A mosaic of 67 images from the Mars Express spacecraft of Kasei Valles on Mars. Credit: ESA/DLR/FU (G. Neukum)
Over 3 billion years ago, dramatic flood events likely carved this gigantic channel system on Mars. It extends some 3,000 km and covers over 1.55 million square kilometers. ESA released this flyover video today, on the 10th anniversary of the Mars Express spacecraft’s launch to the Red Planet on January 14, 2004.
ESA describes the scene in the video:
The scene spans 987 km in the north–south direction, 19–36°N, and 1550 km in the east–west direction (280–310°E). It covers 1.55 million square kilometers, an area equivalent to the size of Mongolia.
Kasei Valles splits into two main branches that hug a broad island of fractured terrain — Sacra Mensa — rising 2 km above the channels that swerve around it. While weaker materials succumbed to the erosive power of the fast-flowing water, this hardier outcrop has stood the test of time.
Slightly further downstream, the flood waters did their best to erase the 100 km-wide Sharonov crater, crumpling its walls to the south. Around Sharonov many small streamlined islands form teardrop shapes rising from the riverbed as water swept around these natural obstacles.
The International Space Station captured as it passed in front of the Moon on Dec. 6, 2013, as seen from Puerto Rico. Credit and copyright: Juan Gonzalez-Alicea.
We can dream, right? … because we’d all love to have a space station on the Moon. But this is as close as we’re going to get for the foreseeable future, anyway. Juan Gonzalez-Alicea of Sociedad de Astronomia del Caribe in Puerto Rico captured this great image of the International Space Station crossing in front of the crescent Moon on Dec. 6, 2013. He used a Canon 7D with a 300 mm lens, and actually got a fair amount of detail. A shot like this is tricky, as from our vantage point on Earth, it takes just a half second for the International Space Station to fly across the face of the Moon, so timing is everything!
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
Hey, remember Comet C/2012 S1 ISON? Who can forget the roller-coaster ride that the touted “Comet of the Century” took us on last year. Well, ISON could have one more trick up its cosmic sleeve –although it’s a big maybe — in the form of a meteor shower or (more likely) a brief uptick in meteor activity this week.
In case you skipped 2012 and 2013, or you’re a time traveler who missed their temporal mark, we’ll fill you in on the story thus far.
Comet ISON was discovered by Artyom Novichonok and Vitali Nevski on September 21st, 2012 as part of the ongoing International Scientific Optical Network (ISON) survey. Shortly after its discovery, researchers knew they had spotted something special: a sungrazing comet already active at over 6.4 Astronomical Units (A.U.s) from the Sun. The Internet then did what it does best, and promptly ran with the story. There were no shortage of Comet ISON conspiracy theories for science writers to combat in 2013. It’s still amusing to this day to see predictions for comet ISON post-perihelion echo through calendars, almanacs and magazines compiled and sent to press before its demise.
ISON back in the day. Credit-Efrain Morales Rivera, Jaicoa Observatory Aguadilla, Puerto Rico
The frenzy for all things ISON reached a crescendo on U.S. Thanksgiving Day November 28th 2013, as ISON passed just 1.1 million kilometres from the surface of the Sun. Unfortunately, what emerged was a sputtering ember of the comet formerly known as ISON, which faded from view just as it was slated to reenter the dawn sky.
Hey, we were crestfallen as well… we had our semi-secret dark sky site pre-selected for ISON imaging post-perihelion and everything. Despite heroic searches by ground and space-based assets, we’ve yet to see any compelling recoveries of Comet ISON post-perihelion.
This week, however, Comet ISON may put on its last hurrah, in the form of a minor meteor shower. We have to say from the outset that we’re highly skeptical that an “ISON-id meteor outburst” will grace the skies. Known annual showers are fickle enough, and it’s nearly impossible to predict just what might happen during a meteor shower with no past track record.
But you won’t see anything if you don’t try. If anything is set to occur, the night of January 15th into the 16th might just be the time to watch. This is because the Earth will cross the orbital plane of ISON’s path right around 9:00 PM EST/2:00 UT. Last year, ISON passed within 3.3 million kilometres of the Earth’s orbit on its inbound leg. Earlier last year, ISON was estimated to have been generating a prodigious amount of dust, at a rate of about 51,000 kilograms per minute. Any would-be fragments of ISON outbound would’ve passed closest to the Earth at 64 million kilometres distant on the day after Christmas last year. Veteran sky observer Bob King wrote about the prospects for catching ISON one last time during this month back in December 2013.
A simulation showing Earth crossing the plane of Comet ISON’s orbit early on January 16th. Credit: NASA/JPL Solar System Dynamics Small Body Database Browser.
Another idea out there that is even more unlikely is the proposal that dust from Comet ISON may generate an uptick in noctilucent cloud activity. And already, a brief search of the internet sees local news reports attempting to tie every meteor observed to ISON this week, though no conclusive link to any observed fireball has been made.
The radiant to watch for any possible “ISON-ids” sits near the +3.5 magnitude star Eta Leonis in the sickle of Leo. Robert Lundsford of the American Meteor Society notes in a recent posting that any ISON-related meteors would pass through our atmosphere at a moderate 51 kilometres a second, with a visible duration of less than one second.
Note that meteor activity has another strike against it, as the Moon reaches Full on the same night. In fact, the Full Moon of Wednesday January 15th sits in the constellation Gemini,just 32 degrees away from the suspect radiant!
Another caveat is in order for any remaining dooms-dayers: no substantial fragments of ISON are (or ever were) inbound and headed towards our fair planet. Yes, we’re seeing rumblings to this effect in the pseudoscience netherworlds of ye ole Internet, along with ideas that ISON secretly survived, NASA “hid” ISON, ISON cloaked like a Romulan Bird of Prey, you name it. Just dust grains, folks… a good show perhaps, but nothing more.
As near as we can tell, talk of a possible meteor shower generated from Comet ISON goes all the way back to a NASA Science News article online from April 2013. Radio observers of meteor showers should be alert for a possible surge in activity this week as well, and it may be the case that more radio “pings” will be noted than visual activity what with the light-polluting Full Moon in the sky. The radiant for any would-be “ISON-ids” transits highest in the sky for northern hemisphere observers at around 2 AM local.
But despite what it has going against it, we’d be thrilled if ISON put on one last show anyhow. It’s always worth watching for meteor activity and noting the magnitude and from whence the meteor came to perhaps note the pedigree as to the shower it might belong to.
The next annual dependable meteor shower won’t be until the night of April 21st to the 22nd, when the Spring Lyrids are once again active. And this year may just offer a special treat on May 24th, when researchers have predicted that the Earth may encounter debris streams laid down by Comet 209P LINEAR way back in 1803 and 1924… Camelopardalids, anyone? Now, that’s an exotic name for a meteor shower that we’d love to see trending!
-Catch sight of any “ISON-ids?” we’d love to see ‘em… be sure to post said pics at Universe Today’s Flickr pool.
Photo of Chang'e-3 moon lander emblazoned with Chinese national flag taken by the panoramic camera on the Yutu moon rover on Dec. 22, 2013. Credit: CNSA
Chinese Moon Robots Wake up
Photo of Chang’e-3 moon lander emblazoned with Chinese national flag taken by the panoramic camera on the Yutu moon rover on Dec. 22, 2013. Credit: CNSA
Story updated[/caption]
China’s history making moon robots – the Chang’e-3 lander and Yutu rover – have just awoken from the forced slumber of survival during their first, long frigid lunar night and have now resumed full operations – marking a major milestone in the mission.
This landmark achievement offers a realistic prognosis that the best is yet to come for this new dynamic duo of robots dispatched from Earth!
The stationary lander and six wheeled rover were autonomously revived from their dormant mode this weekend.
Both were then placed back into full working science mode in response to commands issued by Chinese space engineers at the Beijing Aerospace Control Center (BACC), according to CCTV, China’s official government broadcast network.
Portrait photo of Yutu moon rover taken by camera on the Chang’e-3 moon lander on Dec. 15, 2013 shortly after rolling all 6 wheels onto lunar surface. Credit: Chinese Academy of Sciences
Yutu woke up first on Saturday, Jan. 11, at 5:09 a.m. Beijing local time.
The Chang’e-3 lander was awoken on Sunday, Jan. 12, at 8:21 a.m. Beijing local time, according to a BACC statement.
Both vehicles depend on their life giving solar panels to produce power in order to function and accomplish their scientific tasks.
They went to sleep to conserve energy since there is no sunlight to generate power with the solar arrays during the lunar night.
During the nocturnal hiatus they were kept alive by a radioisotopic heat source that kept their delicate computer and electronics subsystems warmed inside a box below the deck. It was maintained at a temperature of about minus 40 degrees Celsius to prevent debilitating damage
The simple fact that both spacecraft survived half a month through the extremely harsh lunar night time environment when temperatures plunged to below minus 180 degrees Celsius, or minus 292 degrees Fahrenheit, and then restarted intact, proves the resiliency and robustness of China’s space technology.
“During the lunar night, the lander and the rover were in a power-off condition and the communication with Earth was also cut off,” said Zhou Jianliang, chief engineer of the BACC, to CCTV.
The “Yutu” rover and the Chang’e-3 lander began functioning again on Jan 11 & 12, 2014 in this artists concept. Both had become dormant to ride out the harsh conditions on the moon. Credit: CNSA/CCTV
“When the night ends, they will be started up with the power provided by sunlight and resume operation and communication according to preset programs,” Zhou said.
As night fell on the Earth’s Moon at Christmas time 2013, Yutu and the mother ship lander both entered a state of hibernation – determined to survive the utterly harsh lunar darkness upon the magnificently desolate gray plains.
The mother ship began her nap first on Christmas Day, Dec. 25. Yutu went to sleep on Dec. 26 obeying commands sent by mission control at BACC, according to China’s State Administration of Science, Technology and Industry for National Defence (SASTIND).
The Earth from the Moon – by Chang’e-3 on Christmas Day
Lander camera snapped this image on Christmas Day 2013. Credit: Chinese Academy of Sciences
Now with the dawn of daylight the solar panels were unfurled and the instruments activated on both robots.
Yutu has already resumed roving towards pristine, unexplored lunar terrain surrounding the touchdown zone at Mare Imbrium, nearby the Bay of Rainbows, or Sinus Iridum region.
After driving in a semicircular path around the right side of the stationary lander, and snapping portraits of one another at 5 preselected locations, Yutu parked some 40 meters south of the mother ship – after touchdown and prior to the start of lunar night.
Yutu, which translates as ‘Jade Rabbit’, is departing the landing zone forever, trekking southwards for surface investigations expected to last at least 3 months – and perhaps longer depending on its robustness in the unforgiving space environment.
The Chang’e-3 lander should survive at least a year.
“They will begin to conduct scientific explorations of the geography and geomorphology of the landing spot and nearby areas, and materials like minerals and elements there,” noted Wu Weiren, chief designer of China Lunar Probe Program.
“We will also explore areas 30 meters and 100 meters beneath the lunar soil. The exploration will continue longer than we planned, because all the instruments and equipments are working very well.”
‘Jade Rabbit’ and the lander will use their suites of science instruments including cameras, telescopes, spectrometers and ground penetrating radar to survey the moon’s geological structure and composition to locate the moon’s natural resources for use by potential future Chinese astronauts.
The robotic pair safely soft landed on the Moon on Dec. 14 at Mare Imbrium, located in the upper left portion of the moon as seen from Earth. Seven hour later on Dec. 15, Yutu rolled all 6 wheels onto the moon’s surface, leaving tracks behind as it cut into the loose regolith.
Presumably they will continue exploring for about the next 14 days – the entire time span of their 2nd Lunar Day, unless they need to take a break from the high daylight temperatures.
Thereafter Yutu and Chang’e-3 will function in alternating cycles of 2 weeks on and 2 weeks off for the duration of their independent working lifetimes.
China is only the 3rd country in the world to successfully soft land a spacecraft on Earth’s nearest neighbor after the United States and the Soviet Union.
Stay tuned here for Ken’s continuing Chang’e-3, Orbital Sciences, SpaceX, commercial space, LADEE, Mars and more news.
Albert Einstein during a lecture in Vienna in 1921.
Credit: National Library of Austria/F Schmutzer/Public Domain
One of the benefits of being an astrophysicist is your weekly email from someone who claims to have “proven Einstein wrong”. These either contain no mathematical equations and use phrases such as “it is obvious that..”, or they are page after page of complex equations with dozens of scientific terms used in non-traditional ways. They all get deleted pretty quickly, not because astrophysicists are too indoctrinated in established theories, but because none of them acknowledge how theories get replaced.
For example, in the late 1700s there was a theory of heat known as caloric. The basic idea of caloric was that it was a fluid that existed within materials. This fluid was self-repellant, meaning it would try to spread out as evenly as possible. We couldn’t observe this fluid directly, but the more caloric a material has the greater its temperature.
Ice-calorimeter from Antoine Lavoisier’s 1789 Elements of Chemistry. (Public Domain)
From this theory you get several predictions that actually work. Since you can’t create or destroy caloric, heat (energy) is conserved. If you put a cold object next to a hot object, the caloric in the hot object will spread out to the cold object until they reach the same temperature. When air expands, the caloric is spread out more thinly, thus the temperature drops. When air is compressed there is more caloric per volume, and the temperature rises.
We now know there is no “heat fluid” known as caloric. Heat is a property of the motion (kinetic energy) of atoms or molecules in a material. So in physics we’ve dropped the caloric model in terms of kinetic theory. You could say we now know that the caloric model is completely wrong.
Except it isn’t. At least no more wrong than it ever was.
The basic assumption of a “heat fluid” doesn’t match reality, but the model makes predictions that are correct. In fact the caloric model works as well today as it did in the late 1700s. We don’t use it anymore because we have newer models that work better. Kinetic theory makes all the predictions caloric does and more. Kinetic theory even explains how the thermal energy of a material can be approximated as a fluid.
This is a key aspect of scientific theories. If you want to replace a robust scientific theory with a new one, the new theory must be able to do more than the old one. When you replace the old theory you now understand the limits of that theory and how to move beyond it.
In some cases even when an old theory is supplanted we continue to use it. Such an example can be seen in Newton’s law of gravity. When Newton proposed his theory of universal gravity in the 1600s, he described gravity as a force of attraction between all masses. This allowed for the correct prediction of the motion of the planets, the discovery of Neptune, the basic relation between a star’s mass and its temperature, and on and on. Newtonian gravity was and is a robust scientific theory.
Then in the early 1900s Einstein proposed a different model known as general relativity. The basic premise of this theory is that gravity is due to the curvature of space and time by masses. Even though Einstein’s gravity model is radically different from Newton’s, the mathematics of the theory shows that Newton’s equations are approximate solutions to Einstein’s equations. Everything Newton’s gravity predicts, Einstein’s does as well. But Einstein also allows us to correctly model black holes, the big bang, the precession of Mercury’s orbit, time dilation, and more, all of which have been experimentally validated.
So Einstein trumps Newton. But Einstein’s theory is much more difficult to work with than Newton’s, so often we just use Newton’s equations to calculate things. For example, the motion of satellites, or exoplanets. If we don’t need the precision of Einstein’s theory, we simply use Newton to get an answer that is “good enough.” We may have proven Newton’s theory “wrong”, but the theory is still as useful and accurate as it ever was.
Unfortunately, many budding Einsteins don’t understand this.
Binary waves from black holes. Image Credit: K. Thorne (Caltech) , T. Carnahan (NASA GSFC)
To begin with, Einstein’s gravity will never be proven wrong by a theory. It will be proven wrong by experimental evidence showing that the predictions of general relativity don’t work. Einstein’s theory didn’t supplant Newton’s until we had experimental evidence that agreed with Einstein and didn’t agree with Newton. So unless you have experimental evidence that clearly contradicts general relativity, claims of “disproving Einstein” will fall on deaf ears.
The other way to trump Einstein would be to develop a theory that clearly shows how Einstein’s theory is an approximation of your new theory, or how the experimental tests general relativity has passed are also passed by your theory. Ideally, your new theory will also make new predictions that can be tested in a reasonable way. If you can do that, and can present your ideas clearly, you will be listened to. String theory and entropic gravity are examples of models that try to do just that.
But even if someone succeeds in creating a theory better than Einstein’s (and someone almost certainly will), Einstein’s theory will still be as valid as it ever was. Einstein won’t have been proven wrong, we’ll simply understand the limits of his theory.
Arthur C. Clarke was one of the greatest science fiction writers of all time. He defined the genre, and revolutionized our ideas about what it will take to become a true space faring civilization. In the first of our two part series on Arthur C. Clarke, we examine the man’s life and his books. Continue reading “Astronomy Cast Ep. 330: Arthur C. Clarke”
And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.
In the early pre-dawn hours on December 19, 2013, with a rumble and a roar, a Soyuz rocket blazed through the clouds above the jungle-lined coast of French Guiana, ferrying ESA’s long-awaited Gaia spacecraft into orbit and beginning its mission to map the stars of the Milky Way. The fascinating time-lapse video above from ESA shows the Gaia spacecraft inside the clean room unfurling like a flower during its sunshield deployment test, the transfer of the Soyuz from the assembly building to the pad, and then its ultimate fiery liftoff.
That’s a lot going on in two minutes! But once nestled safely in its L2 orbit 1.5 million kilometers out, Gaia will have over five years to complete its work… read more here.
Credit: ESA–S. Corvaja, M. Pedoussaut, 2013. Source: ESA
Last month's rising "Mini-Moon" of 2013. (Photo by Author)
Last month, (and last year) we wrote about the visually smallest Full Moon of 2013. Now, in a followup act, our natural satellite gives us an even more dramatic lesson in celestial mechanics with an encore performance just one lunation later with the smallest Full Moon of 2014.
We’ve noted the advent of the yearly Mini-Moon, a bizzaro twin to the often over-hyped “SuperMoon,” or Proxigean Full Moon. Occurring approximately six months apart, you can always expect lunar apogee to roughly coincide with the instant of a Full Moon about half a year after it coincides with perigee. In fact, the familiar synodic period that it takes the Moon to return to like phase (such as Full back to Full) of 29.5 days has a lesser known relative known as the anomalistic month, which is the period of time it takes the Moon to return to perigee at 27.55 days.
But the circumstances for “Mini-Moon 2014” are exceptional. The first Full Moon of the year occurs on the night of January 15th at 11:52 PM EST/4:52 Universal Time (on January 16th). This is just 2 hours and 59 minutes after the Moon reaches apogee at 406,536 kilometres distant at 8:53 PM EST/1:53 UT. This isn’t the farthest apogee that occurs in 2014, but it’s close: the Moon is just 32 kilometres more distant on July 28th, 2014. Apogee can vary from 404,000 to 406,700 kilometres, and this month’s apogee falls just 164 kilometres short of the maximum value.
As you can see, this year’s Mini-Moon falls extremely close to apogee… in fact, you have to go all the way back to the Full Moon of November 18th, 1994 to find a closer occurrence, and this year’s won’t be topped until May 13th, 2052! The Moon will appear only 29’ 23” in size on Wednesday night at moonrise, very close to its minimum possible value of 29’ 18”. This is also almost 5 arc minutes smaller than the largest “Super-Moon” possible.
Cool factoid: you actually move closer to the Moon as it rises, until it transits your local meridian and you begin moving away from it, all due to the Earth’s rotation. You can thus gain and lose a maximum of one Earth radii distance from the Moon in the span one night.
We also just passed the most northern Moon of 2014, as it reached a declination of 19 degrees 24’ north this morning at 8:00 UT/3:00 AM EST. This is a far cry from the maximum that can occur, at just over 28 degrees north. This is because we’re headed towards a “shallow year” as the Moon’s motion bottoms out relative to the ecliptic in 2015 and once again begins to widen out in its 18+ year cycle to its maximum in 2024-25.
The position of the Moon Monday night on January 13th in Orion. Credit: Stellarium
This week’s Moon also visits some interesting celestial targets as well. The waxing gibbous Moon sits just 5.1 degrees south of the open cluster M35 tonight. Notice something odd about the Moon’s position Monday night? That’s because it is passing through Orion the Hunter, one of the six non-zodiacal constellations that it can be found in. Can you name the other five? Hint: one was the “13th sign of the zodiac that created a non-traversy a few years back.
On Tuesday evening, the Moon passes six degrees from the planet Jupiter. This presents a fine time to try and spot the planet in the daytime to the Moon’s upper left, just a few hours prior to sunset.
The Moon will also occult the +3.6 magnitude star Lambda Geminorum on January 15th for observers in northwestern North America. In fact, viewers along a line crossing central British Columbia will witness a spectacular graze along the lunar limb as the star winks out behind lunar mountains and pops into view as it shines through lunar valleys along the edge of the Moon. This can make for an amazing video capture, we’re just throwing that out there…
The occultation footprint for Lambda Geminorum for January 15th. (Created using Occult 4.10.11 software)
In addition to being this year’s Mini-Moon, the January Full Moon is also known as the Wolf Moon in the tradition of the Algonquin Native Americans, as January was a time of the mid-winter season when starving wolf packs would howl through the long cold night. The January Full Moon is also sometimes referred to as “The Moon after Yule,” marking the first Full Moon after Christmas.
And just when is the next Super Moon, you might ask? Well, 2014 has three Full Moons occurring within 24 hours of perigee starting on July 15th and finishing up on September 8th. But the most notable is on August 10th, when the Moon passes perigee just 27 minutes from Full. Expect it to be preceded by the usual lunacy that surrounds each annual “Super Moon” as we once again bravely battle the forces of woo and describe just exactly what a perigee Full Moon isn’t capable of. Yes, we still prefer the quixotic term “Proxigean Moon,” but there you go.
Also, be sure to wave a China’s Chang’e-3 lander and rover in the Bay of Rainbows (Sinus Iridum) as you check out this week’s Full Moon, as it just experienced its first lunar sunrise this past week.
Be sure to send those Mini-Moon pics and more in to Universe Today, and let’s get this week’s #MiniMoon trending on Twitter!
New LED lighting along Michigan Street in downtown Duluth, Minn. has brightened and whitened up the area considerably compared to the days of high-pressure sodium lighting. Credit: Bob King
You may have noticed a change underway in your city lighting. High pressure sodium lights, with their familiar orange glow, are quickly being replaced by new, energy efficient blue-white LED (light emitting diode) lighting. Is this the beginning of a new assault on the night or an opportunity to use light more wisely? Many of us first became aware of LEDs in amplifiers, computers and the flashlights we use for seeing our star charts at night. More recently, LEDs became a big hit with Christmas lighting. And why not? Although they cost considerably more, the bulbs last much longer, use a fraction of the energy compared to incandescent and sodium lighting and don’t contain materials like mercury – common in fluorescent lighting – that can harm the environment. A typical incandescent bulb lasts about 750 hours while an LED bulb can glow for up to 50,000 hours. What’s not to like?
Small individually colored LED lights. LEDs light up when an electric current excites electrons inside a semidconductor to produce photons of light. Click to learn more. Credit: Piccolo Namek
The changeover to LED street lighting is already underway in my own city of Duluth, Minn. U.S. I noticed this one night this fall while driving home from work. Buildings and intersections that had been orange the night before were bathed in a far more intense blue-white light. Don’t get me wrong. Our city engineers deserve high marks for adhering to good lighting standards by packaging the new lights in shielded housings with minimal light spill upwards and to the sides. Light in those directions not only creates unwanted glare but seriously brightens the night sky, robbing many of the joys of stargazing.
Comparison of lighting colors and intensity of the new LED streetlights (left) and the older high-pressure sodium vapor lamps.
Still, everything was not OK. The LED street lights were INTENSELY bright, much more so than the “old-fashioned” sodiums. Looking up was like staring into the sun. If you have the opportunity, step under an orange sodium street light and then under an LED. You’ll be amazed at the difference in light intensity. To gauge the approximate difference in brightness between the two, I pulled out my camera and took a light meter reading on the pavement beneath an LED lamp and then under a high-pressure sodium lamp. The LED was brighter by more than more than one camera “stop” or more than twice as bright.
You can’t complain about the color rendition – the whiter LED light is far better – but the increased intensity doesn’t bode well for stargazers.
Direct comparison of two consecutive light standards – LED in the foreground, high pressure sodium behind it. Notice that both lights are well-shielded, ie. no part of the bulb extends beyond its housing. Credit: Bob King
As long as LEDs are shielded, light spill and glare are relatively well-controlled, but light reflected from the ground also goes up into space to light the sky. Here in the northern U.S. where snow typically covers the ground from November through March, winter night skies are the most light polluted; LED street lighting will only exacerbate the situation.
Inexpensive LED wall pack lighting lights a sidewalk and produces large amounts of glare and wasted light. Credit: Bob King
In the big picture however, that’s only a minor headache. LEDs are a wonderful technology, but the benefits they provide in cost savings and long life ultimately guarantee their proliferation in ornamental, building and parking lot illumination. Much of that lighting is unshielded and heavy on glare, making driving at night more difficult, wasting energy and preserving what dark sky remains more challenging. Indeed, the transition is already underway.
Brilliant, unshielded LED ornamental lighting at a new housing development. The full moon is seen at top. Credit: Bob King
Like an outbreak of mushrooms, LED “wall pack” lights – the ones that shine directly outward without any shielding – have started to appear on the outside walls of buildings as a cheap solution for lighting up walkways and parking lots. They’re replacing the equally bad but half as bright sodium lamps. Ornamental LED lamps in a new housing development in town recently turned night into day. Residents complained and wrote letters to the editor. To their credit, the owners dimmed the lights, but the fixtures were poorly designed to start and still too bright for many.
Closeup of LED ornamental light fixtures with little shielding. Credit: Bob King
One additional issue with LED ornamental and street lighting has to do with color. Although natural color LED lighting is available, high-efficiency LED lights emit a much bluer light than sodium vapor. Blue-rich light not only increases the amount of glare sensed by the human eye but also the amount of visible light pollution. Other effects of light trespass and glare include sleeping problems and even an increased risk for certain cancers. We humans need the night more than we know.
LEDs are only part of the problem of course. The real issue is the ever-increasing amount of light pollution worldwide and the potential for new LEDs to make it worse. True, we can take advantage of the ability to adjust and dim current lighting to more suitable levels. LEDs are also highly directional, making it easy to point them just where they’re needed. Finally, new high-efficiency more natural (less blue) LEDs are now available that can help reduce light pollution.
First electric lighting: New York City around 1880.
I encourage everyone to learn all you can about the new lighting and work with you local city councils and town boards to use the light wisely, particularly in new developments, parking lots and for building illumination. There’s no question that LED lighting can be used wisely to make everyone happy – stargazers, drivers, shoppers and walkers. For help and more information, the International Dark-Sky Association(IDA)is a great place to start. Here are some additional resources:
