You probably know who Marie Curie was, but you may not have heard of Rachel Carson. Of the outstanding ladies listed below, who do you think was the most important woman of the past 100 years?

Jane Addams (1860-1935)

Anyone who has ever been helped by a social worker has Jane Addams to thank. Addams helped the poor and worked for peace. She encouraged a sense of community by creating shelters and promoting education and services for people in need. In 1931, Addams became the first American woman to win the Nobel Peace Prize.

Rachel Carson (1907-1964)

If it weren’t for Rachel Carson, the environmental movement might not exist today. Her popular 1962 book Silent Spring raised awareness of the dangers of pollution and the harmful effects of chemicals on humans and on the world’s lakes and oceans.

Sandra Day O’Connor (1930-present)

When Sandra Day O’Connor finished third in her class at Stanford Law School, in 1952, she could not find work at a law firm because she was a woman. She became an Arizona state senator and in 1981, the first woman to join the U.S. Supreme Court. O’Connor gave the deciding vote in many important cases during her 24 years on the top court.

Rosa Parks (1913-2005)

On December 1,1955, in Montgomery, Alabama, Rasa Parks would not give up her seat on a bus to a white passenger. Her simple act landed Parks in prison. But it also set off the Montgomery bus boycott(抵制). It lasted for more than a year, and kicked off the civil-rights movement. “The only tired I was, was tired of giving in,” said Parks.

What do Tom Sawyer and Jumping Frogs have in common? Stories about both of them were created by one man: Mark Twain. When Twain was 4, his family moved to Hannibal, Missouri, lying on the west bank of the Mississippi. Twain grew up there and was attracted greatly with life along the river — the steamboats, the big wooden boats, and the people who worked on them.

The Celebrated Jumping Frog of Calaveras County is one of Twain’s best-loved short stories, and The Adventures of Tom Sawyer is one of his most famous novels. Both these works are celebrated by events held during National Tom Sawyer Days. There’s also a fence-painting competition to see who can paint the fastest. The idea for this competition comes from a scene in Tom Sawyer, in which Tom has been told to paint the fence in front of the house he lives in. It’s a beautiful day, and he would rather be doing anything else. As his friends walk by, he persuades them to paint with him for fun, and they all join in the “fun”. By the end of the day, the fence has three coats of paint!

Although the story of Tom Sawyer is not true, it’s based on fact. If you go to Hannibal, you’ll see the white fence, which still stands at Twain’s boyhood home.

Back in 1807, London became the first city on the planet to have a street lit up by gaslight lamps. For the city’s residents, it seemed like an extraordinary thing to have evening turned into a version of daytime. But more than two centuries later, artificial light has spread across so much of the planet that it has become a threat to us as well as the environment.

The extent of light pollution is evidenced by a study in the journal Science Advances, in which researchers used measurements taken by satellites to study the artificial brightness of Earth’s surface at nighttime. They found the artificially lit outdoor area grew at a rate of 2.2% per year. But those increases are just part of the story. Christopher Kyba, a scientist at German Research Center, says the increasing transition to high-efficiency LED lamps for outdoor lighting, which were regarded by most people originally as a way to reduce our dependence upon fossil (化石的) fuels and slow climate change, may not be saving as much electricity as expected.

The American Medical Association added that the wavelengths (波长) at which the lights operate control the hormone that helps us to sleep. “It is estimated that white LED lamps have a much greater impact on people’s sleep than the former streetlights.” Research shows that such impact may be a significant aspect inducing fatness and other physical disorders. Many species on Earth are active at night, and electric lighting, especially dusk to dawn lighting, represents damage to the environment of these species. A study in Proceedings of the National Academy of Science, for example, found powerful beams of light from the National September 11 Memorial and Museum changed the flight paths and speed of 1.1 million migrating birds over a seven-day period alone. And in Florida, light pollution along beaches is disturbing sea turtles having babies, resulting in thousands of young animals’ dying each year.

But perhaps the most obvious thing about light pollution is that much of it results from wasteful light that isn’t necessary, according to Kyba, who estimates that it could be reduced by five to ten times. “I think we should be asking as taxpayers (纳税人). Why are we paying for lights that shine uselessly into people’s windows and disturb their sleep?”