NASA Astronomy Picture of the Day 15 May 2023: The mesmerizing Eagle Nebula
On a daily basis, NASA leaves us mesmerized with mind-blowing pictures of outer space that its massive telescopes on the ground and up in the sky keep taking. And today is no exception, with the awe-inspiring Eagle Nebula refreshing our jaded spirits. A nebula is a star-birthing region – yes, stars are born, age, and die too – located in Interstellar space, which is the space between stars. It consists of gases, mainly hydrogen, and helium. Although most nebulae belong to just three types – spherical, elliptical, and bipolar, some of them might be irregularly shaped, so much so that they resemble objects on Earth. Some of the most peculiar shapes include the Headphone Nebula, the Heart and Soul Nebula, and the Flying Ghost Nebula. According to NASA, a Nebula can contain as few as ten stars or as many as millions of stars.
Today’s NASA Astronomy Picture of the Day is a snapshot of M16, also known as the Eagle Nebula which spans about 20 light-years across. The nebula, discovered in 1745 by the Swiss astronomer Jean-Philippe Loys de Cheseaux, is located 7,000 light-years from Earth in the constellation Serpens, according to NASA.
What we really found to be mind-boggling is the active part of this star-forming region. It has dense columns at the center known as the Pillars of Creation! These structures are light-years in length, but amazingly, they are slowly contracting gravitationally to form stars.
This awesome picture was captured by astrophotographer Gianni Lacroce.
NASA’s description of the picture
From afar, the whole thing looks like an eagle. A closer look at the Eagle Nebula, however, shows the bright region is actually a window into the center of a larger dark shell of dust. Through this window, a brightly-lit workshop appears where a whole open cluster of stars is being formed. In this cavity, tall pillars and round globules of dark dust and cold molecular gas remain where stars are still forming. Already visible are several young bright blue stars whose light and winds are burning away and pushing back the remaining filaments and walls of gas and dust.
The Eagle emission nebula, tagged M16, lies about 6500 light years away, spans about 20 light-years, and is visible with binoculars toward the constellation of the Serpent (Serpens). This picture involved long and deep exposures and combined three specific emitted colors emitted by sulfur (colored as yellow), hydrogen (red), and oxygen (blue).
A "supervolcano" in Italy last erupted in 1538. Experts warn it's "nearly to the breaking point" again. – CBS News
A long-dormant “supervolcano” in southern Italy is inching closer to a possible eruption — nearly six centuries after it last erupted, according to European researchers.
The Campi Flegrei volcano, which is located near the city of Naples, has become weaker over time and as a result is more prone to rupturing, according to a peer-reviewed study conducted by researchers from England’s University College London and Italy’s National Research Institute for Geophysics and Volcanology.
The study used a model of volcano fracturing to interpret the patterns of earthquakes and ground uplift. There have been tens of thousands of earthquakes around the volcano, and the town of Pozzuoli, which rests on top of Campi Flegrei, has been lifted by about 13 feet as a result of them. The quakes and rising earth have stretched parts of the volcano “nearly to the breaking point,” according to a news release about the study, and the ground seems to be breaking, rather than bending.
The earthquakes are caused by the movement of fluids beneath the surface, the news release said. It’s not clear what those fluids are, but researchers said they may be molten rock, magma or natural volcanic gas.
The earthquakes have taken place during the volcano’s active periods. While it last erupted in 1538, it has been “restless” for decades, with spikes of unrest occurring in the 1950s, 1970s and 1980s. There has been “a slower phase of unrest” in the past 10 years, researchers said, but 600 earthquakes were recorded in April, setting a new monthly record.
According to LiveScience, Campi Flegrei is often referred to as a “supervolcano,” which can produce eruptions reaching a category 8 — the highest level on the Volcano Explosivity Index. However, Campi Flegrei’s biggest-ever eruption technically ranked as a category 7, which is still considered a very large and disastrous eruption, LiveScience reported.
While Campi Flegrei — which means “burning fields” — may be closer to rupture, there is no guarantee that this will actually result in an eruption, the study concluded.
“The rupture may open a crack through the crust, but the magma still needs to be pushing up at the right location for an eruption to occur,” said Professor Christopher Kilburn, who studies earth sciences at University College London and was the lead author of the study.
Kilburn said that this is the first time the model has been applied to a volcano in real-time. Since first using the model in 2017, the volcano has behaved as predicted, Kilburn said, so researchers plan to expand the use of the model to look at other volcanoes that reawakened after long periods of dormancy. The goal is to establish more reliable criteria to decide if an eruption is likely and establish a model that can be applied to multiple volcanoes.
“The study is the first of its kind to forecast rupture at an active volcano. It marks a step change in our goal to improve forecasts of eruptions worldwide,” Kilburn said.
Mountains 3 To 4 Times Higher Than Mount Everest Found Deep Inside Earth: Scientists – NDTV
The deep Earth contains mountains with peaks three to four times higher than Mount Everest, scientists have found. According to the BBC, a team of experts from Arizona State University used seismology centres in Antarctica and found these astonishingly huge mountains in the boundary between the core and mantle, around 2,900 kilometres deep inside our planet.
“The mountain-like structures they revealed are utterly mysterious,” the BBC report read. Scientists explained that these underground mountain ranges – dubbed ultra-low velocity zones or ULVZs – had managed to escape the experts’ gaze all these years until earthquakes and atomic explosions generated enough seismic data to be spotted by them.
Scientists believe that these huge mountain ranges are over 24 miles (38 kilometres) in height, while Mount Everest is around 5.5 miles (8.8 kilometres) from the surface. “Analysing 1000’s of seismic recordings from Antarctica, our high-definition imaging method found thin anomalous zones of material at the CMB [core-mantle boundary] everywhere we probed,” Arizona State University geophysicist Edward Garnero said in a statement.
“The material’s thickness varies from a few kilometres to 10’s of kilometres. This suggests we are seeing mountains on the core, in some places up to 5 times taller than Mt. Everest,” he added.
Also Read | Stephen Hawking’s Famous Theory Could Mean That Entire Universe Is Doomed To Evaporate: Study
Further, as per the report, experts explained the possible reason behind the formation of these mysterious mountain peaks. They believe that these ancient formations were created when oceanic crusts were formed into Earth’s interior. They also argue that it might have begun with tectonic plates slipping down into our planet’s mantle and sinking to the core-mantle boundary. These then slowly spread out to form an assortment of structures, leaving a trail of both mountains and blobs. This would, therefore, mean that these mysterious mountains are made of ancient oceanic crust, which is a combination of basalt rock and sediments from the ocean floor.
Now, with this recent discovery, scientists are seeking to argue that these underground mountains may play a critical role in how heat escapes the Earth’s core. “Seismic investigations, such as ours, provide the highest resolution imaging of the interior structure of our planet, and we are finding that this structure is vastly more complicated than once thought,” study co-author and University of Alabama geoscientist Samantha Hansen said in a statement.
“Our research provides important connections between shallow and deep Earth structure and the overall processes driving our planet,” she added.
Campi Flegrei volcano edges closer to possible eruption
The Campi Flegrei volcano in southern Italy has become weaker and more prone to rupturing, making an eruption more likely, according to a new study by researchers at UCL (University College London) and Italy’s National Research Institute for Geophysics and Volcanology (INGV).
The volcano, which last erupted in 1538, has been restless for more than 70 years, with two-year spikes of unrest in the 1950s, 1970s and 1980s, and a slower phase of unrest over the last decade. Tens of thousands of small earthquakes have occurred during these periods and the coastal town of Pozzuoli has been lifted by nearly 4 m (13 ft), roughly the height of a double-decker bus.
The new study, published in the journal Communications Earth & Environment, used a model of volcano fracturing, developed at UCL, to interpret the patterns of earthquakes and ground uplift, and concluded that parts of the volcano had been stretched nearly to breaking point.
Lead author Professor Christopher Kilburn (UCL Earth Sciences) said, “Our new study confirms that Campi Flegrei is moving closer to rupture. However, this does not mean an eruption is guaranteed. The rupture may open a crack through the crust, but the magma still needs to be pushing up at the right location for an eruption to occur.”
“This is the first time we have applied our model, which is based on the physics of how rocks break, in real-time to any volcano.”
“Our first use of the model was in 2017 and since then Campi Flegrei has behaved as we predicted, with an increasing number of small earthquakes indicating pressure from below.”
“We will now have to adjust our procedures for estimating the chances of new routes being opened for magma or gas to reach the surface.”
“The study is the first of its kind to forecast rupture at an active volcano. It marks a step change in our goal to improve forecasts of eruptions worldwide.”
Dr. Nicola Alessandro Pino from the Vesuvius Observatory, which represents the INGV in Naples, said, “Our results show that parts of the volcano are becoming weaker. This means that it might break even though the stresses pulling it apart are smaller than they were during the last crisis 40 years ago.”
Campi Flegrei is the closest active volcano to London. It is not an obvious volcano because, instead of growing into a traditional mountain, it has the shape of a gentle depression 12-14 km (7.5-8.5 miles) across (and thus is known as a caldera). This explains why 360,000 people now live on its roof.
For the past decade, the ground below Pozzuoli has been creeping upwards at about 10 cm (4 in) a year. Persistent small earthquakes have also been registered for the first time since the mid-1980s. More than 600 were recorded in April, the largest monthly number so far.
The disturbance has been caused by the movement of fluids about 3 km (2 miles) beneath the surface. Some of the fluids may be molten rock, or magma, and some may be natural volcanic gas. The latest phase of unrest appears likely to be caused by magmatic gas that is seeping into gaps in the rock, filling the 3 km-thick crust like a sponge.
The earthquakes occur when faults (cracks) slip due to the stretching of the crust. The pattern of earthquakes from 2020 suggests the rock is responding in an inelastic way, by breaking rather than bending.
Dr. Stefania Danesi from INGV Bologna said, “We cannot see what is happening underground. Instead we have to decipher the clues the volcano gives us, such as earthquakes and uplift of the ground.”
In their paper, the team explained that the effect of the unrest since the 1950s is cumulative, meaning an eventual eruption could be preceded by relatively weak signals such as a smaller rate of ground uplift and fewer earthquakes. This was the case for the eruption of the Rabaul caldera in Papua New Guinea in 1994, which was preceded by small earthquakes occurring at a tenth of the rate than had occurred during a crisis a decade earlier.
Campi Flegrei’s current tensile strength (the maximum stress a material can bear before breaking when it is stretched) is likely to be about a third of what it was in 1984, the researchers said.
The team emphasized that an eruption was not inevitable. Dr. Stefano Carlino from the Vesuvius Observatory explained, “It’s the same for all volcanoes that have been quiet for generations. Campi Flegrei may settle into a new routine of gently rising and subsiding, as seen at similar volcanoes around the world, or simply return to rest. We can’t yet say for sure what will happen. The important point is to be prepared for all outcomes.”
Professor Kilburn and colleagues will now apply the UCL model of volcano fracturing to other volcanoes that have reawakened after a long period of time, seeking to establish more reliable criteria for deciding if an eruption is likely. Currently, eruptions are forecast using statistical data unique to each volcano, rather than drawing on fundamental principles that can be applied to multiple volcanoes.
Potential for rupture before eruption at Campi Flegrei caldera, Southern Italy, Communications Earth & Environment (2023). DOI: 10.1038/s43247-023-00842-1
University College London
Campi Flegrei volcano edges closer to possible eruption (2023, June 9)
retrieved 9 June 2023
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