It feels as if US politics reached a major inflection point on Wednesday when the news broke that high-profile right-wing activist Charlie Kirk, an important ally of Donald Trump, had been shot dead while speaking at a campus event at a university in Utah. Social media exploded, with some calling for calm and urging people to be mindful of a young life lost and a wife and small children left bereaved. Other, less measured, voices spoke of retribution.

There is a real risk of political violence in the US spinning out of control. Driven by a polarisation of political debate and cheapened by a dangerous dehumanisation of people’s “enemies” on the other side of the ideological divide, messages of division and hate can spread like wildfire in a country where the second amendment means there are far too many guns. Kirk himself was an advocate for the second amendment. But, as his legacy is fought over, it should be remembered that he was also known for his dedication to free debate.

In the Amazon, Indigenous activists are also using modern tools of communication with a different goal. To bring the everyday realities of their love for their land to a wider audience. And if you’ve been terrified by the nasties on the TV series Alien: Earth, our scientists are here to reassure you that not all of them are plausible creations.