While space travel still gets lot of attention, not enough attention has been paid to the exploration of oceans, about which we know much less than the dark side of the moon.   

Ninety percent of the ocean floor has not even been recorded and while we have been to the moon, the technology to explore the ocean's floors is still being developed. For example, a permanent partially-underwater sea exploration station, called the Sea Orbiter, is currently in development.

The oceans play a major role in controlling our climate. But we have not learned yet how to use them to cool us off rather than contribute to our overheating. Ocean organisms are said to hold the promise of cures for a wide of the unique eyes of skate (ray fish) led to advances in conquering blindness, the horseshoe crab was important in developing a test for bacterial pollution, and sea urchins helped in the development of test-tube fertilization(人工授精). The toadfish's' ability to regenerate its central nervous system is of much interest to neuroscientists. A recent Japanese study concluded that the drug Eribulin, which was taken from sea sponges, is effective in fighting with breast, colon, and Urinary cancer.

Given the approaching crisis of water insufficiency, we badly need to improve current methods, of desalinating(淡化) ocean water and make them more efficient and less costly. By 2025, 1.8 billion people are expected to suffer from severe water shortage, with that number jumping to 3. 9 billion by 2050-well over a third of the entire global population.   

If the oceans do not make your heart go beating faster, how about engineering a bacterium that eats carbon dioxide — and thus helps protect the world from overheating — and produces fuel which will allow us to drive our cars and machines, without oil? I cannot find any evidence that people young or old, Americans or citizens of other nations would be less impressed or less inspired with such a breakthrough than with one more set of photos of a faraway galaxy or a whole Milky Way full of stars.

Clothing rental is a hot new industry and retailers (零售商) are demanding to get on board in hopes of attracting green shopper.

But is renting fashion actually more environmentally-friendly than buying it, and if so, how much more? Journalist and author Elizabeth Cline investigated (调查) this question and concluded that it's not as sustainable as it seems.

Take shipping, for example, which has to go two ways if an item is rented — receiving and returning. Cline writes that consumer transportation has the second largest carbon footprint of our collective fashion habit after manufacturing.

She writes, ''An item ordered online and then returned can send out 20 kilograms of carbon each way, and increases up to 50 kilograms for rush shipping. By comparison, the carbon impact of a pair of jeans purchased from a physical store and washed and worn at home is 33.4 kilograms, according to a 2015 study by Levi's.''

Then there's the burden of washing, which has to happen for every item when it's returned, regardless of whether or not it was worn. For most rental services, this usually means dry cleaning, a high impact and polluting process. All the rental services that Cline looked into have replaced perchloroethylene (氯乙烯), a carcinogenic (致癌的) air pollutant, still used by 70 percent of US dry cleaners, with alternatives, although these aren't great either.

Lastly, Cline fears that rental services will increase our appetite for fast fashion, simply because it's so easily accessible. There's something called ''share washing'' that makes people waste more precisely because a product or service is shared and thus is regarded as more eco-friendly. Uber is one example of this, advertised as ''a way to share rides and limit ear ownership.'' and yet ''it has been proven to discourage walking,bicycling, and public transportation use.''

Renting clothes is still preferable to buying them cheap and throwing them in the dustbin after a few wears, but we shouldn't let the availability of these services make us too satisfied. There's an even better step — that's wearing what is already in the closet.

How does an ecosystem (生态系统) work? What makes the populations of different species the way they are? Why are there so many flies and so few wolves? To find an answer, scientists have built mathematical models of food webs, noting who eats whom and how much each one eats.

With such models, scientists have found out some key principles operating in food webs. Most food webs, for instance, consist of many weak links rather than a few strong ones. When a predator (掠食动物) always eats huge numbers of a single prey (猎物), the two species are strongly linked; when a predator lives on various species, they are weakly linked. Food webs may be dominated by many weak links because that arrangement is more stable over the long term. If a predator can eat several species, it can survive the extinction (灭绝) of one of them. And if a predator can move on to another species that is easier to find when a prey species becomes rare, the switch allows the original prey to recover. The weak links may thus keep species from driving one another to extinction.

Mathematical models have also revealed that food webs may be unstable, where small changes of top predators can lead to big effects throughout entire ecosystems. In the 1960s, scientists proposed that predators at the top of a food web had a surprising amount of control over the size of populations of other species—including species they did not directly attack.

And unplanned human activities have proved the idea of top-down control by top predators to be true. In the ocean, we fished for top predators such as cod on an industrial scale, while on land, we killed off large predators such as wolves. These actions have greatly affected the ecological balance.

Scientists have built an early-warning system based on mathematical models. Ideally, the system would tell us when to adapt human activities that are pushing an ecosystem toward a breakdown or would even allow us to pull an ecosystem back from the borderline. Prevention is key, which scientists says because once ecosystems pass their tipping point (临界点), it is remarkably difficult for them to return.