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China's “Fake Moons” can make light pollution Nearly fifty times worse, astronomer warns

" Jiutian traditional tower illuminated at night with full moon in the background, Chengdu, China A city in China is…

Jiutian traditional tower illuminated at night with full moon in the background, Chengdu, China

A city in China is planning to launch a satellite planned to be eight times as full as the full moon to illuminate city streets at night, but an astronomer thinks it can exacerbate light pollution by a factor of 47.

As reported by People’s Daily Online, researchers in the Chengdu city of southwestern China believe that they can cut streetlights by launching an “illumination satellite” that can give enough light for between six and 50 square miles of the city.

When can fake moons be launched?

The plans for 202o were sketched by Wu Chunfeng, President of Chengdu Aerospace Science and Technology Microelectronics System Research Institute Co (CASX) said that the satellite would complement the moonlight. China Daily reported, however, that three many moon will be launched in 2022. “Then, the three big mirrors come after sharing the 360-degree plane and realize to illuminate an area for 24 hours continuously, “quoted Wu. “Using artificial moon to illuminate an area of ​​50 square kilometers can save 1.2 billion yuan of electric charge.” It’s about $ 172 million.

Why are “false moons” such a bad idea?

“Chengdu Artificial Moon” would significantly increase the nightlight strength of an already polluted city, creating problems for both Chengdus residents who can not sharpen the unwanted light as well as for the urban wildlife population that can not only go entering and closing the shutters, says John Barentine, Head of Public Policy at the International Dark -Sky Association, told Forbes . “This potentially creates significant new environmental issues with what initially seems like a new approach to an already resolved issue.”

Exactly how bright are the “fake moon”?

People’s Daily Story says that the brightness of the artificial moon can be eight times the light of the real moon. An academic magazine from last year, How Light is Moonlight ?, found that the lightest possible Full Moon under ideal conditions has an illuminance of about 0.3 lux, but it is often only 0.15-0.2 lux. “This means that the” artificial moon “can give a brightness as high as 1.6 lux,” says Barentine, author of The Lost Constellations: A Story of Outdated, Extinct, or Forgotten Star Lore. He adds that although it is difficult to calculate the luminance of the Chinese satellites without knowing the size of their reflective surfaces, if the 1.6 lux is uniformly transmitted by the whole sky (fixed angle = 2π steradians) then it would be equivalent to a brightness of 1.6 / (2π) = 255 mcd / m2, or about 14.1 greats per square arch. “It corresponds to the intensity of skyglow in a very densely urban area, as in the world’s largest cities,” he says.

Why false moons would cause much more light pollution

Stargazers already avoid a full moon because its light pollution makes the stars much more difficult to see, but fake moons will cause much more light pollution than that is said, according to Barentine. “F or for comparison, the sky’s brightness across central Chengdu due to skyglow is forecast to be 5.43 mcd / m2, or about 18.25 magnitudes per square arch second, using satellite data obtained in 2015″, he says . If it is assumed that the light is radiated evenly over the night sky, it represents an illuminance of about 0.00543 cd / m2 * 2π steradians = 0.034 lux (calculations of Barentine). “Therefore, the” artificial moon “would increase the illumination level on the ground by a factor of about 47,” he said.

A full moon near the Chinese flag (AP Photo / Ng Han Guan)


In 1993, Russia tested a “space mirror”, but in German researcher in the 1920s Hermann Oberth moved the tank on space station from which a 100 m wide concave mirror can be used to reflect sunlight in a certain place on earth. His concept later interested the German army as the foundation of a “solar gun” during World War II.

What is international observance of the moon night?

The “Fake Moons” idea comes as NASA is preparing to mark “International Observer Moonnight” on Saturday. An annual event worldwide, at the time of writing, there were 761 moonlight events planned, including 19:30 at Intrepid Sea, Air & Space Museum in New York, where NASA’s Ernie Wright speaks. Others include from 19:00 p.m. at University of California in Los Angeles, where telescopes will be tuned to the UCLA Math Sciences Building Rooftop (9th floor) and at the Lowell Observatory in Flagstaff, Arizona.

Next year’s “International Observe the Moon Night” event will take place on October 5, 2019.

Wishing you clear skies and steep eyes

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