1 . Composite image of Europe and North Africa at night, 2016. Credit： NASA Earth NPP Observatory images by Joshua Stevens, using Suomi VIIRS data from Miguel Roman, is oftenNASA's Goddard Space Flight Center. Artificial light seen as a sign of progress: the march of civilization shines a light in the dark； it takes back the night； it illuminates. But a chorus of scientists and advocates argues that unnaturally bright nights are bad not just for astronomers but also for nocturnal (夜间活动的)animals and even for human health.
Now research shows the night is getting even brighter. From 2012 to 2016 the earth's artificially lit area expanded by an estimated 2. 2 percent a year (map), according to a study published last November in Science Advances. Even that increase may understate the problem, however. The measurement excludes light from most of the energy-efficient LED lamps that have been replacing sodium-vapor technology in cities all over the world, says lead study author Christopher Kyba, a postdoctoral researcher at the German Research Center for Geosciences in Potsdam.
The new data came from a NASA satellite instrument called the Visible Infrared Imaging Radiometer Suite (VIIRS). It can measure long-wavelengths of light, such as those produced by traditional yellow-and-orange sodium-vapor street lamps. But VIIRS cannot see the shortwavelength blue light produced by white LEDs. This light has been shown to disrupt human sleep cycles and nocturnal animals, behavior.
Credit: Mapping Specialists ； Source: Artificially Lit Surface of Earth at Night Increasing in Radiance and Extent," by Christopher C. M. Kyba et al. , in Science Advances, Vol. 3, No. 11, Article No. E1701528 ； November 22, 2017.
The team believes the ongoing switch to LEDs caused already bright countries such as Italy, the Netherlands, Spain and the U. S. to register as having stable levels of illumination in the VIIRS data. In contrast, most nations in South America, Africa and Asia brightened, suggesting increases in the use of traditional lighting. Australia actually appeared to lose lit area一but the researchers say that is because wildfires skewed the data.
"The fact that VIIRS finds an increase (in many countries) , despite its blindness in the part of the spectrum that increased more, is very sad," says FabioFalchi, a researcher at Italy's Light Pollution Science and Technology Institute, who did not participate in the study. In 2016 Falchi, along with Kyba and several other members of his research team, published a global atlas of artificial lighting that showed one third of the world's population currently lives under skies too bright to see the Milky Way at night.
The data also cast doubt on the idea that the LED lighting revolution will lead to energy cost savings. Between 2012 and 2016 the median nation pumped out 15 percent more long- wavelength light as its GDP increased by 13 percent. And overall, countries, total light production correlated with their GDP. In other words, Kyba says, "we buy as much light as we are willing to spend money on."
1. Which is not true about the spread of lit areas?| A．Lit area expanded by an estimated 2. 2 percent a year. |
| B．Artificial light is often seen as a sign of progress. |
| C．The increase in GDP is due to the increase in light. |
| D．It is bad for noctumal animals and even for human health. |
| A．It is a kind of NASA satellite device. |
| B．It can record and analyzed long-wavelength light. |
| C．The blue light generated by white LEDs can disrupt human sleep cycles. |
| D．VIIRS has found an increase of traditional lighting in lots of nations. |
| A．Artificial LED lights at nights are harmful to people's health. |
| B．It is a sign of civilization in modern society. |
| C．The blue light disrupts human and animals" life cycles. |
| D．Artificially lit surface of Earth increasing because of LEDs. |
| A．show the VIIRS data from NASA |
| B．demonstrate the significance of VIIRS for its measurement of wavelengths |
| C．reveal the relationship between wavelength light and GDP |
| D．arouse peoples awareness of light pollution |
