Study: Light Pollution Continues to Dim Stars

Study: Light Pollution Continues to Dim Stars

A new study has found that light pollution is making the night sky brighter and the stars dimmer.

The study examined data from more than 50,000 citizen star watchers across the world. It found that man-made, or artificial, lighting¹ is making the night sky about 10 percent brighter each year.

Data for the study was collected from 2011 to 2022. The research findings recently appeared in the publication Science.

The result was a much faster rate of change than scientists had estimated in the past.

"We are losing, year by year, the possibility to see the stars," said Fabio Falchi. He is a physicist² at the University of Santiago de Compostela in Spain. He was not involved in the study.

"If you can still see the dimmest stars, you are in a very dark place," Falchi said. "But if you see only the brightest ones, you are in a very light-polluted place."

As cities expand and put up more lights, a "skyglow" is created in the sky. Skyglow is a term scientists use to describe light that becomes more intense.

Christopher Kyba is a physicist at the German Research Centre for Geosciences in Potsdam. He was a co-writer of the study. He told The Associated Press that the 10 percent change was "a lot bigger" than he had expected.

The research team gave an example to explain the result. If a child is born where 250 stars can be seen on a clear night, by the time that child turns 18, only 100 stars will be seen.

"This is real pollution, affecting people and wildlife," Kyba said. He urged policymakers to do more to reduce light pollution. Some communities have set limits.

Past studies involving artificial lighting used satellite images of the Earth at night. They had estimated the yearly increase in sky brightness to be about 2 percent a year.

But the satellites used are not able to identify light with wavelengths³ toward the blue end of the spectrum⁴ – including light given off by energy-effective LED bulbs.

The researchers noted⁵ that more than half the new outdoor lights put in across the United States during the past 10 years have been LED lights.

The satellites are also better at finding light that gets spread upward – like a spotlight⁶ – than light that spreads out from side to side, Kyba said.

Skyglow affects human circadian rhythms as well as other forms of life, said Georgetown University biologist Emily Williams. She was not part of the study.

"Migratory⁷ songbirds normally use starlight to orient where they are in the sky at night," Williams said. "And when sea turtle babies hatch, they use light to orient toward the ocean – light pollution is a huge deal for them."

Falchi, the physicist at the University of Santiago de Compostela, said part of what is being lost is a universal human experience. "The night sky has been, for all the generations before ours, a source of inspiration for art, science, literature," he added.

Words in This Story

dim – adj. not bright or clear

spectrum – n. all the different ideas, opinions and possibilities that exist

bulb – n. a glass object that contains a wire and produces light from electricity

circadian rhythms – n. a natural cycle of physical, mental and behavioral changes that the body goes through in 24 hours

orient – v. to direct something toward the interests of a particular group

hatch – v. to produce young by incubation: to sit on eggs to get them to open by the warmth of the body

inspiration – n. someone or something that gives you ideas for doing something

1 lighting   

n.照明，光线的明暗，舞台灯光

参考例句：

• The gas lamp gradually lost ground to electric lighting.煤气灯逐渐为电灯所代替。
• The lighting in that restaurant is soft and romantic.那个餐馆照明柔和而且浪漫。

2 physicist   

n.物理学家，研究物理学的人

参考例句：

• He is a physicist of the first rank.他是一流的物理学家。
• The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。

3 wavelengths   

n.波长( wavelength的名词复数 )；具有相同的/不同的思路；合拍；不合拍

参考例句：

• I find him difficult to talk to—we're on completely different wavelengths. 我没法和他谈话，因为我们俩完全不对路。 来自《简明英汉词典》
• Sunlight consists of different wavelengths of radiation. 阳光由几种不同波长的射线组成。 来自辞典例句

4 spectrum   

n.谱，光谱，频谱；范围，幅度，系列

参考例句：

• This is a kind of atomic spectrum.这是一种原子光谱。
• We have known much of the constitution of the solar spectrum.关于太阳光谱的构成，我们已了解不少。

5 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

6 spotlight   

n.公众注意的中心，聚光灯，探照灯，视听，注意，醒目

参考例句：

• This week the spotlight is on the world of fashion.本周引人瞩目的是时装界。
• The spotlight followed her round the stage.聚光灯的光圈随着她在舞台上转。

7 migratory   

n.候鸟，迁移

参考例句：

• Many migratory birds visit this lake annually.许多候鸟每年到这个湖上作短期逗留。
• This does not negate the idea of migratory aptitude.这并没有否定迁移能力这一概念。