Christmas lighting displays like this one near Duluth, Minn. U.S. are visible from outer space. Credit: Bob King
Call it holiday light creep. A NASA satellite has been tracking the spread of Christmas lighting from 512 miles up for the past three years and according to the data, nighttime lights around many major U.S. cities shine 20 to 50 percent brighter during Christmas and New Year’s when compared to light output during the rest of the year. Not surprisingly, most it comes from suburban areas.
Christmas isn’t the only time holiday festivities spill into the cosmic night. In some Middle Eastern Cities nighttime lights shine more than 50 percent brighter during Ramadan than the rest of the year. Because snow reflects so much light, the researchers could only analyze snow-free cities lest they risk comparing apples to oranges. The team focused on the U.S. West Coast from San Francisco to Los Angeles and on cities south of a rough line from St. Louis to Washington, D.C.
The map compares the nighttime light signals from December 2012 and 2013 to the average light output for the rest of 2012 to 2014 in and around several large cities in Texas. Dark green shadings indicates increased lighting in December, primarily from outdoor holiday lights. Credit: NASA’s Earth Observatory/Jesse Allen
As someone who has spent many winter nights observing I can attest to snow being a major factor in nighttime sky brightness. Even downward shielded lighting must necessarily reflect upward and into the heavens when it strikes the snow below. Summer is a far darker time of year than winter across much of the northern U.S.
Close-ups of three cities using the Suomi-NPP satellite data. Dark green pixels are areas where the lights are 50 percent brighter. Credit: NASA’s Earth Observatory/Jesse Allen
The orbital images were all taken by the Suomi NPP satellite, a joint NASA/National Oceanic and Atmospheric Administration mission, carries an instrument called the Visible Infrared Imaging Radiometer Suite (VIIRS) that detects light in a range of wavelengths from green to near-infrared as it flies over at roughly 1:30 a.m. and 1:30 p.m. each day. VIIRS has a low-light sensor that can distinguish night lights tens to hundreds of times better than previous satellites. In the U.S. the lights starting getting brighter the day after Thanksgiving and continued through News Year’s Day. Miguel Román, a scientist at NASA’s Goddard Space Flight Center and member of the Suomi NPP Land Discipline Team, made the discovery while researching urban energy use patterns in the context of greenhouse emissions. And you thought all those twinkly bulbs were just for fun.
NASA Sees Holiday Lights from Space
The science team found that light intensity increased by 30 to 50 percent in the suburbs and outskirts of major cities. Lights in the central urban areas didn’t increase as much as in the suburbs, but still brightened by 20 to 30 percent. This makes sense when you consider that folks in the ‘burbs not only decorate their homes but often extend Christmas displays across the yard and up into the trees.
In several cities in the Middle East, city lights brighten during the Muslim holy month of Ramadan, as seen using a new analysis of daily data from the NASA-NOAA Suomi NPP satellite. Dark green pixels are areas where the lights are 50 percent brighter, or more, during Ramadan. Credit: NASA’s Earth Observatory/Jesse Allen
Holiday lighting – a simple joy of the season. Yet it reflects both the hopes and wishes of human culture and the mundane facts of energy use. Through satellites, we can step back and watch the world change in ways never thought possible. We truly live in the Age of the Anthopocene, a newly designated era reflecting the profound effect our species has had and continues to have on the planet. To see all the holiday space photos, check out Goddard’s Flickr page.
An overhead view of the Eastern U.S. Click for a Flick page showing all U.S. cities in the survey. Credit: NASA’s Earth Observatory / Jesse Allen
Artist's conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech
It’s alive! NASA’s Kepler space telescope had to stop planet-hunting during Earth’s northern-hemisphere summer 2013 when a second of its four pointing devices (reaction wheels) failed. But using a new technique that takes advantage of the solar wind, Kepler has found its first exoplanet since the K2 mission was publicly proposed in November 2013.
And despite a loss of pointing precision, Kepler’s find was a smaller planet — a super-Earth! It’s likely a water world or a rocky core shrouded in a thick, Neptune-like atmosphere. Called HIP 116454b, it’s 2.5 times the size of Earth and a whopping 12 times the mass. It circles its dwarf star quickly, every 9.1 days, and is about 180 light-years from Earth.
“Like a phoenix rising from the ashes, Kepler has been reborn and is continuing to make discoveries. Even better, the planet it found is ripe for follow-up studies,” stated lead author Andrew Vanderburg of the Harvard-Smithsonian Center for Astrophysics.
Kepler ferrets out exoplanets from their parent stars while watching for transits — when a world passes across the face of its parent sun. This is easiest to find on huge planets that are orbiting dim stars, such as red dwarfs. The smaller the planet and/or brighter the star, the more difficult it is to view the tiny shadow.
Infographic showing how the Kepler space telescope continued searching for planets despite two busted reaction wheels. Credit: NASA Ames/W Stenzel
The telescope needs at least three reaction wheels to point consistently in space, which it did for four years, gazing at the Cygnus constellation. (And there’s still a lot of data to come from that mission, including the follow-up to a bonanza where Kepler detected hundreds of new exoplanets using a new technique for multiple-planet systems.)
The drawback is Kepler needs to change positions every 83 days since the Sun eventually gets in the telescope’s viewfinder; also, there are losses in precision compared to the original mission. The benefit is it can also observe objects such as supernovae and star clusters.
Kepler-62f, an exoplanet that is about 40% larger than Earth. It’s located about 1,200 light-years from our solar system in the constellation Lyra. Credit: NASA/Ames/JPL-Caltech
“Due to Kepler’s reduced pointing capabilities, extracting useful data requires sophisticated computer analysis,” CFA added in a statement. “Vanderburg and his colleagues developed specialized software to correct for spacecraft movements, achieving about half the photometric precision of the original Kepler mission.”
That said, the first nine-day test with K2 yielded one planetary transit that was confirmed with measurements of the star’s “wobble” as the planet tugged on it, using the HARPS-North spectrograph on the Telescopio Nazionale Galileo in the Canary Islands. A small Canadian satellite called MOST (Microvariability and Oscillations of STars) also found transits, albeit weakly.
A paper based on the research will appear in the Astrophysical Journal.
Comet Finlay on December 16th showing a bright coma and short tail. Credit: FRAM team
Short-period comet 15P/Finlay, which had been plunking along at a dim magnitude +11, has suddenly brightened in the past couple days to +8.7, bright enough to see in 10×50 or larger binoculars. Czech comet observer Jakub Cerny and his team photographed the comet on December 16th and discovered the sudden surge. Wonderful news!
While comets generally brighten as they approach the Sun and fade as they depart, any one of them can undergo a sudden outburst in brightness. You can find Finlay right now low in the southwestern sky at nightfall near the planet Mars. While outbursts are common, astronomers still aren’t certain what causes them. It’s thought that sub-surface ices, warmed by the comet’s approach to the Sun, expand until the pressure becomes so great they shatter the ice above, sending large fragments flying and exposing fresh new ice. Sunlight gets to work vaporizing both the newly exposed vents and aerial shrapnel. Large quantities of dust trapped in the ice are released and glow brightly in the Sun’s light, causing the comet to quickly brighten.
Some comets flare up dramatically. Take 29P/Schwassmann-Wachmann. Normally a dim bulb at 17th magnitude, once or twice a year it flares to magnitude 12 and occasionally 10!
Animated movie showing the expansion of the coma of Comet Holmes over 9 nights during its spectacular outburst in November 2007. Credit: 3.6-meter Canada-France-Hawaii telescope on Mauna Kea / David Jewitt
Whatever the reason, outbursts can last from days to weeks. It’s anybody’s guess how long 15P/Finlay will remain a relatively easy target for comet hungry skywatchers. While not high in the sky, especially from the northern U.S., it can be seen during early evening hours if you plan well.
By good luck, Comet Finlay will track with Mars through December into early January. On December 23rd, they’ll come together in a remarkably close conjunction. This map shows the nightly position of the comet from Dec. 18th through Jan. 12th. Mars’ location is shown every 5 nights. Positions plotted for 6:15 p.m. (CST) 1 hour and 45 minutes after sunset. Stars shown to magnitude 8. Star magnitudes are underlined. Click to enlarge and print for outside use. Source: Chris Marriott’s SkyMap software
Comet Finlay was discovered by William Henry Finlay from South Africa on September 26, 1886. It reaches perihelion or closest approach to the Sun on December 27th and was expected to brighten to magnitude +10 when nearest Earth in mid-January at 130 million miles (209 million km). Various encounters with Jupiter since discovery have increased its original period of 4.3 years to the current 6.5 years and shrunk its perihelion distance from 101 million to 90 million miles.
Comet Finlay appears considerably fainter in this pre-outburst photo taken on December 14th. Credit: Alfons Diepvens
Looking at the map above it’s amazing how closely the comet’s path parallels that of Mars this month. Unlike Comet Siding Spring’s encounter with that planet last October, Finlay’s proximity is line of sight only. Still, it’s nice to have a fairly bright planet nearby to point the way to our target. Mars and Finlay’s paths intersect on December 23rd, when the duo will be in close conjunction only about 10? apart (1/3 the diameter of the Full Moon) for observers in the Americas. They’ll continue to remain almost as close on Christmas Eve. Along with Comet Q2 Lovejoy, this holiday season is turning out to be a joyous occasion for celestial fuzzballs!
To give you a little context to make finding Comet FInlay easier, use this wide-view map. A line from bright Vega in the western sky left through Altair will take you directly to Mars and the comet. This map shows the sky at nightfall tonight when the comet will be about 15° high in the southwestern sky. Source: Stellarium
A number companies are deploying satellites this year to create space-based internet services. Credit: AMNH.
The hazy, white horizon lifts away slowly, giving way to the blue and green, cloud-swept marble we call home. I take in a deep breath, astonished by the Earth’s staggering beauty in stark contrast to the sprinkled backdrop.
People are still shuffling into the 429-seat Hayden Planetarium at the American Museum of Natural History, their shadows projected onto the arched ceiling. A voice resonates in the dome’s spacious cavity. Brian Abbott, the planetarium’s assistant director, is welcoming everyone to the show. It’s a “highlights tour,” he says, covering most of the known universe in one fell swoop.
As we leave Earth further behind, the satellites appear, swarming above our planet like bees around a hive. Soon the curved orbits of other planets become visible and we fly toward Mars.
In minutes we are hovering above Valles Marineris, a canyon so massive it would stretch from Manhattan to Los Angeles. The projectors display six-meter resolution data from the Mars Global Surveyor. We see the canyon ridges in such incredible, 3D detail it seems we could reach out and touch the tallest peaks with our fingers.
Abbott’s voice is slow and soothing. He speaks with authority, mindful of every inflection he makes and every word he uses. He carefully constructs his sentences, but also takes the time to crack a few jokes along the way. It’s just another day at the office, and yet it sounds like he’s having the time of his life.
Abbott in his office at AMNH. Credit: Shannon Hall
Abbott never dreamed of becoming an astronomer. In high school he was on a very different path, headed toward a career in art. Then, in 1985, Halley’s comet was scheduled to appear in the night sky. “For some reason I needed to find it,” he said. So, from his backyard outside Philadelphia, he learned how to pinpoint the constellations and spot distant objects, like galaxies, nebulae and star clusters. When the comet finally came, he was able to spot it, a tiny target in the vast sky. It was a revelation that pumped him full of adrenalin on that long, dark night.
Yet while Abbott left art as a career choice behind, he has been able to integrate art with astronomy, as his planetarium show demonstrates. “I admire the niche he has created for himself in the intersection between art, visualization and science,” said colleague Jana Grcevich, a postdoctoral researcher at AMNH.
Just before starting work at the museum in 1999, however, Abbott was an unhappy graduate student in the astronomy department at the University of Toledo. “Who can explain what gets you out of bed in the morning,” he said. “It just wasn’t what moved me.” Frustrated with his lot in life, he had plans to drive his car across the country, Jack Kerouac style. But first, he attended one last meeting: the American Astronomical Society’s annual conference in Chicago.
There, among all the job listings, he saw only one that wasn’t a research or a faculty position. The AMNH needed someone to create the world’s first interactive atlas of the Universe. So Abbott started sniffing around and coincidentally ran into the planetarium’s famed director, Neil DeGrasse Tyson, in the hallway of their hotel. Yet “Neil wasn’t Neil back then,” Abbott recalled. “He was somewhat known but he wasn’t mobbed with people.”
The duo started talking, and in two weeks Abbott found himself living in New York City with a new job. But he doesn’t regret it for a second. “I feel like I’m almost divorced from the night sky living here. I’m not able to just go out in my backyard and set up a telescope and see stuff. But we have this great dome. And I can go in there and see the entire Universe far better than I can see in the night sky.”
Now, Abbott spends his days visualizing large data sets. For the past 14 years, he has been creating a three-dimensional map of the Universe. He’s constantly updating the atlas with recent data hot off the world’s biggest telescopes and best satellites. And in the planetarium, he turns this abstract data into the planets, stars and galaxies that visitors flock to see. “What we want to do is focus on the scientific story of the universe,” said Abbott. “And we want that reflected in our dome.”
As the Hayden Planetarium’s popularity suggests, there’s a surprising public appetite for such strict scientific cartography. “There’s always at least one time in the show when the air comes out of the room,” said Abbott, referring to the moment when the audience takes a collective breath, in awe of the universe above them.
I can recall easily when that moment came for me. We had just left the Milky Way galaxy. Looking back on our home galaxy, the bright yellow core was surrounded by gorgeous blue spiral arms and sweeping dust lanes. Swarms of smaller galaxies began to appear. In minutes, we saw the Tully Catalogue, which covers an astonishing 30,000 galaxies in total.
The audience gasped in awe at the sheer number of galaxies in our local neighborhood. It’s impossible not to feel small at a moment like that.
But we were nowhere near the farthest reaches of the Universe yet. In moments, we saw the total number of galaxies ever recorded in the Sloan Digital Sky Survey. A chill ran down my spine. There were over one million galaxies projected onto the dome. Each one has over 100 billion stars. And each one of those likely has 5 or even ten planets. There are so many opportunities for life in our vast Universe.
We continued to zoom out, until we reached the edges of the 46.6 billion-light-year-wide observable Universe. In just over an hour, the tour had grossly violated the speed of light. “So that’s the Universe,” Abbott said. “Any questions?”
After a 20 month trek across Mars and careful analysis of data, NASA scientists have announced two separate detection of organics - in the surface and the air of Mars. (Photo Credit: NASA/JPL, Illustration - T. Reyes)
On Tuesday, December 16, 2014, NASA scientists attending the American Geophysical Union Fall Meeting in San Francisco announced the detection of organic compounds on Mars. The announcement represents the discovery of the missing “ingredient” that is necessary for the existence – past or present – of life on Mars.
Indeed, the extraordinary claim required extraordinary evidence – the famous assertion of Dr. Carl Sagan. The scientists, members of the Mars Science Lab – Curiosity Rover – mission, worked over a period of 20 months to sample and analyze Martian atmospheric and surface samples to arrive at their conclusions. The announcement stems from two separate detections of organics: 1) ten-fold spikes in atmospheric Methane levels, and 2) drill samples from a rock called Cumberland which included complex organic compounds.
The Tunable Laser Spectrometer, one of the tools within the Sample Analysis at Mars (SAM) laboratory on NASA’s Curiosity Mars rover. By measuring absorption of light at specific wavelengths, it measures concentrations of methane, carbon dioxide and water vapor in Mars’ atmosphere. (Image Credit: NASA/JPL-Caltech)
Methane, of the simplest organic compounds, was detected using the Sample Analysis at Mars instrument (SAM). This is one of two compact laboratory instruments embedded inside the compact car-sized rover, Curiosity. Very soon after landing on Mars, the scientists began to use SAM to periodically measure the chemical content of the Martian atmosphere. Over many samples, the level of Methane was very low, ~0.9 parts per billion. However, that suddenly changed and, as scientists stated in the press conference, it was a “wow” moment that took them aback. Brief daily spikes in Methane levels averaging 7 parts per billion were detected.
The detection of methane at Mars has been claimed for decades, but more recently, in 2003 and 2004, independent research teams using sensitive spectrometers on Earth detected methane in the atmosphere of Mars. One group led by Vladimir Krasnopolsky of Catholic University, and another led by Dr. Michael Mumma from NASA Goddard Space Flight Center, detected broad regional and temporal levels of Methane as high as 30 parts per billion. Those announcements met with considerable skepticism from the scientific community. And the first atmospheric measurements by Curiosity were negative. However, neither group backed down from their claims.
Regions where methane appears notably localized in Northern Summer (A, B1, B2), and their relationship to mineralogical and geo-morphological domains. (A.) Observations of methane near the Syrtis Major volcanic district. (B.) Geologic map of Greeley and Guest (41) superimposed on the topographic shaded-relief from MOLA (42). The most ancient terrain (Npld, Nple) is Noachian in age (~3.6 – 4.5 billion years old, when Mars was wet), and is overlain by volcanic deposits from Syrtis Major of Hesperian (Hs) age (~3.1 – 3.6 billion yrs old). (Credit: Mumma, et al., 2009, Figure 3)
The sudden detection of ten-fold spikes in methane levels in Gale crater is not inconsistent with the earlier remote measurements from Earth. The high seasonal concentrations were in regions that do not include Gale Crater, and it remains possible that the Curiosity measurements are of a similar nature but due to some less active process than exists at the regions identified by Dr. Mumma’s team.
This graphic shows tenfold spiking in the abundance of methane in the Martian atmosphere surrounding NASA’s Curiosity Mars rover, as detected by a series of measurements made with the Tunable Laser Spectrometer instrument in the rover’s Sample Analysis at Mars laboratory suite. (Image Credit: NASA/JPL-Caltech)
The NASA scientists at AGU led by MSL project scientist Dr. John Grotzinger emphasized that they do not yet know how the methane is being generated. The process could be biological or not. There are abiotic chemical processes that could produce methane. However, the MSL SAM detections were daily spikes and represent an active real on-going process on the red planet. This alone is a very exciting aspect of the detection.
The team presented slides to describe how methane could be generated. With the known low background levels of methane at ~ 1 part per billion, an external cosmic source, for example micro-meteoroids entering the atmosphere and releasing organics which is then reduced by sunlight to methane, could be ruled out. The methane source must be of local origin.
This image illustrates possible ways methane might be added to Mars’ atmosphere (sources) and removed from the atmosphere (sinks). NASA’s Curiosity Mars rover has detected fluctuations in methane concentration in the atmosphere, implying both types of activity occur on modern Mars. A longer caption discusses which are sources and which are sinks. (Image Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan)
The scientists illustrated two means of production. In both instances, there is some daily – or at least periodic – activity that is releasing methane from the subsurface of Mars. The source could be biological which is accumulated in subsurface rocks then suddenly released. Or an abiotic chemistry, such as a reaction between the mineral olivine and water, could be the generator.
The subsurface storage mechanism of methane proposed and illustrated is called clathrate storage. Clathrate storage involves lattice compounds that can trap molecules such as methane which can subsequently be released by physical changes in the clathrate, such as solar heating or mechanical stresses. Through press Q&A, the NASA scientists stated that such clathrates could be preserved for millions and billions of years underground.
The second discovery of organics involved more complex compounds in surface materials. Also since arriving at Mars, Curiosity has utilized a drilling tool to probe the interiors of rocks. Grotzinger emphasized how material immediately at the surface of Mars has experienced the effects of radiation and the ubiquitous soil compound perchlorate reducing and destroying organics both now and over millions of years. The detection of no organics in loose and exposed surface material had not diminished NASA scientists’ hopes of detecting organics in the rocks of Mars.
Comparisons between the amount of an organic chemical named chlorobenzene detected in the “Cumberland” rock sample and amounts of it in samples from three other Martian surface targets analyzed by NASA’s Curiosity Mars rover. (Image Credit: NASA/JPL-Caltech)
Drilling was performed on several selected rocks and it was finally a mud rock called Cumberland that revealed the presence of organic compounds more complex than simple methane. The scientists did emphasize that what exactly these organic compounds are remains a mystery because of the confounding presence of the active chemical perchlorate which can quickly breakdown organics to simpler forms.
Examples from the Sample Analysis at Mars (SAM) laboratory’s detection of Martian organics in a sample of powder that the drill on NASA’s Curiosity Mars rover collected from a rock target called “Cumberland.” (Image Credit: NASA/JPL-Caltech)
The detection of organics in the mud rock Cumberland required the drilling tool and also the scoop on the multifaceted robotic arm to deliver the sample into the SAM laboratory for analysis. To detect methane, SAM has an intake valve to receive atmospheric samples.
Dr. Grotzinger described how Cumberland was chosen as a sample source. The rock is called a mud stone which has undergone a process called digenesis – the metamorphosis of sediment to rock. Grotzinger emphasized that fluids will move through such rock during digenesis and perchlorate can destroy organics in the process. Such might be the case for many metamorphic rocks on the Martian surface. The panel of scientists showed a comparison between rock samples measured by SAM. Two in particular – from the rock “John Klein” and the Cumberland rock — were compared. The former showed no organics as well as other rocks that were sampled; but Cumberland’s drill sample from its interior did reveal organics.
Illustration of some of the reasons why finding organic chemicals on Mars is challenging. Whatever organic chemicals may be produced on Mars or delivered to Mars face several possible modes of being transformed or destroyed. (Image Credit: NASA/JPL-Caltech)
The analysis of the work was painstaking – harking back to the Sagan statement. The importance of discovering organics on Mars could not be understated by the panel of scientists and Grotzinger called these two discoveries as the lasting legacy of the Mars Curiosity Rover. Furthermore, he stated that the discovery and analysis methods will go far to guide the choice of instruments and their use during the Mars 2020 rover mission.
The discovery of organics completes the necessary set of “ingredients” for past or present life on Mars: 1) an energy source, 2) water, and 3) organics. These are the basic requirements for the existence of life as we know it. The search for life on Mars is still just beginning and the new discoveries of organics is still not a clear sign that life existed or is present today. Nevertheless, Dr. Jim Green, introducing the panel of scientists, and Dr. Grotzinger both emphasized the magnitude of these discoveries and how they are tied into the objectives of the NASA Mars program — particularly now with the emphasis on sending humans to Mars. For the Mars Curiosity rover, the journey up the slopes of Mount Sharp continues and now with greater earnestness and a continued search for rocks similar to Cumberland.
Astronomy is all about thinking big, both in time and space.
The Earth turns on its axis, the Moon passes through its phases, and the planets come into opposition and solar conjunction on a routine basis.
Of course, on the other end of the spectrum, there are some events which traverse such colossal spans of time that the mere mortal life span of measly homo sapiens such as ourselves can never expect to cover them. Many comets have periods measured in centuries, or thousands of years. The axis of the Earth wobbles like a top, completing one turn every 26,000 years in what’s known as the Precession of the Equinoxes. Our solar system completes one revolution about the galactic center every quarter billion years…
Feeling puny yet? Sure, astronomy is also about humility. But among these stupendous cycles, there are some astronomical events that you just might be able to live through. One such instance is the orbits of double stars. And as 2015 approaches, we challenge you to see of the most famous white dwarf of them all, as it reaches a favorable viewing position over the next few years: Sirius B.
Sirius A and B in x-rays courtesy of Chandra. Credit: NASA/SAO/CXC.
Sirius itself is easy to find, as it’s the brightest star in Earth’s sky shining at magnitude -1.42. In fact, you can spot Sirius in the daytime sky if you know exactly where to look.
But it is one of the ultimate in cosmic ironies that the most conspicuous of stars in our sky also hosts such an elusive companion. The discovery of Sirius B awaited the invention of optics capable of resolving it next to its dazzling host. Alvan Clark Jr. and Sr. first spied the enigmatic companion on January 31st, 1862 while testing their newly constructed 18.5 inch refractor, which was the largest at the time. The discovery was soon verified from the Harvard College Observatory, adding Sirius A and B to the growing list of multiple stars.
A 19th century refractor similar to the one used to discover Sirius B. Photo by the author.
And what a strange companion it turned out to be. Today, we know that Sirius B is a white dwarf, the cooling dense ember of a main sequence star at the end of its life. We call the matter in such a star degenerate, not as a commentary on its moral stature, but the state the electrons and the closely packed nuclei within under extreme pressure. Our Sun will share the same ultimate fate as Sirius B, about six billion years from now.
A comparison of a white dwarf (center) and our Sun (right) Credit: RJHall/Wikimedia Commons.
The challenge, should you choose to accept it, is to spot Sirius B in the glare of its host. The contrast in brightness between the pair is daunting: shining at magnitude +11, the B companion is more than 63,000 times fainter than -1.46 magnitude Sirius A.
The changing position angle of Sirius B. Note that the graphic is inverted, with north at the bottom. Created by the author.
A feat of visual athletics, indeed. Still, Sirius B breaks 10” in separation from its primary in 2015, as it heads towards apastron — its most distant point from its primary, at just over 11” in separation — in 2019. Sirius B varies from 8.2 and 31.5 AUs from its primary. Sirius B is on a 50.1 year orbit, meaning the time to cross this one off of your life list is over the upcoming decade. Perhaps making an animation showing the motion of Sirius B from 2015-2025 would present a supreme challenge as well.
Sirius culminates at local midnight right around New Year’s Eve, shining at its highest to the south as the “ball drops” ushering in 2015. Of course, this is only a fortuitous circumstance that is possible in our current epoch, and precession and the proper motions of both Sirius and Sol will make this less so millennia hence.
Sirius crossing the meridian at local midnight on New Year’s Eve. Credit: Stellarium.
Newsflash: there’s a very special visual treat in the offing next week, as comet C/2014 Q2 Lovejoy is currently hovering around +6th magnitude and passes 19 degrees south of Sirius on Christmas Day… more to come!
Magnification and good seeing are your friends in the hunt for Sirius B. Two factors describe the position of a secondary star in a binary pair: its position angle in degrees, and separation in arc seconds. When it comes to stars that are a tough split, I find its better to estimate the position angle first before looking it up. A close match can often confirm the observation. Does a friend see the same thing at the eyepiece? A good star to “warm up” on is the +6.8 magnitude companion to Rigel in the foot of Orion, with a separation of 9”.
Nudging Sirius just out of view might allow the B companion to become apparent. Another nifty star-spliting tool is what’s known as an occulting bar eyepiece. Making an occultation bar eyepiece is easy: we’ve used everything from a small strip of foil to a piece of guitar string (heavy E gauge works nicely) for the central bar. An occulting bar eyepiece is also handy for hunting down the moons of Mars near opposition.
Sirius B also works its way into cultural myths and lore, not the least of which are the curious tales of the Dogon people of Mali. At the outset, it seems that these ancient people have knowledge of a small dense hidden companion star to Sirius, knowledge that requires modern technology to reproduce. Carl Sagan noted, however, that cultural contamination may have resulted in the late 19th century discovery of Sirius B making its way into the Dogon pantheon. The science of anthropology is rife with anecdotes that have been carefully fed to credulous anthropologists only to be reported later as fact, all in the name of a good story.
A comparison of Sirius B’s real versus apparent trajectory. Credit: SiriusB/Wikimedia Commons.
All amazing things to ponder as you begin your 2015 quest for Sirius B, a bashful but fascinating star.
The world’s most powerful particle collider is waking up from a well-earned rest. After roughly two years of heavy maintenance, scientists have nearly doubled the power of the Large Hadron Collider (LHC) in preparation for its next run. Now, it’s being cooled to just 1.9 degrees above absolute zero.
“We have unfinished business with understanding the universe,” said Tara Shears from the University of Liverpool in a news release. Shears and other LHC physicists will work to better understand the Higgs Boson and hopefully unravel some of the secrets of supersymmetry and dark matter.
On February 11, 2013 the LHC shut down for roughly two years. The break, known as LS1 for “long stop one,” was needed to correct several flaws in the original design of the collider.
The LHC’s first run got off to a rough start in 2008. Shortly after it was fired up, a single electrical connection triggered an explosion, damaging an entire sector (one-eighth) of the accelerator. To protect the accelerator from further disaster, scientists decided to run it at half power until all 10,000 copper connections could be repaired.
So over the last two years, scientists have worked around the clock to rework every single connection in the accelerator.
Now that the step (along with many others) is complete, the collider will operate at almost double its previous power. This was tested early last week, when scientists powered up the magnets of one sector to the level needed to reach the high energy expected in its second run.
With such a powerful new tool, scientists will look for deviations from their initial detection of the Higgs boson, potentially revealing a deeper level of physics that goes well beyond the Standard Model of particle physics.
Many theorists have turned to supersymmetry — the idea that for every known fundamental particle there exists a “supersymmetric” partner particle. If true, the enhanced LHC could be powerful enough to create supersymmetric particles themselves or prove their existence in subtler ways.
“The higher energy and more frequent proton collisions in Run 2 will allow us to investigate the Higgs particle in much more detail,” said Victoria Martin from Edinburgh University. “Higher energy may also allow the mysterious “dark matter” observed in galaxies to be made and studied in the lab for the first time.”
It’s possible that the Higgs could interact with — or even decay into — dark matter particles. If the latter occurs, then the dark matter particles would fly out of the LHC without ever being detected. But their absence would be evident.
So stay turned because these issues might be resolved in the spring of 2015 when the particle accelerator roars back to life.
ALMA image of the dust surrounding the star HD 107146. Dust in the outer reaches of the disk is thicker than in the inner regions, suggesting that a swarm of Pluto-size planetesimals is causing smaller objects to smash together. The dark ring-like structure in the middle portion of the disk may be evidence of a gap where a planet is sweeping its orbit clear of dust. Credit: L. Ricci ALMA (NRAO/NAOJ/ESO); B. Saxton (NRAO/AUI/NSF)
A planetary system’s early days readily tell of turmoil. Giant planets are swept from distant birthplaces into sizzling orbits close to their host star. Others are blasted away from their star into the darkness of space. And smaller bodies, like asteroids and comets, are being traded around constantly.
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have seen the latter: swarms of Pluto-size objects turning to dust around a young star. And the image is remarkable.
“This system offers us the chance to study an intriguing time around a young, Sun-like star,” said coauthor Stuartt Corder and ALMA Deputy Director in a news release. “We are possibly looking back in time here, back to when the Sun was about 2 percent of its current age.”
The young star, HD 107146, is located roughly 90 light-years from Earth in the direction of the constellation Coma Berenices. Although the star itself is visible in any small telescope, ALMA can probe the star’s radically faint protoplanetary disk. This is the star’s dusty cocoon that coalesces into planets, comets and asteroids.
ALMA’s image revealed an unexpected bump in the number of millimeter-size dust grains far from the host star. This highly concentrated band spans roughly 30 to 150 astronomical units, the equivalent of Neptune’s orbit around the Sun to four times Pluto’s orbit.
So where is the extra dust coming from?
Typically, dust in the debris disk is simply left over material from the formation of planets. Early on, however, Pluto-size objects (otherwise known as planetesimals) will collide and blast themselves apart, also contributing to the dust. Certain models predict that this leads to a much higher concentration of dust in the most distant regions of the disk.
Although this is the case for HD 107146, “this is the opposite of what we see in younger primordial disks where the dust is denser near the star,” said lead author Luca Ricci from the Harvard-Smithsonian Center for Astrophysics. “It is possible that we caught this particular debris disk at a stage in which Pluto-size planetesimals are forming right now in the outer disk while other Pluto-size bodies have already formed closer to the star.”
Adding to this hypothesis is the fact that there’s a slight depression in the dust at 80 astronomical units, or twice Pluto’s average distance from the Sun. This could be a slight gap in the dust, where an Earth-size planet is sweeping the area clear of a debris disk.
If true, this would be the first observation of an Earth-size planet forming so far from its host star. But for now that’s a big if.
The results will be published in the Astrophysical Journal and are available online.
Artist's impression of the planets in our solar system, along with the Sun (at bottom). Credit: NASA
It’s is no secret that Earth is the only inhabited planet in our Solar System. All the planets besides Earth lack a breathable atmosphere for terrestrial beings, but also, many of them are too hot or too cold to sustain life. A “habitable zone” which exists within every system of planets orbiting a star. Those planets that are too close to their sun are molten and toxic, while those that are too far outside it are icy and frozen.
But at the same time, forces other than position relative to our Sun can affect surface temperatures. For example, some planets are tidally locked, which means that they have one of their sides constantly facing towards the Sun. Others are warmed by internal geological forces and achieve some warmth that does not depend on exposure to the Sun’s rays. So just how hot and cold are the worlds in our Solar System? What exactly are the surface temperatures on these rocky worlds and gas giants that make them inhospitable to life as we know it?
Mercury:
Of our eight planets, Mercury is closest to the Sun. As such, one would expect it to experience the hottest temperatures in our Solar System. However, since Mercury also has no atmosphere and it also spins very slowly compared to the other planets, the surface temperature varies quite widely.
What this means is that the side exposed to the Sun remains exposed for some time, allowing surface temperatures to reach up to a molten 465 °C. Meanwhile, on the dark side, temperatures can drop off to a frigid -184°C. Hence, Mercury varies between extreme heat and extreme cold and is not the hottest planet in our Solar System.
Venus is an incredibly hot and hostile world, due to a combination of its thick atmosphere and proximity to the Sun. Image Credit: NASA/JPL
Venus:
That honor goes to Venus, the second closest planet to the Sun which also has the highest average surface temperatures – reaching up to 460 °C on a regular basis. This is due in part to Venus’ proximity to the Sun, being just on the inner edge of the habitability zone, but also to Venus’ thick atmosphere, which is composed of heavy clouds of carbon dioxide and sulfur dioxide.
These gases create a strong greenhouse effect which traps a significant portion of the Sun’s heat in the atmosphere and turns the planet surface into a barren, molten landscape. The surface is also marked by extensive volcanoes and lava flows, and rained on by clouds of sulfuric acid. Not a hospitable place by any measure!
Earth:
Earth is the third planet from the Sun, and so far is the only planet that we know of that is capable of supporting life. The average surface temperature here is about 14 °C, but it varies due to a number of factors. For one, our world’s axis is tilted, which means that one hemisphere is slanted towards the Sun during certain times of the year while the other is slanted away.
This not only causes seasonal changes, but ensures that places located closer to the equator are hotter, while those located at the poles are colder. It’s little wonder then why the hottest temperature ever recorded on Earth was in the deserts of Iran (70.7 °C) while the lowest was recorded in Antarctica (-89.2 °C).
Mars’ thin atmosphere, visible on the horizon, is too weak to retain heat. Credit: NASA
Mars:
Mars’ average surface temperature is -55 °C, but the Red Planet also experiences some variability, with temperatures ranging as high as 20 °C at the equator during midday, to as low as -153 °C at the poles. On average though, it is much colder than Earth, being just on the outer edge of the habitable zone, and because of its thin atmosphere – which is not sufficient to retain heat.
In addition, its surface temperature can vary by as much as 20 °C due to Mars’ eccentric orbit around the Sun (meaning that it is closer to the Sun at certain points in its orbit than at others).
Jupiter:
Since Jupiter is a gas giant, it has no solid surface, so it has no surface temperature. But measurements taken from the top of Jupiter’s clouds indicate a temperature of approximately -145°C. Closer to the center, the planet’s temperature increases due to atmospheric pressure.
At the point where atmospheric pressure is ten times what it is on Earth, the temperature reaches 21°C, what we Earthlings consider a comfortable “room temperature”. At the core of the planet, the temperature is much higher, reaching as much as 35,700°C – hotter than even the surface of the Sun.
Saturn and its rings, as seen from above the planet by the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute/Gordan Ugarkovic
Saturn:
Due to its distance from the Sun, Saturn is a rather cold gas giant planet, with an average temperature of -178 °Celsius. But because of Saturn’s tilt, the southern and northern hemispheres are heated differently, causing seasonal temperature variation.
And much like Jupiter, the temperature in the upper atmosphere of Saturn is cold, but increases closer to the center of the planet. At the core of the planet, temperatures are believed to reach as high as 11,700 °C.
Uranus:
Uranus is the coldest planet in our Solar System, with a lowest recorded temperature of -224°C. Despite its distance from the Sun, the largest contributing factor to its frigid nature has to do with its core.
Much like the other gas giants in our Solar System, the core of Uranus gives off far more heat than is absorbed from the Sun. However, with a core temperature of approximately 4,737 °C, Uranus’ interior gives of only one-fifth the heat that Jupiter’s does and less than half that of Saturn.
Neptune photographed by Voyager 2. Image credit: NASA/JPL
Neptune:
With temperatures dropping to -218°C in Neptune’s upper atmosphere, the planet is one of the coldest in our Solar System. And like all of the gas giants, Neptune has a much hotter core, which is around 7,000°C.
In short, the Solar System runs the gambit from extreme cold to extreme hot, with plenty of variance and only a few places that are temperate enough to sustain life. And of all of those, it is only planet Earth that seems to strike the careful balance required to sustain it perpetually.
The Opportunity rover captured this analemma showing the Sun's movements over one Martian year. Images taken every third sol (Martian day) between July, 16, 2006 and June 2, 2008. Credit: NASA/JPL/Cornell/ASU/TAMU
Stand in the same spot every day. Take a picture of the Sun. What happens? Slowly, you see our closest star shifting positions in the sky. That motion over an entire year is called an analemma. The Opportunity rover on Mars even captured one on the Red Planet, which you can see above, and it’s a different shape than what you’ll find on Earth.
An April Astronomy Picture of the Day post (highlighted this weekend on Reddit) explains that Earth’s analemma of the Sun is figure-8-shaped, while that on Mars looks somewhat like a pear (or a teardrop, we think.) The Earth and Mars each have about the same tilt in their orbit — that same tilt that produces the seasons — but the orbit of Mars is more elliptical (oval) than that of Earth.
An analemma of the Sun, taken from Budapest, Hungary over a one year span. (Courtesy of György Soponyai, used with permission).
“When Mars is farther from the Sun, the Sun progresses slowly in the martian sky creating the pointy top of the curve,” the APOD post stated. “When close to the Sun and moving quickly, the apparent solar motion is stretched into the rounded bottom. For several sols some of the frames are missing due to rover operations and dust storms.”
The picture you see at the top of the post was taken every third sol (or Martian day, which is 24 hours and 37 minutes) between July 2006 and June 2008. The landscape surrounding the analemma is from Victoria Crater, where Opportunity was roaming at that time. (The rover is now on the rim of Endeavour Crater, still trucking after nearly 11 full years on the surface.)
In 2006, APOD also published a simulated analemma from Sagan Memorial Station, the landing site of the Sojourner spacecraft and tiny Pathfinder rover. In this case, the simulation showed the Sun’s movements every 30 sols. A Martian year is 668 sols.
