“This is how we know nature. It is the best idea humans have ever come up with.”
– Bill Nye, Science Guy and CEO of The Planetary Society
In this latest video from NOVA’s Secret Life of Scientists and Engineers, science guy Bill Nye talks about the incredible influence that Carl Sagan had on his life, from attending his lectures on astronomy at Cornell University to eventually becoming CEO of The Planetary Society, which was co-founded by Sagan in 1980.
“I took astronomy from Carl Sagan.” Now there’s a statement that’ll get people’s attention. (It got mine, anyway.)
A screen grab of the new zoomable Milky Way mosaic that uses Microsoft's WorldWide Telescope viewer. Click to use. Credit: NASA
Touring the Milky Way’s a blast with this brand new 360-degree interactive panorama. More than 2 million infrared photos taken by NASA’s Spitzer Space Telescope were jigsawed into a 20-gigapixel click-and-zoom mosaic that takes the viewer from tangled nebulae to stellar jets to blast bubbles around supergiant stars.
Magnetic loops carry gas and dust above disks of planet-forming material circling stars, as shown in this artist’s conception. These loops give off extra heat, which NASA’s Spitzer Space Telescope detects as infrared light. The colors in this illustration show what an alien observer with eyes sensitive to both visible light and infrared wavelengths might see. Credit: NASA/JPL-Caltech/R. Hurt (IPAC)
The new composite, using infrared images taken over the past decade, was compiled by a team led by UW-Madison astronomer Barbara Whitney and unveiled at a TEDactive conference in Vancouver, Canada Thursday. Unlike visual light, infrared penetrates the ubiquitous dust concentrated in the galactic plane to reveal structures otherwise obscured.
Catching a GLIMPSE of the Milky Way in this short video presentation
“For the first time, we can actually measure the large-scale structure of the galaxy using stars rather than gas,” explained Edward Churchwell, UW-Madison professor of astronomy and team co-leader. “We’ve established beyond the shadow of a doubt that our galaxy has a large bar structure that extends halfway out to the sun’s orbit. We know more about where the Milky Way’s spiral arms are.”
Named GLIMPSE360 (Galactic Legacy Mid-Plane Survey Extraordinaire project), the deep infrared survey captures only about 3% of the sky, but because it focuses on the plane of the Milky Way, where stars are most highly concentrated, it shows more than half of all the galaxy’s 300 billion suns.
The Milky Way is a spiral galaxy with several prominent arms containing stellar nurseries swathed in pink clouds of hydrogen gas. The sun is shown near the bottom in the Orion Spur. Credit: NASA
Using your imagination to hover high above the galactic plane, you’d see the Milky Way is a flat spiral galaxy sporting a stubby bar of stars crossing its central bulge. The solar system occupies a tiny niche in a minor spiral arm called the Orion Spur two-thirds of the way from the center to the edge. At 100,000 light years across, the Milky Way is vast beyond comprehension and yet it’s only one of an estimated 100 billion galaxies in the observable universe.
Bubbles of gas and sites of star formation are seen in this close up in a region in the constellation Sagittarius. Credit:
While you and I sit back and marvel at all the stellar and nebular eye candy, the Spitzer images are helping astronomers determine where the edge of the galaxy lies and location of the spiral arms. GLIMPSE images have already revealed the Milky Way to be larger than previously thought and shot through with bubbles of expanding gas and dust blown by giant stars.
Spitzer can see faint stars in the “backcountry” of our galaxy — the outer, darker regions that went largely unexplored before.
Barbara Whitney, co-leader of the GLIMPSE360 team
“There are a whole lot more lower-mass stars seen now with Spitzer on a large scale, allowing for a grand study,” said Whitney. “Spitzer is sensitive enough to pick these up and light up the entire ‘countryside’ with star formation.”
The new 360-degree view will also help NASA’s upcoming James Webb Space Telescope target the most interesting sites of star-formation, where it will make even more detailed infrared observations.
When you play around with the interactive mosaic, you’ll notice a few artifacts here and there among the images. Minor stuff. What took some getting used to was how strikingly different familiar nebulae appeared when viewed in infrared instead of visual light. The panorama is also available on the Aladin viewing platform which offers shortcuts to regions of interest.
Neil deGrasse Tyson, astrophysicist and host of the new Cosmos TV series, gave the third line of our “cosmic address” as the Milky Way after ‘Earth’ and ‘Solar System’. After a few minutes with GLIMPSE360 you’ll better appreciate the depth and breadth of our galactic home.
Zodiacal light tilts upward from the western horizon and points at the Pleiades star cluster in this photo taken March 19, 2009. Clouds at bottom reflect light pollution from nearby Duluth, Minn. U.S. Credit: Bob King
Welcome to the first day of spring! If you have a clear night between now and April 1, celebrate the new season with a pilgrimage to the countryside to ponder the eerie glow of the zodiacal light. Look for a large, diffuse, tapering cone of light poking up from the western horizon between 90 minutes and two hours after sunset. While the zodiacal light appears only as bright as the Milky Way, you’re actually looking at the second brightest object in the night sky. No kidding. If you could crunch it all into a little ball, it would shine at magnitude -8.5, far brighter than Venus and bested only by the full moon.
The zodiacal (Zo-DIE-uh-cull) light is centered on the plane of the solar system called the ecliptic. This is the same band of sky where you’ll find the planets and zodiac constellations, hence the name. On late March nights, you can trace it from near the western horizon more than 45 degrees (halfway up the sky). Created with Stellarium
Sunlight reflecting off countless dust particles shed by comets and spawned by asteroid collisions creates the luminous cone of light. First time observers might think they’re looking at skyglow from light pollution but the tapering shape and distinctive tilt mark this glow as interplanetary dust.
Photo of coronal and zodiacal light taken by the Clementine spacecraft when the sun was hidden by the moon. At right is Venus. Clementine measured the brightness of the light to arrive at an integrated magnitude of -8.5. It also estimated dust particle sizes and origin. Credit: NASA
Like the planets, the dust resides in the plane of the solar system. In spring, that plane (called the ecliptic) tilts steeply up from the western horizon after sunset, “lifting” the chubby thumb of light high enough to clear the horizon haze and stand out against a dark sky for northern hemisphere observers. In October and November the ecliptic is once again tilted upright, but this time before dawn. While the zodiacal light is present year-round, it’s usually tipped at a shallow angle and camouflaged by horizon haze. No so for skywatchers in tropical and equatorial latitudes. There the ecliptic is tilted steeply all year long, and the light can be seen anytime there’s no moon in the sky.
The combined glow of dust particles in the plane of the solar system reaching from the sun’s vicinity out to at least Jupiter is responsible for creating the zodiacal light. Dust closest to the sun glow more brightly, the reason the bottom of the zodiacal light cone is brighter than the tip. Planets are shown as colored disks. Illustration: Bob King
Now through April 1 and again from April 17-30 are the best nights for viewing because the moon will be absent from the sky. The cone is widest near the western horizon and narrows as you direct your gaze upward and to the left. At its apex, where it touches the V-shape Hyades star cluster, it continues into the even fainter zodiacal band and gegenschein, but more about that in a moment. Sweep your gaze in broad strokes back and forth across the western sky to help you discern the Z-light’s distinctive conical shape. And be sure to look for something HUGE. This thing is a monster – indeed, one of the largest entities in the solar system.
Scanning electron microscope photo of an interplanetary dust particle collected by a high-altitude plane. It measures about 8 microns across or a little less than twice the size of a human red blood cell. Scientists recently discovered that dust particles can act as tiny factories to built water molecules. Credit: Donald Brownlee and Elmar Jessberger
Observers fortunate enough to live under or with access truly dark skies can trace the zodiacal light all the way across the sky as the zodiacal band.
Midway along its length, 180 degrees opposite the sun, a slightly brighter circular patch called the gegenschein (German for ‘counter glow’) embedded in the band.
Dust particles there get an extra brightness boost because they face the sun square on, much like the moon does when full. While I usually see only a section of the zodiacal band from my dark observing site, the gegenschein is often visible as a diffuse, hazy patch of light about 6 degree across a little brighter than the sky background.
Incredible 360-degree-wide view of morning and evening zodiacal light cones (far left and right), the fainter zodiacal band and the brighter spot of gegenschein (center) and the Milky Way photographed from Mauna Kea. Click to enlarge. Credit: Miloslav Druckmuller and Shadia Habbal
Dutch astronomer H. C. van de Hulst determined that the dust particles responsible for the zodiacal light and its cousins the zodiacal band and gegenschein are about 0.04 inch (1 mm) in diameter and separated, on average, by about 5 miles (8 km).
The gegenschein, an oval shaped brighter spot within the faint zodiacal band, is easiest to when due south and highest in the sky at local midnight (1 a.m. Daylight Saving Time). Currently it’s in northern Virgo. Since the ‘counter glow’ will always be opposite the sun, it will slide down closer to Spica in April. Created with Stellarium
The particles form a low density, lens-shaped cloud of dust that’s thickest within the plane of the solar system but in reality covers the entire sky but ever so thinly. Sunlight absorbed by the particles is re-emitted as invisible infrared (heat) radiation. This re-radiation robs the dust of energy, causing the particles to spiral slowly into the sun. Fresh dust from the vaporization of cometary ices as well as collisions of asteroids replenishes the cloud.
Zodiacal light cones in the fall morning sky (left) and in late March. Both times of year we see the plane of the solar system tipped at a high angle in the sky. Credit: Bob King
According to a study by Joseph Hahn and colleagues of the Clementine Mission data, comet dust accounts for the majority of the zodiacal dust within 1 a.u. (93 million miles) of the sun; a mix of asteroidal and comet dust makes up the remainder.
Stepping out on a spring evening to look at the zodiacal light, we can appreciate how small things can come together to create something grand.
Illustration of the twin Van Allen Probes (formerly Radiation Belt Storm Probes) in orbit (JHUAPL/NASA)
Earth’s inner radiation belt displays a curiously zebra-esque striped pattern, according to the latest findings from NASA’s twin Van Allen Probes. What’s more, the cause of the striping seems to be the rotation of the Earth itself — something that was previously thought to be impossible.
“…it is truly humbling, as a theoretician, to see how quickly new data can change our understanding of physical properties.”
– Aleksandr Ukhorskiy, Johns Hopkins University Applied Physics Laboratory
Our planet is surrounded by two large doughnut-shaped regions of radiation called the Van Allen belts, after astrophysicist James Van Allen who discovered their presence in 1958. (Van Allen died at the age of 91 in 2006.) The inner Van Allen belt, extending from about 800 to 13,000 km (500 to 8,000 miles) above the Earth, contains high-energy electrons and protons and poses a risk to both spacecraft and humans, should either happen to spend any substantial amount of time inside it.
The Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) is a time-of-flight versus energy spectrometer (JHUAPL)
Launched aboard an Atlas V rocket from Cape Canaveral AFS on the morning of Aug. 30, 2012, the Van Allen Probes (originally the Radiation Belt Storm Probes) are on a two-year mission to investigate the belts and find out how they behave and evolve over time.
One of the instruments aboard the twin probes, the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE), has detected a persistent striped pattern in the particles within the inner belt. While it was once thought that any structures within the belts were the result of solar activity, thanks to RBSPICE it’s now been determined that Earth’s rotation and tilted magnetic axis are the cause.
“It is because of the unprecedented high energy and temporal resolution of our energetic particle experiment, RBSPICE, that we now understand that the inner belt electrons are, in fact, always organized in zebra patterns,” said Aleksandr Ukhorskiy of the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Md., co-investigator on RBSPICE and lead author of the paper. “Furthermore, our modeling clearly identifies Earth’s rotation as the mechanism creating these patterns. It is truly humbling, as a theoretician, to see how quickly new data can change our understanding of physical properties.”
The model of the formation of the striped patterns is likened to the pulling of taffy.
RBSPICE data of stripes within the inner Van Allen belt (Click for animation) Credit: A. Ukhorskiy/JHUAPL
“If the inner belt electron populations are viewed as a viscous fluid,” Ukhorskiy said, “these global oscillations slowly stretch and fold that fluid, much like taffy is stretched and folded in a candy store machine.”
“This finding tells us something new and important about how the universe operates,” said Barry Mauk, a project scientist at APL and co-author of the paper. “The new results reveal a new large-scale physical mechanism that can be important for planetary radiation belts throughout the solar system. An instrument similar to RBSPICE is now on its way to Jupiter on NASA’s Juno mission, and we will be looking for the existence of zebra stripe-like patterns in Jupiter’s radiation belts.”
Jupiter’s Van Allen belts are similar to Earth’s except much larger; Jupiter’s magnetic field is ten times stronger than Earth’s and the radiation in its belts is a million times more powerful (source). Juno will arrive at Jupiter in July 2016 and spend about a year in orbit, investigating its atmosphere, interior, and magnetosphere.
Thanks to the Van Allen Probes. Juno now has one more feature to look for in Jupiter’s radiation belts.
“It is amazing how Earth’s space environment, including the radiation belts, continue to surprise us even after we have studied them for over 50 years. Our understanding of the complex structures of the belts, and the processes behind the belts’ behaviors, continues to grow, all of which contribute to the eventual goal of providing accurate space weather modeling.”
– Louis Lanzerotti, physics professor at the New Jersey Institute of Technology and principal investigator for RBSPICE
The Van Allen Probes are the second mission in NASA’s Living With a Star program, managed by NASA’s Goddard Space Flight Center in Greenbelt, MD. The program explores aspects of the connected sun-Earth system that directly affect life and society.
Every few dozen million years there’s a devastating event on Earth that kills nearly all the living creatures on our planet. Dr. Michael Habib explains how life always finds a way of recovering.
“Hello, my name is Michael Habib, and I’m an assistant professor of Cell and Neurobiology at the University of Southern California. I’m a biomechanist and paleontologist.”
How does life survive a mass extinction?
“One of the most amazing things about life on earth is that if you don’t kill EVERYTHING, it will eventually recover. Extinction is forever – if you kill a group, you’ll never have that group again, but what we find is that often the same ecologies show up again after a major extinction, because other groups end up diversifying to do the same things as groups we’d seen elsewhere.”
“So the world doesn’t end up looking entirely different after a mass extinction, although it would be quite different in a lot of ways. And even the great End Permian extinction killed about 99 percent of all species, or at least all the ones we can measure in the fossil record, and left that one percent, that’s all it takes to eventually recover.”
“Now, I imagine if you took a time machine to the first six months of the Triassic, it would be a very lonely, kinda ugly world. You’d notice that animals and plants were missing. The massive extinction affected all sorts of organisms.But, at the scales we’re looking at in the geologic record – tens of millions of years, a time span that’s pretty much unfathomable to human experience, you can eventually recover that diversity, with speciation event after speciation event kicks in and eventually creates a new diversity.”
“But after each mass extinction event, the world looks a bit different. You know, if I were to drop you in a time machine before the End Permian extinction, you’d notice a lot of things different about the world. You’d notice strange large mammal-like reptiles with large saber teeth running around as the large terrestrial organisms. You would see a few of the major groups of vertebrates that exist today, especially marine, but a lot of the terrestrial groups would be very different.”
“If I jump to after the End Permian extinction, enough that life had recovered, you’ll see those ancestors to dinosaurs, those terrasaurs, would show up in the mid to late Triassic. Then you start to see some plant groups that look more familiar to us, like plants that look a little bit more like modern conifers, things like that. So the world would definitely look different, but life does go on.”
The bright star Regulus will disappear for observers living along the path between the red lines. The disappearance is longest - up to 14 seconds - along the center green line. Credit: Google Maps / IOTA
North America’s brightest predicted asteroid occultation may be one-upped by a much bigger occultation – a solid blanket of clouds. Asteroid 163 Erigone will cover or occult the bright star Regulus shortly after 2 a.m. Eastern Daylight Time tomorrow morning March 20. Observers along a 45-mile-wide (73-km) belt stretching from the wilderness of Nunavut to the salty seas of Bermuda could see the star vanish for up to 14 seconds. Provided they can find a hole in the clouds.
National forecast map for 8 p.m. EDT tonight March 19. A low pressure region is expected to bring rain and snow to the Northeast and Ontario today and overnight with clearing skies later tomorrow. Click for latest New York City weather forecast. Credit: NOAA
Overcast skies with a mix of rain or snow are predicted along virtually the entire track from the tiny berg of Cochrane in northern Ontario south through New York City, Connecticut and New Jersey. A sluggish cold front isn’t expected to clear skies until … no surprise here … after the event is over.
Bermuda, perhaps the best place to watch the occultation, crosses the eastern edge (blue line) of the asteroid’s shadow. The red line marks one sigma of uncertainty in the shadow edge. Credit: Google Maps/IOTA
But there is one place where maybe, just maybe, the clouds may part to let Erigone do its job. Bermuda. The Bermuda Weather Service forecast calls for highs in the low 70s mid-week, but that balmy air may come packaged with a partly to mostly cloudy sky at the time of the occultation. A few determined observers are on their way there right now, hoping for better weather. In case the islands are socked in, some plan to rent planes to rise above the low-lying clouds typical this time of year and revel in the shadow of an asteroid. Even if clear, Bermuda lies near the eastern edge of the path. Any occultation there will be brief.
Illustration showing asteroid 163 Erigone about to cover Leo’s brightest star Regulus around 2:07 Eastern Daylight Time Thursday morning March 20, 2014. As the asteroid’s shadow passes over the ground, observers will see Regulus briefly disappear. Illustration: Bob King with ESO/NASA images
Yes, there will be more occultations, but bright ones that the public can enjoy with the naked eye are rare.
Skywatchers are nothing if not hopeful. We believe in the sucker hole, the name given to rogue clearings in an otherwise overcast sky. We are patient and steadfast when it comes to glimpsing the rarest of the rare. I know this because my friends and I have stood outside on winter mornings staring at the western sky, waiting for clouds to peel back that we might glimpse a Martian dust storm or new comet.
If it does clear tomorrow, face southwest shortly before 2 a.m. to find Leo’s brightest star Regulus. The star will be about 40 degrees high (four ‘fists’ held at arm’s length against the sky). Above is the the Sickle of Leo, shaped like a backwards question mark. Brilliant Jupiter shines well to its lower right. Stellarium
If there’s an astronomer’s credo, it’s this: “The sky might clear yet!” The latest weather word (9 a.m. March 19) for U.S. and Canadian observers indicates thinner clouds along the southern end of the track in New Jersey. Many of us considered driving to the event but changed our minds because of work, worries about weather and other commitments. Assuming the credo holds true, you’ll be able to watch Regulus disappear live from the comfort of your home thanks to the efforts of several observers planning to stream the event on the Web.
Here’s a list of streamers so far:
* Brad Timerson plans to go live with audio at 2 a.m. at a rest area along I-90 just west of Syracuse, NY.
A new interactive mosaic from NASA's Lunar Reconnaissance Orbiter covers the north pole of the moon from 60 to 90 degrees north latitude at a resolution of 6-1/2 feet (2 meters) per pixel. Close-ups of Thales crater (right side) zoom in to reveal increasing levels of detail.
Image Credit: NASA/GSFC/Arizona State University
OMG – breathtaking! That was my reaction when I clicked on this incredible new interactive map of the moon’s north polar region. Be prepared to be amazed. It took four years and 10,581 images for the LROC (Lunar Reconnaissance Orbiter Camera) team to assemble what’s believed to be the largest publicly available image mosaic in existence. With over 650 gigapixels of data at a resolution of 2 meters per pixel, you’ll feel like you’re dropping in by parachute to the lunar surface.
Wide view of the 91-km Karpinskiy Crater from the new interactive north pole mosaic. See image below for a zoomed-in view. Credit: NASA/GSFC/Arizona State Univ.
When you call up the map, be sure to click first on the full-screen button below the zoom slider. Now you’re ready for the full experience. With mouse in hand, you’re free to zoom and pan as you please. Take in the view of Whipple Crater shadowed in polar darkeness or zoom to the bottom of Karpinskiy Crater and fly like a bird over its fractured floor.
In this photo, we come in for a closer look at the fracture or rill in Karpinskiy’s floor. Notice the small, lighter-toned boulders on the cliff side. The images were all taken with the Lunar Reconnaissance Orbiter’s Narrow Angle Camera (NAC). Credit: NASA/GFSC/Arizona State Univ.
The images are so detailed and the zoom so smooth, there’s nothing artificial about the ride. Except the fact you’re not actually orbit. Darn close though. All the pictures were taken over the past few years by NASA’s Lunar Reconnaissance Orbiter which can fly as low as 50 km (31 miles) over the lunar surface and resolve details the size of a desk.
Printed at 300 dpi – a high-quality printing resolution that requires you to peer very closely to distinguish pixels – the mosaic map would be larger than a football field. Credit: NASA
There are 10 snapshots along the bottom of the map – click them and you’ll be swiftly carried directly to that feature. One of them is the lunar gravity probe GRAIL-B impact site.
The region the gigapixel map covers superimposed on the outline of the U.S. Credit: NASA
To create the 2-D map, a polar stereographic projection was used in to limit mapping distortions. In addition, the LROC team used information from the LOLA and GRAIL teams and an improved camera pointing model to accurately project each image in the mosaic to within 20 meters. For more information on the project, click HERE.
This artist's conception could resemble a planetary system in front of a background star. Image Credit: NASA Goddard Space Flight Center / Francis Reddy
When astronomers detect new exoplanets they typically do so using one of two techniques. First, there’s the famous transit technique, which looks for slight dips in light as a planet passes in front of its host star, and second is the radial velocity technique, which senses the motion of a star due to the gravitational pull of its planet.
But then there is gravitational microlensing, the chance magnification of the light from a distant star by the mass of a foreground star and its planets due to the distortion in the fabric of spacetime. While this technique sounds almost improbable, it is so accurate that every detection skips nominating planets as candidates and immediately verifies them as bona-fide worlds.
But without follow-up observations, the microlensing technique struggles with characterizing the incredibly faint host star. Now, a team of international astronomers led by PhD candidate Jennifer Yee from Ohio State University has detected the first microlensing signature, lovingly called MOA-2013-BLG-220Lb, that looks like a confirmed planet orbiting a candidate brown dwarf — an object so faint because it isn’t massive enough to kick-off nuclear fusion in its core.
Matter — no matter how great or small — curves the fabric of spacetime. It can ultimately acts like a lens by curving the background light around it and therefore magnifying the background source. In microlensing, the intervening matter is simply a faint star or perhaps a planetary system.
“As the ‘lens system’ passes in front of a distant, background star, the magnification of that background star changes as a function of time,” Yee told Universe Today. “By measuring the changing magnification of the background star, we can learn about the lensing star and perhaps whether or not it has a planet.”
In a planetary system, the light from the background star will be magnified when the foreground star passes in front of it. If there is a cirlcing planet, there will be an additional cusp in brightness (to a lesser extent but still a tell-tale detection nonetheless).
A sketch of a microlensing signature with a planet in the lens system. Image Credit: NASA / ESA / K. Sahu / STScI
At the moment the planetary system transits in front of the background star (and for many years after) we can’t separate the two objects. While the light of the background star may be greatly magnified, its image is distorted because its light merges with the planetary system.
So the microlensing signature cannot tell astronomers anything about the lens system’s star. “It’s out of the ordinary,” Andrew Gould, Yee’s PhD advisor and coauthor on the paper, told Universe Today. “In other techniques people have definitely detected a star and they’re struggling to detect the planet. But microlensing is just the opposite. We detect the planet very clearly, but we can’t detect the host star.”
However, the microlensing signature does give away the lens system’s proper motion — the apparent change in distance over time — as it passes in front of the background star. MOA-2013-BLG-220Lb’s proper motion is extremely high, clocking in at 12.5 milliarcseconds (a distance on the sky that is 2400 times smaller than the size of the full moon) per year. This is roughly three times higher than average.
A high proper motion may be caused by an object that is very close by and is moving slowly or a very distant object moving rapidly. As most stars tend not to move at high speeds, the team assumes the object is relatively close, placing it at a distance of 6,000 light-years.
With a distance fixed, the team is also able to assume a mass for the object. It weighs in below the hydrogen-burning limit and is therefore considered the best brown dwarf candidate microlensing has detected.
“The double-edged sword of microlensing is that no light from the lens star is required,” Yee told Universe Today. “On the one hand, microlensing can find planets around dark or faint objects like brown dwarfs. The flip side is that it’s very difficult to characterize the lens star if its light is not detected.”
Astronomers will have to wait until 2021 to take a second look at the lens system. This time frame is how long we expect it to take before the candidate brown dwarf separates appreciably on the sky from the background star. Once it has done so astronomers will be able to verify whether or not the candidate is truly a brown dwarf.
A portion of a collage of galaxies included in the Herschel Reference Survey, in false color to show different dust temperatures. (Blue is colder, and red is warmer). Credit: ESA/Herschel/HRS-SAG2 and HeViCS Key Programmes/L. Cortese (Swinburne University)
While dust is easy to ignore in small quantities (says the writer looking at her desk), across vast reaches of space this substance plays an important role. Stick enough grains together, the theory goes, and you’ll start to form rocks and eventually planets. On a galaxy-size scale, dust may even effect how the galaxy evolves.
A new survey of 323 galaxies reveals that dust is not only affected by the kinds of stars in the vicinity, but also what the galaxy is made of.
“These dust grains are believed to be fundamental ingredients for the formation of stars and planets, but until now very little was known about their abundance and physical properties in galaxies other than our own Milky Way,” stated lead author Luca Cortese, who is from the Swinburne University of Technology in Melbourne, Australia.
“The properties of grains vary from one galaxy to another – more than we originally expected,” he added. “As dust is heated by starlight, we knew that the frequencies at which grains emit should be related to a galaxy’s star formation activity. However, our results show that galaxies’ chemical history plays an equally important role.”
Galaxies in the Herschel Reference Survey in infrared/submillimeter wavelengths (with the Herschel space telescope, at left) and the Sloan Digital Sky Survey (right). Herschel’s false-color image shows galaxies with cold dust (blue) and warm dust (red). Sloan highlights young stars (blue) and old stars (red). “Together, the observations plot young, dust-rich spiral/irregular galaxies in the top left, with giant dust-poor elliptical galaxies in the bottom right,” the European Space Agency stated. Credit: ESA/Herschel/HRS-SAG2 and HeViCS Key Programmes/Sloan Digital Sky Survey/ L. Cortese (Swinburne University)
Data was captured with two cameras on the just-retired Herschel space telescope: Spectral and Photometric Imaging Receiver (SPIRE) and Photodetecting Array Camera and Spectrometer (PACS). These instruments examined different frequencies of dust emission, which shows what the grains are made of. You can see a few of those galaxies in the image above.
“The dust-rich galaxies are typically spiral or irregular, whereas the dust-poor ones are usually elliptical,” the European Space Agency stated. “Dust is gently heated across a range of temperatures by the combined light of all of the stars in each galaxy, with the warmest dust being concentrated in regions where stars are being born.”
Astronomers initially expected that a galaxy with speedy star formation would display more massive and warmer stars in it, corresponding to warmer dust in the galaxy emitting light in short wavelengths.
“However, the data show greater variations than expected from one galaxy to another based on their star formation rates alone, implying that other properties, such as its chemical enrichment, also play an important role,” ESA said.
Comet c/2012 K1 PanSTARRS as imaged by Dan Crowson on February 22nd, 2014. Image credit: Dan Crowson, used with permission.
Get those binoculars ready: an icy interloper from the Oort cloud is about to grace the night sky.
The comet is C/2012 K1 PanSTARRS, and it’s currently just passed from the constellation Hercules into Corona Borealis and presents a good target for observers high in the sky in the hours before dawn. In fact, from our Tampa based latitude, K1 PanSTARRS is nearly at the zenith at around 6 AM local.
Observers currently place K1 PanSTARRS at magnitude +10.5 and brightening and showing a small condensed coma. Through the eyepiece, a comet at this stage will often resemble a fuzzy, unresolved globular star cluster.
And the good news is, K1 PanSTARRS will continue to brighten, headed northward through the early morning and then into the evening sky before reaching solar conjunction on August 9th, when it’ll actually pass behind the Sun for a few hours as seen from from our vantage point. We actually get two good apparitions of Comet K1 PanSTARRS: one for the northern hemisphere in the Spring and one for the southern hemisphere after it reaches perihelion and crosses south of the ecliptic plane in August.
And it’ll be worth keeping an eye out for K1 PanSTARRS online as well, as it passes into the view of SOHO’s LASCO C3 camera on August 2 before exiting its 15 degree field of view on August 16th.
This actually means the comet will reach opposition twice from our Earthbound vantage point: once on April 15th, and again on November 7th. And, as is often the case, this comet arrives six months early –or late, depending how you look at it- to be a fine naked eye object. Had K1 PanSTARRS reached perihelion in January, we’d have really been in for a show, with the comet only around 0.05 Astronomical Units (about 7.7 million kilometers) from the Earth!
The orbit of comet K1 PanSTARRS through the inner solar system. The yellow arrows denote the motion of the planets and the comet as seen from north of the ecliptic plane. Credit-NASA/JPL Horizons Solar System Dynamics generator.
But alas, such was not to be. At its best, K1 PanSTARRS will be hidden by the glare of the Sun at its very best, to emerge into the southern sky. The comet has a steeply inclined 142 degree retrograde orbit, and thus approaches the inner solar system from high above the ecliptic plane.
These coming last weeks of March are a great time to search out K1 PanSTARRS as the Moon reaches Last Quarter this weekend and heads towards New on March 30th, beginning a two week “moonless period for AM observing in early April. Projections by veteran comet observer Seiichi Yoshida suggest that K1 PanSTARRS will begin to brighten dramatically towards +8th magnitude through April. We first picked up the now posthumous comet ISON with binoculars around this magnitude last Fall. Keep in mind, like nebula and galaxies, the apparent brightness of a comet is spread out over its surface area. This can make a +10th magnitude comet much tougher to spot than a pinpoint +10 magnitude star.
We actually prefer our trusty Canon 15x45IS image stabilized binoculars for comet hunting… they’re powerful and easy to deploy on a cold March morning!
Here’s a handy list of notable events to watch for as Comet C/2012 K1 PanSTARRS crosses the springtime sky. Only passages of less than one degree near stars greater than magnitude +6 are mentioned except where otherwise noted:
March 17th: Comet C/2012 K1 PanSTARRS passes into the constellation Corona Borealis.
March 21st: Passes the +5.8 magnitude star Upsilon Coronae Borealis.
March 29th: Passes the +5.4 magnitude star Rho Coronae Borealis.
March 30th: The Moon reaches New phase.
The path of comet K1 PanSTARRS in one week intervals through March and April. Created using Stellarium.
April 2nd: Passes the +4.8 magnitude star Kappa Coronae Borealis.
April 7th: Passes the +5.2 magnitude star Mu Coronae Borealis.
April 10th: Passes into the constellation of Boötes.
April 10th: Passes the +5 magnitude wide binary pair Nu Boötis.
April 15th: Comet K1 PanSTARRS reaches opposition, rising opposite to the setting Sun and moving into the evening sky.
April 20th: K1 PanSTARRS becomes circumpolar for observers above 45 degrees north until May 25th.
April 26th: Passes into the constellation Ursa Majoris.
April 29th: Passes the bright +1.9th magnitude star Alkaid in the handle of the Big Dipper asterism. This is the brightest star that K1 PanSTARRS will pass near for this apparition, and Alkaid will make a great “finder” to spot the comet.
April 29th: The Moon reaches New phase.
April 30th: Approaches the +4.7 magnitude star 24 Canum Venaticorum.
The Spring path of comet K1 PanSTARRS from mid-March through late June. Credit: Starry Night Education Software.
May 1st: Passes less than 2 degrees from the galaxy M51… photo op!
May 3rd: Passes the 5.1 magnitude star 21 Canum Venaticorum.
May 6th: K1 PanSTARRS Reaches a maximum declination of 49.5 degrees north.
May 11th: Passes the 5.3 magnitude star 3 Canum Venaticorum.
May 14th: Passes into the constellation Ursa Major.
May 17th: Another great photo ops awaits astrophotographers, as the comet passes the +3.7 magnitude star Chi Ursae Majoris and the +12 magnitude galaxy NGC 3877.
May 25th: Passes the 3rd magnitude star Psi Ursae Majoris.
May 28th: The Moon reaches New phase.
May 28th: Passes the 4.7 magnitude star Omega Ursae Majoris.
June 7th Passes into the constellation Leo Minor.
June 15th: Passes the +4.5 magnitude star 21 Leo Minoris.
June 22nd: Passes into the constellation Leo.
July 1- Passes to within 40 degrees elongation from the Sun.
And from there, Comet K1 PanSTARRS reaches perihelion just outside of the Earth’s orbit at 1.05 A.U. on August 27, and plunges south across the celestial equator on September 15.
Video animation of comet C/2012 K1 PanSTARRS over the span of an evening. Credit: Dan Crowson of Dardenne Prairie Missouri, used with permission.
It’s also worth noting that K1 PanSTARRS will make its first of two approaches at a minimum distance of 1.471 A.U.s from Earth May 4th and will be moving at about a degree a day – twice the diameter of the Full Moon – before receding from us once more for a closer 1.056 A.U. approach to Earth on August 25th.
Discovered on May 19th, 2012 by the PanSTARRS telescope based on the island of Maui, Comet K1 PanSTARRS was first spotted at 8.7 A.U.s distant, well past the orbit of Jupiter. The PanSTARRS survey has been a prolific discoverer of asteroids and comets, including the brilliant comet C/2011 L4 PanSTARRS that graced dusk skies in March of last year.
And those are just the binocular comets that are scheduled to perform… remember, the next “big one” could come barreling in towards the inner solar system at any time to put on a memorable performance worthy of another comet Hyakutake or Hale-Bopp… just not TOO close!
– Be sure to send those comet pics in to Universe Today.
