The environmental cost of light pollution


On my to-read list today is Light Pollution of the Mountain Areas in Poland by Ściężor, Kubala and Kaszowski. A quick skim sug­gests it’s about the mech­an­ics of meas­ur­ing light pol­lu­tion in Poland, but the ref­er­ences look like they could make the prob­lem more inter­est­ing. It’s not just about astro­nomy, there are meas­ur­able bio­lo­gical impacts from arti­fi­cial lighting.

It’ll be dif­fi­cult to see if there’s a sim­ilar prob­lem in the UK, because so much of it is well-lit. That means bio­lo­gical dam­age is the new nor­mal and there­fore not a prob­lem. Elsewhere this prob­lem is called the Shifting Baseline. http://​www​.ted​.com/​t​a​l​k​s​/​d​a​n​i​e​l​_​p​a​u​l​y​_​t​h​e​_​o​c​e​a​n​_​s​_​s​h​i​f​t​i​n​g​_​b​a​s​e​l​i​n​e​.​h​tml

See also:

#twt   #astro­nomy   #LightPollution  

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Light Pollution of the Mountain Areas in Poland / Zanieczyszczenie Świetlne W Obszarach Górskich W Polsce : Archives of Environmental Protection
Abstract. The exist­ence of extens­ive records for the impact of night sky bright­ness on the anim­als’ beha­vior in their nat­ural envir­on­ment shows the need to invest­ig­ate the level of arti­fi­cially induce…

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Some splendid lunar animations


I’m work­ing on a talk today. At one point it threatened to be inter­est­ing, but I think I’ve got that under con­trol. Something that might spoil that plan though are some lunar anim­a­tions from NASA. You can Dial-A-Moon at their web­site and down­load anim­a­tions of lunar phases and libration.

Libration is inter­est­ing. It’s the wobble in the moon as it gets pulled around in orbit. The down­load­able anim­a­tions bring this out nicely and NASA has gone to some lengths to make them as usable as pos­sible for people. You can down­load the files in vari­ous formats from or watch them via YouTube.

#blog   #moon   #astro­nomy  

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Can you preserve sites on the Moon?

Boot print in the lunar regolith

This might sound like it’s either mad, who’s going to dam­age sites on the moon? or bleed­ing obvi­ous, if we could still see Columbus’s first foot­print on Hispaniola we’d pre­serve it, right?

Boot print in the lunar regolith

Boot print in the lunar rego­lith. Photo: NASA / Buzz Aldrin

As the NYT points out, the Google X Prize is aimed at mak­ing the Moon more access­ible and that will have knock-on effects when it comes to pre­serving his­toric sites on the lunar sur­face. No-one’s going to inten­tional dam­age Neil Armstrong’s foot­print are they? Well once tour­ists arrive it’s inev­it­able I think. There’s some hom­inin foot­prints at Laetoli. They’re among the earli­est foot­prints of our human-like ancest­ors. And they’re now pro­tec­ted because of dam­age. Tourists couldn’t res­ist put­ting their foot into the foot­print to compare.

Listing the Moon land­ings as her­it­age sites might seem obvi­ous, but it’s also cur­rently impossible. You can only list sites on your ter­rit­ory. Through vari­ous treat­ies the Moon (and Antarctica) aren’t recog­nised as national ter­rit­or­ies, so they can’t have her­it­age list­ings. The USA can claim own­er­ship of any­thing they’ve left on the moon, but not of the dust on its surface.

So long as humans can’t get back to the moon it might still look like navel-gazing, but one of the things that’s mak­ing space archae­ology an inter­est­ing field is that a few archae­olo­gists are now look­ing back at how unpro­tec­ted key sites from the space race are on Earth. KSC, Kourou and Baikonur are all still in use, but Woomera is no longer used by the British. The Australian gov­ern­ment has used it as site for hold­ing immigrants.

Once you start look­ing at earth­side sites things get messier because they have human con­sequences. Alice Gorman has noted Peenemünde is a key site in the devel­op­ment of rock­etry, but list­ing it as a her­it­age site can’t be done without think­ing about deaths among the Jewish work­ers there, or those killed at the British tar­gets. She’s also poin­ted out that some other sites chosen because they were remote and no one lived there, turned out to have indi­gen­ous peoples who thought their homes were very local to where they lived.

For more on Space Archaeology
Beth O’Leary has a site on Lunar Legacies at http://​space​grant​.nmsu​.edu/​l​u​n​a​r​l​e​g​a​c​i​es/
Alice Gorman has a web­log Space Age Archaeology at http://​zohar​esque​.blog​spot​.com/
and there’s a Space Archaeology Wiki at http://​www​.spacear​chae​ology​.org/​w​i​ki/

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How I Killed Pluto and Why It Had It Coming by Mike Brown


I’ve known about this book for a while, but the title put me off read­ing it. It sounds too smug to me, and while there are reas­ons for reclas­si­fy­ing Pluto I don’t think it’s some­thing astro­nomers could be smug about. Planet was not a term inven­ted by astro­nomers, it came from pop­u­lar cul­ture in the ancient world. I’m also wary of how use­ful a rigid defin­i­tion of planet is. The ter­restrial plan­ets are clearly not like the Gas Giants, and per­haps you could even dis­tin­guish between Gas Giants and Ice Giants. The defin­i­tion for dwarf planet is ter­rible, and how can a dwarf planet not be a planet. Finally Mike Brown dis­covered Xena, which he argued could be the tenth planet, but I can recall there were a rash of plan­ets dis­covered. Wasn’t Sedna sup­posed to be big­ger than Pluto too? Then there was Eris and Dynomia too. So I wasn’t expect­ing to read much bey­ond the first chapter.

So first up, I still think it’s a bad title. Not because it’s smug, but because the book is the oppos­ite. It’s warm, endear­ing and very human. The author is also extremely well-placed to write the book because there was indeed a rash of plan­ets dis­covered, and he was the guy who assembled the team respons­ible for them, includ­ing Quaoar, Sedna, Xena and the moon Gabrielle which are now offi­cially named Eris and Dysnomia. Basically if it’s a dis­tant body in the solar sys­tem that I’ve heard of, it’s likely that Mike Brown dis­covered it.

This could have so eas­ily been a book purely about number-crunching, pro­gram­ming and extremely faint dots on pho­to­graphic slides. He’s also included a lot about his fam­ily life, espe­cially the birth of his daugh­ter. A quick skim of the reviews on Amazon show that some people hate this. They have an opin­ion that Science is pure logic devoid of emo­tion. I blame Spock. In con­trast I think it’s very import­ant. It shows how sci­ence is a human activ­ity. The removal of Pluto from the plan­ets wasn’t done in isol­a­tion, it was part of a very human desire to explore.

The import­ance of humanity’s rela­tion­ship to plan­ets comes through very early. More or less straight away he points out that people recog­nised plan­ets long before they had pro­fes­sional astro­nomers. He also notices that there’s very little evid­ence of plan­et­shock the first time a planet was dis­covered since ancient times. If you’d asked me before I read this book I would have said it was Uranus that was the first planet dis­covered since antiquity in 1781. I would have been wrong.

Though plan­ets were so deeply embed­ded into many aspects of every­day life, there is no record­ing of the pub­lic reac­tion to the first and most sig­ni­fic­ant shock to the word planet. In the six­teenth cen­tury the idea began to spread that the sun, rather than the earth, was at the cen­ter of the uni­verse and that the earth and the plan­ets revolved around it. Suddenly, the wan­der­ers were in dis­ar­ray. Instead of the sun and the moon and the other plan­ets revolving around the earth, five of them (the plan­ets) went around one of them (the sun), while the sev­enth (the moon) went around the earth. The earth, like five of the wan­der­ers, also went around the sun.

Once you have a helio­centric sys­tem Earth has to be a planet. I’m kick­ing myself for not real­ising that. With hind­sight it’s obvi­ous, though you can see why the dis­cov­ery of Earth as a planet wasn’t a big trauma in itself. He also tackles the minor plan­ets like Ceres and Pallas and their quiet demo­tion into asteroids.

None of this is done with a sense of “how stu­pid people were for not know­ing this”. Instead I get a sense that Mike Brown believes that people were using the word planet in a way that was use­ful to them at the time. Likewise with more recent astro­nomers he’s happy to give credit to their work. Where he has been able to go fur­ther he’s acknow­ledged that he has had the bene­fit of liv­ing at a time with tech­niques like com­puter ana­lysis that weren’t avail­able to earlier astro­nomers. At one point he argues that Clyde Tombaugh could have seen Eris, were it not for Eris being at the far point of its orbit.

He also tackles the con­tro­versy over the dis­cov­ery of Haumea. At the time I got the vague impres­sion that a slow team of astro­nomers had missed a planet in their data and, when it was pub­licly released, another team ana­lysed the data and found it. Neither side of the dis­pute claim that’s what happened, so I was utterly wrong there. Mike Brown explains why he delayed announ­cing the dis­cov­ery of Haumea. At the top of the post I said Sedna was big­ger than Pluto. It isn’t. Its much more shiny, and that’s why it was thought to be big­ger. Mike Brown’s team were tak­ing nine months from dis­cov­ery to pub­lic­a­tion and it was when the code­name for the planet was released that it was dis­cov­er­able in a Google search on some tele­scope logs. This also explains why Xena was rush announced and partly my con­fu­sion over exactly what was and was not discovered.

The book closes with the vote in Prague to say there are eight plan­ets in the solar sys­tem. From what I heard of the meet­ing the event was chaotic, so he does an excel­lent job find­ing a nar­rat­ive to fol­low. It also explains the awful ‘dwarf planet’ term. The first vote was to demote Pluto to a ‘dwarf planet’ which is not a planet. It makes no sense until he then says there was an amend­ment to call the 8 plan­ets ‘clas­sical plan­ets’, which is another awful term. If that second vote had passed then Pluto would have been smuggled back as a planet. So the reason we have ‘dwarf plan­ets’ that are not plan­ets is a botched job at a compromise.

He also argues that the defin­i­tion of a planet itself doesn’t mat­ter that much. The defin­i­tion, he argues, isn’t about what is a planet, more an explan­a­tion of why Pluto isn’t a planet — even if it’s a bad explan­a­tion. Instead he argues that con­cepts are more import­ant rather than defin­i­tions that wan­nabe law­yers can wrestle with.

The lan­guage is access­ible. You’re not going to be able to dis­cover your own planet after read­ing this book, but you’ll have a bet­ter impres­sion of what life is like when research­ing. For example there’s this:

Looking at vastly more sky than any­one else had ever looked at for large objects out in the Kuiper belt was so immensely excit­ing that I could hardly con­tain myself. I knew that there would be big dis­cov­er­ies, and hav­ing new pic­tures come in night after night after night with only a break for the full moon kept everything at a con­stant peak. I talked to my friends about new plan­ets. I thought about names for new plan­ets. I gave lec­tures about the pos­sib­il­ity of new plan­ets. I did everything I could, except find new planets.

I think that fail­ure to make any pro­gress on what you’re sure is an excit­ing pro­ject is famil­iar to most researchers.

With the IAU’s poor hand­ling of Pluto, it’s easy to see how this could have been a dread­ful book. I still think the title is going to put a lot of people off. Is it really going to appeal to Plutophiles? That’s a shame because inside the cov­ers is one of the most like­able books I’ve read for a long while. It’s def­in­itely worth a read when the paper­back comes out.

You can read some of the book in excerpts at Mike Brown’s blog.

My God, it’s full of stars!

Orion in the night sky

I saw a shoot­ing star last night as it streaked across a sky full of stars. I kid you not! You could look up and see thou­sands of stars. Now, astro­nomy mavens might not be too impressed by that. Many people can see stars as dim as mag­nitude six in a dark sky, lucky people can see dim­mer stars. There accounts for around 6000 vis­ible naked-eye stars. But for many of us that’s simply not true.

I used to live in a sub­urb of Derby. When I moved to Powys I noticed there were more stars in the sky. A lot more. So many I was temp­ted to buy a tele­scope. The next 30 days were clouded out, so that killed that idea, but on the days when stars are vis­ible they’re stun­ningly impress­ive. There is a way to quantify how impress­ive the night sky is that you can help with next year.

Orion in the night sky

Orion, the Hunter by Eduardo Mariño.

When I was in Derby I took part in GLOBE at Night. It’s a sur­vey that asks you to describe what you can see. The ver­sion I took part in asked people to say which stars they could see in Orion, the image on the right. It’s a good choice because the belt makes it easy to identify. I could see those. I could also see Betelguese (top-left), Bellatrix (top-right) and Rigel (bottom-right). If I squin­ted and stared hard I could ima­gine I could see Saiph (bottom-left), but really I couldn’t. There was a sodium glow of dank yel­low reach­ing up into the sky like lurid phlegm-coloured fog. It was the first time I’d real­ised how bad the local light pol­lu­tion was. In con­trast, I can’t account for every star in the photo shown, partly because as your eye dark-adapts you see more stars. However, this image is a very good impres­sion of what I saw. I had no trouble at all see­ing Orion’s belt. It didn’t look like a fig­ure of gems on a vel­vet back­ground. Instead the major stars looked like gems over a back­ground where someone had sneezed dia­mond dust.

It’s pos­sible this long-term cold I’ve had since September is affect­ing me more than I think.

The dif­fer­ence isn’t just in quant­ity. A dark sky makes a big dif­fer­ence to the qual­ity of the sky. I thought I knew my way around the night sky pretty well. Last night I could see Orion out of my win­dow, but took a little while to find Taurus. Again, a good ama­teur astro­nomer might find this funny. Taurus should be unmiss­able. Even more so when you have a dark sky, mak­ing the stars even easier to see. In the Northern hemi­sphere you look a little way to the right and you’ll see the horns of Taurus the bull live a V shape. Aldebaran sits at the top of one of the horns. This V is made of bright stars, it’s the most vis­ible part of the con­stel­la­tion, it is strik­ing. But when you have a prop­erly dark sky it’s strik­ing among a whole load of other stars. In Derby Taurus was to the right of Orion. In Powys it still is, but this time there’s an awful lot of stars in between them. It’s easier to find your when around the night sky when you can only see the prom­in­ent stars. Here, it’s almost like the sky has developed a glit­ter­ing inter­fer­ence pattern.

I know that light pol­lu­tion has been a topic of pain for astro­nomers for dec­ades. In my head I can fully under­stand it as a quant­it­ive argu­ment. Dark skies = more stars. That might not be enough for a power­ful emotive argu­ment. Imagine you live some­where where the night sky is rub­bish. Reducing light pol­lu­tion isn’t such a big deal. It just means more rub­bish look­ing stars. I also won­der if heavy light pol­lu­tion, which is worst nearest the hori­zon, helps dis­tance people from the Cosmos. Banishing the vis­ible stars to the highest parts of the sky emphas­ise the sep­ar­a­tion between earthly life and the rest of the uni­verse. A dark sky shows that where you are is the place where the Earth meets the Sky. Below you soil, above only the unima­gin­able heights to the edge of the uni­verse, and you smack in the middle.

That feels dif­fer­ent and it’s some­thing you can’t repro­duce in a planetarium.

Photo: Orion by Eduardo Mariño. Licenced under a Creative Commons BY-NC-SA licence.

As a coda, I remem­ber read­ing about the after­math of Hurricane Andrew in Astronomy magazine. After the power had been cut the night sky was exposed. People phoned up local uni­ver­sit­ies, plan­et­aria and obser­vat­or­ies to ask what the lights in the sky were. At the time I lived in the coun­try, so I found the idea that people could be puzzled by stars hil­ari­ous. Having lived in a city now, and know­ing that many people have never lived any­where else I have a lot more empathy. Imagine liv­ing through a hur­ricane and then, for the first time in your life, the uni­verse arrives on your door­step. No won­der you’d want to phone someone to check it’s normal.

Oxygen found around Rhea but alas no life

Rhea orbiting Saturn. Photo NASA/JPL/Space Science Institute.
Rhea orbiting Saturn. Photo NASA/JPL/Space Science Institute.

Rhea orbit­ing Saturn. Photo NASA/JPL/Space Science Institute.

I got quite excited by the head­line Saturn’s moon Rhea has thin atmo­sphere on the BBC. Even more so when I saw the atmo­sphere had oxy­gen. Rhea is the second largest moon orbit­ing Saturn, but it’s noth­ing like the size of Titan (which is big­ger than Mercury), so find­ing an atmo­sphere is inter­est­ing. It’s much more inter­est­ing when you see that it’s partly made of oxygen.

Oxygen isn’t the sort of gas you’d expect to find in an atmo­sphere. That sounds daft, there a lot of it around Earth, but Earth is weird. Oxygen is a highly react­ive gas. The reason the sur­face of Mars looks rus­ted is that Oxygen has reacted with chem­ic­als in the rocks of Mars. To have Oxygen around long enough to spot it with astro­nom­ical instru­ments, you need a source to replen­ish what’s being lost. Life does that on Earth. On Rhea there’s ice, as a source of water, prob­ably a rocky core — and we know of extremo­philes that live deep within the rocks in Earth’s crust. If there’s a heat source, and plan­ets can heat the cores of moons as they orbit by squish­ing them with tidal forces, then are we look­ing at bac­teria on another world?

Sadly, no.

Rhea is in Saturn’s mag­netic field. That means that lots of charged particles get accel­er­ated and smash into the ice on Rhea’s sur­face. When they hit a water molecule with that kind of energy they break it H2O into its com­pon­ents and that’s how you get Oxygen. That then gets stripped away by the same forces, which is partly why Rhea hasn’t built atmo­sphere. It’s prob­ably this lack of per­man­ence that means exo­sphere is a bet­ter word for what’s around Rhea than atmosphere.

That’s slightly dis­ap­point­ing to me. I remem­ber being told that Oxygen would be one of the best indic­at­ors of life on another world, and here it’s not the case. On the plus side, it’s another reminder to visit the Cassini site, where these res­ults are com­ing from. There’s plenty of images as well as video.

JPL Video on Cassini/Huygens mission.