather than a mechanical claw. This is because they paid more attention to the actions of a social being rather than a machine," noted Marie Padberg, the first author of the study.



<h2 class="wp-block-heading" id="h-attention-improves-social-memory">Attention improves social memory</h2>



To understand this better, the researchers partnered with the <a href="https://www.unisa.edu.au" target="_blank" rel="noreferrer noopener">University of South Australia</a>. They used artificial intelligence (AI) to analyze regular video recordings of the apes. 



The AI technology measured the apes' heart rates to determine their attention levels during the experiment.



The results showed that apes paid more attention during social demonstrations. Higher attention was directly linked to better memory, showing how closely attention and memory are connected.



<h2 class="wp-block-heading" id="h-processing-social-stimuli">Processing social stimuli</h2>



Interestingly, improved memory for social events was evident only in adult apes. Younger apes, including juveniles and infants, did not show memory enhancement when viewing social models. 



This outcome differs from humans, who exhibit superior social memory from infancy. These findings suggest a developmental difference between humans and other apes in processing social stimuli.



Study senior author Daniel Haun is the director of the Department of Comparative Cultural Psychology at the Max Planck Institute for Evolutionary Anthropology.



"Non-human ape infants and juveniles did not show superior memory for social events. There could be several reasons for this, including the nature of the objects, the complexity of the task, or the duration of the videos," noted Haun.



"Further research is needed to determine whether superior social memory at younger ages is truly a uniquely human phenomenon."



<h2 class="wp-block-heading" id="h-developmental-timing-and-memory">Developmental timing and memory</h2>



This study highlights how important the timing of cognitive development is in primates. It suggests that non-human primates, like apes, might only show improved memory from social interactions as they grow older.



Younger apes do not experience this benefit early in life, unlike human infants who show strong social memory from birth. 



By understanding these differences in developmental timing, scientists can better distinguish how human thinking differs from that of other primates.



<h2 class="wp-block-heading" id="h-social-memory-across-apes">Social memory across apes</h2>



The research took place at the <a href="https://www.eva.mpg.de/comparative-cultural-psychology/studying-non-human-primates/wolfgang-koehler-primate-research-center/" target="_blank" rel="noreferrer noopener">Wolfgang Köhler Primate Research Center</a> in Leipzig, Germany. 



The scientists studied 42 great apes, including chimpanzees, bonobos, gorillas, and orangutans. These apes ranged in age from as young as 3 months to as old as 47 years.



This study is the first to investigate how social memory develops as apes grow older. The results represent an important step forward in understanding similarities and differences between human and ape psychology.



<h2 class="wp-block-heading" id="h-future-research-directions">Future research directions</h2>



The detailed results are published in the journal Animal Behaviour. They show how paying attention to social interactions helps improve memory in different species.



Future research may explore how the difficulty of tasks, familiarity with objects, and interactions within social groups affect memory. These studies will help scientists understand more clearly how both humans and other primates develop and use social memory.



The study is published in the journal <a href="https://www.sciencedirect.com/science/article/pii/S0003347225000089?via%3Dihub" target="_blank" rel="noreferrer noopener">Animal Behaviour</a>.



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Social interactions have a surprising influence on memory in great apes

Memory plays a critical role in learning and survival across...

The natural environment is repeatedly reinventing itself with dynamic processes which have a tendency to continue on for millions of years. Extinction events are among the strongest forces which not only kill specific life forms but also offer the basis for fresh avenues of evolution. 



A recent study evokes a fascinating image of the process, revealing how the death of the largest dinosaurs indirectly created the fruit-rich habitats which were so important to our primate ancestors.



The research was led by Christopher Doughty, an ecoinformatics professor at <a href="https://nau.edu/" target="_blank" rel="noreferrer noopener">Northern Arizona University</a>.



<h2 class="wp-block-heading" id="h-a-prehistoric-legacy">A prehistoric legacy</h2>



Sauropods, the long-necked, plant-munching dinosaurs of the ancient world, had a massive influence on the world around them. These hulking dinosaurs knocked over trees on a routine basis and munched through tons of plant matter. 



When Sauropods went extinct some 66 million years ago, their loss profoundly changed ecosystems. Forests rebounded and closed up, which decreased the amount of sunlight on the ground and paved the way for an impressive evolutionary shift.



<h2 class="wp-block-heading" id="h-sauropods-and-ecological-change">Sauropods and ecological change</h2>



The extinction of Sauropods enabled trees to evolve without interruptions. The forests became denser, and tree competition for light intensified. 



Trees developed larger fruits and seeds to dominate others, and these provided their offspring with an advantage over others by supplying them with additional energy and greater survival chances in shaded conditions.



"At first glance, the darker forest understory caused by dinosaur extinctions may seem unimportant, but it could have directly led to the evolution of our fruit-eating primate ancestors," said Professor Doughty.



<h2 class="wp-block-heading" id="h-the-dinosaur-fruit-connection">The dinosaur-fruit connection</h2>



Before the dinosaurs went extinct, fruits were scarce, and seeds were small. But with the ecological niche left open by the sauropods, plants evolved immediately. 



Stronger seedlings, with larger seeds, were able to compete for limited sunlight. In addition, fleshy fruits evolved as an incredibly efficient way of enticing animals to scatter seeds and reproduce.



Even though this evolution scenario was previously theorized, no fossil records existed to conform the hypothesis.



To investigate, Professor Doughty and his team developed a cutting-edge model of seed and fruit size evolution after the dinosaurs became extinct. The model precisely replicated fossil records for the last 65 million years and decisively substantiated the hypothesis.



<h2 class="wp-block-heading" id="h-reversal-of-dinosaur-driven-fruit-trends">Reversal of dinosaur-driven fruit trends</h2>



Interestingly, the model also forecasted a future reversal of seed evolutionary patterns. 



Seeds began to shrink about 35 million years ago. This coincided with the appearance of new large mammals that were successful in duplicating, though on a smaller scale, the forest-clearing behavior previously shown by sauropods.



"Our model predicted these animals would open the forest enough that sufficient light began to enter the understory, and larger seeds were no longer successful over smaller seeds," explained Doughty. 



"The evolutionary pressure for seed size to increase began to diminish. Thus, we were able to explain the trends in seed size over time without resorting to external influences such as climate change."



<h2 class="wp-block-heading" id="h-megafauna-extinction-and-ecological-reset">Megafauna extinction and ecological reset</h2>



About 50,000 years ago, large mammals like mammoths went extinct. These animals previously opened forests by knocking down trees and clearing vegetation. Their extinction allowed forests to become dense and dark again. 



With less sunlight reaching the forest floor, plants adapted by producing larger seeds. This highlights how big animals shape their environment, influencing the evolution of plants.



<h2 class="wp-block-heading" id="h-humans-as-ecosystem-shapers">Humans as ecosystem shapers </h2>



Modern human activity mimics the prehistoric impacts of the giants. Current selective forest harvesting mimics the prehistoric pressure imposed by dinosaurs on seed size and dispersal.



But if humans stop modifying forest structure and are not substituted by other megafauna, forests will shift back to more dense, dark structures, and this may trigger another evolutionary adjustment towards larger seeds. 



"These results provide a striking example of how large dinosaurs - and their eventual extinction - not only shaped their contemporary environment but also triggered cascading effects on ecosystems for millions of years," said Benjamin Wiebe, an NAU researcher.



"The next time you're eating fruit or pondering, 'why am I here,' consider the impact of the dinosaur extinctions."



The study is published in the journal <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1111/pala.70002" target="_blank" rel="noreferrer noopener">Palaeontology</a>.



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How dinosaur extinction influenced fruit evolution

The natural environment is repeatedly reinventing itself with dynamic processes...

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Today&#8217;s Video of the Day from the <a href="https://www.acs.org/">American Chemical Society</a> series Reactions describes the science behind the perfect dog food.
What is it that keeps dogs interested in coming back for the same meal every day?
Most dog food formulas are similar, consisting of grains, meats, fats, vitamins, and additives. 
The secret to attracting dogs, however, are special ingredients developed by flavor chemists called palatants. These chemicals, which literally smell like dead bodies, are often sprayed on the outside of dog food kibbles to keep canines coming back for more. 
&#8212;
By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer
Video Credit: American Chemical Society

What makes some dog food irresistable?

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