Longest Total Lunar Eclipse Of 21st Century Wows Star-Gazers For Over 100 Minutes

The longest total lunar eclipse of the century transformed the moon into a reddish orange color for more than 100 minutes, according to NASA.

The eclipse was not visible from North America, Noah Petro, a scientist for the NASA Goddard Space Flight Center, told ABC News. Star-gazers in areas near the Middle East, south or eastern Africa, western and southeast Asia and India were be able to catch a glimpse of the celestial event as long as the weather permits, Petro said.

In those areas, the totality of the lunar eclipse — when the moon will retain its red color — lasted for about an hour and 42 minutes. The entire event will last about six hours and 13 minutes, Petro said.

Residents in Australia were able to see the lunar eclipse as the moon sets, while those in eastern Brazil and western Europe could see it as the moon is rising.

Petro suggested either renting a boat and driving it to the middle of the Indian Ocean or visiting relatives in Ethiopia for the “best seat in the house.”

A San Antonio couple named Miguel and Sara who experienced the eclipse from Cairo, Egypt described it as a “beautiful” sight.

“It looks like a giant tangerine,” Miguel told ABC News, adding that Cairo” was “a little bit colder than Texas right now.”

Cloudy weather conditions in cities like London, Moscow and Hong Kong obstructed views of the blood moon in those areas.

ABC News correspondent Matt Gutman described the sight of the lunar eclipse from Hong Kong as “more like a gray smudge,” due to the weather.

However, cities like Rome and Cairo, as well as several areas in Africa, had a clear picture of the moon.

In the U.S., the lunar eclipse began around 1:14 p.m. ET, with the maximum period of totality will starting around 4:21 p.m. ET, making it too light outside for the blood moon to be visible, Petro said.

Although U.S. residents weren’t able to see the eclipse, they should still note that the Lunar Reconnaissance Orbiter — NASA’s robotic spacecraft orbiting the moon — experienced it first-hand, Petro said. The LRO was launched in June 2009 to provide detailed maps to identify “safe and interesting” landing sites on the moon for future human and robotic exploration.

“The moon really holds the secret to understanding how the solar system works,” Petro said.

It’s a good time for Americans to start getting excited about the moon, as NASA will begin celebrating the 50th anniversary of Apollo 11, the spaceflight that made astronauts Neil Armstrong and Buzz Aldrin the first two people on the moon, in October, Petro said. Armstrong and Aldrin landed on the moon on July 20, 1969.

The next total lunar eclipse visible in the U.S. will be on Jan. 21, 2019, according to NASA. It will be a super moon as well, which is a full moon or new moon that coincides with the moon’s position at it’s closest to the Earth.

A partial lunar eclipse — which looks “like someone took a bite out of the moon — will also be visible in the U.S. in July 2019, Petro said. The partial lunar eclipse involves the southern half of the moon passing into the earth’s shadow, he added.

What exactly is a blood moon?

A blood moon is a term used to describe a total lunar eclipse, which is when the moon appears darkened as it passes through the Earth’s shadow.

The total lunar eclipse is given the “blood” nickname because of the “beautiful” red color caused by the projection of all of the Earth’s sunrises and sunsets onto its surface, Petro told ABC News earlier this year, before the super blue blood moon event that took place on Jan. 31.

Galaxy Outskirts Likely Hunting Grounds For Dying Massive Stars And Black Holes

Findings from a Rochester Institute of Technology study provide further evidence that the outskirts of spiral galaxies host massive black holes. These overlooked regions are new places to observe gravitational waves created when the massive bodies collide, the authors report.

The study winds back time on massive black holes by analyzing their visible precursors — supernovae with collapsing cores. The slow decay of these massive stars creates bright signatures in the electromagnetic spectrum before stellar evolution ends in black holes.

Using data from the Lick Observatory Supernova Search, a survey of nearby galaxies, the team compared the supernovae rate in outer spiral galaxies with that of known hosts — dwarf/satellite galaxies — and found comparable numbers for typical spiral outskirts and typical dwarf galaxies, roughly two core-collapse supernovae per millennium.

The study, “Supernova Rate beyond the Optical Radius,” will appear in an upcoming issue of Astrophysical Journal Letters.

Low levels of elements heavier than hydrogen and helium found in dwarf/satellite galaxies create favorable conditions for massive black holes to form and create binary pairs. A similar galactic environment in the outer disks of spiral galaxies also creates likely hunting grounds for massive black holes, said Sukanya Chakrabarti, lead author and assistant professor in the RIT School of Physics and Astronomy.

“If these core-collapse supernovae are the predecessors to the binary black holes detected by LIGO (Laser Interferometer Gravitational-wave Observatory), then what we’ve found is a reliable method of identifying the host galaxies of LIGO sources,” said Chakrabarti. “Because these black holes have an electromagnetic counterpart at an earlier stage in their life, we can pinpoint their location in the sky and watch for massive black holes.”

The study’s findings complement Chakrabarti’s 2017 study, which showed that the outer parts of spiral galaxies could contribute to LIGO detection rates. The regions form stars at a comparable rate to dwarf galaxies and are low in heavy element content, creating a conducive home for massive black holes. The current study isolates potential candidates within these favorable galactic environments.

“We see now that these are both important contributors,” Chakrabarti said. “The next step is to do deeper surveys to see if we can improve the rate.”

Co-author Brennan Dell, a recent graduate from RIT’s computer science program, analyzed the data with Chakrabarti during his undergraduate co-op.

“This work may help us determine which galaxies to be on the lookout for electromagnetic counterparts of massive black holes,” Dell said.

Total Lunar Eclipse 2018: How To Watch The July ‘Blood Moon’ Live

A total lunar eclipse will turn the moon blood red today, but even if the celestial show isn’t visible from your corner of the world, there are still ways to watch the eclipse live.

The entire event will last 3 hours and 55 minutes. The period when the moon is completely engulfed in Earth’s shadow — a phenomenon known as totality — will last 1 hour and 43 minutes, making it the longest total lunar eclipse of this century.

“This eclipse is special because just by chance it happens that the moon will cross the shadow of the Earth almost along its diameter, which makes the eclipse a few minutes longer than usual,” Francisco Diego, an astronomer at University College London in the U.K., told NBC News MACH in an email.

During totality, which begins at around 3:30 p.m. EDT (19:30 UTC), the moon will be immersed in Earth’s shadow and will be “illuminated by red light filtered by the [Earth’s] atmosphere,” Diego said. For this eclipse, Diego says skywatchers can expect to see a “bright red-orange moon.”

Skywatchers can witness the eclipse in parts of South America, the Middle East, eastern Africa and central Asia. The sky show will not be visible from North America, but there’s still a way to catch all the action surrounding the “blood moon” online. NBC News will be hosting a livestream — part of a digital special hosted by Simone Boyce called “Space Is Awesome” — starting at 4 p.m. EDT (20:00 UTC).

If you happen to be in the Eastern Hemisphere, you’re in luck. According to NASA, the best places to witness the celestial event from start to finish are eastern Africa, the Middle East, India and central Asia. Skywatchers in southern Africa and the Middle East will be able to see totality around midnight local time. Viewers in central Asia will see the moon pass into Earth’s shadow at 10:44 p.m. local time and can expect the eclipse to peak at around midnight.

The sky show will be partially visible as the moon rises just after sunset in parts of Europe, West Africa and South America. In eastern Asia, Australia, and parts of the western Pacific, the eclipse will be visible before sunrise on Saturday (July 28), as the moon sets.

Lunar eclipses occur up to three times a year, so if you miss this week’s sky show, there will be other opportunities in the future. The next total lunar eclipse will happen on Jan. 21, 2019, and will be visible from North America, South America, and parts of Africa, Europe and the central Pacific. The period of totality for this eclipse will last 1 hour and 2 minutes. Skywatchers in South America, Europe, Africa, Asia and Australia will also be able to see a partial lunar eclipse on July 16, 2019.

Young Galaxy’s Halo Offers Clues To Its Growth And Evolution

A team of astronomers has discovered a new way to unlock the mysteries of how the first galaxies formed and evolved.

In a study published today in Astrophysical Journal Letters, lead author Dawn Erb of the University of Wisconsin-Milwaukee and her team — for the very first time — used new capabilities at W. M. Keck Observatory on Maunakea, Hawaii to examine Q2343-BX418, a small, young galaxy located about 10 billion light years away from Earth.

This distant galaxy is an analog for younger galaxies that are too faint to study in detail, making it an ideal candidate for learning more about what galaxies looked like shortly after the birth of the universe.

BX418 is also attracting astronomers’ attention because its gas halo is giving off a special type of light.

“In the last several years, we’ve learned that the gaseous halos surrounding galaxies glow with a particular ultraviolet wavelength called Lyman alpha emission. There are a lot of different theories about what produces this Lyman alpha emission in the halos of galaxies, but at least some of it is probably due to light that is originally produced by star formation in the galaxy being absorbed and re-emitted by gas in the halo,” said Erb.

Erb’s team, which includes Charles Steidel and Yuguang Chen of Caltech, used one of the observatory’s newest instruments, the Keck Cosmic Web Imager (KCWI), to perform a detailed spectral analysis of BX418’s gas halo; its properties could offer clues about the stars forming within the galaxy.

“Most of the ordinary matter in the universe isn’t in the form of a star or a planet, but gas. And most of that gas exists not in galaxies, but around and between them,” said Erb.

The halo is where gas enters and exits the system. The gas surrounding galaxies can fuel them; gas from within a galaxy can also escape into the halo. This inflow and outflow of gas influences the fate of stars.

“The inflow of new gas accreting into a galaxy provides fuel for new star formation, while outflows of gas limit a galaxy’s ability to form stars by removing gas,” says Erb.

“So, understanding the complex interactions happening in this gaseous halo is key to finding out how galaxies form stars and evolve.”

This study is part of a large ongoing survey that Steidel has been leading for many years. Previously, Steidel’s team studied BX418 using other instruments at Keck Observatory.

This most recent study using KCWI adds detail and clarity to the image of the galaxy and its gas halo that was not possible before; the instrument is specifically engineered to study wispy currents of faint gas that connect galaxies, known as the cosmic web.

“Our study was really enabled by the design and sensitivity of this new instrument. It’s not just an ordinary spectrograph — it’s an integral field spectrograph, which means that it’s a sort of combination camera and spectrograph, where you get a spectrum of every pixel in the image,” said Erb.

The power of KCWI, combined with the Keck telescopes’ location on Maunakea where viewing conditions are among the most pristine on Earth, provides some of the most detailed glimpses of the cosmos.

Erb’s team used KCWI to take spectra of the Lyman alpha emission of BX418’s halo. This allowed them to trace the gas, plot its velocity and spatial extent, then create a 3-D map showing the structure of the gas and its behavior.

The team’s data suggests that the galaxy is surrounded by a roughly spherical outflow of gas and that there are significant variations in the density and velocity range of this gas.

Erb says this analysis is the first of its kind. Because it has only been tested on one galaxy, other galaxies need to be studied to see if these results are typical.

Now that the team has discovered a new way to learn about the properties of the gaseous halo, the hope is that further analysis of the data they collected and computer simulations modeling the processes will yield additional insights into the characteristics of the first galaxies in our universe.

“As we work to complete more detailed modeling, we will be able to test how the properties of Lyman alpha emission in the gas halo are related to the properties of the galaxies themselves, which will then tell us something about how the star formation in the galaxy influences the gas in the halo,” Erb said.

Another Volcano? Jupiter Probe Sees Hotspot on Roiling Moon Io

NASA’s Jupiter-orbiting Juno spacecraft may have just boosted the already-impressive volcano tally on the gas giant’s lava-spewing moon Io.

Juno’s Jovian InfraRed Auroral Mapper instrument, or JIRAM, detected a sizable “hotspot” near Io’s south pole on Dec. 16, 2017, during one of the probe’s close Jupiter flybys. Juno was about 290,000 miles (470,000 kilometers) away from Io at the time, NASA officials said.

“The new Io hotspot JIRAM picked up is about 200 miles (300 kilometers) from the nearest previously mapped hotspot,” Alessandro Mura, a Juno co-investigator from the National Institute for Astrophysics in Rome, said in a statement. [Amazing Photos: Jupiter’s Volcanic Moon Io]

“We are not ruling out movement or modification of a previously discovered hotspot, but it is difficult to imagine one could travel such a distance and still be considered the same feature,” Mura added.

Io is the most volcanically active body in the solar system, with its insides roiled and churned by Jupiter’s powerful gravity and the tugs of its fellow Galilean satellites, Callisto, Ganymede and Europa. Thanks to the efforts of ground-based telescopes and NASA probes such as the Jupiter-orbiting Galileo and the Saturn-studying Cassini, astronomers have already mapped about 150 volcanoes on the moon, some of which blast lava 250 miles (400 km) out into space.

So, confirming a new Io volcano wouldn’t come as much of a shock. Indeed, according to NASA officials, about 250 additional volcanoes likely await discovery on Io, which is the fourth-largest moon in the solar system. (With a diameter of about 2,260 miles, or 3,640 km, Io is slightly larger than Earth’s moon.)

The $1.1 billion Juno mission arrived in orbit around Jupiter on July 4, 2016. The spacecraft loops around the gas giant on a highly elliptical path, making close flybys like the Dec. 16 encounter every 53 days. During these passes, Juno studies Jupiter’s composition, structure, and gravitational and magnetic fields, looking for clues about the huge planet’s formation and evolution (and also collecting a wealth of other data, as the Io observations show).

How Might Dark Matter Interact With Ordinary Matter?

An international team of scientists that includes University of California, Riverside, physicist Hai-Bo Yu has imposed conditions on how dark matter may interact with ordinary matter — constraints that can help identify the elusive dark matter particle and detect it on Earth.

Dark matter — nonluminous material in space — is understood to constitute 85 percent of the matter in the universe. Unlike normal matter, it does not absorb, reflect, or emit light, making it difficult to detect.

Physicists are certain dark matter exists, having inferred this existence from the gravitational effect dark matter has on visible matter. What they are less certain of is how dark matter interacts with ordinary matter — or even if it does.

In the search for direct detection of dark matter, the experimental focus has been on WIMPs, or weakly interacting massive particles, the hypothetical particles thought to make up dark matter.

But Yu’s international research team invokes a different theory to challenge the WIMP paradigm: the self-interacting dark matter model, or SIDM, a well-motivated framework that can explain the full range of diversity observed in the galactic rotation curves. First proposed in 2000 by a pair of eminent astrophysicists, SIDM has regained popularity in both the particle physics and the astrophysics communities since around 2009, aided, in part, by work Yu and his collaborators did.

Yu, a theorist in the Department of Physics and Astronomy at UCR, and Yong Yang, an experimentalist at Shanghai Jiaotong University in China, co-led the team analyzing and interpreting the latest data collected in 2016 and 2017 at PandaX-II, a xenon-based dark matter direct detection experiment in China (PandaX refers to Particle and Astrophysical Xenon Detector; PandaX-II refers to the experiment). Should a dark matter particle collide with PandaX-II’s liquefied xenon, the result would be two simultaneous signals: one of photons and the other of electrons.

Yu explained that PandaX-II assumes dark matter “talks to” normal matter — that is, interacts with protons and neutrons — by means other than gravitational interaction (just gravitational interaction is not enough). The researchers then search for a signal that identifies this interaction. In addition, the PandaX-II collaboration assumes the “mediator particle,” mediating interactions between dark matter and normal matter, has far less mass than the mediator particle in the WIMP paradigm.

“The WIMP paradigm assumes this mediator particle is very heavy — 100 to 1000 times the mass of a proton — or about the mass of the dark matter particle,” Yu said. “This paradigm has dominated the field for more than 30 years. In astrophysical observations, we don’t, however, see all its predictions. The SIDM model, on the other hand, assumes the mediator particle is about 0.001 times the mass of the dark matter particle, inferred from astrophysical observations from dwarf galaxies to galaxy clusters. The presence of such a light mediator could lead to smoking-gun signatures of SIDM in dark matter direct detection, as we suggested in an earlier theory paper. Now, we believe PandaX-II, one of the world’s most sensitive direct detection experiments, is poised to validate the SIDM model when a dark matter particle is detected.”

The international team of researchers reports July 12 in Physical Review Letters the strongest limit on the interaction strength between dark matter and visible matter with a light mediator. The journal has selected the research paper as a highlight, a significant honor.

“This is a particle physics constraint on a theory that has been used to understand astrophysical properties of dark matter,” said Flip Tanedo, a dark matter expert at UCR, who was not involved in the research. “The study highlights the complementary ways in which very different experiments are needed to search for dark matter. It also shows why theoretical physics plays a critical role to translate between these different kinds of searches. The study by Hai-Bo Yu and his colleagues interprets new experimental data in terms of a framework that makes it easy to connect to other types of experiments, especially astrophysical observations, and a much broader range of theories.”

PandaX-II is located at the China Jinping Underground Laboratory, Sichuan Province, where pandas are abundant. The laboratory is the deepest underground laboratory in the world. PandaX-II had generated the largest dataset for dark matter detection when the analysis was performed. One of only three xenon-based dark matter direct detection experiments in the world, PandaX-II is one of the frontier facilities to search for extremely rare events where scientists hope to observe a dark matter particle interacting with ordinary matter and thus better understand the fundamental particle properties of dark matter.

Particle physicists’ attempts to understand dark matter have yet to yield definitive evidence for dark matter in the lab.

“The discovery of a dark matter particle interacting with ordinary matter is one of the holy grails of modern physics and represents the best hope to understand the fundamental, particle properties of dark matter,” Tanedo said.

For the past decade, Yu, a world expert on SIDM, has led an effort to bridge particle physics and cosmology by looking for ways to understand dark matter’s particle properties from astrophysical data. He and his collaborators have discovered a class of dark matter theories with a new dark force that may explain unexpected features seen in the systems across a wide range, from dwarf galaxies to galaxy clusters. More importantly, this new SIDM framework serves as a crutch for particle physicists to convert astronomical data into particle physics parameters of dark matter models. In this way, the SIDM framework is a translator for two different scientific communities to understand each other’s results.

Now with the PandaX-II experimental collaboration, Yu has shown how self-interacting dark matter theories may be distinguished at the PandaX-II experiment.

“Prior to this line of work, these types of laboratory-based dark matter experiments primarily focused on dark matter candidates that did not have self-interactions,” Tanedo said. “This work has shown how dark forces affect the laboratory signals of dark matter.”

Yu noted that this is the first direct detection result for SIDM reported by an experimental collaboration.

“With more data, we will continue to probe the dark matter interactions with a light mediator and the self-interacting nature of dark matter,” he said.

Breakthrough In The Search For Cosmic Particle Accelerators

Using an internationally organised astronomical dragnet, scientist have for the first time located a source of high-energy cosmic neutrinos, ghostly elementary particles that travel billions of light years through the universe, flying unaffected through stars, planets and entire galaxies. The joint observation campaign was triggered by a single neutrino that had been recorded by the IceCube neutrino telescope at the South Pole, on 22 September 2017. Telescopes on earth and in space were able to determine that the exotic particle had originated in a galaxy over three billion light years away, in the constellation of Orion, where a gigantic black hole serves as a natural particle accelerator. Scientists from the 18 different observatories involved are presenting their findings in the journal Science. Furthermore, a second analysis, also published in Science, shows that other neutrinos previously recorded by IceCube came from the same source.

The observation campaign, in which research scientists from Germany played a key role, is a decisive step towards solving a riddle that has been puzzling scientists for over 100 years, namely that of the precise origins of so-called cosmic rays, high-energy subatomic particles that are constantly bombarding Earth’s atmosphere. “This is a milestone for the budding field of neutrino astronomy. We are opening a new window into the high-energy universe,” says Marek Kowalski, the head of Neutrino Astronomy at DESY, a research centre of the Helmholtz Association, and a researcher at the Humboldt University in Berlin. “The concerted observational campaign using instruments located all over the globe is also a significant achievement for the field of multi-messenger astronomy, that is the investigation of cosmic objects using different messengers, such as electromagnetic radiation, gravitational waves and neutrinos.”

Messengers from the high-energy universe

One way in which scientists expect energetic neutrinos to be created is as a sort of by-product of cosmic rays, that are expected to be produced in cosmic particle accelerators, such as the vortex of matter created by supermassive black holes or exploding stars. However, unlike the electrically charged particles of cosmic rays, neutrinos are electrically neutral and therefore not deflected by cosmic magnetic fields as they travel through space, meaning that the direction from which they arrive points straight back at their actual source. Also, neutrinos are scarcely absorbed. “Observing cosmic neutrinos gives us a glimpse of processes that are opaque to electromagnetic radiation,” says Klaus Helbing from the Bergische University of Wuppertal, spokesperson for the German IceCube network.””Cosmic neutrinos are messengers from the high-energy universe.”

Demonstrating the presence of neutrinos is extremely complicated, however, because most of the ghostly particles travel right through the entire Earth without leaving a trace. Only on very rare occasions does a neutrino interact with its surroundings. It therefore takes huge detectors in order to capture at least a few of these rare reactions. For the IceCube detector, an international consortium of scientists headed by the University of Wisconsin in Madison (USA) drilled 86 holes into the Antarctic ice, each 2500 metres deep. Into these holes they lowered 5160 light sensors, spread out over a total volume of one cubic kilometre. The sensors register the tiny flashes of light that are produced during the rare neutrino interactions in the transparent ice.

Five years ago, IceCube furnished the first evidence of high-energy neutrinos from the depths of outer space. However, these neutrinos appeared to be arriving from random directions across the sky. “Up to this day, we didn’t know where they originated,” says Elisa Resconi from the Technical University of Munich, whose group contributed crucially to the findings. “Through the neutrino recorded on 22 September, we have now managed to identify a first source.”

From radio waves to gamma radiation

The energy of the neutrino in question was around 300 tera-electronvolts, more than 40 times that of the protons produced in the world’s largest particle accelerator, the Large Hadron Collider at the European accelerator facility CERN outside Geneva. Within minutes of recording the neutrino, the IceCube detector automatically alerted numerous other astronomical observatories. A large number of these then scrutinised the region in which the high-energy neutrino had originated, scanning the entire electromagnetic spectrum: from high-energy gamma- and X-rays, through visible light, to radio waves. Sure enough, they were able for the first time to assign a celestial object to the direction from which a high-energy cosmic neutrino had arrived.

“In our case, we saw an active galaxy, which is a large galaxy containing a gigantic black hole at its centre,” explains Kowalski. Huge “jets” shoot out into space at right angles to the massive vortex that sucks matter into the black hole. Astrophysicists have long suspected that these jets generate a substantial proportion of cosmic particle radiation. “Now we have found key evidence supporting this assumption,” Resconi emphasises.

The active galaxy that has now been identified is a so-called blazar, an active galaxy whose jet points precisely in our direction. Using software developed by DESY researchers, the gamma-ray satellite Fermi, operated by the US space agency NASA, had already registered a dramatic increase in the activity of this blazar, whose catalogue number is TXS 0506+056, around 22 September. Now, an earthbound gamma-ray telescope also recorded a signal from it. “In the follow-up observation of the neutrino, we were able to observe the blazar in the range of very high-energy gamma radiation too, using the MAGIC telescope system on the Canary Island La Palma,” says DESY’s Elisa Bernardini, who coordinates the MAGIC observations. “The gamma-rays are closest in energy to neutrinos and therefore play a crucial role in determining the mechanism by which the neutrinos are created.” The programme for the efficient follow-up observation of neutrinos using gamma-ray telescopes was developed by Bernardini’s group.

The NASA X-ray satellites Swift and NuSTAR also registered the eruption of the blazar, and the gamma-ray telescopes H.E.S.S., HAWC and VERITAS as well as the gamma-ray and X-ray satellites AGILE, belonging to the Italian Space Agency ASI, and Integral, belonging to the European Space Agency ESA, all took part in the follow-up observations. All in all, seven optical observatories (the ASAS-SN, Liverpool, Kanata, Kiso Schmidt, SALT and Subaru telescopes, as well as the Very Large Telescope VLT of the European Southern Observatory, ESO) observed the active galaxy, and the Karl G. Jansky Very Large Array (VLA) studied its activity in the radio spectrum. This led to a comprehensive picture of the radiation emitted by this blazar, all the way from radio waves to gamma-rays carrying up to 100 billion times as much energy.

Search in archives reveals further neutrinos

A worldwide team of scientists from all the groups involved worked flat out, conducting a complicated statistical analysis to determine whether the correlation between the neutrino and the gamma-ray observations was perhaps just a coincidence. “We calculated that the probability of it being a mere coincidence was around 1 in 1000,” explains DESY’s Anna Franckowiak, who was in charge of the statistical analysis of the various different data sets. This may not sound very large, but it is not small enough to quell the professional scepticism of physicists.

A second line of investigation rectified this. The IceCube researchers searched through their data from the past years for possible previous measurements of neutrinos coming from the direction of the blazar that had now been identified. And they did indeed find a distinct surplus of more than a dozen of the ghost particles arriving from the direction of TXS 0506+056 during the time between September 2014 and March 2015, as they are reporting in a second paper published in the same edition of Science. The likelihood of this excess being a mere statistical outlier is estimated at 1 in 5000, “a number that makes you prick up your ears,” says Christopher Wiebusch from RWTH Aachen, whose group had already noted the hint of excess neutrinos from the direction of TXS 0506+056 in an earlier analysis. “The data also allows us to make a first estimate of the neutrino flux from this source.” Together with the single event of September 2017, the IceCube data now provides the best experimental evidence to date that active galaxies are in fact sources of high-energy cosmic neutrinos.

“We now have a better understanding of what we should be looking for. This means that we can in future track down such sources more specifically,” says Elisa Resconi. And Marek Kowalski adds, “Since neutrinos are a sort of by-product of the charged particles in cosmic rays, our observation implies that active galaxies are also accelerators of cosmic ray particles. More than a century after the discovery of cosmic rays by Victor Hess in 1912, the IceCube findings have therefore for the first time located a concrete extragalactic source of these high-energy particles.”