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NASA Says Saturn’s Moon Has “The Ingredients Necessary For a Habitable Environment”

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A New Discovery

NASA just released evidence that a liquid water ocean that could support life lies beneath the icy surface of Saturn’s moon Enceladus. The agency reports that the world has many of the “ingredients needed for a habitable environment.”

Thanks to Cassini, organic chemicals—carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur—which are the basic building blocks of life, were seen spraying forth from the “tiger stripe” cracks on the cold surface of the moon.

Additionally, in the paper published in Science, which comes from researchers on the Cassini mission, it was revealed that molecular hydrogen, which NASA notes, “could potentially provide a chemical energy source for life,” is pouring into the ocean on Enceladus via hydrothermal vents on the seafloor.

It has almost all of the ingredients you would need to support life as we know it.

In an interview with The Washington Post, Peter Girguis, a deep sea biologist at Harvard who is not associated with the research, noted the significance in relation to discovering microbial life: “For a microbiologist thinking about energy for microbes, hydrogen is like the gold coin of energy currency. If you had to have one thing, one chemical compound, coming out of a vent that would lead you to think there’s energy to support microbial life, hydrogen is at the top of that list.”

“Confirmation that the chemical energy for life exists within the ocean of a small moon of Saturn is an important milestone in our search for habitable worlds beyond Earth,” added Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory, in a NASA press release. “We now know that Enceladus has almost all of the ingredients you would need to support life as we know it on Earth,” she continued.

Water Means Life

To clarify, water, which supports and cradles life on Earth, is abundant in our solar system. As University of Michigan planetary scientist Sushil Atreya told Scientific American, water is necessary for life-as-we-know-it for a number of important reasons: “Liquid water acts as a solvent, as a medium and as a catalyst for certain types of proteins, and those are three main things that allow life to flourish.”

Indeed, everywhere that we find water on Earth, we find life—and enough water appears to be on this world, and in the proper conditions, that it seems likely that we will find alien life there.

“The way the jets react so responsively to changing stresses on Enceladus suggests they have their origins in a large body of liquid water,” Christophe Sotin co-author and Cassini team member said in the NASA release. “Liquid water was key to the development of life on Earth, so these discoveries whet the appetite to know whether life exists everywhere water is present” (pun, probably, intended).

“Although we can’t detect life, we’ve found that there’s a food source there for it. It would be like a candy store for microbes,” said Hunter Waite, lead author of the Cassini study.

In a statement, Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at Headquarters in Washington, succinctly summarized the significance of the find: “This is the closest we’ve come, so far, to identifying a place with some of the ingredients needed for a habitable environment. These results demonstrate the interconnected nature of NASA’s science missions that are getting us closer to answering whether we are indeed alone or not.”

References: NASA, Scientific American, Live Science

The Water You Drink Is Older Than The Planet You're Standing On

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The next time you reach for a glass of water you might want to think about its primordial origins. A new study suggests that upwards of 50% of the Earth's water may be older thank the solar system itself. A recent experiment conducted by Ilse Cleeves at the University of Michigan may finally settle a debate about just how far back in galactic history our planet and our solar system's water formed.

There are two schools of thought on the matter: (1) the molecules in comet ices and terrestrial oceans were born within the solar system itself, or (2) the water originated much earlier in the cold molecular cloud that generated the sun and its protoplanetary disk.

According to Cleeves, it's the latter; her simulation shows that between 30-50% came from the molecular cloud, making it roughly a million years older than the solar system. From the University of Michigan release:

To arrive at that estimate, Cleeves and Ted Bergin, a professor of astronomy, simulated the chemistry that went on as our solar system formed. They focused on the ratio of two slightly different varieties of water—the common kind and a heavier version. Today, comets and Earth's oceans hold particular ratios of heavy water—higher ratios than the sun contains.

"Chemistry tells us that Earth received a contribution of water from some source that was very cold—only tens of degrees above absolute zero, while the sun being substantially hotter has erased this deuterium, or heavy water, fingerprint," Bergin said.

To start their solar system simulation, the scientists wound back the clock and zeroed out the heavy water. They hit "go" and waited to see if eons of solar system formation could lead to the ratios they see today on Earth and in comets.

"We let the chemistry evolve for a million years—the typical lifetime of a planet-forming disk—and we found that chemical processes in the disk were inefficient at making heavy water throughout the solar system," Cleeves said. "What this implies is if the planetary disk didn't make the water, it inherited it. Consequently, some fraction of the water in our solar system predates the sun."

One of the implications of this study is our sense of how much water — an important precursor for life — exists in the galaxy and in individual solar systems. This model suggests that other stellar systems also had access to the same ancient water reserves which were crucial for the development of life on Earth.

Water, therefore, may be quite abundant in the Milky Way and beyond.

"The implications of these findings are pretty exciting," Cleeves said. "If water formation had been a local process that occurs in individual stellar systems, the amount of water and other important chemical ingredients necessary for the formation of life might vary from system to system. But because some of the chemically rich ices from the molecular cloud are directly inherited, young planetary systems have access to these important ingredients."

To which Bergin added: "Based on our simulations and our growing astronomical understanding, the formation of water from hydrogen and oxygen atoms is a ubiquitous component of the early stages of stellar birth. It is this water, which we know from astronomical observations forms at only 10 degrees above absolute zero before the birth of the star, that is provided to nascent stellar systems everywhere."

Check out the entire study at Science: "The ancient heritage of water ice in the solar system." Supplementary info via University of Michigan.

Scientists Discover Incredible New Kind Of Ice Thought To Exist In Uranus

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Scientists have created a “strange” new form of water that behaves like a cross between a liquid and a solid. The substance, known as “superionic water ice”, is thought to be a key component in the structure of distant planets in our solar system. Researchers had predicted the existence of such a substance as far back as 1988, and while numerical simulations appeared to prove its existence, these are the first experiments to confirm those findings.

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“These are very challenging experiments, so it was really exciting to see that we could learn so much from the data,” said Dr Marius Millot, a physicist at Lawrence Livermore National Laboratory in California, who led the study. “Especially since we spent about two years making the measurements and two more years developing the methods to analyse the data.”

Depiction of the movement of hydrogen ions (pink) within the solid crystal lattice of oxygen ions within superionic water ice (S Hamel/M Millot/J Wickboldt/LLNL/NIF)

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The scientists used a technique called “laser-driven shock compression” to not only confirm the existence of the substance, but also verify predictions about the composition of planets like Neptune and Uranus.

“Our work provides experimental evidence for superionic ice and shows that these predictions were not due to artefacts in the simulations, but actually captured the extraordinary behaviour of water at those conditions,” said Dr Millot.

The research was published in the journal Nature Physics. While normal ice consists of water molecules linked up to form a solid, superionic water ice is made up of ions – atoms that carry positive or negative charges. Specifically, its structure consists of hydrogen ions flowing through a solid crystal made from oxygen ions.

Laser-driven shock compression experiment to recreate planetary interior conditions and study the properties of superionic water ice (M Millot/E Kowaluk/J Wickboldt/LLNL/LLE/NIF)

“That’s a really strange state of matter,” Dr Millot told the New York Times.

Unlike conventional ice, the superionic variety requires incredibly high temperatures to form, as well as high pressures. The research team achieved this by crushing ice between two diamonds, before firing a laser at it to further increase the pressure and heat. At nearly 5,000C and two times atmospheric pressure, the scientists saw evidence a superionic water ice had formed and then melted. In total, the whole experiment only took between 10 and 20 nanoseconds. The next step, according to the scientists, is to determine the structure of the oxygen crystals found in superionic water ice.

Though superionic water ice is not found anywhere on Earth, it may be present in large quantities inside Uranus and Neptune, where the high temperatures and pressures are similar to those created by Dr Millot and his team in their experiments. Some scientists have suggested the presence of this matter inside these distant planets may explain their unusual magnetic fields.

“Magnetic fields provide crucial information about the interiors and evolution of planets, so it is gratifying that our experiments can test – and in fact, support – the thin-dynamo idea that had been proposed for explaining the truly strange magnetic fields of Uranus and Neptune,” said Professor Raymond Jeanloz, a co-author of the paper based at the University of California, Berkeley. “It’s also mind-boggling that frozen water ice is present at thousands of degrees inside these planets, but that’s what the experiments show.”

New Map Of Moon Titan Reveals It Has A Sea Level Similar To Earth

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Ligeia Mare, a look at the second largest known body of liquid on the Surface of Saturn’s moon Titan. Image Credit: NASA/JPL-Caltech

Titan, Saturn’s giant satellite, is more Earth-like than previously thought.

Previous observations have shown that Titan has a dense atmosphere and stable liquid on its surface.

Of course, its seas and lakes are not made of water, but methane and ethane.

Now, researchers have found a new way in which this distant alien satellite looks disturbingly like our planet: it has sea level, a constant average elevation in relation to gravitational attraction.

The new study, based on data from NASA’s Cassini spacecraft and published in the journal Geophysical Research Letters, finds that Titan’s seas are constantly rising relative to their gravitational pull, just like Earth’s oceans.

It seems that the smallest lakes on Titan appear at elevations several hundred meters higher than sea level.

On Earth, lakes are also commonly found at high altitudes.

The highest lake navigable by large ships, the Titicaca, located at more than 3,700 meters above sea level.

The new study suggests that elevation is important because Titan’s liquid bodies appear to be connected below the surface in something like an aquifer system on Earth.

The hydrocarbons seem to flow below the surface of the moon in a similar way as water flows through porous underground rock or gravel on our planet, which means that nearby lakes communicate with each other and share a common liquid level.

A rendered size-comparison sheet between the Planet Earth, the Moon, and Saturn’s Moon Titan. Image Credit: Shutterstock.

“We’re measuring the elevation of a liquid surface on another body 10 astronomical units away from the sun to an accuracy of roughly 40 centimeters,” explains Alex Hayes, of Cornell University.

“Because we have such amazing accuracy we were able to see that between these two seas the elevation varied smoothly about 11 meters, relative to the center of mass of Titan, consistent with the expected change in the gravitational potential. We are measuring Titan’s geoid. This is the shape that the surface would take under the influence of gravity and rotation alone, which is the same shape that dominates Earth’s oceans.”

Much of the study was based on the data obtained by the Cassini radar instrument.

A new topographic map published in Geophysical Research Letters offered new insight into Titan.

The map exposed several new features on Titan, including new mountains, none of more than 700 meters in elevation.

It also offered a global view of the highs and lows of its topography, which allowed scientists to confirm that two places in the equatorial region of Titan which are in fact depressions that could be ancient dry seas or cryovolcanic flows.

The map also revealed that Titan is a bit more flattened than previously known, suggesting that there is more variability in the thickness of its crust than previously thought.

Despite the fact that we have learned much about Titan in recent years, only 9 percent of Titan has been mapped in high-resolution, while around 30 percent was imaged in lower resolution.

Breaking: Alien Life ‘May Be Thriving On Saturn’s Moon’

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Alien life may be thriving in a warm, underground ocean on Saturn’s icy moon Enceladus, according to new research. Scientists say tidal forces could have kept the subterranean sea liquid for billions of years – enough time for organisms to have developed. The mysterious world has a very fragmented and porous rocky interior, ideal conditions for flowing water with the friction creating 10 gigawatts of heat.

This amount of energy would light and heat more than 7 million homes – and explains all the global properties of Enceladus observed by Cassini. Earlier this year NASA's spacecraft picked up the first evidence of chemical reactions deep below the frozen crust – suggesting an environment capable of supporting life. It was one of its final successes before plunging into Saturn’s atmosphere at the end of its 12 year expedition to the ringed planet.

The latest study published in Nature Astronomy is based on a state-of-the-art computer model using Cassini’s observations. These showed Enceladus has a global ocean fed by intense hydrothermal activity beneath the surface. Its measurements of water escaping from geysers at the south pole showed the sea is salty – and contains organic molecules. But tidal forces within the ice are not sufficient to sustain this activity.

Without an additional contribution the ocean would freeze in less than 30 million years. So planetary scientist Dr Gael Choblet and colleagues explored the possibility this additional heating comes from the effect of tidal forces acting on the highly porous core.

They found enough heat would be generated by the resulting hydrothermal activity to keep the ocean liquid for “tens of millions to billions of years.” This heat is dissipated mainly at the poles – explaining why the ice shell is thinner there. The model suggests an ocean has existed within Enceladus for eons – even though the small moon is only 887 million miles away from the Sun.

Dr Choblet said: “What we show is hydrothermal processes probably provide means to have efficient interactions between rocks and hot water in a large volume deep within the moon. What had been shown earlier is hydrothermal processes were very likely occurring right now within Enceladus. What we show in our study is the context of this activity. We also suggest this activity is relatively stable – for at least 10s of millions of years.”

He said the life expectancy of the ocean and – perhaps more importantly – how long the hydrothermal activity has been occurring would be key to the emergence of microbes and other organisms.

Dr Choblet, of Nantes University in France, said: “Only future missions equipped with instruments capable of analysing the organic molecules in the plume with higher accuracy than the Cassini measurements will tell us whether the required conditions have been sustained long enough for life to have emerged on this distant ocean world. Projected missions back to Enceladus are currently under consideration – especially in the US.

If selected these would already enable us to analyse the chemicals emitted though Enceladus plumes with a much better precision than the instruments onboard the Cassini spacecraft could – especially the complex organics. With a possible launch in 2024 this means that new, more precise use information could be obtained in the 2030s.”

In October 2015 NASA sent Cassini into a deep dive through one of the plumes of spray which shoot up into the atmosphere through cracks in the ice, and discovered hydrogen and carbon dioxide. Scientists are certain they were created by reactions between warm water and rocks on the ocean floor.

Crucially, if hydrogen is present it can mix with carbon dioxide to form methane, which is consumed by microbes in the deep, dark seas of our own planet. Enceladus is the sixth largest moon of Saturn.

It is around 310 miles in diameter and approximately 790 million miles from Earth. Scientists had long suspected that liquid water could exist on the moon because of the extreme tidal forces acting on the satellite from Saturn’s gravity.

Although scientists previously thought Enceladus’ icy crust was around 13 miles thick, Cassini found at the South Pole it could be as little as three miles deep. The distant moon has long been hailed as one of the three best potential locations for finding extraterrestrial life in the solar system. The others are Mars and Jupiter’s satellite Europa. Such a discovery of even primitive microbes would make it almost certain life is widespread throughout the universe.

Dr Choblet said: “Chemical analyses indicate that the ocean is salty and is fed by ongoing hydrothermal activity. Here, we show that more than 10 GW of heat can be generated by tidal friction inside the unconsolidated rocky core. Water transport in the tidally heated permeable core results in hot narrow upwellings with temperatures exceeding 363K (90 degrees Celsius) characterised by powerful hotspots of 1 to 5 GW at the seafloor, particularly at the south pole.” Recent data from Cassini has shown that at the south pole, it could be as little as three miles deep.

The release of heat in narrow regions favours intense interaction between water and rock, and the transport of hydrothermal products from the core to the plume sources. We predict that this internal activity can be sustained for tens of millions to billions of years.”

Via Telegraph

NASA: "The Death of a Planet" -- Venus Had an Ocean and Habitable Surface Temperatures for Two Billion Years

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“These results show ancient Venus may have been a very different place than it is today,” siad Michael Way, a researcher at NASA’s Goddard Institute for Space Studies (GISS) in New York. Venus today is a hellish world. It has a crushing carbon dioxide atmosphere 90 times as thick as Earth’s. There is almost no water vapor. Temperatures reach 864 degrees Fahrenheit (462 degrees Celsius) at its surface. Venus may have had a shallow liquid-water ocean and habitable surface temperatures for up to 2 billion years of its early history, according to computer modeling of the planet’s ancient climate by scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York.

Artist’s Impression of Venus When It Was like Earth Billions of Years Ago

The findings, published in the journal Geophysical Research Letters, were obtained with a model similar to the type used to predict future climate change on Earth. “Many of the same tools we use to model climate change on Earth can be adapted to study climates on other planets, both past and present,” said Michael Way, a researcher at GISS and the paper’s lead author. The research was done as part of NASA’s Planetary Science Astrobiology program through the Nexus for Exoplanet System Science (NExSS) program, which seeks to search for life on planets orbiting other stars, or exoplanets, by combining insights from the fields of astrophysics, planetary science, heliophysics, and Earth science.

Scientists long have theorized that Venus formed out of ingredients similar to Earth’s, but followed a different evolutionary path. Measurements by NASA’s Pioneer mission to Venus in the 1980s first suggested Venus originally may have had an ocean.

However, Venus is closer to the sun than Earth and receives far more sunlight. As a result, the planet’s early ocean evaporated, water-vapor molecules were broken apart by ultraviolet radiation, and hydrogen escaped to space.

With no water left on the surface, carbon dioxide built up in the atmosphere, leading to a so-called runaway greenhouse effect that created present conditions.

Previous studies have shown that how fast a planet spins on its axis affects whether it has a habitable climate. A day on Venus is 117 Earth days. Until recently, it was assumed that a thick atmosphere like that of modern Venus was required for the planet to have today’s slow rotation rate.

However, newer research has shown that a thin atmosphere like that of modern Earth could have produced the same result.

That ultimately means an ancient Venus with an Earth-like atmosphere could have had the same rotation rate it has today. Another factor that impacts a planet’s climate is topography. The GISS team postulated ancient Venus had more dry land overall than Earth, especially in the tropics. That limits the amount of water evaporated from the oceans and, as a result, the greenhouse effect by water vapor.

This type of surface appears ideal for making a planet habitable; there seems to have been enough water to support abundant life, with sufficient land to reduce the planet’s sensitivity to changes from incoming sunlight. Way and his GISS colleagues simulated conditions of a hypothetical early Venus with an atmosphere similar to Earth’s, a day as long as Venus’ current day, and a shallow ocean consistent with early data from the Pioneer spacecraft.

The researchers added information about Venus’ topography from radar measurements taken by NASA’s Magellan mission in the 1990s, and filled the lowlands with water, leaving the highlands exposed as Venusian continents. The study also factored in an ancient sun that was up to 30 percent dimmer. Even so, ancient Venus still received about 40 percent more sunlight than Earth does today.

“In the GISS model’s simulation, Venus’ slow spin exposes its dayside to the sun for almost two months at a time,” co-author and fellow GISS scientist Anthony Del Genio said.

“This warms the surface and produces rain that creates a thick layer of clouds, which acts like an umbrella to shield the surface from much of the solar heating. The result is mean climate temperatures that are actually a few degrees cooler than Earth’s today.”

The findings have direct implications for future NASA missions, such as the Transiting Exoplanet Survey Satellite and James Webb Space Telescope, which will try to detect possible habitable planets and characterize their atmospheres.

Via DailyGalaxy

BRERAKING: Large Amounts Of Water Found On Mars, And It's Tantalizingly Within Reach

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Scientists say they’ve found significant deposits of water ice hiding extremely close to the surface of Mars. This is a type of discovery that could be hugely beneficial for future Mars exploration missions. The findings, published in the journal Science, were led by Colin Dundas from the US Geological Survey in Arizona.

The discovery was made using the HiRISE (High Resolution Imaging Science Experiment) instrument on the Mars Reconnaissance Orbiter. They found eight mid-latitude locations where escarpments (or scarps), steep banks or cliffs that have been eroded away, had exposed huge cross-sections of ice. In some of the regions, the ice was an astonishing 100 meters (330 feet) thick, and it starts just 1 or 2 meters (3.3 to 6.6 feet) below the surface.

What's more, the ice appears to be layered, not too dissimilar to sedimentary layers on Earth. This means the sheets could show us different geological periods in the history of Mars.

“This gives us a much more detailed window into the vertical structure of some Martian ice sheets, and shows that they have only a thin debris cover and in some cases fine layers,” Dundas told IFLScience.

“The key point is that there are layered ice sheets on Mars that can be quite shallowly buried.”

Some of the exposed ice can be seen here in blue. Dundas et al/Science

We already knew that Mars has water ice, but this research highlights just how close some of that ice is to the surface in mid-latitude regions on Mars. This could make it accessible to future exploration missions, such as the European ExoMars rover in early 2021, which will include a drill that can go 2 meters (6.6 feet) under the surface.

The sheets discovered by Dundas and his team are steeply angled, suggesting the ice is strong. A lack of craters also hints that they are extremely young, perhaps less than a million years old. Huge chunks of rock were seen to have fallen from some sections of the ice, suggesting that erosion is occurring and the ice is retreating by a few millimeters each summer.

Some NASA concepts suggest we could use ice to build habitats on Mars. NASA/Team Space Exploration Architecture and Clouds Architecture Office

This is also the result of sublimation, as the ice turns directly into gas in the low-pressure Martian environment.

Future human exploration missions could make use of water ice on Mars, using it as a consumable resource or even as fuel. HiRISE has only imaged 3 percent of the surface so far, so there may well be more such discoveries to come.

“This ice... is expected to preserve a record of climate history, influences the planet’s habitability, and may be a potential resource for future exploration,” the team wrote.

This article was initially published on IFLScience. You can read the article here.

Vast "Ocean" Of Water Detected At Nearby Galaxy's Core --"30 Trillion Times Earth's Oceans, With A Diameter 15 Million Times Distance Of Earth To The Sun"

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A new studyled by Miguel Pereira Santaella, research associate at the oxford university department of physics used the ALMA observatory and detected the (670 μm) water transition in space, for the first time. The molecules were spotted in a nearby spiral galaxy (160 million light years away) at a point where the universe is vastly expanded, and the atmosphere is therefore at its most transparent (red-shifted at 676 μm).

The water vapor emission in this galaxy originates at its core, in its nucleus, where most star formation takes place. To give you an idea of how enormous this galaxy is, the nucleus contains an equivalent amount of water 30 trillion times that of earth's oceans combined, and has a diameter 15 million times the distance from earth to the sun.

From clouds to rivers, and glaciers to oceans, water is everywhere on earth. What's less well-known, though, is how abundant the molecule is in space. Unlike on earth, most of the water in space takes either the form of vapor or forms ice mantles stuck to interstellar dust grains. This is because the extremely low density of interstellar space - which is trillions of times lower than air, prevents the formation of liquid water. The birth of star formations can tell us about how the universe behaves. But, since the only way to study them in such dust obscured environments is through the infrared light, detecting water transitions capable of detecting this light, is of vital importance.

Water molecules experience fluctuating quantum energy levels. This activity allows us to observe them and is known as a water transition. The term refers to the best point for scientific observation, which is the exact wavelength at which water molecules go from one quantum state to another, emitting light and increasing their visibility as they do so.

The majority of these transitions are not very energetic so they appear in the far-infrared and sub-millimeter ranges of the electromagnetic spectrum, with tiny wavelengths (ranging from 50 μm and 1000 μm (1 mm)). Observing these water transitions from the ground is very difficult because the thick vapor in earth's atmosphere almost completely blocks the emission from view.

Improvements in technology and the development of super telescopes offer an increasing gateway to the universe, and planetary insights are moving at rapid pace. We can now detect water transitions in ways that we just could not before. They are best seen from telescopic observatories situated at high-altitude, in extremely dry sites. Such as, the atacama large millimeter array (ALMA), which is located in the atacama desert (chile) at 5000 m above sea level.

So what sets this water transition apart from others observed in the past? Their analysis revealed that these water molecules intensify their rate of emission when they come into contact with infrared light photons. This increase in activity makes it easier for scientists to observe them. Water molecules are most attracted to photons with specific wavelengths of 79 and 132 μm, which, when absorbed, strengthen the transition's outline, therefore increasing its visibility. For this reason, this specific water transition has the ability to show the intensity of the infrared light in the nucleus of galaxies, at spatial scales much smaller than those allowed by direct infrared observations.

Infrared light is produced during events like the growth of supermassive black holes or extreme bursts of star-formation. These events usually occur in extremely dust obscured environments where the optical light is almost completely absorbed by dust grains. The energy absorbed by the grains increases their temperature and they begin to emit thermal radiation in the infrared.

Capturing these events can tell us a great deal about how the universe behaves. But, since the only way to study them in such dust obscured environments is through the infrared light, detecting water transitions that capture this infrared light, is vital.

Moving forward the oxford team plans to observe this water transition in more galaxies where dust blocks all the optical light. This will reveal what hides behind these dust screens and help us to understand how galaxies evolve from star-forming spirals, like the milky way, to dead elliptical galaxies where no new stars are formed.

A mere 46 million light-years distant, spiral galaxy NGC 2841 is shown at the top of the page with its striking yellow nucleus and galactic disk. Dust lanes, small, pink star-forming regions, and young blue star clusters are embedded in the patchy, tightly wound spiral arms. In contrast, many other spirals exhibit grand, sweeping arms with large star-forming regions. NGC 2841 has a diameter of over 150,000 light-years, even larger than our own milky way. ( Hubble, Subaru; Roberto Colombari)

Source: Oxford Science Blog