Kimberly K. Arcand's Blog, page 3
June 20, 2017
Astronauts, Black holes, and Aliens: A Q&A with Kim
The following few questions are some of the most frequent questions I get when talking to people about what I do. I hope you enjoy finding out a little more about me:So what do you do? Are you an astronaut?
I am definitely not an astronaut – but I have had the privilege to work with some of them. I am the Visualization Lead for NASA’s Chandra X-ray Observatory, and I’m based at the Smithsonian Astrophysical Observatory in Cambridge, Mass.Sometimes, when people hear “NASA,” it’s followed up with, “Have you ever gone up into space?” Though I did want to be an astronaut when I was a little kid, these days my feet are firmly planted on the ground. Only about 560 people in the history of humanity have been trained astronauts, and they have stronger stomachs than I do.The telescope I get to work for, Chandra, is one of NASA’s great observatories, a sister to the Hubble Space Telescope. Chandra was launched back in 1999, and in orbit it goes about a third of the way to the Moon at its farthest point from Earth. Chandra looks at the high-energy regions of the Universe such as exploded stars, clusters of galaxies, and black holes. It’s pretty extreme physics. But X-ray data don’t really look like the more familiar optical data that we’re most used to seeing from, say, the Hubble telescope or even a backyard telescope (see photo of me, at left, with a friend's amazing telescope; photo courtesy of Stephanie A. Ewens).. X-ray light is invisible to human eyes. So if we can’t see it, how do we make high-energy data accessible? That’s where my job comes in. I manage a team that approaches that question in a number of ways. My group has studied and applied new technologies to make sure the data takes the form that is both scientifically accurate and aesthetically pleasing. Essentially I use data from Chandra, as well as other telescopes, to tell stories about the Universe whether that story takes the form of a three-dimensional model of an exploded star, an image, or a tweet.
An artist’s illustration of NASA’s Chandra X-ray Observatory. Credit: NGSTIs this stuff for real?With the fleet of telescopes in space and giant observatories on the ground, we are in what many consider to be a golden age of astronomy. These powerful telescopes produce thousands if not millions of images a year, many of which make their way into the public realm. We see them on billboards, in commercials, and across computer and tablet screens everywhere. Many of these images are spectacular, but I am often asked, “Is this real?”When astronomers talk about light, they aren’t referring just to the kind humans can see with their eyes. This is a teeny tiny fraction of the light that exists. There are many kinds of light, from radio waves to infrared light to X-rays and gamma-rays. Each of these different types of light reveals something unique about the Universe. For example, infrared light generally shows cooler objects, while hotter and more energetic things give off X-rays. In order to truly understand and explore the Universe, astronomers need to collect all types of light.In the past, astronomers used to capture images on film. Today, most data from all types of light arrives digitally, coded in the form of 1’s and 0’s. Scientific software is used to translate that data into a visual representation of the object, that is, an image. Scientists use additional processing to enhance the data, including things like removing artifacts, cropping in closer to the object of interest, and adding color.So though some of the images of our Universe might look pretty fantastical, they are real. They aren’t giant selfies of the sky, but rather processed data that is translated into images that we can see. And really, just like in portrait or landscape photography here on Earth, the photographer has a point of view. He or she chooses the field of view, adjusts the lighting, adds or subtracts frames, etc. But those choices don’t make the resulting photo less real. In our case, we always make sure the science is the star.
An image of NGC 2392 (nicknamed the "Eskimo Nebula"), a planetary nebula, a phase that results when a star like the sun becomes a red giant and sheds its outer layers. X-ray: NASA/CXC/IAA-CSIC/N.Ruiz et al, Optical: NASA/STScIWhy should we care about space?The sky belongs to everyone. Whether you live in Boston or Budapest or Bombay, every child and adult should be able to explore the Universe he or she lives in. And, in my opinion, astronomy is one of the most enticing portals to the greater constellation of STEM (science, technology, engineering and math) fields, particularly for the young and the curious. The notion of black holes and dark matter, and the discovery of new planets or the potential for life on Mars, can not only fuel the imagination, but also incorporate a variety of related disciplines including math, physics, chemistry, geology, and more. It’s also hard to quantify the many other benefits humans have enjoyed thanks to our exploration of space – both by astronauts who go into orbit and by the telescopes who look out into cosmos on our behalf. There are countless spinoff technologies that have become part of our daily lives – everything from X-ray scanners in airports to the chips in your smartphone cameras. Beyond that, however, I think the pursuit of knowledge is something that helps define us as a society. We never know where science will take us, and it’s an important part of our species to explore and learn. Space is just one realm – albeit a rather large one – to make that happen.Are there aliens out there?I’m asked this question all the time and I love talking about it. The short answer is: No, researchers haven’t found any aliens (despite what the conspiracy theorists say). However, many do think it’s a distinct possibility that life in some form is out there. Here’s my take: I am certainly no astrobiology expert, but when we consider the explosion in the field of exoplanets (planets outside of our Solar System) over the past decade it’s pretty incredible. When I started working in astronomy in 1998, there were only a couple exoplanet candidates detected at that point. Fast-forward to today and we have thousands. Astronomers now think that most stars in our Galaxy have at least one planet if not more. And when you consider the billions of stars in our Milky Way alone (not even counting the other billions of galaxies out there), the numbers of exoplanet candidates escalates quickly. If only a very tiny percentage of those are in habitable zones, there is at least a possibility for life on other planets. But of course, what form might that life take? Even if it were just a single celled organism, it would be an incredible discovery. And that isn’t considering the places in our own Solar System where life might be able to thrive, or perhaps could have existed in a different time period. Mars isn’t off the table completely, nor is Venus. Both perhaps *could* have been able to sustain life at some point in the distant past. When you move out to some of the moons around the gas giants (Jupiter and Saturn, for example), there are yet more fascinating locations still waiting to be studied in detail. 
One of Jupiter's most interesting moons, Europa. Credit: NASA/JPLWhat is the coolest thing you’ve ever seen or learned about in astronomy?This is rather hard to narrow down, as I literally learn something new every day in this job. But I would say that getting to know more about our home galaxy, the Milky Way, is one of my favorite things. Particularly, learning about the black hole at the center of our Galaxy has been fascinating. Just a few decades ago, black holes were the stuff of science fiction. Today, we can pretty much watch black holes in action. A black hole is a dense, compact object whose gravitational pull is so strong that—within a certain distance of it—nothing can escape, not even light. Black holes range in size from a few times the mass of the Sun to millions or even billions of times the Sun’s mass. Using Chandra, astronomers have learned a great deal about black holes and how they influence their environments. One of the most important black holes to study is the one found at the center of our Milky Way galaxy. Astronomers have even given it a name -- Sagittarius A* -- and we know this black hole is about 4 million times the mass of the Sun. Black holes are often set up as giant vacuum cleaners, sucking up all the material that comes anywhere near them. Of course some material does indeed pass the “event horizon,” or the point of no return, to be lost within the black hole’s incredibly strong gravitational pull. But that danger zone is a relatively small area around the black hole, comparatively speaking. Black holes are actually more like giant cosmic recycling centers. They have a big influence on the material all around them, from their powerful jets, to their flares that push material away from the black hole and back out into the cosmic environment.Scientists have learned much about black holes so far, but the exciting thing is that they are just getting started. That’s the great thing about studying space and, really, science in general – you never know what you are going to find next. The fun part is being able to take that ride (for me, from the safety of the ground) and explore.
The Galactic Center and the area around Sagittarius A*. Credit: NASA/CXC/Univ. of Wisconsin/Y.Bai, et al.-Kim Arcand
I am definitely not an astronaut – but I have had the privilege to work with some of them. I am the Visualization Lead for NASA’s Chandra X-ray Observatory, and I’m based at the Smithsonian Astrophysical Observatory in Cambridge, Mass.Sometimes, when people hear “NASA,” it’s followed up with, “Have you ever gone up into space?” Though I did want to be an astronaut when I was a little kid, these days my feet are firmly planted on the ground. Only about 560 people in the history of humanity have been trained astronauts, and they have stronger stomachs than I do.The telescope I get to work for, Chandra, is one of NASA’s great observatories, a sister to the Hubble Space Telescope. Chandra was launched back in 1999, and in orbit it goes about a third of the way to the Moon at its farthest point from Earth. Chandra looks at the high-energy regions of the Universe such as exploded stars, clusters of galaxies, and black holes. It’s pretty extreme physics. But X-ray data don’t really look like the more familiar optical data that we’re most used to seeing from, say, the Hubble telescope or even a backyard telescope (see photo of me, at left, with a friend's amazing telescope; photo courtesy of Stephanie A. Ewens).. X-ray light is invisible to human eyes. So if we can’t see it, how do we make high-energy data accessible? That’s where my job comes in. I manage a team that approaches that question in a number of ways. My group has studied and applied new technologies to make sure the data takes the form that is both scientifically accurate and aesthetically pleasing. Essentially I use data from Chandra, as well as other telescopes, to tell stories about the Universe whether that story takes the form of a three-dimensional model of an exploded star, an image, or a tweet.An artist’s illustration of NASA’s Chandra X-ray Observatory. Credit: NGSTIs this stuff for real?With the fleet of telescopes in space and giant observatories on the ground, we are in what many consider to be a golden age of astronomy. These powerful telescopes produce thousands if not millions of images a year, many of which make their way into the public realm. We see them on billboards, in commercials, and across computer and tablet screens everywhere. Many of these images are spectacular, but I am often asked, “Is this real?”When astronomers talk about light, they aren’t referring just to the kind humans can see with their eyes. This is a teeny tiny fraction of the light that exists. There are many kinds of light, from radio waves to infrared light to X-rays and gamma-rays. Each of these different types of light reveals something unique about the Universe. For example, infrared light generally shows cooler objects, while hotter and more energetic things give off X-rays. In order to truly understand and explore the Universe, astronomers need to collect all types of light.In the past, astronomers used to capture images on film. Today, most data from all types of light arrives digitally, coded in the form of 1’s and 0’s. Scientific software is used to translate that data into a visual representation of the object, that is, an image. Scientists use additional processing to enhance the data, including things like removing artifacts, cropping in closer to the object of interest, and adding color.So though some of the images of our Universe might look pretty fantastical, they are real. They aren’t giant selfies of the sky, but rather processed data that is translated into images that we can see. And really, just like in portrait or landscape photography here on Earth, the photographer has a point of view. He or she chooses the field of view, adjusts the lighting, adds or subtracts frames, etc. But those choices don’t make the resulting photo less real. In our case, we always make sure the science is the star. An image of NGC 2392 (nicknamed the "Eskimo Nebula"), a planetary nebula, a phase that results when a star like the sun becomes a red giant and sheds its outer layers. X-ray: NASA/CXC/IAA-CSIC/N.Ruiz et al, Optical: NASA/STScIWhy should we care about space?The sky belongs to everyone. Whether you live in Boston or Budapest or Bombay, every child and adult should be able to explore the Universe he or she lives in. And, in my opinion, astronomy is one of the most enticing portals to the greater constellation of STEM (science, technology, engineering and math) fields, particularly for the young and the curious. The notion of black holes and dark matter, and the discovery of new planets or the potential for life on Mars, can not only fuel the imagination, but also incorporate a variety of related disciplines including math, physics, chemistry, geology, and more. It’s also hard to quantify the many other benefits humans have enjoyed thanks to our exploration of space – both by astronauts who go into orbit and by the telescopes who look out into cosmos on our behalf. There are countless spinoff technologies that have become part of our daily lives – everything from X-ray scanners in airports to the chips in your smartphone cameras. Beyond that, however, I think the pursuit of knowledge is something that helps define us as a society. We never know where science will take us, and it’s an important part of our species to explore and learn. Space is just one realm – albeit a rather large one – to make that happen.Are there aliens out there?I’m asked this question all the time and I love talking about it. The short answer is: No, researchers haven’t found any aliens (despite what the conspiracy theorists say). However, many do think it’s a distinct possibility that life in some form is out there. Here’s my take: I am certainly no astrobiology expert, but when we consider the explosion in the field of exoplanets (planets outside of our Solar System) over the past decade it’s pretty incredible. When I started working in astronomy in 1998, there were only a couple exoplanet candidates detected at that point. Fast-forward to today and we have thousands. Astronomers now think that most stars in our Galaxy have at least one planet if not more. And when you consider the billions of stars in our Milky Way alone (not even counting the other billions of galaxies out there), the numbers of exoplanet candidates escalates quickly. If only a very tiny percentage of those are in habitable zones, there is at least a possibility for life on other planets. But of course, what form might that life take? Even if it were just a single celled organism, it would be an incredible discovery. And that isn’t considering the places in our own Solar System where life might be able to thrive, or perhaps could have existed in a different time period. Mars isn’t off the table completely, nor is Venus. Both perhaps *could* have been able to sustain life at some point in the distant past. When you move out to some of the moons around the gas giants (Jupiter and Saturn, for example), there are yet more fascinating locations still waiting to be studied in detail. One of Jupiter's most interesting moons, Europa. Credit: NASA/JPLWhat is the coolest thing you’ve ever seen or learned about in astronomy?This is rather hard to narrow down, as I literally learn something new every day in this job. But I would say that getting to know more about our home galaxy, the Milky Way, is one of my favorite things. Particularly, learning about the black hole at the center of our Galaxy has been fascinating. Just a few decades ago, black holes were the stuff of science fiction. Today, we can pretty much watch black holes in action. A black hole is a dense, compact object whose gravitational pull is so strong that—within a certain distance of it—nothing can escape, not even light. Black holes range in size from a few times the mass of the Sun to millions or even billions of times the Sun’s mass. Using Chandra, astronomers have learned a great deal about black holes and how they influence their environments. One of the most important black holes to study is the one found at the center of our Milky Way galaxy. Astronomers have even given it a name -- Sagittarius A* -- and we know this black hole is about 4 million times the mass of the Sun. Black holes are often set up as giant vacuum cleaners, sucking up all the material that comes anywhere near them. Of course some material does indeed pass the “event horizon,” or the point of no return, to be lost within the black hole’s incredibly strong gravitational pull. But that danger zone is a relatively small area around the black hole, comparatively speaking. Black holes are actually more like giant cosmic recycling centers. They have a big influence on the material all around them, from their powerful jets, to their flares that push material away from the black hole and back out into the cosmic environment.Scientists have learned much about black holes so far, but the exciting thing is that they are just getting started. That’s the great thing about studying space and, really, science in general – you never know what you are going to find next. The fun part is being able to take that ride (for me, from the safety of the ground) and explore. The Galactic Center and the area around Sagittarius A*. Credit: NASA/CXC/Univ. of Wisconsin/Y.Bai, et al.-Kim Arcand
October 7, 2016
Our next book announced!
Our next book project was recently announced in Publishers Weekly:The work will examine “the most fascinating orders of magnitude throughout the universe, from the smallest known objects to the largest.” It will be illustrated by Katie Peek, the graphics editor at Popular Science. Expected in late 2017. Stay tuned for more details.
July 27, 2016
How do you hold a dead star in your hand?
Objects in space are rather far away. The Moon is our closest celestial neighbor at nearly a quarter million miles from Earth, and the nearest star, our Sun, is 93 million miles away.These extreme distances mean that it’s usually impossible to touch real objects in space (meteorites that fall to the ground not withstanding). Advances in both astronomy and technology, however, now allow you to do the next best thing: hold a 3-D model of one based on real data.Find out about the journey of going from 2D data to timed data to 3D in my TED talk recently filmed in Providence, RI, "How to hold a dead star in your hand."
May 25, 2016
How We Know Everything We Know About the Universe: A Book Review of Ethan Siegel’s “Beyond the Galaxy”
I have spent my academic and professional life reading and writing about astronomy. From my undergraduate days as an astronomy major to graduate school in science journalism and then moving on to work as the press officer for NASA’s Chandra X-ray Observatory for over 15 years and writing popular science books, I have read many thousands of pages about astronomy.Some books about our Universe are clearly meant to be textbooks, with jargon-filled explanations and pages covered in lengthy equations. Others seek to capture the fascination of the public with eye-catching visuals and dramatic narratives to lure in the reader.Ethan Siegel’s new book, “Beyond the Galaxy” (published by World Scientific), is a fascinating piece of science writing that successfully walks the line down the middle of those two genres. In his preface, Siegel tells of his surprise at discovering there was no singular book that told the story of how we know what we know about the Universe when he went to teach his first college introductory astronomy course. Instead of lamenting the situation, Professor Siegel took it upon himself to right this cosmic wrong.
I imagine that reading “Beyond the Galaxy” is the best thing next to sitting next to Siegel and sharing an espresso or beer (or two) while he regales us with stories of how we’ve come to know everything that we know about the Universe. One of the most impressive aspects of this book is Siegel’s depth of knowledge of both the science and the people who helped discover it. Along the way, Siegel doesn’t shy away from theories that didn’t work. In fact, Siegel respectfully explains why some people might have stuck to idea that in hindsight we can say is wrong today. Such “dead end” theories are often left out when books cover the currently accepted ideas, though I personally think they paint the full and truer picture of how science is done when covered in a thoughtful way as Siegel does.It’s clear that Siegel is a natural teacher and his writing is engaging, as many people may know by reading his blog, “Starts with a Bang”. Unlike many astronomy books (including many I’ve read), “Beyond the Galaxy” doesn’t stay clear of writing in the first person and with an active voice, allowing the reader to feel like he or she is part of a conversation – not simply the audience of a one-sided lecture.While “Beyond the Galaxy” is perfect for any introductory astronomy course, I also see it as a wonderful read for the astronomy enthusiast who is looking for a complete tale of astronomy, from antiquity through today. There’s plenty of well-explained science in here for a reader of any background. I learned many things and gained new perspectives on pieces of information that I’ve had floating around in my mind for many years.From the architecture of our Solar System (and how humans finally figured it out) to the mysteries of dark energy and the fate of the Universe (something we’re still working on), Siegel has got you covered. Pull up a chair and enjoy.
I imagine that reading “Beyond the Galaxy” is the best thing next to sitting next to Siegel and sharing an espresso or beer (or two) while he regales us with stories of how we’ve come to know everything that we know about the Universe. One of the most impressive aspects of this book is Siegel’s depth of knowledge of both the science and the people who helped discover it. Along the way, Siegel doesn’t shy away from theories that didn’t work. In fact, Siegel respectfully explains why some people might have stuck to idea that in hindsight we can say is wrong today. Such “dead end” theories are often left out when books cover the currently accepted ideas, though I personally think they paint the full and truer picture of how science is done when covered in a thoughtful way as Siegel does.It’s clear that Siegel is a natural teacher and his writing is engaging, as many people may know by reading his blog, “Starts with a Bang”. Unlike many astronomy books (including many I’ve read), “Beyond the Galaxy” doesn’t stay clear of writing in the first person and with an active voice, allowing the reader to feel like he or she is part of a conversation – not simply the audience of a one-sided lecture.While “Beyond the Galaxy” is perfect for any introductory astronomy course, I also see it as a wonderful read for the astronomy enthusiast who is looking for a complete tale of astronomy, from antiquity through today. There’s plenty of well-explained science in here for a reader of any background. I learned many things and gained new perspectives on pieces of information that I’ve had floating around in my mind for many years.From the architecture of our Solar System (and how humans finally figured it out) to the mysteries of dark energy and the fate of the Universe (something we’re still working on), Siegel has got you covered. Pull up a chair and enjoy.
February 20, 2016
Our Latest in the Daily Beast & HuffPo
Lately, we've been blogging over at the Daily Beast and the Huffington Post. You can catch up with our most recent pieces here:It’s Time to Abolish Science’s Boys Club This has been a challenging year for women in the fields of science, technology, engineering, and math, otherwise known by the acronym STEM. To be sure, every year is challenging for women and other under-represented groups. But lately more of those issues that plague them are being brought to light.Let’s celebrate the UN’s first ever International Day of Women and Girls in Science by vowing to abolish the sexism and other prejudices in fields of science, tech, engineering, and math. More at http://www.thedailybeast.com/articles/2016/02/10/it-s-time-to-abolish-science-s-boys-club.html7 Awesome Images of Light from 2015We are intimately connected with light in countless ways. From the practical (think of life without photosynthesis or heat from the Sun) to the convenient (modern technologies ranging from communication to health), light is part of our every day lives in a host of different ways. Celebrate the closing ceremonies of the International Year of Lightwith us.You'll find a few other recent light-related pieces at our blog at the Huffington Post as well.
February 3, 2016
Light Giveaway!
Our publisher is running a Goodreads giveaway of "Light: The Visible Spectrum and Beyond" (perfectly timed for the end of the UN's International Year of Light). 14 copies are available:
https://www.goodreads.com/book/show/2...
The giveaway ends Feb 16, 2015. Good luck!
https://www.goodreads.com/book/show/2...
The giveaway ends Feb 16, 2015. Good luck!
November 28, 2015
A Universe of X-rays (Light Facts #7)
X-rays are useful in doctor and dentist offices – and also for studying black holes and dark matter.
Dental X-rays are useful for detecting cavities. Credit: Wikimedia Commons/Dmitry G Most of us encounter X-rays when we have an unfortunate experience with a broken bone or cavity. The concept medical or dental X-rays is pretty simple. Place the thing you want to see inside of (bone, tooth, etc.) between two things: a machine that produces X-rays and then film or an instrument that can detect them. Where more X-rays pass through, you likely have a fracture or a cavity.
Centaurus A, an active galaxy about 12 million light years from Earth, shown in X-ray light collected by NASA's Chandra X-ray Observatory. Credit: NASA/CXC/U.Birmingham/M.Burke et al. Far away from the doctor’s office, we find X-rays coming from other places that don’t involve machines. It turns out that many, many things in outer space generate X-rays by themselves. Objects in the Universe glow in X-ray light when they either have a lot of energy or are really hot, as in millions of degrees. In order to study the X-rays from space, scientists have to put their telescopes above the Earth’s atmosphere, which, thankfully, blocks this potentially-damaging light from ever reaching us here on the surface. Astronomers use X-ray telescopes to look at everything from material in its death spiral around a black hole to the blistering hot remains of an exploded star. Heck, even things like comets and planets can give off or reflect X-rays. Just think of that the next time you’re strapped into the dentist’s chair.
Dental X-rays are useful for detecting cavities. Credit: Wikimedia Commons/Dmitry G Most of us encounter X-rays when we have an unfortunate experience with a broken bone or cavity. The concept medical or dental X-rays is pretty simple. Place the thing you want to see inside of (bone, tooth, etc.) between two things: a machine that produces X-rays and then film or an instrument that can detect them. Where more X-rays pass through, you likely have a fracture or a cavity.Centaurus A, an active galaxy about 12 million light years from Earth, shown in X-ray light collected by NASA's Chandra X-ray Observatory. Credit: NASA/CXC/U.Birmingham/M.Burke et al. Far away from the doctor’s office, we find X-rays coming from other places that don’t involve machines. It turns out that many, many things in outer space generate X-rays by themselves. Objects in the Universe glow in X-ray light when they either have a lot of energy or are really hot, as in millions of degrees. In order to study the X-rays from space, scientists have to put their telescopes above the Earth’s atmosphere, which, thankfully, blocks this potentially-damaging light from ever reaching us here on the surface. Astronomers use X-ray telescopes to look at everything from material in its death spiral around a black hole to the blistering hot remains of an exploded star. Heck, even things like comets and planets can give off or reflect X-rays. Just think of that the next time you’re strapped into the dentist’s chair.
November 24, 2015
Butterflies, Insects & Claude Monet (Light Facts #6)
Most animals cannot see ultraviolet light, but there are exceptions including some butterflies, insects, and maybe Claude Monet.
Bees, important for distributing pollen, can detect some UV light. (Credit: Wikimedia Commons - Jon Sullivan)Ultraviolet, or “UV,” as it’s often called, is probably best known for its propensity to give us sunburns. In many parts of the world, we are inundated with products that claim to protect us from this harmful form of light. Of course, too much sunlight can be damaging to human skin, but UV also provides health benefits including the production of bone-strengthening vitamin D.For most living creatures on Earth, UV light falls outside of what can be seen. Many fruits, flowers, and seeds, however, stand out from their backgrounds more distinctly in UV light than in visible light. This has led some insects such as bumblebees to develop receptors that are sensitive to UV. Also, certain types of butterflies can detect UV and use it for communication and even in their mating practices.In humans, there is a rare condition that lets a small number of people detect UV light. For those with this disorder, known as “aphakia,” they lack a lens in their eye. The lens normally blocks UV, so with aphakia, specialized cells at the back of the eye can activate when exposed to UV light. In some cases, this means people with aphakia can actually detect some UV light that appears to them as a whitish-blue or whitish-violet color. One report suggests that Claude Monet, the famous Impressionist painter, acquired aphakia when he had a cataract removed at the age of 82. This may have given him the ability to see “extra” color in his final years of painting.
Bees, important for distributing pollen, can detect some UV light. (Credit: Wikimedia Commons - Jon Sullivan)Ultraviolet, or “UV,” as it’s often called, is probably best known for its propensity to give us sunburns. In many parts of the world, we are inundated with products that claim to protect us from this harmful form of light. Of course, too much sunlight can be damaging to human skin, but UV also provides health benefits including the production of bone-strengthening vitamin D.For most living creatures on Earth, UV light falls outside of what can be seen. Many fruits, flowers, and seeds, however, stand out from their backgrounds more distinctly in UV light than in visible light. This has led some insects such as bumblebees to develop receptors that are sensitive to UV. Also, certain types of butterflies can detect UV and use it for communication and even in their mating practices.In humans, there is a rare condition that lets a small number of people detect UV light. For those with this disorder, known as “aphakia,” they lack a lens in their eye. The lens normally blocks UV, so with aphakia, specialized cells at the back of the eye can activate when exposed to UV light. In some cases, this means people with aphakia can actually detect some UV light that appears to them as a whitish-blue or whitish-violet color. One report suggests that Claude Monet, the famous Impressionist painter, acquired aphakia when he had a cataract removed at the age of 82. This may have given him the ability to see “extra” color in his final years of painting.
November 22, 2015
Seeing Color (Light Facts #5)
Just because someone has “color blindness” doesn’t mean that they can’t see any color.
Do you have any color deficiencies in your vision? If not, you should clearly see the number 74 above. If so, you might see a 21 or no numbers at all. Image: WikipediaThe term “color blindness” might conjure up a world that looks like an old school black and white television program. (If you were born in the 1980s or after, you might not have ever seen one of things in person, but trust us, they were real.) While some people with color blindness do experience this, there are actually many ways that condition can manifest itself. To understand how color blindness works, you first have to understand a little bit about how the human eye detects the colors (red, orange, yellow, green, blue, and violet) of the visible light portion of light. The retinas in the back of our eyes contain millions of light-sensitive nerve cells called “rods” and “cones”. The rods deal with the brightness of light, while cones tackle color in three flavors: red, green, and blue. Both rods and cones have chemicals that change when they are hit by light. This causes an electrical signal to travel to the brain along the optic nerve, which ultimately allows our brain to produce an image in color.There are times when the rods and cones don’t respond as they should – and this range of scenarios is often lumped together under “color blindness.” In fact, most people who have this condition only have trouble distinguishing between red and green. The reason for this is that the cones in their eyes either lost or never had the correct chemicals to make that distinction for their brain, but other colors remain visible. For more information on color deficiencies, visit the National Eye Institute’s page of the subject.
Do you have any color deficiencies in your vision? If not, you should clearly see the number 74 above. If so, you might see a 21 or no numbers at all. Image: WikipediaThe term “color blindness” might conjure up a world that looks like an old school black and white television program. (If you were born in the 1980s or after, you might not have ever seen one of things in person, but trust us, they were real.) While some people with color blindness do experience this, there are actually many ways that condition can manifest itself. To understand how color blindness works, you first have to understand a little bit about how the human eye detects the colors (red, orange, yellow, green, blue, and violet) of the visible light portion of light. The retinas in the back of our eyes contain millions of light-sensitive nerve cells called “rods” and “cones”. The rods deal with the brightness of light, while cones tackle color in three flavors: red, green, and blue. Both rods and cones have chemicals that change when they are hit by light. This causes an electrical signal to travel to the brain along the optic nerve, which ultimately allows our brain to produce an image in color.There are times when the rods and cones don’t respond as they should – and this range of scenarios is often lumped together under “color blindness.” In fact, most people who have this condition only have trouble distinguishing between red and green. The reason for this is that the cones in their eyes either lost or never had the correct chemicals to make that distinction for their brain, but other colors remain visible. For more information on color deficiencies, visit the National Eye Institute’s page of the subject.
November 21, 2015
Heating up with Infrared (Light Facts #4)
If you think infrared light is all about heat, try pointing your TV remote at yourself and pressing buttons.
Thermograms of buildings and houses are often used to help study heat loss or energy inefficienices; Image by Passivhaus Institut For many people who are familiar with “infrared” light or radiation (which essentially mean the same thing), their association is often with heat. And for good reason. After all, we hear a lot of about infrared products as sources of heat these days in cooktops, space heaters, and saunas. You may also have heard how infrared light is used in thermal imaging (another way of saying "pictures of heat") in everything from military and law applications to making homes more energy efficient.All of these ties with heat are valid, but that is only part of what infrared light can do. That’s because the range of infrared light spans an enormous swath of the electromagnetic spectrum – a thousand times bigger than the “visible light” we can see with our eyes. It’s so vast that scientists, engineers, and others who use it often break it up into smaller chunks. The type of infrared light that provides heat is known as “far infrared”. Another type is so-called near infrared, which has a bunch of applications in our day-to-day life as well and does not provide any heat. For example, near-infrared light is often used in fiber optics communications, which often brings you your phone, internet, and cable these days. But perhaps one of the most common uses for near infrared is in your TV, thus allowing you to remain firmly on the couch for as long as you want - though it won't keep you any warmer.
Thermograms of buildings and houses are often used to help study heat loss or energy inefficienices; Image by Passivhaus Institut For many people who are familiar with “infrared” light or radiation (which essentially mean the same thing), their association is often with heat. And for good reason. After all, we hear a lot of about infrared products as sources of heat these days in cooktops, space heaters, and saunas. You may also have heard how infrared light is used in thermal imaging (another way of saying "pictures of heat") in everything from military and law applications to making homes more energy efficient.All of these ties with heat are valid, but that is only part of what infrared light can do. That’s because the range of infrared light spans an enormous swath of the electromagnetic spectrum – a thousand times bigger than the “visible light” we can see with our eyes. It’s so vast that scientists, engineers, and others who use it often break it up into smaller chunks. The type of infrared light that provides heat is known as “far infrared”. Another type is so-called near infrared, which has a bunch of applications in our day-to-day life as well and does not provide any heat. For example, near-infrared light is often used in fiber optics communications, which often brings you your phone, internet, and cable these days. But perhaps one of the most common uses for near infrared is in your TV, thus allowing you to remain firmly on the couch for as long as you want - though it won't keep you any warmer.
