A snowy morning scene in March 2018 at the Ocean Grove pier in New Jersey. Posted to EarthSky Facebook by John Entwistle.

A new study – published March 13, 2018, in the peer-reviewed journal Nature Communications – again links warming Arctic temperatures to colder weather. Although this correlation is far-from-settled science, these particular researchers did find that severe winter weather in the eastern U.S. is two to four times more likely when the Arctic is abnormally warm than when the Arctic is abnormally cold. Likewise, according to this study, northern latitudes of Europe and Asia may have colder winters when the Arctic is warm. This research has drawn fire from global warming deniers and prompted contrarian viewpoints in some publications. How can we know who or what to believe?

Here’s what we can know, with some confidence. Measurements show that the Arctic has been abnormally warm, and sea ice in the Arctic has been low. Measurements have their uncertainties also, but many measurements – for example, sea ice measurements from the National Snow and Ice Data Center in Boulder, Colorado – show these trends in the Arctic. It appears that the Arctic is not only warming, but warming at a rate two to three times faster than the observed rate of warming for the rest of the globe. This phenomenon is known among climate scientists as Arctic amplification.

• Explainer: How do scientists measure global temperature?

At the same time, as many of us know, the winter of 2017-2018 was extreme. There were record-breaking polar vortex disruptions, severe bomb cyclones and nor’easters in the U.S. Northeast and record-breaking cold and snow in the U.S. and Europe.

So … what’s happening here? It seems counterintuitive that a warmer Arctic would cause colder winters.

Should we believe this new study?

View larger. | Geographic locations of cities analyzed in the new study. The authors said: “We chose a geographically diverse set of 12 cities to analyze Arctic variability and severe winter weather, though we chose more cities in the northeastern and mid-western U.S. where severe winter weather is more common than in other regions of the U.S.”

Image via Cohen et al.

In deciding whether you believe it, it’s important to realize that measurements are in a different category in science from analysis. The March 13 study – authored by Judah Cohen of MIT, Karl Pfeiffer of Atmospheric & Environmental Research, Inc. and Jennifer Francis of Rutgers – used the tools of science to analyze existing data. These authors described their study as an:

… extensive, quantitative analysis of the link between Arctic variability and severe winter weather across the mid-latitudes. In this study we find a robust relationship between Arctic temperatures and severe winter weather in the United States. When the Arctic is warm, both cold temperatures and heavy snowfall are more frequent compared to when the Arctic is cold.

Jennifer Francis commented in a statement from Rutgers on March 13:

Basically, this confirms the story I’ve been telling for a couple of years now. Warm temperatures in the Arctic cause the jet stream to take these wild swings, and when it swings farther south, that causes cold air to reach farther south.

These researchers found that when Arctic warming occurred near Earth’s surface, the correlation with severe winter weather was weak. But when the warming over the Arctic extended high into the atmosphere, into the stratosphere, disruptions of the stratospheric polar vortex were likely.

View larger. | These authors assert in their study that: “As the Arctic warms, the continents become colder.”

 See a complete explanation of this image via Cohen et al.

Global warming skeptics pounced on this study. For example, Steven Milloy – who is, among other things, the publisher of the website JunkScience.com, a former columnist for Fox News and a co-creator and manager of the Free Enterprise Action Fund – posted the following tweet, which lifts language directly from Cohen et al.’s Nature paper:

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He’s pointing to the part of Cohen, Pfeiffer and Francis’ own study where they themselves point out some of this study’s unknowns and challenges, and, by extension, some of the unknowns and challenges inherent in modern climate science. Do these acknowledged unknowns and challenges undercut this study – or almost all climate studies – as Milloy suggests?

Let’s look at the answer in a wider context. Does asking scientific questions in any field suggest that area of science is not worth pursuing?

Of course not.

If it did, science as a whole would have come to a dead standstill long ago, and our lives would be far less easy and comfortable than they are today. Think of electricity. Do you suppose Thomas Edison had questions, as he figured it out? Do you think he might have had challenges?

The fact is, scientists are supposed to question themselves and each other. They’re supposed to work through challenges. It’s what they’re trained to do. It’s how science gets done. It might be helpful here to mention that all science is a process, as all scientists and many non-scientists know. Scientists question, and try to answer their own questions or learn how other scientists have answered them, and this constant questioning-and-answering pushes their investigations of nature forward … or, I should say, our investigations of nature, since science is a cultural activity, paid for in large part by our tax dollars.

Do global warming skeptics like Steven Milloy understand that questioning is part of the process of science? I have no idea. It’s possible he doesn’t; he’s trained as a lawyer, not a scientist.

Should we believe that Arctic warming is correlated with colder winters as this study suggests? Belief or disbelief doesn’t enter into it, for scientists, and it shouldn’t for you either. The results are just out there, for you and me to read about, be informed about and think about, and for future scientific studies to either confirm or refute.

This study is one small clue in the investigation of climate change, which has already been going on for decades. Will this one little clue be swept away by better ones? Maybe. Time will tell.

Until then, claims that the study has been undercut because scientists are questioning themselves and each other … well, those claims just show some writers’ ignorance of – unawareness of, unconsciousness of, unfamiliarity with, inexperience with, lack of information about – the way science works.

It may be willful ignorance, or not.

See how Step #5 (Make a Conclusion) has an arrow leading back to Step #1 (Ask a Question)? Scientists are continually questioning because science isn’t a body of facts; it’s a way of investigating nature.

Image via SlidePlayer.com.

By the way, someone is bound to ask in the comments who supported the study by Cohen, Pfeiffer and Francis. That is a valid and excellent question. For virtually any published science study, you can find a section at the very bottom called Acknowledgements. These authors’ acknowledgements are as follows:

We are grateful to Barbara Mayes-Boustead and Steve Hallberg for generously sharing with us the AWSSI [Accumulated Winter Season Severity Index] data. J.C. is supported by the National Science Foundation grants AGS-1303647 and PLR-1504361. J.F. is supported by NASA grant NNX14AH896 and NSF/ARCSS grant 1304097.

In his criticism of the study, Steven Milloy didn’t have as established a mechanism for mentioning who currently funds him, but he’s well-known for having been a paid advocate for Philip Morris, ExxonMobil and other corporations. Read more about who funds Steven Milloy.

Wondering who funds EarthSky? Our small organization receives revenues from three sources: ads on this website, donations and sales in our store.

A cold winter, via Onepony/Fotolia/ScienceDaily.

Bottom line: A warm Arctic means colder, snowier winters in the northeastern U.S., according to a new study. You don’t have to believe it; just think about it.

Source: Warm Arctic episodes linked with increased frequency of extreme winter weather in the United States

Via Rutgers University

Composite infrared image from Juno of clusters of massive cyclones surrounding Jupiter’s north pole.

Image via NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM.

The Juno spacecraft has found that the giant planet Jupiter is full of big surprises; its interior composition and structure seem to be quite different, and its winds even more active, than originally thought. Now, giant cyclones at the planet’s poles have been seen in greater detail than ever before. They are not only stunning, but unique from atmospheric storms of any other planet in our solar system, even other gas and ice giants. Also, other new data from Juno builds on previous findings, including showing that the planet’s strong winds penetrate deep into the atmosphere and last longer than any similar ones on our planet.

The new findings are published (here and here) in the March 8, 2018, edition of the peer-reviewed journal Nature.

In a statement from NASA, Scott Bolton, principal investigator of Juno from the Southwest Research Institute, San Antonio, said:

These astonishing science results are yet another example of Jupiter’s curve balls, and a testimony to the value of exploring the unknown from a new perspective with next-generation instruments. Juno’s unique orbit and evolutionary high-precision radio science and infrared technologies enabled these paradigm-shifting discoveries.

Juno is only about one-third the way through its primary mission, and already we are seeing the beginnings of a new Jupiter.

Since astronomers first started using telescopes, it could be seen that Jupiter seemed to be an active world, with its well-known colorful atmospheric belts, and of course the Great Red Spot. Thanks to probes like Voyager, Galileo and now Juno, we can see these phenomena in much greater detail than ever before. The atmospheric belts are incredibly turbulent, with jet streams and storms far more powerful than any on Earth.

Jupiter’s atmospheric marvels are not limited to its equatorial regions, however; Juno has provided unprecedented views of the planet’s poles, where massive cyclones churn with unearthly ferocity. Infrared images created from data taken by the Jovian Infrared Auroral Mapper (JIRAM) instrument look almost surreal, like cosmic artwork.

The clusters of cyclones around the poles look kind of like a space pizza – a dazzling, yet unearthly sight. Alberto Adriani, Juno co-investigator from the Institute for Space Astrophysics and Planetology, Rome, and lead author of oneof the new papers, said:

Prior to Juno we did not know what the weather was like near Jupiter’s poles. Now, we have been able to observe the polar weather up-close every two months.

Each one of the northern cyclones is almost as wide as the distance between Naples, Italy, and New York City – and the southern ones are even larger than that. They have very violent winds, reaching, in some cases, speeds as great as 220 mph (350 kph). Finally, and perhaps most remarkably, they are very close together and enduring.

There is nothing else like it that we know of in the solar system.

Jupiter’s south pole has cyclones, too. This computer-generated image of cyclones at Jupiter’s south pole was created using data from the Jovian Infrared Auroral Mapper (JIRAM) instrument on Juno.

Image via NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM.

Interestingly, the cyclones remain close to each other but never seem to merge together.

Not only are Jupiter’s storms unearthly, so are its auroras, which are much more powerful than any here, and “defy earthly laws of physics.”

Juno had also already shown that the planet’s equatorial belts extend much farther down into the atmosphere than thought, and new gravity measurements have also now shown a north-south asymmetry. Luciano Iess, Juno co-investigator from Sapienza University of Rome, said:

Juno’s measurement of Jupiter’s gravity field indicates a surprising north-south asymmetry, similar to the asymmetry observed in its zones and belts.

The stronger the asymmetry, the deeper the jet streams are. The Jovian weather layer, from the very top to a depth of 1,900 miles (3,000 kilometers), is now estimated to contain about one percent of Jupiter’s mass (about 3 Earth masses). Earth’s atmosphere is less than one millionth the mass of the planet itself, by comparison.

Another, more distant view of Jupiter’s south pole.

Image via NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt.

Juno has also sent back incredible views of Jupiter’s colorful belts in the equatorial regions.

Image via NASA/SwRI/MSSS/Gerald Eichstädt/Seán Doran.

Color-enhanced image showing intricate details in Jupiter’s cloud patterns.

Image via NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt/Seán Doran.

Tristan Guillot, a Juno co-investigator from the Université Côte d’Azur, Nice, France, and lead author of the March 8 paper on Jupiter’s deep interior, said:

Juno also found that Jupiter rotates almost as a solid body, beneath the active weather layer.

This is really an amazing result, and future measurements by Juno will help us understand how the transition works between the weather layer and the rigid body below.

Juno’s discovery has implications for other worlds in our solar system and beyond. Our results imply that the outer differentially-rotating region should be at least three times deeper in Saturn and shallower in massive giant planets and brown dwarf stars.

Juno has conducted 10 science passes over Jupiter so far; the next one will be on April 1.

Visit the Juno mission’s website

This story was originally published at AmericaSpace. Re-printed here with permission.

Bottom line: Thanks to Juno, we now know that Jupiter’s interior composition and structure appear different, and its winds more active, than originally thought. Also, Juno has now seen giant cyclones at Jupiter’s poles in greater detail than ever before.

Source: Jupiter’s atmospheric jet streams extend thousands of kilometres deep

Source: A suppression of differential rotation in Jupiter’s deep interior

What’s the media’s role in helping to fix a perception that science is broken, if such a perception exists?

Image via Authenticrecognition.com.

Have you heard people say that NASA lies, or that scientists are just chasing grants, or even that science itself is brokenor in crisis? We at EarthSky often hear these comments, and, while they don’t surprise us anymore, we do ponder the general public’s perception of science, especially given the public debate in the U.S. over climate change and other science-related issues, and especially in a media climate that allows fake news. This month (March 12, 2018), in the peer-reviewed Proceedings of the National Academy of Sciences (PNAS), communications scholar Kathleen Hall Jamieson documented three alternative news narratives about science and its challenges in media today.

She argued that science isn’t broken or in crisis. And she said it’s the job of the media to educate people about how science works.

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First, what is the public’s perception of science? Has that perception deteriorated? This short article at the Pew Research Center – from April, 2017 – suggests it hasn’t and that, in fact:

… public confidence in science has remained stable for decades.

However, Pew said, a segment of the U.S. population (6 percent) has “hardly any confidence” in the scientific community. Pew is basing its conclusion on data collected by NORC, an independent research organization at the University of Chicago, whose General Social Survey (GSS) has been running each year since 1972. Pew said GSS results released a year ago – on March 29, 2017 – show:

… that 40 percent of Americans have a great deal of confidence in the scientific community, while half (50 percent) have only some confidence and 6 percent have hardly any confidence.

Pew even said:

Public confidence in scientists stands out among the most stable of about 13 institutions rated in the GSS survey since the mid-1970s.

Via Pew Research Center, April, 2017.

Despite these survey results, Kathleen Hall Jamieson and others worry about a public perception of science as broken. Jamieson is a communications professor and director of the Annenberg Public Policy Center at the University of Pennsylvania. This academic center runs FactCheck.org, which examines the factual accuracy of U.S. political campaign advertisements. She and Joe Hilgard of Illinois State University contributed a chapter to The Oxford Handbook of the Science of Science Communication, published in 2017. Their chapter was titled Science as “Broken” Versus Science as “Self-Correcting.”

What does it mean for science to be self-correcting?

In her March 12 essay, Jamieson outlined three narratives used by the media in science stories. She included the quest discovery narrative, the counterfeit discovery narrative and the systemic problem narrative (the overall idea that science is broken).

Science as honorable quest? Image via Nerdist.

Quest discovery, she said, is a classic literary genre used from Gilgamesh to The Lord of the Rings.

In typical quest discovery stories about science, you’ll find words like advance, path-breaking, breakthrough, or discovery.

Jamieson pointed out that this narrative is employed particularly when presenting science that’s useful to humankind. And many science stories do lean that way. Of the 60 studies that received the most media coverage from May 2016 to April 2017, she wrote, nearly half were related to human health and well-being, according to the tracking firm Altmetric.

Science “just for the money” or for personal advancement? Image via a BigThink article titled What’s More Dishonest: Scientists Taking Corporate Cash or Mudslingers Attacking Them?

On the other hand, Jamieson said, the media also frequently employs a counterfeit discovery narrative. We’ve all read this story. It’s the tale of a deceptive scientist and a dishonorable quest, the story of someone who has “gulled custodians of knowledge” such as science journal editors and peer reviewers. Jamieson provided an interesting sequence of headlines related to Haruko Obokata, who reported having developed a method of developing pluripotent stem cells. The sequence started with:

Study says new method could be a quicker source of stem cells, The New York Times, January 9, 2014.

And Obokata’s story quickly deteriorated in the media, ending (in Jamieson’s sequence) less than a year later with:

Stem cell scandal scientist Haruko Obokata resigns, BBC News, December 19, 2014.

In recent years, the soft science of psychology has been riddled with counterfeit discovery headlines. Jamieson pointed to The Atlantic’s March 2016 article titled Psychology’s replication crisis can’t be wished away, for example. Jamieson commented:

Indictments of null hypothesis testing and P values [both commonly used in psychology] were rationalized away as well. Such inaction warranted “broken, uncorrecting” and perhaps even “crisis” characterizations, and the inference that such terms were more realistic than histrionic.

In other words, some sciences – such as psychology – may have their own unique and troublesome issues.

Image via Lisa Larson-Walker, in an article in Slate titled Is Science Broken? Or Is It Self-Correcting?

The psychology example feeds into Jamieson’s argument that the third narrative – science is broken – is an overgeneralization. Yet, in media today, many stories do suggest science as a whole (or in some large part) is broken. You can find stories like that here and here and here and here. Jamieson also pointed to some science writers today, who tend to concentrate on what she calls a problem-focused news narrative in science, with headlines and storylines to match. She said:

In such accounts, scientists are portrayed as publicizing problems, not proffering solutions.

Jamieson doesn’t think science is broken. She stated in her essay:

… generalizations about a crisis in science aren’t justified by the available evidence.

But she thinks the issue is important, because news media portrayals of science affect how we all think about it. That’s why she concluded that:

… those who communicate science, including journalists, scholars, and scientists themselves, should more accurately convey its investigatory nature, the self-correction process, and corrective measures without legitimizing a faulty narrative.

By the way, Jamieson identified ways that science narratives can be improved in the media. Among her suggestions:Science journalism is many things. Is part of its job to educate people about science? Artist’s illustration via Nature.

Include information that reflects the practices and protections of science, such as the trial-and-error process, and the ways that science detects and protects itself from deception;

Reserve “dire characterizations of the state of science” for cases in which “integrity-threatening problems are being ignored”;

Treat self-correction as a central part of the scientific process, not an afterthought – before regarding a rise in retractions as a “crisis in science,” consider the argument that they are a “signal that science is working”;

Focus on problems without shortchanging solutions: “To perform their accountability function well, reporters should not only alert the public to problems in consequential science but also scrutinize how and how well they are being addressed.”

Her essay concluded:

By responsibly publicizing both breaches of integrity and attempts to forestall them, news can perform its accountability function without undermining public trust in the most reliable form of knowledge generation humans have devised.

Kathleen Hall Jamieson via BillMoyers.com.

Bottom line: Kathleen Jamieson analyzed narratives used in media to portray science. She argued that science isn’t broken or in crisis and that it’s the job of the media to educate people about how science works.

Source: Crisis or self-correction: rethinking media narratives about the well-being of science, PNAS, March 12, 2018

Via Annenberg Public Policy Center

Image via Arizona State University.

By Karin Valentine/Arizona State University

TRAPPIST-1 is an ultra-cool red dwarf star that is slightly larger, but much more massive, than the planet Jupiter, located about 40 light-years from the sun in the constellation Aquarius.

Among planetary systems, TRAPPIST-1 is of particular interest because seven planets have been detected orbiting this star, a larger number of planets than have been than detected in any other exoplanetary system. In addition, all of the TRAPPIST-1 planets are Earth-sized and terrestrial, making them an ideal focus of study for planet formation and potential habitability.

Arizona State University (ASU) scientists Cayman Unterborn, Steven Desch and Alejandro Lorenzo of the School of Earth and Space Exploration, with Natalie Hinkel of Vanderbilt University, have been studying these planets for habitability, specifically related to water composition. Their findings were published March 19, 2018, in Nature Astronomy.

The calculations equal water

The TRAPPIST-1 planets are curiously light. From their measured mass and volume, all of this system’s planets are less dense than rock. On many other, similarly low-density worlds, it is thought that this less-dense component consists of atmospheric gases. Geoscientist Unterborn explained:

But the TRAPPIST-1 planets are too small in mass to hold onto enough gas to make up the density deficit. Even if they were able to hold onto the gas, the amount needed to make up the density deficit would make the planet much puffier than we see.

So scientists studying this planetary system have determined that the low-density component must be something else that is abundant: water. This has been predicted before, and possibly even seen on larger planets like GJ1214b, so the interdisciplinary ASU-Vanderbilt team, comprised of geoscientists and astrophysicists, set out to determine just how much water could be present on these Earth-sized planets and how and where the planets may have formed.

But how much is there?

To determine the composition of the TRAPPIST-1 planets, the team used a unique software package, developed by Unterborn and Lorenzo, that uses state-of-the-art mineral physics calculators. The software, called ExoPlex, allowed the team to combine all of the available information about the TRAPPIST-1 system, including the chemical makeup of the star, rather than being limited to just the mass and radius of individual planets.

Much of the data used by the team to determine composition was collected from a dataset called the Hypatia Catalog, developed by contributing author Hinkel. This catalog merges data on the stellar abundances of stars near to our sun, from over 150 literature sources, into a massive repository.

What they found through their analyses was that the relatively “dry” inner planets (“b” and “c”) were consistent with having less than 15 percent water by mass (for comparison, Earth is 0.02 percent water by mass). The outer planets (“f” and “g”) were consistent with having more than 50 percent water by mass. This equates to the water of hundreds of Earth-oceans. The masses of the TRAPPIST-1 planets continue to be refined, so these proportions must be considered estimates for now, but the general trends seem clear. Steven Desch, ASU astrophysicist and contributing author, said:

What we are seeing for the first time are Earth-sized planets that have a lot of water or ice on them.

But the researchers also found that the ice-rich TRAPPIST-1 planets are much closer to their host star than the ice line. The “ice line” in any solar system, including TRAPPIST-1’s, is the distance from the star beyond which water exists as ice and can be accreted into a planet; inside the ice line water exists as vapor and will not be accreted. Through their analyses, the team determined that the TRAPPIST-1 planets must have formed much farther from their star, beyond the ice line, and migrated in to their current orbits close to the host star.

There are many clues that planets in this system and others have undergone substantial inward migration, but this study is the first to use composition to bolster the case for migration. What’s more, knowing which planets formed inside and outside of the ice line allowed the team to quantify for the first time how much migration took place.

Because stars like TRAPPIST-1 are brightest right after they form and gradually dim thereafter, the ice line tends to move in over time, like the boundary between dry ground and snow-covered ground around a dying campfire on a snowy night. The exact distances the planets migrated inward depends on when they formed. Desch said:

The earlier the planets formed, the farther away from the star they needed to have formed to have so much ice.

But for reasonable assumptions about how long planets take to form, the TRAPPIST-1 planets must have migrated inward from at least twice as far away as they are now.

This graph shows the minimum starting distances of the ice-rich TRAPPIST-1 planets (especially f and g) from their star (horizontal axis) as a function of how quickly they formed after their host star was born (vertical axis). The blue line represents a model where water condenses to ice at 170 K[-153 Fahrenheit, -103 Celsius], as in our solar system’s planet-forming disk. The red line applies to water condensing to ice at 212 K [-78 F, -61 C], appropriate to the TRAPPIST-1 disk. If planets formed quickly, they must have formed farther away (and migrated in a greater distance) to contain significant ice. Because TRAPPIST-1 dims over time, if the planets formed later, they could have formed closer to the host star and still be ice-rich.

Too much of a good thing

Interestingly, while we think of water as vital for life, the TRAPPIST-1 planets may have too much water to support life. Hinkel explained:

We typically think having liquid water on a planet as a way to start life, since life, as we know it on Earth, is composed mostly of water and requires it to live. However, a planet that is a water world, or one that doesn’t have any surface above the water, does not have the important geochemical or elemental cycles that are absolutely necessary for life.

Ultimately, this means that while M-dwarf stars, like TRAPPIST-1, are the most common stars in the universe (and while it’s likely that there are planets orbiting these stars), the huge amount of water they are likely to have makes them unfavorable for life to exist, especially enough life to create a detectable signal in the atmosphere that can be observed. Hinkel said:

It’s a classic scenario of “too much of a good thing.”

So, while we’re unlikely to find evidence of life on the TRAPPIST-1 planets, through this research we may gain a better understanding of how icy planets form and what kinds of stars and planets we should be looking for in our continued search for life.

Bottom line: All 7 of the TRAPPIST-1 planets are Earth-sized and terrestrial, making them an ideal focus of study for planet formation and potential habitability.

The Magellanic Stream is a faint and diffuse cloud of gas, long associated with the Large and Small Magellanic Clouds, dwarf galaxies orbiting our Milky Way. These astronomers used distant quasars, here labeled A, B and C, to understand the source of the gas cloud.

Image via UW-Madison/STScI. Read more about this image.

Astronomers said on March 23, 2018, that they’ve now confirmed the source of a huge cloud of gas arching around our Milky Way galaxy. The gas cloud is known as the Magellanic Stream. It’s galaxy-sized, 300,000 light-years long, in contrast to our Milky Way’s 100,000 light-year diameter. The cloud appears to be shunted away from the Large and Small Magellanic Clouds, two of the many dwarf galaxies orbiting our Milky Way. But which of the Clouds is the source of the stream of gas? Now, by scrutinizing the chemical makeup of the gas, astronomers say they’re confident one branch of the cloud, sometimes called the Leading Arm, is coming from the Small Magellanic Cloud.

The gravity of the Large Magellanic Cloud has apparently tugged the gas stream from its smaller companion. The new study is published in the peer-reviewed Astrophysical Journal.

The gas in the Magellanic Stream is difficult to study directly because it’s so faint and tenuous. Astronomers seeking the source of the gas don’t look at the gas directly.

Instead, they aim toward distant quasars located behind the Magellanic Stream. As the quasars’ light pierces the gas, trace amounts of various elements in the gas absorb specific wavelengths of the quasar-light. The team used spectroscopic analysis of the quasars’ light to reveal chemical abundances in the gas cloud. The measurements came from the Cosmic Origins Spectrograph on the Hubble Space Telescope as well as spectrographs on the Green Bank Telescope in Green Bank, West Virginia.

Astronomers first sighted the Magellanic Stream in 1965. They first linked it to the Magellanic Clouds in 1974. This arching stream of gas, now known to connect the Magellanic Clouds to the Milky Way, is thought to be younger than our galaxy, only 1 or 2 billion years old.

The astronomers on the new study credit Blair Savage, an emeritus professor of astronomy at the University of Wisconsin-Madison, for laying the groundwork that led to the current understanding of the Magellanic Stream. Savage worked for decades to understand the gas complexes around the Milky Way, including the Magellanic Stream. Six of the astronomers on the current paper – now at various institutions including the Space Telescope Science Institute and University of Wisconsin-Madison – were originally recruited by Savage to tackle the problem during their training at UW-Madison.

The authors of the new study said knowledge about the Magellanic Stream will help astronomers refine their models of how the Large and Small Magellanic Clouds orbit our Milky Way. Elena D’Onghia of University of Wisconsin-Madison, one of the new study’s authors, commented in a statement:

We still don’t know how the Milky Way has formed. We have this huge amount of gas sitting around the Milky Way, and we still don’t know its origin. Knowing where it comes from helps us understand how galaxies form, including our Milky Way.

From the Southern Hemisphere, the Magellanic Clouds appear in the sky as fuzzy offshoots of the starlit trail of the Milky Way. The gas cloud cannot be perceived with the unaided eye, despite the fact that it contains the mass of several hundred million suns.

Astronomers say this gas that might someday rain down on our galaxy and spark new star formation.

The Large and Small Magellanic Clouds (at bottom) are seen in this 8-minute time exposure, above the Southern African Large Telescope.

Image via Jeff Miller/ UW-Madison.

Bottom line: Astronomers have been working for decades to gain insights into the vast gas cloud, called the Magellanic Stream, that arches around our Milky Way galaxy. They now say the Small Magellanic Cloud is the source of the Leading Arm of the Stream.

Source: Chemical Abundances in the Leading Arm of the Magellanic Stream

Via University of Wisconsin

Tiangong-1 potential reentry area. Map showing the area between 42.8 degrees north and 42.8 degrees south latitude (in green), over which Tiangong-1 could reenter.

Image via ESA CC BY-SA IGO 3.0.

Have you been hearing specific reentry locations for China’s first space station, Tiangong-1, aka Heavenly Palace 1? I heard Michigan at one point, then Wisconsin. Don’t believe these specific predictions. Experts are still saying reentry will take place anywhere between 43 degrees north and 43 degrees south (see map below). At no time will a precise time or location prediction for reentry be possible.

It is possible to narrow down the time of reentry, however. The most recent calculation by Aerospace Corporation (March 22, 2018) is now calling for it to happen around April 1, 2018 plus or minus three days. The European Space Agency (ESA), in its March 23 update, is giving the dates as March 30 to April 3, and still calls these dates highly variable. And, of course, they are subject to change.

You can get a last glimpse of Tiangong-1 – during one of its very last passages across our skies – via the Virtual Telescope Project and Tenagra Observatories. Currently, this live coverage is scheduled for March 28, 2018, starting at 12 UTC (7 a.m. CDT on March 28; translate to your time zone). Virtual Telescope’s page says the time of the event is also subject to change, if the Tiangong-1 situation changes quickly. Click here to view online and for updates.

The spacecraft’s main body is approximately 34 feet (10.4 meters) long.

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Jonathan McDowell

✔@planet4589

Reference: here is an illustration of Tiangong-1 by the manufacturer CAST

10:04 PM - Mar 7, 2018

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ESA has said that Tiangong-1 will “substantially burn up” in Earth’s atmosphere. Will pieces crash to Earth? Possibly. Will they crash in populated areas? It’s not possible to say, but the chances are small that any human being will be harmed, according to a statement from Aerospace, a research organization that advises government and private enterprise on space flight. Aerospace said:

There is a chance that a small amount of Tiangong-1 debris may survive reentry and impact the ground. Should this happen, any surviving debris would fall within a region that is a few hundred kilometers in size and centered along a point on the Earth that the station passes over.

Aerospace also warned that the space station might be carrying a highly toxic and corrosive fuel called hydrazine on board.

As of today’s date (March 24, 2018), the spacecraft is at about 134 miles (215 km) altitude. That’s down from 155 miles (258 km) the last time I checked, on March 7. Its orbit is clearly decaying as you can see if you follow the spacecraft’s descent here. The end will come more or less suddenly, due in part to changing conditions in Earth’s upper atmosphere, which is why it’s so inherently unpredictable.

• Click here to learn how to see Tiangong-1 before it falls

Tiangong-1 is not designed to withstand reentry, as some spacecraft are. But it will mostly burn up when it falls, due to the extreme heat and friction generated by its high-speed passage through Earth’s atmosphere.

Tiangong 1 predicted reentry, as of March 6, 2018, via ESA.

Tiangong-1’s major goal was to test and master technologies related to orbital rendezvous and docking. One uncrewed and two crewed missions – executed by the Shenzhou (Divine Craft) spacecraft – took place during its operational lifetime. ESA explained:

Following launch in 2011, the Tiangong-1 orbit began steadily decaying due to the faint, yet not-zero, atmospheric drag present even at 300 or 400 km altitude [~200 to 250 miles altitude]. This affects all satellites and spacecraft in low-Earth orbit, like the International Space Station, for example.

ESA is updating its forecast for Tiangong-1’s reentry frequently; click here to go to ESA’s updates.

Bottom line: China’s first space station will soon undergo an uncontrolled reentry into Earth’s atmosphere. As of March 22, Aerospace Corporation was predicting April 1 ± 3 days. As of March 23, ESA was predicting March 30 to April 3. At no time will a precise time or location prediction for reentry be possible.

Live, real-time tracking of Tiangong-1 here