Merrit Kennedy

Could there be life under the icy surface of Saturn's moon Enceladus?

Scientists have found a promising sign.

NASA announced on Thursday that its Cassini spacecraft mission to Saturn has gathered new evidence that there's a chemical reaction taking place under the moon's icy surface that could provide conditions for life. They described their findings in the journal Science.

Canada has taken a major step toward legalizing marijuana for recreational use.

Prime Minister Justin Trudeau's government introduced legislation that would allow adults to possess, share and purchase marijuana, while also strengthening penalties for those who give or sell the products to youth.

This law has been hotly anticipated, with pot producers and the medical community watching closely.

Boko Haram militants have used 27 children to carry out suicide bombing attacks in the first three months of this year in Nigeria, Chad, Niger and Cameroon, according to a new report from UNICEF.

This marks a major increase — 30 children were used in bombings for all of 2016 in those four countries, where Boko Haram is active.

UNICEF says 117 children have been used in suicide attacks since 2014. Eighty percent of them were girls.

Wondering how many kinds of trees there are? There's now a database that can answer that.

Scientists from the U.K.-based Botanic Gardens Conservation International say they have compiled the first-ever comprehensive list of all known tree species, totaling 60,065 different kinds.

Updated at 6:00 p.m. ET

Three explosions went off near the bus of Germany's Borussia Dortmund soccer team on Tuesday evening in the city of Dortmund, local police say.

The team said on Twitter that one of its players, defender Marc Bartra, suffered a broken wrist and is being treated in a hospital. The injury required surgery.

Amnesty International says there were fewer executions worldwide last year than the year before — but the number of death sentences handed down is the highest it has ever recorded.

In its annual report, Amnesty estimates that China carried out more executions than all the other countries put together. The human rights group says China put thousands of people to death. The exact figure is classified as a state secret and is not included in Amnesty's worldwide total.

North Korea is threatening "tough counteraction" after a U.S. Navy strike group was routed toward the Korean Peninsula following the rogue nation's continued ballistic missile and nuclear testing.

"We never beg for peace but we will take the toughest counteraction against the provocateurs in order to defend ourselves by powerful force of arms and keep to the road chosen by ourselves," the official Korean Central News Agency reported in English, quoting a Foreign Ministry official.

Dylann Roof, who gunned down nine people in the basement of a historically black church in Charleston in 2015, pleaded guilty to murder charges at a South Carolina state court.

In exchange, a circuit judge is expected to hand down a life sentence Monday afternoon, as The Post and Courier reported.

For the second consecutive year, aerial surveys show severe coral bleaching in the Great Barrier Reef off the coast of Australia.

While severe bleaching events have occurred three other times in the past 20 years — in 1998, 2002 and 2016 — this year marks the first time it's known to have happened two years in a row. Scientists say the damage is caused by higher water temperatures due to global warming.

In an elaborate ceremony, Thailand's king has signed the country's military-backed constitution. The document paves the way for Thailand to hold elections in the coming months, but critics say it only solidifies the power of the military.

Updated at 12:18 p.m. ET

House Intelligence Chairman Devin Nunes says he is temporarily stepping aside from the committee's probe into Russian meddling in the 2016 election, as the House Ethics Committee opens an inquiry into whether he improperly disclosed classified information.

Nunes will continue to serve as the committee's chairman and remain involved in other matters before the panel. Rep. Mike Conaway, R-Texas, will take the lead on the Russia investigation.

A dog is being credited with saving lives by intervening to stop a suicide bomber who was attempted to enter a wedding party near Maiduguri, Nigeria.

Army radio says that the dog grappled with the teen girl bomber until the explosives went off, killing them both, as NPR's Ofeibea Quist-Arcton reports.

"Most Belbelo villagers were reportedly at the wedding when the dog pounced on the would-be suicide bomber, who was reportedly hovering on the outskirts of the ceremony on Sunday morning," Ofeibea adds.

A huge, internally flawless, 59.60-carat diamond called the "Pink Star" went for a whopping $71.2 million at auction in Hong Kong — the highest price ever for a jewel.

The oval gem was purchased at Sotheby's by Hong Kong-based jewelry company Chow Tai Fook in a bid placed over the phone by the chairman, who renamed the jewel "CTF PINK STAR" in honor of his late father.

Former Maricopa County Sheriff Joe Arpaio routinely pointed to the notorious, outdoor Tent City Jail he opened in the 1990s as a symbol of his "tough on crime" stance. Inmates live in tents through the sweltering Arizona summer heat and are issued old-fashioned striped prison jumpsuits and pink underwear.

Now, it's shutting down.

This story starts with the mystery of a missing cow.

University of Utah researchers placed seven cow carcasses in Utah's Great Basin Desert, and set up cameras to learn about the behavior patterns of local scavengers.

But a week later, researcher Evan Buechley returned to one of the sites and found no sign of the cow.

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