No one knows where it came from, but it’s here now. And the chase is on.

Astronomers around the world are monitoring an interstellar comet hurtling through the solar system, known for the moment as C/2019 Q4. It’s the second time in less than two years that they’ve seen an object from another star swing through our cosmic neighborhood. The first time around, the discovery kicked off a worldwide sprint to inspect the object before it got away. It was mysterious enough that some astronomers even began to consider whether it was dispatched by an advanced alien civilization.

This second interstellar object was spotted in late August by Gennady Borisov, an amateur astronomer in Crimea. Borisov has a reputation for catching never-before-seen comets with his telescopes, but they’re from around here; like everything else in the solar system—the planets, the moons, a sea of asteroids—they trace an orbit around the sun. And over the past few weeks, it’s become very clear that this comet does not.

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To be a parent is to be compromised. You pledge allegiance to justice for all, you swear that private attachments can rhyme with the public good, but when the choice comes down to your child or an abstraction—even the well-being of children you don’t know—you’ll betray your principles to the fierce unfairness of love. Then life takes revenge on the conceit that your child’s fate lies in your hands at all. The organized pathologies of adults, including yours—sometimes known as politics—find a way to infect the world of children. Only they can save themselves.

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Our son underwent his first school interview soon after turning 2. He’d been using words for about a year. An admissions officer at a private school with brand-new, beautifully and sustainably constructed art and dance studios gave him a piece of paper and crayons. While she questioned my wife and me about our work, our son drew a yellow circle over a green squiggle.

Years ago, when she was practicing her closing arguments at the family dinner table, Martha Kavanaugh often returned to her signature line as a state prosecutor. “Use your common sense,” she’d say. “What rings true? What rings false?”

Those words made a strong impression on her young son, Brett. They also made a strong impression on us, as we embarked on our 10-month investigation of the Supreme Court justice. We conducted hundreds of interviews with principal players in Kavanaugh’s education, career, and confirmation. We read thousands of documents. We reviewed hours of television interviews, along with reams of newspaper, magazine, and digital coverage. We studied maps of Montgomery Country, Maryland, as well as housing-renovation plans and court records. We watched Kavanaugh’s confirmation hearings multiple times.

During the 2016 campaign, I received a phone call from an influential political journalist and author, who was soliciting my thoughts on Donald Trump. Trump’s rise in the Republican Party was still something of a shock, and he wanted to know the things I felt he should keep in mind as he went about the task of covering Trump.

At the top of my list: Talk to psychologists and psychiatrists about the state of Trump’s mental health, since I considered that to be the most important thing when it came to understanding him. It was Trump’s Rosetta stone.

I wasn’t shy about making the same case publicly. During a July 14, 2016, appearance on C-SPAN’s Washington Journal, for example, I responded to a pro-Trump caller who was upset that I opposed Trump despite my having been a Republican for my entire adult life and having served in the Reagan and George H. W. Bush administrations and the George W. Bush White House.

The MIT Media Lab has an integrity problem. It’s not just that the lab took donations from Jeffrey Epstein and tried to conceal their source. As that news was breaking, Business Insider reported that the lab’s much-hyped “food computer” didn’t work and that staff had tried to mislead funders into thinking it did. These stories are two sides of the same problem: sugar-daddy science—the distortion of the research process by the pursuit of money from ultra-wealthy donors, no matter how shady.

Historically, research has been funded by grants. Government agencies and foundations announce that they want to fund X, and you, the scientist, write a proposal about why you’ll be awesome at X. If they agree, they give you money to do X.

In the 15th century, when Europeans first reached the island now named Puerto Rico, it was home to between 30,000 and 70,000 people, sometimes known collectively as Taíno. They came from various ethnic groups descended from several waves of ancestors who came to the island in succession, beginning as early as 3,000 B.C. But a century after the colonizers arrived, official traces of these indigenous peoples were all but impossible to find.

Under a regime of forced relocations, starvation, disease, and slavery, their numbers plummeted. At the same time, colonial officials elided their existence, removing them as a distinct group from the census and recategorizing many—from Christian converts to wives of colonists—as Spanish or “other.”

Along Alaska’s west coast, about 80 miles above the Arctic circle, sits the village of Kivalina, situated on a narrow strip of land between a lagoon and the Chukchi Sea—one of several native coastal villages dealing with problems due to the warming of the Arctic. Joe Raedle, a photographer for Getty, recently flew to Kivalina to spend some time with the villagers and photograph their lives and surroundings. The warming climate has led to troubles such as the accelerated erosion of the land the village sits on, which used to be mitigated by sea ice (which is vanishing), and permafrost (which is melting). Fish and wildlife that villagers rely on for food have been forced to change their migration patterns—and poor hunting means more food must be bought from a store, further increasing the cost of living. Raedle: “The residents of Kivalina are hoping to stay on their ancestral lands, where they can preserve their culture, rather than dispersing due to their island being swallowed by the rising waters of the ocean.”

Updated on September 18 at 3:10 p.m. ET

In 2016, Bernie Sanders described the Working Families Party (WFP), a grassroots progressive organization, as “the closest thing there is” to his “vision of democratic socialism.” The group endorsed him in his primary race against Hillary Clinton, and it’s grown more powerful in the past three years, as it has sought to build a multiracial populist movement nationwide. But this time around, with Sanders taking another shot for the White House, the group is throwing its weight behind someone else: Elizabeth Warren. The group’s surprising decision could be an early indicator of how progressives—including those who backed Sanders in the past—are planning to organize and vote next year.

Annika Reinhold says that she likes playing with animals (she has two cats) and “doing unconventional things that no one has done before.” When the chance came up to teach rats to play hide-and-seek, she was a natural candidate.

One might question the wisdom of training rats to hide, but there’s a good reason to do so. In neuroscience, animal research is traditionally about control and conditioning—training animals, in carefully regulated settings, to do specific tasks using food rewards. But those techniques aren’t very useful for studying the neuroscience of play, which is universal to humans, widespread among animals, and the antithesis of control and conditioning. Playing is about freedom and fun. How do you duplicate those qualities in a lab?

In aviation, the black box is a source of knowledge: a receptacle of crucial data that might help investigators understand catastrophe. In technology, a black box is the absence of knowledge: a catchall term describing an algorithmic system with mechanics its creators can’t—or won’t—explain. Algorithms, in this telling, are unknowable, uncontrollable, and independent of human oversight, even as they promote extremist content, make decisions affecting our health, or act in potential violation of antitrust law.

In investigative reports and international courts, Amazon, Google, and other tech platforms have been accused of tweaking their search algorithms to boost their own profits and sidestep antitrust regulations. Each company denies interfering with its respective search algorithm, and because of the murky mechanics of how search works, proving the allegations is nearly impossible.