It is important to protect yourself from harmful rays. But if you think a high-factor sunscreen keeps you safe from harmful rays, you may be wrong. Research in this week's Nature shows that while factor 50 reduces the number of melanomas（黑瘤）and delays their occurrence, it can't prevent them. Melanomas are the most aggressive skin cancers. You have a higher risk if you have red or blond hair, fair skin, blue or green eyes, or sunburn easily, or if a close relative has had one. Melanomas are more common if you have periodic intense exposure to the sun. Other skin cancers are increasingly likely with long-term exposure.

    There is continuing debate as to how effective sunscreen is in reducing melanomas – the evidence is weaker than it is for preventing other types of skin cancer. A 2011 Australian study of 1,621 people found that people randomly selected to apply sunscreen daily had half the rate of melanomas of people who used cream as needed. A second study, comparing 1,167 people with melanomas to 1.101 who didn't have the cancer, found that using sunscreen routinely, alongside other protection such as hats, long sleeves or staying in the shade, did give some protection. This study said other forms of sun protection – no sunscreen – seemed most beneficial. The study relied on people remembering what they had done over each decade of their lives, so it's not entirely reliable. But it seems reasonable to think sunscreen gives people a false sense of security in the sun.

    Many people also don't use sunscreen properly applying insufficient amounts, failing to reapply after a couple of hours and staying in the sun too long. It is sunburn that is most worrying – recent research shows five episodes of sunburn in the teenage years increases the risk of all skin cancers.

    The good news is that a combination of sunscreen and covering up can reduce melanoma rates, as shown by Australian figures from their slip-slop-slap campaign. So if there is a heat wave this summer, it would be best for us, too, to slip on a shirt, use sunscreen and slap on a hat.

    Following news of the potential for life on the recently-discovered TRAPPIST-1 system, there may be another competitor ready to take its place.

    With the help of the Cassini spacecraft, NASA (National Aeronautics and Space Administration) scientists have picked up the first evidence that chemical reactions are taking place deep below the surface of Enceladus, Saturn's (土星的) sixth-largest moon. This means that there could be life in Enceladus' warm underground seas.

    An early study found that liquid oceans exist miles below Enceladus' surface. But to reveal what is happening down there, scientists must rely on the plumes (股) of water that spray (喷射) through cracks in Enceladus' icy surface. In October 2015, NASA sent Cassini into a deep dive into one of the plumes.

    Cassini's findings, published on April 13 in the journal Science, showed that hydrogen (氢) not only exists on Enceladus, but is also responsible for a chemical reaction between hot rocks and water in the ocean beneath its surface.

    This same process on Earth provides energy for entire ecosystems around volcanic vents (火山口). There, tiny creatures are able to survive without sunlight, using hydrogen and carbon dioxide as fuel in a process known as “methanogenesis (甲烷生成)”.

    The discovery of this chemical energy source on Enceladus means it could be a very good candidate to host life.

    “Confirmation (确认) that the chemical energy for life exists within the ocean of a small moon of Saturn is an important milestone (里程碑) in our search for habitable (可居住的) worlds beyond Earth,” Linda Spilker, Cassini project scientist at NASA, told the Daily Mail.

    Alien life was once only thought possible on habitable planets within the “Goldilocks zone” – far enough from our sun not to be a fireball, but not so far as to be freezing.

    Research on Enceladus is still in its early stages, but the recent findings have important meanings for future exploration.

    “At present, we know of only one genesis (诞生) of life, the one that led to us,” David Rothery, professor of planetary geosciences (行星与地球科学) from the Open University in the UK, told The Telegraph.

    “If we knew that life had started independently in two places in our solar system, then we could be pretty confident that life also got started on some of the tens of billions of planets and moons around other stars in our galaxy,” he said.

    A new family moved in next door and I got to meet the mother of the family, Lydia. Lydia is Korean, and her family moved to our city so her husband could go to graduate school. We started talking, and she was apologetic about how bad her English was, but I didn't care. I knew how hard it was to learn a second language. I enjoyed chatting with Lydia as we watched our kids play.

    It was what came next that challenged me: Lydia asked if I'd be willing to help her with her English. Now, I am not a teacher. I admire teachers, and I'm grateful for teachers, and it's because I admire what they do so much that I was very very sure that I couldn't do it myself.

    But Lydia was sure that she wanted my help. I was doubtful. I wasn't sure my "help" was even worth being called by that name. But because she asked me, I said "yes." And that was the beginning of a friendship. Lydia and I spent afternoons sitting together and reading the newspaper, and as we did, she asked me questions when she had them questions about language, yes, but also questions about the new culture she found herself in. In turn, I asked my own questions, growing curious about her home country and culture. We bonded over our shared faith and our struggles as mothers of kids with special needs, When I complimented（恭维） her cooking, she began to teach me about Korean food, eventually leading to a shared trip to explore the Korean grocery stores in our city. Because of Lydia, 1 learned more about my own hometown than I ever could have learned by myself. I'm still not sure that I'm any good as a teacher. But I'm grateful I said "yes" when my neighbor asked me to help her with her English. That meant spending extra time with my neighbor, and that extra time meant she didn't remain just my neighbor. She became my friend.

    Traveling to Europe to see its famous monuments like the Eiffel Tower in Paris and the Colosseum(古罗马竞技场)in Rome, is not exactly the ideal vacation for kids. Fortunately, Europe has more to offer than lots of old churches and ancient history. You can enjoy some fun with your kids in the sun at some of the famous beaches of the continent.

    Mykonos, Greece

    The closer you get to the equator, the longer the beach season is, and Greece is wonderful for that. You can enjoy beautiful green water, public chairs and lovely umbrellas at the beaches in Mykonos.

    Dubrovnik, Croatia

    There's nothing more attractive than the beautiful beaches bordering Dubrovnik, Croatia's most beautiful city. It's surrounded by stone walls like a castle. It almost makes you feel like you're suntanning(晒黑皮肤)at Hogwarts, where the hero Harry Potter of the story is trained!

    Sicily, Italy

    Rabbit Beach on the island of Sicily offers shallow and crystal clear waters, making it a perfect beach for families with young children. And if you want to add interest to your experience, try snorkeling(徒手潜水).

    Nice, France

    Lined with palm trees and first-class hotels, the city of Nice, located on the French Riviera, offers a whole coastline of Mediterranean beaches. Because they're in the heart of the city, these beaches attract a large crowd. So if you're looking for something more private, you'll have to travel a few miles outside of the city center.

    Ribadeo, Spain

    At low tide, Playa de las Catedrales in Ribadeo, Spain is the perfect beach to take in the natural wonders without urban amusements like restaurants, bars or huge crowds. It boasts beautiful wild flowers and unique rock formations making it truly a picture worthy.

    Scientists say they discovered an earth­like planet orbiting the star closest to our planet other than the sun. It is the closest planet ever found outside our solar system that could support life as we know it. This planet is just 4.2 light years away from us. It is so close that space scientists have compared it to a next door neighbor. They say it could be reached by an unmanned spacecraft before the end of the century. The newly­discovered planet is a little larger than the earth. Scientists have named it Proxima b. It orbits its sun, Proxima Centauri, once every 11days.

    Alan Boss is the Chairman of NASA's advisory group for planet exploration. He told VOA that Proxima b not only confirms the discovery of a planet, but also increases the number of other possible "earths" by a huge amount. Boss said it is possible that most stars may have at least one earth­like planet orbiting them.

    This makes the possibility of living organisms increasingly likely. Boss said he believes human beings will prove that there is life in places other than the earth in his lifetime. "I am 65," he told VOA, "But I expect to still be alive when it happens."

    Paul Butler works at the Carnegie Institution of Washington. He told VOA that finding Proxima b "makes the case concrete" that there are other planets where life could exist. Paul Butler said the researchers used two telescopes in different countries to look for possible planets like the earth. Discovering Proxima b, he believes, changes the world.

    "This work has resulted in the discovery of hundreds of planets around the nearest stars, and now a potentially habitable planet around the nearest star is in the sky," Butler said.