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Space News Update — June 19, 2020 —

Contents

In the News

Story 1: Are Planets with Oceans Common in the Galaxy? It’s Likely,

NASA Scientists Find

Story 2:

New Ideas in the Search for Dark Matter

Story 3: Scientists Reveal a Lost Eight Billion Light Years of Universe Evolution

Departments

The Night Sky

ISS Sighting Opportunities

Space Calendar

NASA-TV Highlights

Food for Thought

Space Image of the Week

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1. Are Planets with Oceans Common in the Galaxy? It’s Likely, NASA Scientists

Find

Several years ago, planetary scientist Lynnae Quick began to wonder whether any of the more than 4,000 known exoplanets, or planets beyond our solar system, might resemble some of the watery moons around Jupiter and Saturn. Though some of these moons don’t have atmospheres and are covered in ice, they are still among the top targets in NASA’s search for life beyond Earth. Saturn’s moon Enceladus and Jupiter’s moon Europa, which scientists classify as “ocean worlds,” are good examples.

“Plumes of water erupt from Europa and Enceladus, so we can tell that these bodies have subsurface oceans beneath their ice shells, and they have energy that drives the plumes, which are two requirements for life as we know it,” says Quick, a NASA planetary scientist who specializes in volcanism and ocean worlds. “So if we’re thinking about these places as being possibly habitable, maybe bigger versions of them in other planetary systems are habitable too.”

Quick, of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, decided to explore whether — hypothetically — there are planets similar to Europa and Enceladus in the Milky Way galaxy. And, could they, too, be geologically active enough to shoot plumes through their surfaces that could one day be detected by telescopes.

Through a mathematical analysis of several dozen exoplanets, including planets in the nearby TRAPPIST-1 system, Quick and her colleagues learned something significant: More than a quarter of the exoplanets they studied could be ocean worlds, with a majority possibly harboring oceans beneath layers of surface ice, similar to Europa and Enceladus. Additionally, many of these planets could be releasing more energy than Europa and Enceladus.

Scientists may one day be able to test Quick’s predictions by measuring the heat emitted from an exoplanet or by detecting volcanic or cryovolcanic (liquid or vapor instead of molten rock) eruptions in the wavelengths of light emitted by molecules in a planet’s atmosphere. For now, scientists cannot see many exoplanets in any detail. Alas, they are too far away and too drowned out by the light of their stars. But by considering the only information available — exoplanet sizes, masses and distances from their stars — scientists like Quick and her

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colleagues can tap mathematical models and our understanding of the solar system to try to imagine the conditions that could be shaping exoplanets into livable worlds or not.

While the assumptions that go into these mathematical models are educated guesses, they can help scientists narrow the list of promising exoplanets to search for conditions favorable to life so that NASA’s upcoming James Webb Space Telescope or other space missions can follow up.

“Future missions to look for signs of life beyond the solar system are focused on planets like ours that have a global biosphere that’s so abundant it’s changing the chemistry of the whole atmosphere,” says Aki Roberge, a NASA Goddard astrophysicist who collaborated with Quick on this analysis. “But in the solar system, icy moons with oceans, which are far from the heat of the Sun, still have shown that they have the features we think are required for life.”

To look for possible ocean worlds, Quick’s team selected 53 exoplanets with sizes most similar to Earth, though they could have up to eight times more mass. Scientists assume planets of this size are more solid than gaseous and, thus, more likely to support liquid water on or below their surfaces. At least 30 more planets that fit these parameters have been discovered since Quick and her colleagues began their study in 2017, but they were not included in the analysis, which was published on June 18 in the journal Publications of the Astronomical Society of the Pacific.

With their Earth-size planets identified, Quick and her team sought to determine how much energy each one could be generating and releasing as heat. The team considered two primary sources of heat. The first, radiogenic heat, is generated over billions of years by the slow decay of radioactive materials in a planet’s mantle and crust. That rate of decay depends on a planet’s age and the mass of its mantle. Other scientists already had determined these relationships for Earth-size planets. So, Quick and her team applied the decay rate to their list of 53 planets, assuming each one is the same age as its star and that its mantle takes up the same proportion of the planet’s volume as Earth’s mantle does.

Next, the researchers calculated heat produced by something else: tidal force, which is energy generated from the gravitational tugging when one object orbits another. Planets in stretched out, or elliptical, orbits shift the distance between themselves and their stars as they circle them. This leads to changes in the gravitational force between the two objects and causes the planet to stretch, thereby generating heat. Eventually, the heat is lost to space through the surface.

One exit route for the heat is through volcanoes or cryovolcanoes. Another route is through tectonics, which is a geological process responsible for the movement of the outermost rocky or icy layer of a planet or moon. Whichever way the heat is discharged, knowing how much of it a planet pushes out is important because it could make or break habitability.

For instance, too much volcanic activity can turn a livable world into a molten nightmare. But too little activity can shut down the release of gases that make up an atmosphere, leaving a cold, barren surface. Just the right amount supports a livable, wet planet like Earth, or a possibly livable moon like Europa.

In the next decade, NASA’s Europa Clipper will explore the surface and subsurface of Europa and provide insights about the environment beneath the surface. The more scientists can learn about Europa and other potentially habitable moons of our solar system, the better they’ll be able to understand similar worlds around other stars — which may be plentiful, according to today’s findings.

"Forthcoming missions will give us a chance to see whether ocean moons in our solar system could support life,” says Quick, who is a science team member on both the Clipper mission and the Dragonfly mission to Saturn’s moon Titan. “If we find chemical signatures of life, we can try to look for similar signs at interstellar distances.”

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When Webb launches, scientists will try to detect chemical signatures in the atmospheres of some of the planets in the TRAPPIST-1 system, which is 39 light years away in the constellation Aquarius. In 2017, astronomers announced that this system has seven Earth-size planets. Some have suggested that some of these planets could be watery, and Quick’s estimates support this idea. According to her team’s calculations, TRAPPIST-1 e, f, g and h could be ocean worlds, which would put them among the 14 ocean worlds the scientists identified in this study.

The researchers predicted that these exoplanets have oceans by considering the surface temperatures of each one. This information is revealed by the amount of stellar radiation each planet reflects into space. Quick’s team also took into account each planet’s density and the estimated amount of internal heating it generates compared to Earth.

“If we see that a planet’s density is lower than Earth’s, that’s an indication that there might be more water there and not as much rock and iron,” Quick says. And if the planet’s temperature allows for liquid water, you’ve got an ocean world.

“But if a planet’s surface temperature is less than 32 degrees Fahrenheit (0 degrees Celsius), where water is frozen,” Quick says, “then we have an icy ocean world, and the densities for those planets are even lower.”

Other scientists who participated in this analysis with Quick and Roberge are Amy Barr Mlinar from the Planetary Science Institute in Tucson, Arizona, and Matthew M. Hedman from the University of Idaho in Moscow.

Source: NASA Return to Contents

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2. New Ideas in the Search for Dark Matter

Since the 1980s, researchers have been running experiments in search of particles that make up dark matter, an invisible substance that permeates our galaxy and universe.

Coined dark matter because it gives off no light, this substance, which constitutes more than 80 percent of matter in our universe, has been shown repeatedly to influence ordinary matter through its gravity. Scientists know it is out there but do not know what it is.

So researchers at Caltech, led by Kathryn Zurek, a professor of theoretical physics, have gone back to the drawing board to think of new ideas. They have been looking into the possibility that dark matter is made up of "hidden sector" particles, which are lighter than particles proposed previously, and could, in theory, be found using small, underground table-top devices. In contrast, scientists are searching for heavier dark matter candidates called WIMPs (weakly interacting massive particles) using large-scale experiments such as XENON, which is installed underground in a 70,000-gallon tank of water in Italy.

"Dark matter is always flowing through us, even in this room" says Zurek, who first proposed hidden sector particles over a decade ago. "As we move around the center of the galaxy, this steady wind of dark matter mostly goes unnoticed. But we can still take advantage of that source of dark matter, and design new ways to look for rare interactions between the dark matter wind and the detector."

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In a new paper accepted for publication in the journal Physical Review Letters, the physicists outline how the lighter-weight dark matter particles could be detected via a type of quasiparticle known as a magnon. A quasiparticle is an emergent phenomenon that occurs when a solid behaves as if it contains weakly interacting particles. Magnons are a type of quasiparticle in which electron spins--which act like little magnets--are collectivity excited. In the researchers' idea for a table-top experiment, a magnetic crystalized material would be used to look for signs of excited magnons generated by dark matter.

"If the dark matter particles are lighter than the proton, it becomes very difficult to detect their signal by conventional means," says study author Zhengkang (Kevin) Zhang, a postdoctoral scholar at Caltech. "But, according to many well-motivated models, especially those involving hidden sectors, the dark matter particles can couple to the spins of the electrons, such that once they strike the material, they will induce spin excitations, or magnons. If we reduce the background noise by cooling the equipment and moving it underground, we could hope to detect magnons generated solely by dark matter and not ordinary matter."

Such an experiment is only theoretical at this point but may eventually take place using small devices housed underground, likely in a mine, where outside influences from other particles, such as those in cosmic rays, can be minimized.

One telltale sign of a dark matter detection in the table-top experiments would be changes to the signal that depend on the time of day. This is due to the fact that the magnetic crystals that would be used to detect the dark matter can be anisotropic, meaning that the atoms are naturally arranged in such a way that they tend to interact with the dark matter more strongly when the dark matter comes in from certain directions.

"As Earth moves through the galactic dark matter halo, it feels the dark matter wind blowing from the direction into which the planet is moving. A detector fixed at a certain location on Earth rotates with the planet, so the dark matter wind hits it from different directions at different times of the day, say, sometimes from above, sometimes from the side," says Zhang.

"During the day, for example, you may have a higher detection rate when the dark matter comes from above than from the side. If you saw that, it would be pretty spectacular and a very strong indication that you were seeing dark matter."

The researchers have other ideas about how dark matter may reveal itself, in addition to through magnons. They have proposed that the lighter dark matter particles could be detected via photons as well as with another type of quasiparticle called a phonon, which is caused by vibrations in a crystal lattice. Preliminary experiments based on photons and phonons are underway at UC Berkeley, where the team was based prior to Zurek joining the Caltech faculty in 2019. The researchers say that the use of these multiple strategies to look for dark matter is crucial because they complement each other and would help confirm each other's results.

"We're looking into new ways to look for dark matter because, given how little we know about dark matter, it's worth considering all the possibilities," says Zhang.

Source: Spaceref.com Return to Contents

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3. Scientists Reveal a Lost Eight Billion Light Years of Universe Evolution

Last year, the Advanced LIGO-VIRGO gravitational-wave detector network recorded data from 35 merging black holes and neutron stars. A great result—but what did they miss? According to Dr. Rory Smith from the ARC Centre of Excellence in Gravitational Wave Discovery at Monash University in Australia—it's likely there are another 2 million gravitational wave events from merging black holes, "a pair of merging black holes every 200 seconds and a pair of merging neutron stars every 15 seconds" that scientists are not picking up.

Dr. Smith and his colleagues, also at Monash University, have developed a method to detect the presence of these weak or "background" events that to date have gone unnoticed, without having to detect each one individually.The method—which is currently being test driven by the LIGO community—"means that we may be able to look more than 8 billion light years further than we are currently observing," Dr. Smith said.

"This will give us a snapshot of what the early universe looked like while providing insights into the evolution of the universe."

The paper, recently published in the Royal Astronomical Society journal, details how researchers will measure the properties of a background of gravitational waves from the millions of unresolved black hole mergers.

Binary black hole mergers release huge amounts of energy in the form of gravitational waves and are now routinely being detected by the Advanced LIGO-Virgo detector network. According to co-author, Eric Thrane from OzGrav-Monash, these gravitational waves generated by individual binary mergers "carry information about spacetime and nuclear matter in the most extreme environments in the Universe. Individual observations of gravitational waves trace the evolution of stars, star clusters, and galaxies," he said.

"By piecing together information from many merger events, we can begin to understand the environments in which stars live and evolve, and what causes their eventual fate as black holes. The further away we see the

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gravitational waves from these mergers, the younger the Universe was when they formed. We can trace the evolution of stars and galaxies throughout cosmic time, back to when the Universe was a fraction of its current age."

The researchers measure population properties of binary black hole mergers, such as the distribution of black hole masses. The vast majority of compact binary mergers produce gravitational waves that are too weak to yield unambiguous detections—so vast amounts of information is currently missed by our observatories.

"Moreover, inferences made about the black hole population may be susceptible to a 'selection bias' due to the fact that we only see a handful of the loudest, most nearby systems. Selection bias means we might only be getting a snapshot of black holes, rather than the full picture," Dr. Smith warned.

The analysis developed by Smith and Thrane is being tested using real world observations from the LIGO-VIRGO detectors with the program expected to be fully operational within a few years, according to Dr. Smith.

Explore further

Future detectors to detect millions of black holes and the evolution of the universe

Source: Phys.org Return to Contents

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The Night Sky FRIDAY, JUNE 19

■ Leo the Lion is mostly a constellation of late winter and spring. But he's not gone yet. As twilight ends look due west, somewhat low, for Regulus, his brightest and now lowest star: the forefoot of the Lion stick figure.

The Sickle of Leo extends upper right from Regulus, as shown in the second scene below. The rest of the Lion's constellation figure extends for almost three fists to the upper left, to his tail star Denebola, the highest. He'll soon be treading away into the sunset.

SATURDAY, JUNE 20

■ The June solstice arrives today at 5:44 p.m. EDT (21:44 UT). This is when the Sun reaches its northernmost declination in Earth's sky and begins its six-month return southward. Summer begins in the Northern Hemisphere, winter in the Southern Hemisphere.

For us northerners, this is the longest day and shortest night of the year.

It's also the day when (in the north temperate latitudes) the midday Sun passes the closest it ever can to being straight overhead, and thus when your shadow becomes the shortest it can ever be at your location. This happens at local apparent [solar] noon, which is probably rather far removed from noon in your civil (clock) time. And if you have a good west-northwest horizon (again in mid-northern latitudes), mark very precisely where the last bit of the Sun sets. In a few days you should be able to detect that the Sun is again starting to set a just little south (left) of that point.

SUNDAY, JUNE 21

■ After dark look southeast, fairly low, for orange Antares, "the Betelgeuse of summer." Both are 1st-magnitude "red" supergiants. Around and to the upper right of Antares are the other, whiter stars of upper Scorpius forming its distinctive shape. The rest of the Scorpion curls down toward the horizon.

And right after dark, spot Arcturus way up high toward the south. Three fists below it is Spica. A fist and a half to Spica's lower right, four-star Corvus, the springtime Crow, is heading down and away as spring draws to a close.

■ New Moon (exact at 2:41 a.m. on this date EDT).

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■ Annular eclipse of the Sun for parts of east-central Africa, the southern Arabian Peninsula, Pakistan, northern India, mainland China, Taiwan, and the Pacific. Partial eclipse of the Sun for nearly all of southeastern Europe, Africa, and Asia. Map and details. Timetables for your location.

MONDAY, JUNE 22

■ In bright twilight look for the slim crescent Moon, less then two days old, low in the afterglow of sunset. It's lower left of Pollux and Castor, as shown below. Bring binoculars.

Source: Sky & Telescope Return to Contents

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ISS Sighting Opportunities

For Denver: No sighting opportunities Sighting information for other cities can be found at NASA’s Satellite Sighting Information NASA-TV Highlights (all times Eastern Daylight Time)

June 19, Friday 11 a.m. - SpaceCast Weekly (All Channels) 1:10 p.m. – International Space Station Expedition 63 in-flight educational event with recorded questions from students at Challenger Learning Centers and Expedition 63 Commander Chris Cassidy and NASA astronauts Bob Behnken and Doug Hurley (All Channels) June 24, Wednesday 1:10 p.m. – International Space Station Expedition 63 in-flight event with CBS’ "Late Late Show" with James Corden and NPR’s Morning Edition and astronauts Bob Behnken and Doug Hurley of NASA (All Channels) 2 p.m. – International Space Station Expedition 63 spacewalk preview briefing (All Channels)

Watch NASA TV on the Net by going to the NASA website. Return to Contents

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Space Calendar • Jun 19 - Moon Occults Venus • Jun 19 - Comet P/2007 Q2 (Gilmore) At Opposition (1.464 AU) • Jun 19 - Comet 175P/Hergenrother At Opposition (1.736 AU) • Jun 19 - Comet P/2012 SB6 (Lemmon) Perihelion (2.277 AU) • Jun 19 - Comet C/2020 H8 (PANSTARRS) At Opposition (4.077 AU) • Jun 19 - Asteroid 344 Desiderata Occults UCAC4 578-47209 (6.5 Magnitude Star) • Jun 19 - Aten Asteroid 2018 PD22 Near-Earth Flyby (0.044 AU) • Jun 19 - Apollo Asteroid 2101 Adonis Closest Approach To Earth (0.368 AU) • Jun 19 - Apollo Asteroid 2102 Tantalus Closest Approach To Earth (0.483 AU) • Jun 19 - Asteroid 9523 Torino Closest Approach To Earth (1.489 AU)

• Jun 20 - [Feb 13] Summer Solstice, 21:44 UT • Jun 20 - Comet 141P-A/Machholz At Opposition (1.411 AU) • Jun 20 - Comet 141P/Machholz At Opposition (1.413 AU) • Jun 20 - Comet C/2019 F2 (ATLAS) At Opposition (2.695 AU) • Jun 20 - Comet 258P/PANSTARRS Perihelion (3.482 AU) • Jun 20 - Comet 250P/Larson At Opposition (3.799 AU) • Jun 20 - Asteroid 8720 Takamizawa Closest Approach To Earth (1.687 AU) • Jun 20 - Asteroid 21811 Burroughs Closest Approach To Earth (2.501 AU) • Jun 20 - Plutino 28978 Ixion At Opposition (37.964 AU) • Jun 20 - Online Lecture: The BIS Von Karman Line Buster • Jun 20 - 30th Anniversary (1990), David Levy's & Henry Holt's Discovery of the 1st Mars Trojan

Asteroid: 5261 Eureka • Jun 20 - 350th Anniversary (1670), Discovery Of Nova 1670 Vulpecula

• Jun 21 - [Jun 14] Annular Solar Eclipse • Jun 21 - Comet C/2020 H3 (Wierzchos) Closest Approach To Earth (1.619 AU) • Jun 21 - Asteroid 4589 McDowell Closest Approach To Earth (1.325 AU) • Jun 21 - Asteroid 85267 Taj Mahal Closest Approach To Earth (1.708 AU) • Jun 21 - Asteroid 9446 Cicero Closest Approach To Earth (1.723 AU) • Jun 21 - Asteroid 246247 Sheldoncooper Closest Approach To Earth (1.861 AU) • Jun 22 - [Jun 19] SSMS (POC)/ ESAIL/ Athena/ ION CubeSat Carrier/ NEMO-HD/ GHGSat

C1/ Astrocast 1.1-1.10/ PICASSO/ SIMBA/ DIDO 3/ QARMAN/ TRISAT Vega Launch • Jun 22 - Comet P/2002 S7 (SOHO) At Opposition (1.739 AU) • Jun 22 - Comet 378P/McNaught Closest Approach To Earth (2.458 AU) • Jun 22 - Asteroid 2 Pallas Occults UCAC4 561-089839 (11.5 Magnitude Star) • Jun 22 - [Jun 17] Aten Asteroid 2020 LV Near-Earth Flyby (0.014 AU) • Jun 22 - Amor Asteroid 2020 KR1 Near-Earth Flyby (0.030 AU) • Jun 22 - Asteroid 904 Rockefellia Closest Approach To Earth (2.287 AU)

Source: JPL Space Calendar Return to Contents

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Food for Thought

Does Intelligent Life Exist on Other Planets? Technosignatures May Hold New Clues

In 1995 a pair of scientists discovered a planet outside our solar system orbiting a solar-type star. Since that finding—which won the scientists a portion of the 2019 Nobel Prize in Physics—researches have discovered more than 4,000 exoplanets, including some Earth-like planets that may have the potential to harbor life.

In order to detect if planets are harboring life, however, scientists must first determine what features indicate that life is (or once was) present.

Over the last decade, astronomers have expended great effort trying to find what traces of simple forms of life—known as "biosignatures"—might exist elsewhere in the universe. But what if an alien planet hosted intelligent life that built a technological civilization? Could there be "technosignatures" that a civilization on another world would create that could be seen from Earth? And, could these technosignatures be even easier to detect than biosignatures?

Adam Frank, a professor of physics and astronomy at the University of Rochester, has received a grant from NASA that will enable him to begin to answer these questions. The grant will fund his study of technosignatures—detectable signs of past or present technology used on other planets. This is the first NASA non-radio technosignature grant ever awarded and represents an exciting new direction for the search for extraterrestrial intelligence (SETI). The grant will allow Frank, along with collaborators Jacob-Haqq Misra from the international nonprofit organization Blue Marble Space, Manasvi Lingam from the Florida Institute of Technology, Avi Loeb from Harvard University, and Jason Wright from Pennsylvania State University, to produce the first entries in an online technosignature library.

"SETI has always faced the challenge of figuring out where to look," Frank says. "Which stars do you point your telescope at and look for signals? Now we know where to look. We have thousands of exoplanets including planets in the habitable zone where life can form. The game has changed."

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The nature of the search has changed as well. A civilization, by nature, will need to find a way to produce energy, and, Frank says, "there are only so many forms of energy in the universe. Aliens are not magic."

Although life may take many forms, it will always be based in the same physical and chemical principles that underlie the universe. The same connection holds for building a civilization; any technology that an alien civilization uses is going to be based on physics and chemistry. That means researchers can use what they've learned in Earth-bound labs to guide their thinking about what may have happened elsewhere in the universe.

"My hope is that, using this grant, we will quantify new ways to probe signs of alien technological civilizations that are similar or much more advanced to our own," says Loeb, the Frank B. Baird, Jr., Professor of Science at Harvard.

The researchers will begin the project by looking at two possible technosignatures that might indicate technological activity on another planet:

• Solar panels. Stars are one of the most powerful energy generators in the universe. On Earth, we harness energy from our star, the sun, so "using solar energy would be a pretty natural thing for other civilizations to do," Frank says. If a civilization uses a lot of solar panels, the light that is reflected from the planet would have a certain spectral signature—a measurement of the wavelengths of light that are reflected or absorbed—indicating the presence of those solar collectors. The researchers will determine the spectral signatures of large-scale planetary solar energy collection.

• Pollutants. "We have come a long way toward understanding how we might detect life on other worlds from the gases present in those worlds' atmospheres," says Wright, a professor of astronomy and astrophysics at Penn State. On Earth, we are able to detect chemicals in our atmosphere by the light the chemicals absorb. Some examples of these chemicals include methane, oxygen, and artificial gases such as the chloroflourocarbons (CFCs) we once used as refrigerants. Biosignature studies focus on chemicals like methane, which simple life will produce. Frank and his colleagues will catalogue the signatures of chemicals, such as CFCs, that indicate the presence of an industrial civilization.

The information will be gathered in an online library of technosignatures that astrophysicists will be able to use as a comparative tool when gathering data.

"Our job is to say, 'this wavelength band is where you might see certain types of pollutants, this wavelength band is where you would see sunlight reflected off solar panels," Frank says. "This way astronomers observing a distant exoplanet will know where and what to look for if they're searching for technosignatures."

The work is a continuation of Frank's previous research on theoretical astrophysics and SETI, including developing a mathematical model to illustrate how a technologically advanced population and its planet might develop or collapse together; classifying hypothetical "exo-civilizations" based on their ability to harness energy; and a thought experiment asking if a previous, long-extinct technological civilization on Earth would still be detectable today.

Explore further

NASA wants to begin hunting for intelligent aliens who, like us, create technology

Source: Phys.org Return to Contents

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Space Image of the Week

Magnetic Streamlines of the Milky Way Explanation What role do magnetic fields play in interstellar physics? Analyses of observations by ESA's Planck satellite of emission by small magnetically-aligned dust grains reveal previously unknown magnetic field structures in our Milky Way Galaxy -- as shown by the curvy lines in the featured full-sky image. The dark red shows the plane of the Milky Way, where the concentration of dust is the highest. The huge arches above the plane are likely remnants of past explosive events from our Galaxy's core, conceptually similar to magnetic loop-like structures seen in our Sun's atmosphere. The curvy streamlines align with interstellar filaments of neutral hydrogen gas and provide tantalizing evidence that magnetic fields may supplement gravity in not only in shaping the interstellar medium, but in forming stars. How magnetism affected our Galaxy's evolution will likely remain a topic of research for years to come.

Image Credit: ESA, Planck; Text: Joan Schmelz (USRA) Source: APOD Return to Contents