3 . The company SpaceX has already launched hundreds of its Star-link satellites, with plans to put as many as 42,000 of them in Earth orbit. Its goal is to provide high-speed Internet to billions of people. Moving toward that kind of access is important, but it comes at a cost. Glittering with reflected sunlight, these first orbiters, sent up in the past year, are brighter than 99 percent of the 5,000 or so other satellites now circling Earth, and obviously there are going to be a lot more. This sudden increase is bad for astronomy: the probability of a Star-link satellite crossing a telescope’s field of view and ruining an observation will be quite high near sunset. For that reason, my fellow astronomers have signed a petition (请愿书) calling for governments to protect the night sky from this invasion.

In response to protests, SpaceX has promised to address the visibility problem by, for example, applying experimental coatings — essentially painting the satellites black — but the company’s aggressive launch schedule remains unchanged. And the satellites’ illuminated (被照亮) surfaces are mostly their solar panels — exactly the part that cannot be painted over.

Unfortunately, at present no regulations govern how bright a single satellite can be, let alone thousands of them together. Even if there were such regulations, one nation’s laws can not hinder (阻碍) another country’s launches. Space literally has no borders, and the sky will need to be protected at an international level. As a consequence, we hope that the United Nations will find a way to think outside of the box to save the sky for everyone.

When I was growing up in Montana, it was a game to be the first to find a moving satellite among the host of stars in the night sky. Soon it could be a game to recognize the constellations (星座) behind a swarm of moving points of light.

4 . Hardware in general, and smartphones in particular, have become a huge environmental and health problem in the Global South's landfill sites （垃圾填埋场）.

Electronic waste（ e-waste ） currently takes up 5 percent of all global waste, and it is set to increase rapidly as more of us own more than one smartphone, laptop and power bank. They end up in places like Agbogbloshie on the outskirts of Ghana's capital, Accra. It is the biggest e-waste dump in the world, where 10, 000 informal workers walk through tons of abandoned goods as part of an informal recycling process. They risk their health searching for the precious metals that are found in abandoned smartphones.

But Agbogbloshie should not exist. The Basel Convention, a 1989 treaty, aims to prevent developed nations from unauthorized dumping of e-waste in less developed countries. The e-waste industry, however, circumvents the regulations by exporting e-waste labelled as "secondhand goods" to poor countries like Ghana, knowing full well that it is heading for a landfill site.

A recent report found Agbogbloshie contained some of the most dangerous chemicals. This is not surprising: smartphones contain chemicals like mercury （水银），lead and even arsenic（砷）. Reportedly, one egg from a free-range chicken in Agbogbloshie contained a certain chemical which can cause cancer and damage the immune system at a level that's about 220 times greater than a limit set by the European Food Safety Authority（EFSA） . Most worryingly, these poisonous chemicals are free to pollute the broader soil and water system. This should concern us all, since some of Ghana's top exports are cocoa and nuts.

Some governments have started to take responsibility for their consumers' waste. For example, Germany has started a project that includes a sustainable （可持续的）recycling system at Agbogbloshie, along with a health clinic for workers. However, governments cannot solve the problem alone, as there is an almost limitless consumer demand for hardware, especially when governments green policies are focused on issues like climate change.

Only the manufacturers can fix this. A more economically sustainable and politically possible solution is through encouraging hardware manufacturers to make the repair, reuse and recycling of hardware profitable, or at least cost-neutral.