2 . In the endless sky, the unaided human eye should be able to perceive several thousand stars on a clear, dark night. Unfortunately, growing light pollution has disabled people from the nightly view.
New citizen-science-based research throws alarming light on the problem of “sky glow” — the diffuse illumination (漫射照明) of the night sky that is a form of light pollution. The data came from crowd-sourced observations collected from around the world as part of Globe at Night, a program developed by astronomer Connie Walker.
Light pollution has harmful effects on the practice of astronomy but also on human health and wildlife, since it disturbs the cycle from sunlight to starlight that biological systems have evolved alongside. Furthermore, the loss of visible stars is a great loss of human cultural heritage. Until relatively recently, humans throughout history had an impressive view of the starry night sky, and the effect of this nightly spectacle (壮观) is evident in ancient cultures.
Globe at Night has been gathering data on star visibility since 2006. Anyone can submit observations through the Globe at Night web application. Participants record which one best matches what they can see in the sky without any telescopes or other instruments.
Researchers find that the loss of visible stars indicates an increase in sky brightness of 9.6% per year while roughly 2% is measured by satellites. Existing satellites are not well suited to measuring sky glow as it appears to humans, because they can not detect wavelengths shorter than 500 nanometers (纳米). White LEDs, with shorter wavelengths under 500 nanometers, now are increasingly commonly used in outdoor lighting. But human eyes are more sensitive to these shorter wavelengths at nighttime. Space-based instruments do not measure light from windows, either. But these sources are significant contributors to sky glow us seen from the ground.
“The increase in sky glow over the past decade underlines the importance of redoubling our efforts and developing new strategies to protect dark skies,” said Walker. “The Globe at Night dataset is necessary in our ongoing evaluation of changes in sky glow, and we encourage whoever can to get involved to help protect the starry night sky.”
1. What is a purpose of Globe at Night?
| A．To develop new light sources. | B．To collect data on star visibility. |
| C．To help astronomers explore space. | D．To popularize science among citizens. |
2. What does the loss of visible stars lead to?
| A．Poorer human health. | B．Fewer wildlife species. |
| C．More delicate biological systems. | D．Less nightly culture elements of the sky. |
3. What does the author stress in paragraph 5?
| A．Satellites play a vital role. | B．White LEDs are widely used. |
| C．Crowd-sourced data are invaluable. | D．Shorter wavelengths are hard to detect. |
4. What can be inferred from Walker’s words?
| A．Their consistent efforts pay off. | B．The dataset needs to be updated. |
| C．More participants are expected to join in. | D．The sky glow has been over-emphasized. |
