Are We Losing the Night Sky?

Are We Losing the Night Sky?

Hey smart people, Joe here.
For pretty much all of human history, this has meant the end of our day. Sure, we harnessed
fire, and some artificial light, but we are not natural creatures of the night. But now
we’re able to be part of the night like never before in human history. All thanks
to the invention of the light bulb. Try to imagine modern life without artificial lighting.
It just isn’t possible. But… all of that light comes with a dark
side. On January 17, 1994, a powerful earthquake
struck the Los Angeles area and caused a massive blackout. Nearby Griffith Observatory started
receiving calls from residents asking about the strange sky they were seeing. What those
people saw was… the Milky Way. With no artificial light, the sight of the night sky was so unfamiliar;
they didn’t know what they were looking at. Today, more than 80% of the world and more
than 99% of the U.S. and Europe live under light-polluted skies. A third of humans on
Earth can never see the Milky Way. And places like Singapore are so polluted by light that
people’s eyes never fully adjust to the dark. While researching light pollution the past
couple months, I learned a new word: Scotopic. It’s the type of vision we use in very low
light levels. Whereas our normal, bright-light photopic vision is produced by three types
of color-sensitive cone cells, dark scotopic vision is produced by the eye’s rod cells,
which are great at sensing something’s brightness, but can’t discriminate different colors. Anyway, the reason I’d never heard of scotopic
vision before is that most of us don’t experience it much. Night has been taken over by light. It still gets dark at night. Unless you’re
near the north or south pole in summer, the sun still goes down every day. But it’s
not real darkness. So, then… what is real darkness? I’ve
been struggling for a way to explain it, because how do you describe the absence of something?
Well, I figure you don’t try describe what’s missing, you look at what was hiding there
all along. Now I’m not the world’s best astro-photographer
or anything, but I’ve been lucky enough to take pictures in some of the darkest places
left in North America: Big Bend National Park. The Grand Canyon in Arizona. 
And here at McDonald Observatory in West Texas. And while I was out there, I met someone who’s
trying to save darkness. I’m Bill Wren, special assistant to the
superintendent at the University of Texas McDonald Observatory And my job is to keep the skies dark for
ongoing astronomical research here at the observatory “The places where you can go to see a naturally
starry sky are vanishing, they’re shrinking, they’re becoming fewer and farther between.
You have to travel great distances from cities in order to see a naturally dark sky.” An amateur astronomer named John Bortle came
up with a scale to measure the night sky brightness based on how many objects are visible In perfectly dark skies, Bortle scale 1, there’s
between maybe four and five thousand stars bright enough to be visible to the naked eye
from any spot on Earth. I used some software called Stellarium to give you an idea of what
that looks like. It’s actually hard to even pick out constellations. 
But most Americans live at Bortle scale 5 or higher, which means they aren’t seeing
98% of the stars in the sky. We see people all the time at our public star parties who have never seen the Milky Way and they’re just awe inspired Now the beauty of the night sky is one thing,
but there’s a bunch of other reasons we should protect dark skies.
For astronomy I guess it’s pretty straightforward. We’ve gotta be able to see the stars in
the sky to do astronomical research. And there’s other questions about exposure to
too much artificial light at night not being so good for your health. In fact, it affects
the biorhythms of all living creatures on the planet.
There’s a cost efficiency question, in terms of how much light we’re wasting into the
night sky, by poorly designed and poorly installed light fixtures. On the order of billions
of dollars of electricity are wasted into the night sky in the US alone. “This is
about dark skies, not dark ground… no reason to shine it wasted above the horizon and into
the sky” We’ve lit up streets, parking lots, buildings
and every populated space we can mostly to make the night more safe. So when you hear people saying we should use
less light at night, your first reaction might be “That’ll make us less safe!” right?
But as hard as it is to believe, no study has ever shown that more light leads to less
crime. Most property crime occurs during the day. Even the worst crimes, like sexual assaults,
that we normally associate with bad guys in dark alleys, are far more likely to occur
indoors at the hands of someone the victim knows. And bad lighting can actually make
bad guys harder to see. More light at night can actually make us less
healthy too. For hundreds of thousands of years, humans evolved with the rhythms of
night and day. Like other creatures, we have a natural biological clock, our circadian
rhythm, that’s controlled by the cycle of light and dark. In darkness, our bodies produce a hormone
called “melatonin” that helps us sleep, boosts our immune system, and helps a bunch
of organs function. Light at night, especially blue light, can mess with that. And LED lighting,
while it saves energy and money, often peaks in the blue part of the spectrum, making this
problem worse. Night work has even been classified by some medical groups as a risk factor for
many cancers. So consider putting this away at night, and
if you do have to look at a screen, use night mode or an app to reduce the blue light given
off by your screen. The more that scientists study this, the more
it looks like we’ve underestimated the negative effects of light, that it is truly a “pollutant”
in its effect on humans and on wildlife. There are countless wild species being negatively
affected by our light pollution, whether they are nocturnal (active at night) or crepuscular
(active during twilight). Everything from fireflies that can’t find mates to dung
beetles who can no longer navigate by the Milky Way and from baby sea turtles walking
into roads instead of the sea to millions of birds killed every year in collisions with
buildings. Every September 11th in lower Manhattan, 88
7,000 watt searchlights shine into the night sky as a “Tribute in Light” It’s one of the brightest light installations
ever constructed, and even though it’s only on for one night a year, over a million birds
have been lured in by these lights, disrupting their annual migrations, and many have died
after colliding with buildings. That is, until scientists started working with the people
running the Tribute in Light to keep that from happening. Now, if more than a thousand
birds are counted in the lights, they’re turned off for twenty minutes. You can watch
on this radar image as the lights alternate between on and off, and huge clouds of disoriented
birds go safely on their way. I think this is an inspiring example of how
humans and nature can co-exist in a world of artificial light. Because stopping light
pollution doesn’t mean getting rid of all artificial light. That’s crazy. Light pollution
is not “all light at night”. It’s “light out of place”. The reason
satellite views of the dark side of our planet look like this, is because we’re wasting
that light by shining it up into space, instead of using it to light our way down here. Light pollution is unique because it’s the
only kind of pollution we can clean up instantly. Polluted water and air take decades to cleanse
them of human impacts, but cleaning up the night skies is easy. Just turn out the light. “Definitely a sense of awe to stand and
look up at the milky way and see the stars splashed across the sky, and realize the 3-dimensional,
the depth that you can see when you look into the plane of the galaxy. Just the scale that
surrounds us, the dimensions of the universe on the grand scale is just awe-inspiring.”
“I do believe that seeing a naturally dark sky provides one with a sense of context,
that sense of living in a very large space, and being part of something on a very grand
scale, and it does give one a sense, just a thrill. Sometimes a chill up the spine.
To realize that we came out of this universe as opposed to being put into it… but we
won’t get too philosophical here.” Well, Bill may not want to get philosophical,
but I think that beautifully sums up why dark is just as important to our lives as the light. Now, many of the beautiful shots of the night
sky you’ve seen in this video are time lapses, made with long-exposure photos that show you
a bit more than you can see with your own eyes. But I wanted to give you some idea of
what you really can see with the naked eye under those dark skies so few of us get to
experience. and while it’s not the crispiest
shot in the world, I hope it captures a feeling for you… I’ve been trying to think of a way to describe
what it is like to see this. And it is really hard to come up with the words. It is something
that you just have to see. And it’s something that I hope people still get the chance to
see. It makes you feel small and big at the same time. It makes you feel far away and
connected at the same time. And all I know for sure is… it’s good for ya. Stay curious. Hey. You want more space? PBS is bringing
you the universe with SUMMER OF SPACE, which includes six incredible new science and history
shows streaming on and the PBS Video app, along with lots of space-y episodes from
PBS Digital Studios creators Follow me over to AMERICA FROM SCRATCH to
check out their Summer of Space episode on WHETHER OR NOT WE SHOULD COLONIZE MARS. Big thank you to McDonald Observatory for
having me out to experience their dark skies. McDonald Observatory and the International
Dark Sky Association have some fantastic resources on which types of lighting to minimize wasted
light, and maximize useful light without unintended effects on wildlife and plants. We’ll put
links to that and a lot more down in the description.

Only registered users can comment.

  1. Don't be afraid of the dark. Go enjoy it! And keep looking up. Visit to learn more
    Let me know how what you thought of this episode. I'm on Twitter and Instagram at @DrJoeHanson and @okaytobesmart

  2. Just appreciate the fact you weren't born many billion years into the future. I imagine that in an ever expanding universe, eventually we will be essentially alone in our observable universe with the sun as our only star. Assuming our solar system survives long enough..

  3. Hello darkness, my old friend

    I've come to talk with you again

    Because a vision softly creeping

    Left its seeds while I was sleeping

    And the vision that was planted in my brain

    Still remains

    Within the sound of silence

  4. I live in a rural town of 1700. Yesterday, a friend from Dallas was visiting. As we were walking back to the only hotel in town where he was staying, he remarked on how 'starry' the sky was here. Oh, and on the natural circadian rhythm. How about those of us with DPSD (Delayed Sleep Phase Disorder)?

  5. Well Bangladesh looking dark but we have medium electricity compare with Developed countries. but our village or outside area of towns only use low lumen incandescent light for outside and portable torchlight for walking in night. I m happy now

  6. We have the north and south pole. We have plenty of areas on the equator. The night sky isn't a monopoly to hold against human progress in the industrialized world. Hell we are actively exploiting indigenous peoples in various areas on this Earth for the purposes of Science. Literally ever place science is looking towards has a very real human history that science is attempting to hijack.

    You want to get philosophical? Something about this channel I haven't seen lately is the challenge of indigenous peoples and their culture versus the first world capitalistic model of science knowledge being deployed. I get how you "hope" people feel things. I get how you think "it's good for you" to see these things. Listen dude, the vast majority of this planet doesn't need your pontificating about how awesome it is to be: 1) white 2) in a wealthy country 3) have access to the resources to understand the nuances of this topic.

    I'm extremely pro-science. But this video makes no sense. Not every person on this planet wants to see the freaking Milky Way. Thank God. Not every person on this planet needs to see it. We are evolving the Circadian rhythm. Cancer is a current risk, but in time it won't be. We need more production time for scientist and people broadly. That is co-existence.

  7. Soon the population will reach 20 billion and you'll have to drive to the country to see the moon lol

  8. Hi Australia here.We Aussies in the countryside are the luckiest in the world we get to see the night sky every night (except in the full moon nights) If there is a haze we see less, but on clear nights we see the most incredible sky.And i have good night vision and even see the colour in some of the stars. very clearly and on full moon nights i see very well in a lot of colour in the surrounding area like green trees etc. never have seen in no colour at night except on pitch dark nights.

  9. We go on so much about the environment these days but if people are unwilling to solve light pollution which is one
    Of the easiest problems to deal with, how on Earth ( pun intended) can people hope to solve more and much more difficult

  10. To bad u dont address the real issue, chem trails and aerosol injections…tht cause a canopy in the skie in which we dont see the constellations

  11. I never knew that there was a night setting for my devices! Nice. You can go into the woods in Canada or other places and see lots of stars.

  12. The half of the world should have a 1 minute "No Light Day" at night. Lol. If it's possible. The sky will reveal its true colours. That sigh will be incredible. (:

  13. 30 years ago when i was just a kid i can see stars shining so bright like hundreds of them,now i can only see few

  14. Sad aye city born even in the suburbs the suburbs are not dark! glad I live in the country in Canada! On a night there is no moon you can barely see you hand in front of your face. Please stay in the city and the burbs!

  15. On drives between Vegas and Denver I would have to pull over in the middle of Utah and the middle of nowhere at night to pee and I could see the whole sky. When you see it all the first few times it could kind of scare you or make you feel insignificant. Seeing the Milky Way after the the first few times is a spiritual experience.

  16. I live in Singapore and yes, you literally can’t see stars. You only see fake stars that are actually planes lol.

  17. I saw the beautifull and real sky in my country venezuela in "La gran sabana" one of the best experience in my life, just silence, completly black out and just a sky full of magic!!

  18. recently jakarta and west java had a major power outage, and i rlly hoped i could see the milky-way. but that's what i thought, the air is way too polluted here that there was rlly no differences between a regular night, and a night without artificial light.

  19. It's so sad, I take walks in the middle of the night every other day, and being able to see the milky way is very rare, even though I am lucky to live in a small rural town.

  20. Just go caving If you want the darkest thing you’ll ever experience…You’re not gonna see any stars though. And I’m not talking about one of those tourist, hand rail laden caves… just in Kentucky they’re like 40 pretty good sized caves With over a half a mile of passages, plenty to experience true dark. Once you’ve gone past the mouth and opening and around a couple bends It’s insanely dark

  21. If you go into the Australian outback you'll see stars like you've never seen them anywhere else. The Milky Way is so bright your eyes can see colour in it and it you even cast a shadow purely from the stars. So even when there are no lights, it's not as dark as you imagine.

  22. I'm lucky I can see hundreds of stars from my house.
    But I was awestruck when I went to Tobermorey, Ontario and could see the Andromeda Galaxy. It was gorgeous and awe inspiring.

  23. This is why I love science camp. You have access to the sky and can actually see stars. I live in the suburbs and can only see a few stars.

  24. I live out in the middle of nowhere arkansas, about 45 mins from the nearest big city. You're right, a lot if people don't know what they're missing. I can look up and start picking constellations with no trouble, and see the milky way. It's beautiful.

  25. I went to myra falls once and the sky there is exactly how the guy explained it in this video. Its truely an sad amazing thing we miss out on every night

  26. I was 27 years old the first time I drove across the Arizona desert at night.
    I had never noticed that I hadn't really seen the stars before.
    We had to stop the car to take it in.

  27. Praphrased "We are not night creatures, but all that changed with one invention" and I'm like "FIRE!!!!!"… while the dude continues "The Light bulb"…. I'm like "hey, no… fire! :(". Didn't camp fires make it so that young adult men could stay up at night and be on guard towards attackers be it animals or other tribes?

  28. I’m so sad. I wish I could see the stars. I live in the suburbs and I can only see a few stars at night. I’ve never even seen a fraction of that many stars, let alone those colors! Now I know what my dream is to see.

  29. We should have a law where once a year no one in earth 🌍 uses electricity I think it would change our perspective of life.

  30. Just scroll through a comment section of a video like this and you see everyone at their senses go out to the real world and no one even cares about all this

  31. I used to think like Why stars r not visible that much nowadays(we live in a city now) as compared to my childhood(when we were in a village)?
    Whether city's air is that much polluted? OR
    The universe is expanding that much faster??

  32. I've never seen the milky way, even in the darkest area I've ever been in I've only seen a bit more stars than usual but nothing like what was shown in this video, I feel like I've lived my 27 years without one of the basic elements of this earth, the night's sky.

    sorry for my bad English.

  33. ❤️ I love the fact that we turn the lights off on September 11th to protect the birds! What we’re supposed to be remembering on September 11th is the value of life… and the fact that we’re willing to remember the value of other life forms is beautiful. I’m a white water kayaker and the most glorious moments on the river are those so far into Wild and Scenic territory that there is no electricity or WiFi. To watch the sky, especially during the Perseid Meteor Showers is magical.

  34. There should be one day a year where they just switch off all artificial lights, I bet it would get youngsters into astrology and science

  35. I haven’t gotten the chance to see the Milky Way yet, but I got the chance to take a roadtrip down in Utah and Arizona, and wow, I’d never seen more stars in my life! It was so beautiful and although I love exploring cities and the light, there’s beauty in darkness too 🙂

  36. Can somebody please tell me how to find similar music to the one that starts at 0:54 on the background, the one that brings the mysterious feeling it gives me honestly chills and I can't find any on youtube please help

  37. The reaction of the Californians to the actual night sky…oh, DEAR! You poor babies ! Oh, god, the naievety/ignorance is PAINFUL…I mean, I've at least seen pictures of the real night sky!
    I do love that they were calling the OBSERVATORY instead of 911, though. XD "You! You nerds do sky stuff, right?" (points) "WHAT DIS???"

  38. Main electricity source in Java: breaks because of earthquake
    Me and my family: finally, no more light pollution. We can see the night sky again

    Generators owned by neighbours: sksksksksksksksksksksk and i oop-

  39. Im so depressed at these stuff i wish i lived years ago when i wouldnt be a human and the world was natural: snow, forest, desert, plains and language ruined us as well if u think about it and everything TV ats man made even houses

  40. I live in the mountains and it never occurred to me that some people have never seen the milky-way. That's kind of mind blowing to me.

  41. We should have lights turned off during those fireflies mating season because they are going extinct because light pollution.

    We should save them.

  42. That’s not true. The skies are covered with a fake clouds blanket night and day.
    It’s not the light pollution .

  43. Love that I live out in the country. I think my light pollution is only like a 3 or a 4, so I can see the milky way and make out constellations pretty easy. It's amazing compared to when I lived in the suburbs of Dallas.

  44. I am more worried about the people in LA calling out strange phenomenons when the light went out, instead of immediately realizing that those were just stars.

  45. i live in a small town with 2 larger citys nearby and at night i can point out in the distance where the citys are and which ones they are just by the light coming off of them and that the bigger citys light is brighter and larger. i am glad in my town i can see the stars pretty clearly though.

  46. That guy is wrong. We were created by God. The glory of the skies is reflective of His glory. NOTHING has ever been invented by except for by another intelligence. He cannot come up with one example.

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