International Dark Sky Week - April 20-26
International Dark Sky Week, created in 2003 by high-school student Jennifer Barlow, is a key component of Global Astronomy Month (April). The International Dark-Sky Association aims to spread awareness to the issues around light pollution as well as provide solutions to mitigate it.
In 2001, “The First World Atlas of the Artificial Night Sky Brightness” reported two-thirds of the U.S. population and more than 50% of the European population had already lost the ability to see the Milky Way with the naked eye (x). The report also showed that 63% of the world population and 99% of the population of the European Union and the United States (excluding Alaska and Hawaii) lived in regions where the night sky is brighter than the threshold for light-polluted status set by the International Astronomical Union. In 1994, an earthquake knocked out the power in Los Angeles. Many residents called local emergency centres reporting a strange “giant, silvery cloud” in the dark sky. That giant, silvery cloud was the Milky Way, which many residents had just seen for the first time.
Light pollution can also affect human health. Light photons need to impact the retina for biologic effects to occur. Nuisance light becomes a health hazard when there is a lot of artificial light at night, in cities like Manhattan or Las Vegas. This is because there is more opportunity for the retina to be exposed to photons that might disrupt circadian rhythm. The circadian clock is a 24-hour day/night cycle, which affects physiologic processes in most organisms. There is a large amount of epidemiologic evidence that indicates a consistent association between exposure to indoor artificial nighttime light and health problems such as breast cancer (x). This association does not prove that artificial light causes the problem, however laboratory studies have shown exposure to light during the night disrupts circadian and neuroendocrine physiology, which then accelerates tumour growth (x).
Flora and fauna are also affected by light pollution. Prolonged exposure to artificial light has been shown to affect trees from adjusting to seasonal variations, which then affects wildlife that depend on trees for their natural habitat (x). Research on wildlife species has shown that light pollution can alter behaviours, foraging areas, and breeding cycles.
One dramatic example of this is sea turtles. Many species of sea turtles lay their eggs on beaches, and the females of the species return to the same beaches to nest. When these beaches are brightly lit at night, these lights can disorient the females who then wander onto nearby roadways and get struck by vehicles (x). Sea turtle hatchlings typically head toward the sea by orienting away from the dark silhouette of the landward horizon. With bright artificial lights on the beach, these hatchlings become disoriented and navigate toward the artificial light source, never finding the sea.
The image used shows the Bortle Dark Sky Scale, created by John E. Bortle and published here: (1, 2). It is a guide for amateur astronomers and is a nine-level numeric scale that measures the night sky’s and stars’ brightness of a particular location. Class 1 represents the darkest skies available on Earth while Class 9 shows inner-city skies
Reducing light pollution is not just about being able to see the night sky much more effectively. It is also about saving money, energy and reducing greenhouse gases while protecting the environment, wildlife, and improving human health. This is not to say that artificial lighting is bad; it is when artificial lighting becomes inefficient, annoying, and unnecessary that it is known as light pollution. To aid in minimising light pollution, you can shield outdoor lighting, or at least angle it downward and use light only when needed. Motion detectors and timers are also useful. Use only the amount of illumination you need and try reducing lamp wattage.
Stay tuned on The Universe for Dark Sky Week: we’ll be showcasing various Night Sky photographers and their issues with light pollution, throughout the week.
For more information on light pollution, click here.
Sources: 1, 2, 3, 4, 5, 6
Image is a screenshot of the Light Pollution Simulation / Bortle Scale
There’s too much caffeine in your bloodstream and a lack of real spice in your life.
Astronomy Photo of the Day: 04/21/14 - Saturn Lit Up By the Sun
If you aren’t already familiar with this image, your life is incomplete without you even knowing it. This is the first and most spectacular of the images of Saturn taken by the Cassini spacecraft.
Unlike most of Cassini’s images, this one is completely different, for in this image, Saturn is eclipsing the sun. At the center of the image is the body of the gas giant, which in itself is partially lit by the reflection of light from its ring system. Of course, as you move away from center, the majestic rings shine with incredible brightness. Because of this, the image actually revealed the presence of a series of rings that were unknown to scientists at the time.
And, if this image wasn’t already cool enough, it’s about to get cooler. Of course, you see the thick bright bands of Saturn’s iconic rings, and you see the slightly more separated, fainter ring system (i.e. the second farthest ring from the planet, or the G ring). In left hand side, near the 10 o’clock position, you’ll see a little dot. That is the Earth. “That’s here. That’s home. That’s us.”
Can’t make Earth out? See here: http://goo.gl/kg3GTD
Image Credit: NASA/JPL-Caltech