DarkSky Oregon
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Introducing the Oregon Outback International Dark Sky Sanctuary
We are thrilled to share some very exciting news – the first phase of the Oregon Outback International Dark Sky Sanctuary in southeastern Oregon has been certified by DarkSky International! At 2.5 million acres, the Oregon Outback International Dark Sky Sanctuary is the largest Dark Sky Sanctuary in the world. The newly-certified, star-studded Sanctuary in Lake County is within the largest intact area of world class dark skies in the lower 48 states and represents an area about one-half the size of New Jersey!
The Oregon Outback Dark Sky Network that submitted the nomination represents a diverse team of state and local land managers, businesses, nonprofits and private individuals that worked tirelessly for the past four years to reach this outstanding milestone. But they’re not done yet–the Network aspires to expand the certified area eastward into Harney and Malheur Counties to encompass a full 11.4 million acres!
The scale of this designation and the breadth of the partnership effort that went into it reflects the truly remarkable nighttime resource that we have here in Oregon, as well as the value of dark skies—for human and wildlife health, for the preservation of carefully choreographed ecosystem relationships, for our deep cultural history of looking skyward, and for the economic benefits to gateway cities in support of dark sky tourism.
DarkSky Oregon supports the OODS Network’s efforts by analyzing and providing night sky brightness measurement data and maps, which confirm the pristine nature of the Sanctuary’s night skies.
Learn more about this remarkable International Dark Sky Sanctuary and the efforts to protect Oregon’s night skies.
https://www.southernoregon.org/dark-skies/oregon-outback-dark-sky-sanctuary/#
Bees Get All the Credit
Learn about night sky friendly light fixtures and bulbs from DarkSky International:
https://darksky.org/what-we-do/darksky-approved/products-companies/
Example of Amber LED flood light
Amber bulbs from Amazon seller
Bulbs which are yellow in color, and typically have a 2000 Kelvin spec, are sold as "bug lights" because they have similar benefits to the amber colored bulbs. These may be found in the retail stores, if you ask for "bug lights".Here's an example on Amazon of yellow 2000 Kelvin bulbs.
Part 1: Where in Oregon is the Night Sky Most Pristine? And, Most Light Polluted?
DarkSky Oregon and volunteers support a network of Sky Quality Meters across the state which continuously record how bright and how dark the night sky is overhead. The data tell us which areas still have pristine night skies, which areas are polluted by artificial light, and which fall in-between.
This map of Oregon shows the locations of our Sky Quality Meters. The size of the yellow plus symbol tells how starry the night sky is at each spot. The largest plus symbols represent nearly pristine night skies – a very rare environment compared to most of the rest of the USA. The smallest plus symbols represent the light polluted sites – around the cities of Central Oregon, the Willamette Valley and Portland.
The next plot shows in detail how dark the night sky is overhead at our measurement locations – this data was used to make the Oregon map above. The darkest – the most pristine – night sky locations are at the bottom of the plot. The most light polluted are at the top of the plot.
Another way to look at the data in the plot is to compare how much brighter the clear (not cloudy) night sky is at each location by comparison to one of the darker, pristine night sky locations.
The rightmost column of this table shows how much brighter each site is, by comparison to the darkest site measured at present, at Crater Lake National Park. The night skies in the cities of Central Oregon sites are about 5x brighter than at Crater Lake. The night skies in Portland are about 20x brighter.
It turns out that clouds at night reflect light pollution downward in cities, causing the night sky to be very bright. And, away from cities, where there is little light pollution, clouds at night are dark because there is no light pollution to reflect back downward, and moreover, the clouds block out the stars, so the night sky measures very dark.
This last table summarizes the brightness of cloudy night skies at our measurement locations. The rightmost column shows that on cloudy nights, the Central Oregon city skies are 20x brighter and Portland skies are up to 300x brighter than the cloudy night skies at pristine night sky sites, a very un-natural situation.
Support the effort to reduce light pollution. Contact us at:
Key Results from the Oregon SQM Network:
Part 2: Where does the Milky Way stand out best compared to the surrounding night sky?
DarkSky Oregon and volunteers support a network of Sky Quality Meters across the state which continuously record how bright and how dark is the night sky overhead. The data tell us which areas still have pristine night skies, which areas are polluted by artificial light, and which fall in-between. The data also tell us where the Milky Way shines in greatest contrast with the surrounding night sky. We call that an Index of Milky Way Visibility.
This map of Oregon shows the locations of our Sky Quality Meters. The size of the red star symbol tells how well the Milky Way stands out at each spot. The largest stars show the places where the Milky Way stands out best. The smallest star symbols shows where the Milky Way is generally not even visible -- over cities of Central Oregon, cities in the Willamette Valley and Portland.
This map is similar to a map showing where our SQMs measure the most pristine night skies. The plot below shows night sky brightness versus the Index of Milky Way Visibility, demonstrating that similarity, but also allowing separation among the darkest sky sites – on the lower right of the plot.
The plots show that as we would expect, the darker sky sites, those lower on the Y-axis, express increased visibility of the Milky Way. We anticipate that several sites will change position going forward, as additional data, across all seasons becomes available from them all.
The table below shows the data used to make the plot. The Milky Way is most visible at the sites near the bottom of the table, and is mostly not visible for sites at the top of the table.
We calculate the index both from the difference of logarithmic magnitudes/arc second squared data, and from a ratio of linear scale SQM flux data. Both are presented because different observers may prefer one over the other. The indices in each case are consistent, plot against each other in linear fashion (not shown) and each provides useful information.
The first data column in Table 4 lists the difference of the median values at each site, for the night sky brightness when the Milky Way is seen by the SQM versus not. The units are magnitudes per arc second squared.
The second data column in Table 4 shows the same information but as a unitless ratio of linear flux data measured by the SQM. It can be interpreted by noting that, for example, the Milky Way at the Hart Mountain and Crater Lake sites is 1.3x brighter than the surrounding night sky. And at the two Portland sites, the Index value is about 1.0, which indicates that the Milky Way does not stand out in contrast to the surrounding night sky at all.
Support the effort to reduce light pollution.
Contact us at: hello@darkskyoregon.org
Key Results from the Oregon SQM Network:
Part 3: Where are the starry night skies disappearing the fastest in Oregon?
DarkSky Oregon and volunteers support a network of Sky Quality Meters across the state which continuously record how bright and how dark is the night sky overhead. The data tell us which areas still have pristine night skies, which areas are polluted by artificial light, and which fall in-between. Because quite a few of the meters have been operating for two years or more, they also tell us where light pollution has been increasing – where the stars are fast disappearing – and where the night sky has been mostly unchanging.
This map of Oregon shows the locations of our Sky Quality Meters that have been operating for at least two years. Large red diamonds on the map show a strong increase in light pollution overhead, year-by-year. The smallest red diamonds mark sites where no noticeable change overhead has occurred. Most of these sites, all of which have at least 2 years of data, are in Central Oregon because we started this as a pilot project there.
The table summarizes the long-term change information for these sites. The data show increases of 4% to 7% per year for SQM sites near cities. SQM sites away from cities show increases of 2% to 4% per year, while most remote sites tend to show little to no change in skyglow overhead.
It is traditional to quote the percentage change per year, but percentages are comparable to each other only when the starting point is the same. In our case, the starting points all differ – namely we have a range of night sky brightness – from pristine dark to light-polluted bright.
A better gauge is the change over time by comparison to one of the sites where change is slow. So, the first data column in the table shows the rate of change at each site by comparison to the Prineville Reservoir State Park site, which is a certified Dark Sky Park, and where we don’t expect much change in sky brightness. The rate of change at that State Park is given the value of 1.00 and the other sites vary by comparison. Most of the sites in Central Oregon are increasing about 10x faster than at the State Park. The size of the red diamonds in the map are scaled by this rate-of-change column.
As noted, the third column shows the annual percentage change for each site. Note that the percentage change at Prineville Reservoir State Park is estimated to be 1.1% per year, while the percentage change at the Hopservatory is about 6% per year. So, sites with bright, light-polluted, night skies (Hopservatory) appear to have less of an issue when the percentage statistic is used. In reality the rate of change is dramatically larger at the Hopservatory (28x), compared to the State Park site.
Support the effort to reduce light pollution.
Contact us at: hello@darkskyoregon.org
Key Results from the Oregon SQM Network: