There once was a polar bear – science vs the blogosphere

This is a re-post from My View on Climate Change

Blogs on which man-made climate change and its impacts are downplayed are far removed from the scientific literature. That is the conclusion of a new article in Bioscience in which a variety of blogs was compared with the scientific literature regarding the shrinking Arctic sea ice and the impact on polar bears.

Although there is strong agreement within the scientific community about anthropogenic causation of recent climate change, a large segment of the general public has doubts about these conclusions. This is sometimes referred to as the ‘consensus gap’. Blogs and other social media play an important role in spreading misinformation, which fuels the distrust in science.

Jeff Harvey, a Canadian ecologist working at the Netherlands Institute for Ecology (NIOO-KNAW) and the Free University of Amsterdam (VU), set out to investigate how the information on blogs relates to the scientific literature. The focus was on conclusions about Arctic sea ice and polar bears. The results have been published in the article “Internet Blogs, Polar Bears, and Climate-Change Denial by Proxy” in the journal Bioscience. Disclaimer: I’m a co-author of said article.

So what did we find? There is a clear separation amongst blogs, where approximately half of the 90 blogs investigated agree with the majority of the scientific literature, whereas other blogs took a position that is diametrically opposed to the scientific conclusions. Most of the blogs in the latter group based their opinions on one and the same source: Susan Crockford.

90 blogs and 92 scientific articles were classified according to six statements about Arctic sea ice and polar bears and the citation of Crockford. The figure shows the results of a principal component analysis (PCA) of the results. PCA is a technique to show the maximum amount of variation in a dataset with a minimum of newly defined parameters, the so-called principal components. The score on PC1 shows a separation between on the one hand the position that Arctic sea ice extent is shrinking and that this poses a threat to polar bears (most scientific articles and science-based blogs) and on the other side the position that Arctic sea ice is not shrinking or that it’s due to natural variability and that polar bears are not threatened (pseudo-skeptical blogs).

Arctic Sea ice

Arctic sea ice has shrunk dramatically in the past few decades, both in surface area and in thickness. This trend is expected to continue with ongoing global warming as a result of greenhouse gas emissions. Of course the decrease in sea ice doesn’t happen monotonically, but rather with ups and downs as a result of natural variability. When it happens to fit their perspective, such short term fluctuations are framed as a ‘recovery’ on certain blogs, or the decrease in Arctic sea ice is downplayed in other ways.

Polar bears

Polar bears depend on sea ice for catching their main prey, seals. So their habitat literally melts away as temperatures rise. Over time, polar bears have become iconic symbols of the negative effects of global warming. The population has been relatively stable so far, but you can’t just extrapolate that to the future. Biological impacts are often non-linear, and their dependence on sea ice means that in the future polar bears will likely face difficulties from continuing warming trend. Indeed, they have been classified as ‘vulnerable’ by the International Union for the Conservation of Nature (IUCN) and as ‘threatened’ under the US Endangered Species Act.

“No climate report is complete without an obligatory photo of a polar bear balancing on a piece of ice”, John Oliver said in the famous 97% episode of “Last Week Tonight”.

But what about the previous interglacial?

The polar bear species has survived the previous interglacial ~125,000 years ago. Some deduce from that that the polar bear will be fine. However, if CO2 emissions aren’t drastically reduced temperatures will get a lot warmer over the coming centuries and even millennia than during the previous interglacial. Moreover, during the previous interglacial summers were probably not completely ice-free, as is expected to happen  later this century as a consequence of continuing warming (which of course depends on how global emissions evolve). The current warming trend is many times faster than back then, making potential adaptation to new conditions more difficult. Besides shrinking sea ice there are currently also other factors that negatively affect polar bears, such as human settlements, industrial activities, hunting, bio-accumulation of toxins, and smaller seal populations.

Blogs

A future with ‘business as usual’ emissions doesn’t look bright for the polar bear. Blogs appear to fall into two camps in how they write about this topic. On pseudo-skeptical blogs scientific uncertainty is twisted into ignorance, or the current situation is extrapolated into the future without taking into account the available knowledge of polar bear ecology. They usually don’t base themselves on the scientific literature, but rather on the statements of one person. These rather unfounded opinions are consequently recycled via the blogosphere, which in this respect acts as an echo-chamber. Susan Crockford writes a lot about polar bears, but does so mostly on her own website and for anti-mitigation thinktanks such as the Heartland Institute and the Global Warming Policy Foundation (GWPF); not in the scientific literature.

The gap between scientific conclusions and pseudo-skeptical blogs will not be a great surprise to those who closely follow both the scientific and the public debate about climate change. After all, this tendency is more generally visible than only on the topic of Arctic sea ice and polar bears. This is however the first time that this has been demonstrated on the basis of a systematic comparison between the scientific literature and blogs. To close the consensus gap the authors call on their fellow scientists to actively participate in the public debate.

from Skeptical Science http://ift.tt/2irMTuQ

This is a re-post from My View on Climate Change

Blogs on which man-made climate change and its impacts are downplayed are far removed from the scientific literature. That is the conclusion of a new article in Bioscience in which a variety of blogs was compared with the scientific literature regarding the shrinking Arctic sea ice and the impact on polar bears.

Although there is strong agreement within the scientific community about anthropogenic causation of recent climate change, a large segment of the general public has doubts about these conclusions. This is sometimes referred to as the ‘consensus gap’. Blogs and other social media play an important role in spreading misinformation, which fuels the distrust in science.

Jeff Harvey, a Canadian ecologist working at the Netherlands Institute for Ecology (NIOO-KNAW) and the Free University of Amsterdam (VU), set out to investigate how the information on blogs relates to the scientific literature. The focus was on conclusions about Arctic sea ice and polar bears. The results have been published in the article “Internet Blogs, Polar Bears, and Climate-Change Denial by Proxy” in the journal Bioscience. Disclaimer: I’m a co-author of said article.

So what did we find? There is a clear separation amongst blogs, where approximately half of the 90 blogs investigated agree with the majority of the scientific literature, whereas other blogs took a position that is diametrically opposed to the scientific conclusions. Most of the blogs in the latter group based their opinions on one and the same source: Susan Crockford.

90 blogs and 92 scientific articles were classified according to six statements about Arctic sea ice and polar bears and the citation of Crockford. The figure shows the results of a principal component analysis (PCA) of the results. PCA is a technique to show the maximum amount of variation in a dataset with a minimum of newly defined parameters, the so-called principal components. The score on PC1 shows a separation between on the one hand the position that Arctic sea ice extent is shrinking and that this poses a threat to polar bears (most scientific articles and science-based blogs) and on the other side the position that Arctic sea ice is not shrinking or that it’s due to natural variability and that polar bears are not threatened (pseudo-skeptical blogs).

Arctic Sea ice

Arctic sea ice has shrunk dramatically in the past few decades, both in surface area and in thickness. This trend is expected to continue with ongoing global warming as a result of greenhouse gas emissions. Of course the decrease in sea ice doesn’t happen monotonically, but rather with ups and downs as a result of natural variability. When it happens to fit their perspective, such short term fluctuations are framed as a ‘recovery’ on certain blogs, or the decrease in Arctic sea ice is downplayed in other ways.

Polar bears

Polar bears depend on sea ice for catching their main prey, seals. So their habitat literally melts away as temperatures rise. Over time, polar bears have become iconic symbols of the negative effects of global warming. The population has been relatively stable so far, but you can’t just extrapolate that to the future. Biological impacts are often non-linear, and their dependence on sea ice means that in the future polar bears will likely face difficulties from continuing warming trend. Indeed, they have been classified as ‘vulnerable’ by the International Union for the Conservation of Nature (IUCN) and as ‘threatened’ under the US Endangered Species Act.

“No climate report is complete without an obligatory photo of a polar bear balancing on a piece of ice”, John Oliver said in the famous 97% episode of “Last Week Tonight”.

But what about the previous interglacial?

The polar bear species has survived the previous interglacial ~125,000 years ago. Some deduce from that that the polar bear will be fine. However, if CO2 emissions aren’t drastically reduced temperatures will get a lot warmer over the coming centuries and even millennia than during the previous interglacial. Moreover, during the previous interglacial summers were probably not completely ice-free, as is expected to happen  later this century as a consequence of continuing warming (which of course depends on how global emissions evolve). The current warming trend is many times faster than back then, making potential adaptation to new conditions more difficult. Besides shrinking sea ice there are currently also other factors that negatively affect polar bears, such as human settlements, industrial activities, hunting, bio-accumulation of toxins, and smaller seal populations.

Blogs

A future with ‘business as usual’ emissions doesn’t look bright for the polar bear. Blogs appear to fall into two camps in how they write about this topic. On pseudo-skeptical blogs scientific uncertainty is twisted into ignorance, or the current situation is extrapolated into the future without taking into account the available knowledge of polar bear ecology. They usually don’t base themselves on the scientific literature, but rather on the statements of one person. These rather unfounded opinions are consequently recycled via the blogosphere, which in this respect acts as an echo-chamber. Susan Crockford writes a lot about polar bears, but does so mostly on her own website and for anti-mitigation thinktanks such as the Heartland Institute and the Global Warming Policy Foundation (GWPF); not in the scientific literature.

The gap between scientific conclusions and pseudo-skeptical blogs will not be a great surprise to those who closely follow both the scientific and the public debate about climate change. After all, this tendency is more generally visible than only on the topic of Arctic sea ice and polar bears. This is however the first time that this has been demonstrated on the basis of a systematic comparison between the scientific literature and blogs. To close the consensus gap the authors call on their fellow scientists to actively participate in the public debate.

from Skeptical Science http://ift.tt/2irMTuQ

American leaders should read their official climate science report

The United States Global Change Research Program recently released a report on the science of climate change and its causes. The report is available for anyone to read; it was prepared by top scientists, and it gives an overview of the most up to date science. 

If you want to understand climate change and a single document that summarizes what we know, this is your chance. This report is complete, readily understandable, and accessible. It discusses what we know, how we know it, how confident we are, and how likely certain events are to happen if we continue on our business-as-usual path. 

To summarize, our Earth has warmed nearly 2°F (1°C) since the beginning of the 20th century. Today’s Earth is the warmest it has ever been in the history of modern civilization.

Global average surface temperatures over the past 1,700 years. Illustration: United States Global Change Research Program

While the planet has warmed, the climate and the Earth’s environment has responded. We are observing heating of the atmosphere, oceans, and the Earth’s surface. Glaciers are melting at an alarming rate. Snow cover is decreasing and we are experiencing increased water scarcity, particularly in parts of the world that rely on snowmelt for water.

The amount of ice is decreasing. In particular, the ice that floats atop waters in the Arctic have decreased significantly since measurements began. As a result of melting land ice and thermal expansion, sea levels are rising. Oceans have risen, on average, 7–8 inches. In some places, the rise has been much more. Astonishingly, half of the total rise has occurred in the last 30 years. Currently, oceans are rising faster than any point in time in the last ~3,000 years. Not only that, the ocean rise is causing city flooding to accelerate.

According to the report, seal levels will likely rise somewhere between 1–4 feet by the end of the century, but increases up to 8 feet can’t be ruled out (~2.5 meters). For context, approximately 150 million people around the world live within one meter of current sea level. 

If you live away from the shores, you are not immune to the impacts of climate change. The report delves into the increases in extreme weather. For instance, heavy rainfall is increasing across the United States as well as globally. These increases will continue into the future and they are already leading to more severe flooding. The prediction that scientists made that wet areas will become wetter is turning out to be true. 

There are more extreme heatwaves as well. Not only are we seeing more heat waves (and severe droughts), but in the next few decades, the authors predict temperatures will rise by ~2.5°F (~1.5°C) in the United States. This is an enormous change in temperature that will reshape the country. Similar changes are occurring and will occur in other countries.

Click here to read the rest

from Skeptical Science http://ift.tt/2AqmzrX

The United States Global Change Research Program recently released a report on the science of climate change and its causes. The report is available for anyone to read; it was prepared by top scientists, and it gives an overview of the most up to date science. 

If you want to understand climate change and a single document that summarizes what we know, this is your chance. This report is complete, readily understandable, and accessible. It discusses what we know, how we know it, how confident we are, and how likely certain events are to happen if we continue on our business-as-usual path. 

To summarize, our Earth has warmed nearly 2°F (1°C) since the beginning of the 20th century. Today’s Earth is the warmest it has ever been in the history of modern civilization.

Global average surface temperatures over the past 1,700 years. Illustration: United States Global Change Research Program

While the planet has warmed, the climate and the Earth’s environment has responded. We are observing heating of the atmosphere, oceans, and the Earth’s surface. Glaciers are melting at an alarming rate. Snow cover is decreasing and we are experiencing increased water scarcity, particularly in parts of the world that rely on snowmelt for water.

The amount of ice is decreasing. In particular, the ice that floats atop waters in the Arctic have decreased significantly since measurements began. As a result of melting land ice and thermal expansion, sea levels are rising. Oceans have risen, on average, 7–8 inches. In some places, the rise has been much more. Astonishingly, half of the total rise has occurred in the last 30 years. Currently, oceans are rising faster than any point in time in the last ~3,000 years. Not only that, the ocean rise is causing city flooding to accelerate.

According to the report, seal levels will likely rise somewhere between 1–4 feet by the end of the century, but increases up to 8 feet can’t be ruled out (~2.5 meters). For context, approximately 150 million people around the world live within one meter of current sea level. 

If you live away from the shores, you are not immune to the impacts of climate change. The report delves into the increases in extreme weather. For instance, heavy rainfall is increasing across the United States as well as globally. These increases will continue into the future and they are already leading to more severe flooding. The prediction that scientists made that wet areas will become wetter is turning out to be true. 

There are more extreme heatwaves as well. Not only are we seeing more heat waves (and severe droughts), but in the next few decades, the authors predict temperatures will rise by ~2.5°F (~1.5°C) in the United States. This is an enormous change in temperature that will reshape the country. Similar changes are occurring and will occur in other countries.

Click here to read the rest

from Skeptical Science http://ift.tt/2AqmzrX

5 Ways to Keep Your Computer Secure on This Computer Security Day

It's Computer Security Day! Here are 5 quick ways to make sure yours is secure.

from http://ift.tt/2AJmbVQ

It's Computer Security Day! Here are 5 quick ways to make sure yours is secure.

from http://ift.tt/2AJmbVQ

Bright moon and aurora borealis

A composite of 6 overhead photos of the aurora and a bright moon – just 3 days past full – from Doug Short in Anchorage, Alaska. November 7, 2017.

Auroras are beautiful natural phenomena, whose primary cause is activity on the sun. They happen when charged particles from storms on the sun strike atoms and molecules in Earth’s atmosphere. The charged solar particles excite those earthly atoms, causing them to light up, creating the aurora. This sort of activity in Earth’s atmosphere happens during geomagnetic storms, and a full moon has absolutely no effect on either solar storms or geomagnetic storms. Still, as every astronomer knows, a full moon casts a lot of light in the sky. Can that light drown an aurora from view?

The answer depends on the strength of the aurora. A weak auroral display might be drowned in bright moonlight, just as bright moonlight can drown faint stars from view.

But, as the photos on this page show, a strong auroral display can withstand bright moonlight. AndyOz, who wrote a particularly good article on this subject, which you can access here, wrote:

If you get a moderate to high level of [auroral] activity … you should still get a good view of the northern lights. In some cases when there has been a solar storm and the level of activity is very high, the moon can actually enhance the viewing and make the display look even more magical. So it all really depends on how strong a display you are witnessing.

Aurora borealis and rising moon on February 14, 2013 from EarthSky Facebook friend Stigs Netrom in northern Norway.

Some photographers say they actually prefer to capture the aurora when there’s a moon in the sky. Todd Salat at the website AuroraHunter.com wrote of shooting the aurora in moonlight:

I personally like moonlight because it lights up the foreground and makes the sky a deep blue instead of pitch black like with no moon. I watch the lunar phase very carefully.

View larger. | Aurora and a full moon. Photo by Antti Pietikainen via the Aurora Zone. Antti created this mosaic from 10 images, taken from his backyard. He said the weather was good, no clouds and very cold. The moon was high in the sky, and it illuminated the whole landscape. “You could read a book outside!”

Bottom line: Contrary to what you might have heard, it is possible to see the aurora borealis, or northern lights, when there’s a bright moon, even a full moon, in the sky. The key is that the auroral display itself be moderate to strong. A weak display of the aurora might be drowned in bright moonlight.

What causes the aurora borealis or northern lights?

from EarthSky http://ift.tt/2zS1IhW

A composite of 6 overhead photos of the aurora and a bright moon – just 3 days past full – from Doug Short in Anchorage, Alaska. November 7, 2017.

Auroras are beautiful natural phenomena, whose primary cause is activity on the sun. They happen when charged particles from storms on the sun strike atoms and molecules in Earth’s atmosphere. The charged solar particles excite those earthly atoms, causing them to light up, creating the aurora. This sort of activity in Earth’s atmosphere happens during geomagnetic storms, and a full moon has absolutely no effect on either solar storms or geomagnetic storms. Still, as every astronomer knows, a full moon casts a lot of light in the sky. Can that light drown an aurora from view?

The answer depends on the strength of the aurora. A weak auroral display might be drowned in bright moonlight, just as bright moonlight can drown faint stars from view.

But, as the photos on this page show, a strong auroral display can withstand bright moonlight. AndyOz, who wrote a particularly good article on this subject, which you can access here, wrote:

If you get a moderate to high level of [auroral] activity … you should still get a good view of the northern lights. In some cases when there has been a solar storm and the level of activity is very high, the moon can actually enhance the viewing and make the display look even more magical. So it all really depends on how strong a display you are witnessing.

Aurora borealis and rising moon on February 14, 2013 from EarthSky Facebook friend Stigs Netrom in northern Norway.

Some photographers say they actually prefer to capture the aurora when there’s a moon in the sky. Todd Salat at the website AuroraHunter.com wrote of shooting the aurora in moonlight:

I personally like moonlight because it lights up the foreground and makes the sky a deep blue instead of pitch black like with no moon. I watch the lunar phase very carefully.

View larger. | Aurora and a full moon. Photo by Antti Pietikainen via the Aurora Zone. Antti created this mosaic from 10 images, taken from his backyard. He said the weather was good, no clouds and very cold. The moon was high in the sky, and it illuminated the whole landscape. “You could read a book outside!”

Bottom line: Contrary to what you might have heard, it is possible to see the aurora borealis, or northern lights, when there’s a bright moon, even a full moon, in the sky. The key is that the auroral display itself be moderate to strong. A weak display of the aurora might be drowned in bright moonlight.

What causes the aurora borealis or northern lights?

from EarthSky http://ift.tt/2zS1IhW

Lunar halo and clouds over Tucson

Moon rocketing into a halo? No. In fact, the “contrail” is really clouds, and the moon itself – plus ice crystals in the air – made this halo, which skywatchers call a 22-degree halo. Photo taken over Tucson, Arizona – November 29, 2017 – by Eliot Herman. Irex 15 mm lens and Nikon D850 camera.

What makes a halo around the sun or moon?

from EarthSky http://ift.tt/2kbuUcy

Moon rocketing into a halo? No. In fact, the “contrail” is really clouds, and the moon itself – plus ice crystals in the air – made this halo, which skywatchers call a 22-degree halo. Photo taken over Tucson, Arizona – November 29, 2017 – by Eliot Herman. Irex 15 mm lens and Nikon D850 camera.

What makes a halo around the sun or moon?

from EarthSky http://ift.tt/2kbuUcy

Do songbirds share ‘universal grammar’?

EarthSky’s 2018 lunar calendars are here! Get yours while they last.

Many scientists who study birdsong are intrigued by the possibility that human speech and music may be rooted in biological processes shared across a variety of animals. Now, new research, published online in Current Biology on November 22, 2017, provides new evidence to support the idea that songbirds and humans have common biological hardwiring that shapes how they produce and perceive sounds.

In a series of experiments, the researchers found that young zebra finches – a species often used to study birdsong – are intrinsically biased to learn to produce particular kinds of sound patterns over others.

Jon Sakata, Associate Professor of Biology at McGill University, is the paper’s senior author. Sakata said in a statement:

In addition, these sound patterns resembled patterns that are frequently observed across human languages and in music.

Zebra finches. Image via Raina Fan.

The idea for the experiments, say the researchers, was inspired by current hypotheses on human language and music. Linguists have long found that the world’s languages share many common features, termed “universals.” These features encompass the syntactic structure of languages (e.g., word order) as well as finer acoustic patterns of speech, such as the timing, pitch, and stress of utterances. Some theorists, including Noam Chomsky, have postulated that these patterns reflect a “universal grammar” built on innate brain mechanisms that promote and bias language learning. Researchers continue to debate the extent of these innate brain mechanisms, in part because of the potential for cultural propagation to account for universals.

At the same time, vast surveys of zebra finch songs have documented a variety of acoustic patterns found universally across populations. Logan James, co-author of the study, said:

Because the nature of these universals bears similarity to those in humans and because songbirds learn their vocalizations much in the same way that humans acquire speech and language, we were motivated to test biological predisposition in vocal learning in songbirds.

Read about how the researcher performed their experiments

Caroline Palmer is a Professor of Psychology at McGill who was not involved in the study. She said:

These findings have important contributions for our understanding of human speech and music. The research, which controls the birds’ learning environment in ways that are not possible with young children, suggests that statistical learning alone – the degree to which one is exposed to specific acoustic patterns – cannot account for song (or speech) preferences. Other principles, such as universal grammars and perceptual organization, are more likely to account for why human infants as well as juvenile birds are predisposed to prefer some auditory patterns.

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

Bottom line: New research supports the idea that humans and songbirds share common biological hardwiring that shapes how they produce and perceive sounds.

Read more from McGill University

from EarthSky http://ift.tt/2j1QPPW

EarthSky’s 2018 lunar calendars are here! Get yours while they last.

Many scientists who study birdsong are intrigued by the possibility that human speech and music may be rooted in biological processes shared across a variety of animals. Now, new research, published online in Current Biology on November 22, 2017, provides new evidence to support the idea that songbirds and humans have common biological hardwiring that shapes how they produce and perceive sounds.

In a series of experiments, the researchers found that young zebra finches – a species often used to study birdsong – are intrinsically biased to learn to produce particular kinds of sound patterns over others.

Jon Sakata, Associate Professor of Biology at McGill University, is the paper’s senior author. Sakata said in a statement:

In addition, these sound patterns resembled patterns that are frequently observed across human languages and in music.

Zebra finches. Image via Raina Fan.

The idea for the experiments, say the researchers, was inspired by current hypotheses on human language and music. Linguists have long found that the world’s languages share many common features, termed “universals.” These features encompass the syntactic structure of languages (e.g., word order) as well as finer acoustic patterns of speech, such as the timing, pitch, and stress of utterances. Some theorists, including Noam Chomsky, have postulated that these patterns reflect a “universal grammar” built on innate brain mechanisms that promote and bias language learning. Researchers continue to debate the extent of these innate brain mechanisms, in part because of the potential for cultural propagation to account for universals.

At the same time, vast surveys of zebra finch songs have documented a variety of acoustic patterns found universally across populations. Logan James, co-author of the study, said:

Because the nature of these universals bears similarity to those in humans and because songbirds learn their vocalizations much in the same way that humans acquire speech and language, we were motivated to test biological predisposition in vocal learning in songbirds.

Read about how the researcher performed their experiments

Caroline Palmer is a Professor of Psychology at McGill who was not involved in the study. She said:

These findings have important contributions for our understanding of human speech and music. The research, which controls the birds’ learning environment in ways that are not possible with young children, suggests that statistical learning alone – the degree to which one is exposed to specific acoustic patterns – cannot account for song (or speech) preferences. Other principles, such as universal grammars and perceptual organization, are more likely to account for why human infants as well as juvenile birds are predisposed to prefer some auditory patterns.

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

Bottom line: New research supports the idea that humans and songbirds share common biological hardwiring that shapes how they produce and perceive sounds.

Read more from McGill University

from EarthSky http://ift.tt/2j1QPPW

2017 marks 50 years since pulsars were discovered

by George Hobbs, CSIRO; Dick Manchester, CSIRO, and Simon Johnston, CSIRO

A pulsar is a small, spinning star – a giant ball of neutrons, left behind after a normal star has died in a fiery explosion.

With a diameter of only 30 kilometers (18.6 miles), the star spins up to hundreds of times a second, while sending out a beam of radio waves (and sometimes other radiation, such as X-rays). When the beam is pointed in our direction and into our telescopes, we see a pulse.

2017 marks 50 years since pulsars were discovered. In that time, we have found more than 2,600 pulsars (mostly in the Milky Way), and used them to hunt for low-frequency gravitational waves, to determine the structure of our galaxy and to test the general theory of relativity.

Read more: At last, we’ve found gravitational waves from a collapsing pair of neutron stars

CSIRO Parkes radio telescope has discovered around half of all known pulsars. Image via Wayne England.

The discovery

In mid-1967, when thousands of people were enjoying the summer of love, a young PhD student at the University of Cambridge in the UK was helping to build a telescope.

It was a poles-and-wires affair – what astronomers call a “dipole array”. It covered a bit less than two hectares, the area of 57 tennis courts.

By July it was built. The student, Jocelyn Bell (now Dame Jocelyn Bell Burnell), became responsible for running it and analyzing the data it churned out. The data came in the form of pen-on-paper chart records, more than 30 meters (98 feet) of them each day. Bell analyzed them by eye.

Jocelyn Bell Burnell, who discovered the first pulsar.

What she found – a little bit of “scruff” on the chart records – has gone down in history.

Like most discoveries, it took place over time. But there was a turning point. On November 28, 1967, Bell and her supervisor, Antony Hewish, were able to capture a “fast recording” – that is, a detailed one – of one of the strange signals.

In this she could see for the first time that the “scruff” was actually a train of pulses spaced by one-and-a-third seconds. Bell and Hewish had discovered pulsars.

But this wasn’t immediately obvious to them. Following Bell’s observation they worked for two months to eliminate mundane explanations for the signals.

Bell also found another three sources of pulses, which helped to scotch some rather more exotic explanations, such as the idea that the signals came from “little green men” in extraterrestrial civilizations. The discovery paper appeared in Nature on February 24, 1968.

Later, Bell missed out when Hewish and his colleague Sir Martin Ryle were awarded the 1974 Nobel Prize in Physics.

A pulsar on ‘the pineapple’

CSIRO’s Parkes radio telescope in Australia made its first observation of a pulsar in 1968, later made famous by appearing (along with the Parkes telescope) on the first Australian $50 note.

Australia’s first $50 note featured the Parkes telescope and a pulsar.

Fifty years later, Parkes has found more than half of the known pulsars. The University of Sydney’s Molonglo Telescope also played a central role, and they both remain active in finding and timing pulsars today.

Internationally, one of the most exciting new instruments on the scene is China’s Five-hundred-metre Aperture Spherical Telescope, or FAST. FAST has recently found several new pulsars, confirmed by the Parkes telescope and a team of CSIRO astronomers working with their Chinese colleagues.

Why look for pulsars?

We want to understand what pulsars are, how they work, and how they fit into the general population of stars. The extreme cases of pulsars – those that are super fast, super slow, or extremely massive – help to limit the possible models for how pulsars work, telling us more about the structure of matter at ultra-high densities. To find these extreme cases, we need to find lots of pulsars.

Pulsars often orbit companion stars in binary systems, and the nature of these companions helps us understand the formation history of the pulsars themselves. We’ve made good progress with the “what” and “how” of pulsars but there are still unanswered questions.

As well as understanding pulsars themselves, we also use them as a clock. For example, pulsar timing is being pursued as a way to detect the background rumble of low-frequency gravitational waves throughout the universe.

Pulsars have also been used to measure the structure of our galaxy, by looking at the way their signals are altered as they travel through denser regions of material in space.

Pulsars are also one of the finest tools we have for testing Einstein’s theory of general relativity.

Read more: Explainer: Einstein’s Theory of General Relativity

This theory has survived 100 years of the most sophisticated tests astronomers have been able throw at it. But it doesn’t play nicely with our other most successful theory of how the universe works, quantum mechanics, so it must have a tiny flaw somewhere. Pulsars help us to try and understand this problem.

What keeps pulsar astronomers up at night (literally!) is the hope of finding a pulsar in orbit around a black hole. This is the most extreme system we can imagine for testing general relativity.

Finally, pulsars have some more down-to-earth applications. We’re using them as a teaching tool in our PULSE@Parkes program, in which students control the Parkes telescope over the Internet and use it to observe pulsars. This program has reached over 1,700 students, in Australia, Japan, China, The Netherlands, United Kingdom and South Africa.

Pulsars also offer promise as a navigation system for guiding craft travelling through deep space. In 2016 China launched a satellite, XPNAV-1, carrying a navigation system that uses periodic X-ray signals from certain pulsars.

Pulsars have changed our our understanding of the universe, and their true importance is still unfolding.

George Hobbs, Team leader for the Parkes Pulsar Timing Array project, CSIRO; Dick Manchester, CSIRO Fellow, CSIRO Astronomy and Space Science, CSIRO, and Simon Johnston, Senior research scientist, CSIRO

This article was originally published on The Conversation. Read the original article.

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by George Hobbs, CSIRO; Dick Manchester, CSIRO, and Simon Johnston, CSIRO

A pulsar is a small, spinning star – a giant ball of neutrons, left behind after a normal star has died in a fiery explosion.

With a diameter of only 30 kilometers (18.6 miles), the star spins up to hundreds of times a second, while sending out a beam of radio waves (and sometimes other radiation, such as X-rays). When the beam is pointed in our direction and into our telescopes, we see a pulse.

2017 marks 50 years since pulsars were discovered. In that time, we have found more than 2,600 pulsars (mostly in the Milky Way), and used them to hunt for low-frequency gravitational waves, to determine the structure of our galaxy and to test the general theory of relativity.

Read more: At last, we’ve found gravitational waves from a collapsing pair of neutron stars

CSIRO Parkes radio telescope has discovered around half of all known pulsars. Image via Wayne England.

The discovery

In mid-1967, when thousands of people were enjoying the summer of love, a young PhD student at the University of Cambridge in the UK was helping to build a telescope.

It was a poles-and-wires affair – what astronomers call a “dipole array”. It covered a bit less than two hectares, the area of 57 tennis courts.

By July it was built. The student, Jocelyn Bell (now Dame Jocelyn Bell Burnell), became responsible for running it and analyzing the data it churned out. The data came in the form of pen-on-paper chart records, more than 30 meters (98 feet) of them each day. Bell analyzed them by eye.

Jocelyn Bell Burnell, who discovered the first pulsar.

What she found – a little bit of “scruff” on the chart records – has gone down in history.

Like most discoveries, it took place over time. But there was a turning point. On November 28, 1967, Bell and her supervisor, Antony Hewish, were able to capture a “fast recording” – that is, a detailed one – of one of the strange signals.

In this she could see for the first time that the “scruff” was actually a train of pulses spaced by one-and-a-third seconds. Bell and Hewish had discovered pulsars.

But this wasn’t immediately obvious to them. Following Bell’s observation they worked for two months to eliminate mundane explanations for the signals.

Bell also found another three sources of pulses, which helped to scotch some rather more exotic explanations, such as the idea that the signals came from “little green men” in extraterrestrial civilizations. The discovery paper appeared in Nature on February 24, 1968.

Later, Bell missed out when Hewish and his colleague Sir Martin Ryle were awarded the 1974 Nobel Prize in Physics.

A pulsar on ‘the pineapple’

CSIRO’s Parkes radio telescope in Australia made its first observation of a pulsar in 1968, later made famous by appearing (along with the Parkes telescope) on the first Australian $50 note.

Australia’s first $50 note featured the Parkes telescope and a pulsar.

Fifty years later, Parkes has found more than half of the known pulsars. The University of Sydney’s Molonglo Telescope also played a central role, and they both remain active in finding and timing pulsars today.

Internationally, one of the most exciting new instruments on the scene is China’s Five-hundred-metre Aperture Spherical Telescope, or FAST. FAST has recently found several new pulsars, confirmed by the Parkes telescope and a team of CSIRO astronomers working with their Chinese colleagues.

Why look for pulsars?

We want to understand what pulsars are, how they work, and how they fit into the general population of stars. The extreme cases of pulsars – those that are super fast, super slow, or extremely massive – help to limit the possible models for how pulsars work, telling us more about the structure of matter at ultra-high densities. To find these extreme cases, we need to find lots of pulsars.

Pulsars often orbit companion stars in binary systems, and the nature of these companions helps us understand the formation history of the pulsars themselves. We’ve made good progress with the “what” and “how” of pulsars but there are still unanswered questions.

As well as understanding pulsars themselves, we also use them as a clock. For example, pulsar timing is being pursued as a way to detect the background rumble of low-frequency gravitational waves throughout the universe.

Pulsars have also been used to measure the structure of our galaxy, by looking at the way their signals are altered as they travel through denser regions of material in space.

Pulsars are also one of the finest tools we have for testing Einstein’s theory of general relativity.

Read more: Explainer: Einstein’s Theory of General Relativity

This theory has survived 100 years of the most sophisticated tests astronomers have been able throw at it. But it doesn’t play nicely with our other most successful theory of how the universe works, quantum mechanics, so it must have a tiny flaw somewhere. Pulsars help us to try and understand this problem.

What keeps pulsar astronomers up at night (literally!) is the hope of finding a pulsar in orbit around a black hole. This is the most extreme system we can imagine for testing general relativity.

Finally, pulsars have some more down-to-earth applications. We’re using them as a teaching tool in our PULSE@Parkes program, in which students control the Parkes telescope over the Internet and use it to observe pulsars. This program has reached over 1,700 students, in Australia, Japan, China, The Netherlands, United Kingdom and South Africa.

Pulsars also offer promise as a navigation system for guiding craft travelling through deep space. In 2016 China launched a satellite, XPNAV-1, carrying a navigation system that uses periodic X-ray signals from certain pulsars.

Pulsars have changed our our understanding of the universe, and their true importance is still unfolding.

George Hobbs, Team leader for the Parkes Pulsar Timing Array project, CSIRO; Dick Manchester, CSIRO Fellow, CSIRO Astronomy and Space Science, CSIRO, and Simon Johnston, Senior research scientist, CSIRO

This article was originally published on The Conversation. Read the original article.

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