Valladolid Astrotourism Association
What's behind these letters isn't an illustration. It's the sky over Valladolid right now: every star of the Hipparcos catalogue in its place, the planets where they are, the Moon in its phase. Move the cursor across the sky and the constellations will appear.
1.2 · Bad lighting
Join us on this journey into the night we're losing: scroll slowly and watch what happens to this sky. It's the same night and the same time from start to finish; the only thing that changes is the artificial light we switch on.
What light pollution is
It has four faces: the skyglow you see growing over the horizon, the glare that blinds you, the light trespass that creeps in through your window and over-lighting: lighting more than necessary.
How it's measured
At 1, the Milky Way is so bright it casts shadows; at 9 only the Moon, the planets and the brightest stars remain.1 It's the numbered ruler on the right: follow it as you scroll. The precise figure comes from a photometer, in magnitudes per square arcsecond: the lower the number, the brighter —and worse— the sky.
First the Milky Way goes
Light goes up straight from the lamp and bounces off the asphalt. The air spreads it into a background brighter than the faint stars, which are the first to go, and with them the Milky Way: 60% of Europeans can no longer see it from where they live.2
99%
Spain has the third most light pollution in the European Union, after Greece and Malta.3
Then, the constellations
The brightest stars survive, scattered, without the faint ones that joined up the figure. It's the sky over any city centre.
The LED twist
A 4,000 K white LED gives off a lot of blue, and the air scatters 450 nm blue almost three times more than 590 nm amber. On top of that, the dark-adapted eye is more sensitive to it: lumen for lumen, it pollutes about 2.5 times more than the old orange sodium.2 That's what has just happened to this sky.
And from above you can't see it
The sensor that photographs the Earth at night can't see below 500 nm: a city that swaps sodium for white LED looks darker from space. To the naked eye, sky brightness grows by 9.6% a year.4 And since light gets cheaper, more of it gets installed: the planet's lit surface grew by 2.2% a year between 2012 and 2016.5
1.2 · What you don't see
There are four things bad lighting takes with it that you can't see from the street.
01 · Health and sleep
It holds back melatonin, the hormone that tells the body it's night. White LED does so about five times more than sodium; the American Medical Association recommends not going above 3,000 K on the street.6
03 · Energy thrown at the sky
It's the globe streetlight on the VillaLuz high street: 686 of its 3,116 kWh a year light up the sky, not the street. Computed with the simulator's model.
04 · Everyone's heritage
The La Palma Declaration, signed in 2007 with the participation of UNESCO, recognises the right to an unpolluted night sky as a right of humankind.8 It's also the sky astrotourism lives on.
It's the only pollution that leaves the sky the moment the light causing it goes off. And there's no need to switch it off: lighting well is enough.
1.3 · VillaLuz
VillaLuz is the made-up village in our simulator: a high street with its streetlights, computed against the real regulations. Tap each decision and watch the sky on this page: it follows the model, not an effect.
00 / 05
Globe streetlight, 12,000 lm, 4,000 K white light, 22% of the output going skywards and on at 100% all night.
01 / 05
Shielded road luminaire: 0% upward light. All the light that went to the sky comes down to the street… and is now too much.
Shielding without lowering the output isn't enough: the light that went to the sky now falls on the street and over-lights it.
02 / 05
2,500 lm per point, staggered every 16 m at a height of 6 m. The carriageway and both pavements reach their class without overshooting.
Less light, less safety? Switching off, dimming or reducing streetlights in England and Wales was not associated with more night-time collisions or more crime.9 What helps you see is even light that doesn't dazzle.
03 / 05
From 4,000 K to 2,200 K, amber. Blue light is the most scattered in the atmosphere and the one that dirties the sky most.
The LED twist, in reverse: the sky gains 1,351 stars. It's the only decision that raises the bill: the model assumes 122 lm/W at 2,200 K versus 150 lm/W at 4,000 K, so the same lumens cost more watts.
04 / 05
Time-based dimming: 100% until midnight and 50% for the rest of the night.
05 / 05
On top of that: in the small hours the lamp stays on standby (20% of the dimmed level) and goes up to 100% for 90 s when someone passes. Computed with 4 passers-by per hour.
Same street, rules met, 13.5 times less energy and 3,994 more stars than at the start.
Globe streetlight, 12,000 lm, 4,000 K white light, 22% of the output going skywards and on at 100% all night.
Why it fails · Royal Decree 1890/2008 and Castile and León Law 15/2010
Sources for this story
Next story · 2 of 4
What to see in the sky over Valladolid in the next four months.
Website funded by the Provincial Council of Valladolid under the collaboration agreement signed to promote astrotourism in the province.
2 · Coming nights
Dark night: Moon below 20% at 23:00. Dots mark sky events.
Working out planets, Moon and meteors…
Computed in your browser every time you open the page, with the same positions that paint the sky above: the list renews itself. Meteor showers follow the solar longitude of the peak in the International Meteor Organization (IMO) calendar; ZHR is the zenithal hourly rate, the one for a perfect sky with the radiant at the zenith.
Next story · 3 of 4
12 August 2026, from first contact to sunset.
Website funded by the Provincial Council of Valladolid under the collaboration agreement signed to promote astrotourism in the province.
3 · 12 August 2026
~19:30 · First contact
~20:30 · Totality
A ring of sunset all around the horizon. We lived it together, in 21 validated municipalities of the province.
The next one from the province
4·10·2480
Next story · 4 of 4
What we do, our events and how to join.
Website funded by the Provincial Council of Valladolid under the collaboration agreement signed to promote astrotourism in the province.
4.1 · What we do
We reduce light pollution and advise businesses and public bodies so that their lighting meets FHS = 0% and CCT ≤ 3,000 K.
FHS 0% · ≤ 3,000 KWe certify observation sites and establishments at three levels — Bronze, Silver and Gold — audited with SQM photometers and all-sky cameras.
Bronze · Silver · GoldWe connect amateurs, businesses and public bodies in a network of sustainable tourism under the stars, with events, workshops and training open to everyone.
Events · workshops4.2 · Events
The association's upcoming events from its two calendars appear here, each with that night's Moon phase. See all events.
4.3 · Looking north
Exposure 0 min
You've reached the end · back to story 1
What light pollution is, what it does to the sky and how to fix it.
