Two big powers supporting different factions in the Syrian civil war clashed with each other Tuesday when Turkish fighter jets shot down a Russian warplane that Turkey said had strayed into its airspace.Neil MacFarquhar and Steven Erlanger
 Cancer researchers say there has been a substantial increase in women under the age of 26 who have received a diagnosis of early-stage cervical cancer, a pattern that they say is most likely an effect of the Affordable Care Act.Sabrina Tavernise

President Barack Obama presented the Presidential Medal of Freedom to Bonnie Carroll, president of the Tragedy Assistance Program for Survivors, during a ceremony in the East Room of the White House on Tuesday. 

Erik Hill
Chicago officials released a chilling dashcam video of the fatal shooting of a black 17-year-old on Tuesday, just hours after a white police officer was charged with first-degree murder in the encounter.MONICA DAVEY and MITCH SMITH
At least 11 people were killed and 14 injured here Tuesday afternoon by an explosion that heavily damaged a bus carrying members of the president’s security guard.
A private space company founded by Amazon CEO Jeff Bezos announced Tuesday that it had landed a rocket upright and gently enough to be used again, a milestone in commercial aeronautics.Malcolm Ritter | Associated Press
The appearance of numerous large craters in Siberian permafrost has been attributed, at least by some, to the venting of large pockets of methane gas, possibly in a dramatic or sudden way. Chris Mooney | The Washington Post
Police on Tuesday arrested two men suspected of shooting five Black Lives Matter demonstrators, while the family of a black man whose death inspired the protests called for an end to demonstrations that have gone on for days outside a Minneapolis police station.Steve Karnowski
A white Chicago police officer accused of fatally shooting a black teenager was charged with murder Tuesday, just a day ahead of a deadline for the city to release a squad-car video of the killing.The Associated Press
Turkey shot down a Russian warplane on Tuesday that it said ignored repeated warnings and crossed into its airspace from Syria, killing at least one of the two pilots in a long-feared escalation in tensions between Russia and NATO. Russian President Vladimir Putin denounced what he called a "stab in the back" and warned of "significant consequences."Suzan Fraser, Nataliya Vasily | AP
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