【推荐1】Researchers have identified a growing threat to astronomy from the sunlight reflecting off communication devices in space. One such device, a communication satellite called BlueWalker 3, is currently one of the brightest objects visible from Earth, matching the brightness of Procyon and Achemar, two of the brightest stars in the night sky.

“BlueWalker 3 is visible in both dark sky and urban skies, though in urban settings this will be limited to when BlueWalker 3 passes overhead,” said Dr. Jeremy Tregloan-Reed, a co-author of the study at the University of Atacama in Chile. “Large constellations (星座) of bright artificial satellites in low Earth orbit pose significant challenges to ground-based astronomy,” the study’s authors wrote.

Tregloan-Reed said a large reflective brightness means that when a satellite crosses the detector of a telescope, it leaves a mark that can be difficult, if not impossible, to remove. This could lead to loss of data from the affected pixels (像素). But he said space-based astronomy also faced challenges from such satellites, noting that observations by the Hubble telescope had increasingly been affected by marks from Starlink satellites. Besides, the team notes the radio frequencies used by BlueWalker 3 are close to those used for radio astronomy, raising the possibility that such satellites could cause interference.

While BlueWalker 3 was folded when it was launched last year, once in space it opened up to reveal a huge surface area that reflected sunlight. Tregloan-Reed added that even if all the reflective brightness of all satellites was reduced to below the level visible by the naked eye, “the sky background glow will increase due to the accumulative effect of having hundreds of thousands of satellites from various operators from many countries in low Earth orbit. It is disastrous!”

BlueWalker 3, built by AST Space Mobile, is just the first one to be launched. The company is planning a constellation of satellites nicknamed BlueBirds, consisting of over 100 similar satellites and aimed to provide satellite network service for the whole world. You can imagine how bright the night sky will be at that time!

【推荐2】Gardeners are often puzzled by the sudden appearance of an unusual orchid(兰花) or sometimes are disappointed that their annuals have vanished. Scientists have discovered that some British flowers can lie dormant (休眠的) under the ground for up to 20 years, coming out to bloom only when the conditions are just right. Orchids seem particularly good at being dormant for years at a time, the scientists discovered.

Michael Hutchings, Professor of Ecology at the University of Suss, said: “Being underground means they cannot receive sunshine, neither flower nor reproduce. And yet this study has shown that many plants in a large number of species frequently go through dormancy (休眠). Many of these species have found ways to overcome the loss of sunshine during dormancy, especially by gradually developing their ability to get what they need from soil. This allows them to survive and even grow well during dormant periods.”

The research found that dormancy occurs when the weather is poor, or there is a new threat from animals or competing plants. Sometimes winters are so mild that the plant does not realize that spring has begun. Dormancy in seeds has been widely known about and studied for years, but the dormancy in adult plants is far less well-known and understood.

The study, led by Professor Richard Shefferson in University of Tokyo, is the first detailed analysis of the causes. Dormancy appears to be more common near the equator (赤道), where threats from factors such as disease, competition, animals and fire are more severe. Co-author Dr. Eric Menges said:“ In those areas, it is most suitable for plants to remain dormant and then to grow when favourable conditions exist for growth and flowering. ”

【推荐3】You never forget your first whale. The impact it makes upon you is huge and life is never quite the same again. My first whale was a 40-foot grey one, off the coast of California in 1979, and I've been a whale addict ever since. Now I have to go whale watching regularly just to survive normal daily life.

I may be crazy but I am certainly not alone. The world is filled with whale watchers: since its beginnings in the mid-fifties, whale watching has grown dramatically and now more than 13 million people join organized whale watching trips every year.

As a faithful whale watcher, all your holidays center on whales. The only books you read are ones about whales; you wear whale T-shirts, and every time you meet your friends you talk about whales.

So what is it about these larger-than-life animals that makes them so special? Their enormous size is one possible explanation: imagine sitting in a small boat next to a blue whale almost as long as a Boeing 737. The fact that we know so little about them is another possibility: modern technology has taken us to the moon and beyond, yet we are only just beginning to understand these extraordinary forms of intelligent life on our own planet.

Planning and patience are just two essential requirements for successful whale watching. Planning is needed because there are certain whale hot spots-where you have the best chance of seeing them-and because the larger species tend to be on their way from feeding areas to breeding grounds, so rarely do they stay in one place for more than a few months at a time.

Patience is necessary because, even under the best conditions, whales can be tricky to find. However, most commercial whale watching trips have a surprisingly high success rate because they tend to concentrate on well-known whale populations at peak (最高的) seasons.

【推荐1】In early October, Travis Gienger transported an enormous pumpkin (南瓜) from his home in Minnesota to the World Championship Pumpkin Weigh-Off in California. His pumpkin set the record for the biggest one ever grown in North America. How do competitive growers get their pumpkins to grow to massive sizes?     1    

Gienger, who teaches horticulture (园艺学) at Anoka Technical College, begins growing his pumpkins in mid-April, starting with seeds that he grows indoors for the first few weeks, when Minnesota’s soil is too frosty.     2     They can absorb sunlight, nutrients from the soil, and water there. “At their peak, you’re watering them with at least 600 liters a day, ” he says.

Depending on the variety, pumpkin plants can grow up to a dozen fruits on a single vine (藤曼) . But to maximize size, growers remove all but one or two of these pumpkins in order to decrease each individual fruit’s competition for resources.     3    

But what exactly happens inside a pumpkin as it grows? Two factors drive natural growth: cell division and cell expansion. Cell division accounts for most of the growth at the beginning of a fruit’s life. This period lasts for about 20 days in pumpkin plants.     4     Pumpkin cells will expand until around 50 or 60 days after pollination (授粉).

    5     Some varieties of pumpkins have been bred specifically to maximize their size. Still, there is genetic variation even among pumpkins of the same variety. This has led to competition for the best seeds. Following each harvest, many growers auction off (拍卖掉) the seeds from their biggest pumpkins, which will then be used for the following year’s plantings.

【推荐3】Farming today not only sends out greenhouse gas but destroys wildlife habitats. Agriculture now takes up half of Earth’s hospitable land surface, at the expense of these habitats. So I hope to restore current farmland to its natural state by ending the vegetation (植被) stage of crop-growing.

My PhD research at Wageningen University in the Netherlands is inspired by alternative, indoor methods of food production, such as farming leafy green vegetables vertically (垂直地) and growing meat in a laboratory. I wondered — if you can grow meat without an animal, can you grow fruit without a plant? This could be done inside, which might help us to return some agricultural land to nature.

During my master’s programme in agricultural engineering, I discussed indoor fruit production with my professor. He eagerly invited me to write a master’s paper on the subject of growing fruits without the plant.

The main task of my PhD is to collect immature fruit or flowers from tomato plants, and try to grow the stems (茎) into healthy, high-quality tomatoes in the lab. Ultimately, we want to produce fruit from tomato undifferentiated cells from which new plant organs can grow — and skip using a plant entirely.

I had achieved some early results of my research, when I was testing different growing conditions at different stages of tomato development. The lighting is an energy-efficiency measure; we use blue and red LEDs, the best colours for photosynthesis.

Some people get excited about the possibilities of my work, but most are doubtful, which I understand. In the past, people have rushed into using food technologies, such as cage-grown chickens and the extensive use of fertilizer, without considering the potential downsides. An important part of my PhD programme will be to assess the sustainability of my method.