NASA's Cassini spacecraft has discovered signs of what appears to be a large body of water on Enceladus, an icy moon orbiting Saturn. The findings were reported in the journal Science on Thursday.

The Washington Post's Joel Achenbach breaks down the reasons why scientists believe this is actually water: gravity, shape, and plumes. Enceladus appears to have a gravitational asymmetry, with the moon's pull slightly different in the area around the south pole, and calculations make it appear that this is due to liquid water, which is denser than ice. Also at the south pole, there's a depression that bolsters the hypothesis of denser water below the surface. Then there are plumes of water vapor spewing from the south pole, which could be caused by a deep ocean pushing water up through the cracks in the moon's crust.

The report also suggests that Enceladus' sea has a rocky floor, which, The Post adds, "is significant because the contact between liquid water and rock creates the potential for the kind of interesting chemistry that gets astrobiologists excited."

According to NASA, the ocean could be six miles deep, have roughly the same volume of water as Lake Superior, and lie beneath an ice shell 19 to 25 miles thick. Read more at Science. Catherine Garcia

There's been a drop in the number of people getting the flu vaccination, a trend that's worrying infectious disease specialists.

"Flu is serious. Flu is unpredictable," Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention, told reporters Thursday. "Flu often does not get enough respect." In 2015, about 45 percent of the U.S. population received vaccinations, down 1.5 percentage points from 2014, the CDC reports. The largest decrease was in people 50 and up — there was a 3.4 percent drop among people between the ages of 50 and 64, and a 3.3 percent decline among people 65 and over. While most people are hit with mild symptoms, the flu kills 100 children every year, and the elderly are among the most vulnerable to the virus.

While the CDC is urging Americans to get a flu shot now, they are not recommending the nasal spray vaccine, which is often used on kids, due to questions surrounding the vaccine's effectiveness. This year, there are also two new vaccines, NPR reports; one protects against four strains of the flu rather than three, and the other has an "adjuvant," which increases its effectiveness. The CDC expects as many as 168 million vaccines will be available, so "there's plenty for everybody," Frieden said. Catherine Garcia

The New Jersey medical examiner has identified the victim in Thursday morning's train crash in Hoboken as Fabiola Bittar de Kroon, 34.

De Kroon was a resident of Hoboken and native of Brazil, who once worked as a lawyer there at the computer software company SAP, NBC New York reports. She recently moved to Hoboken with her family, and her young daughter was in day care at the time of the accident, which left at least 114 people injured. Officials said de Kroon was waiting on a platform when the New Jersey Transit train came careening into the terminal, and she was hit by falling debris. Catherine Garcia

Hillary Clinton says a Newsweek story about Donald Trump allegedly violating the U.S. trade embargo against Cuba shows he's "puts his personal and business interests ahead of the laws and values and policies of the United States of America."

While investigating the story, published Thursday, Newsweek interviewed former executives of Trump Hotels & Casino Resorts and looked at court filings and company records. They found that in 1998, Trump wanted to get into the Cuban market, and sent a consulting firm to Havana on its behalf to find any business opportunities. The company allegedly spent at least $68,000 in Cuba, without U.S. permission, and Newsweek says they made it appear as though the trip was connected to a Catholic charity. In 1999, Trump wrote in a Miami Herald column that he refused to do business in Cuba because "it would place me directly at odds with the longstanding U.S. policy of isolating Fidel Castro. I had a choice to make: huge profits or human rights. For me, it was a no-brainer."

Trump's campaign manager, Kellyanne Conway, said on Thursday the money was never paid, giving the only statement so far from the Trump camp, the BBC reports. The Cuban-American vote in Florida is huge, and Sen. Marco Rubio (R-Fla.), who has endorsed Trump, told an ESPN/ABC podcast he hopes "the Trump campaign is going to come forward and answer some questions about this, because if what the article says is true — and I'm not saying that it is, we don't know with 100 percent certainty — I'd be deeply concerned about it." Catherine Garcia

A New Jersey Transit commuter train crashed Thursday morning at a station in Hoboken, New Jersey. At least 114 people were injured, New Jersey Gov. Chris Christie (R) told CNN on Thursday afternoon, with many in critical condition. At least one person is confirmed dead.

"I got off my train on the way into work and as I was walking through the station, we could see that a train had come through the place where it's supposed to stop, all the way into the station — not into the waiting room but into the outdoor part," said Nancy Solomon of New York radio station WNYC. Photographs of the crash show significant damage to the station, including a partial collapse of the roof.

The crash happened at the height of the morning commute, around 8:45 a.m., though the number and severity of injuries is still unclear. Preliminary investigation suggests the incident was either accidental or caused by operator error. Full service is expected to resume for evening rush hour.

This post has been updated throughout. Jeva Lange

There's a reason he won all those Tonys.

Sure, Broadway star Lin-Manuel Miranda can make theater sensations out of America's founding history or a dynamic three-day stint in a bustling New York City neighborhood — but that's kid stuff. No, the real talent comes out when you're tasked with making musical magic out of a single stump speech sentence:

Miranda is one of GQ's October 2016 cover men, and you can read the magazine's profile of him here. Kimberly Alters

Hillary Clinton held an early voting campaign event in Des Moines, Iowa, on Thursday, focusing on her lifelong fight "for kids and families," which she said would be "the mission of my presidency."

Clinton and other Democrats are hoping to encourage voters to cast ballots early for fear that a lack of enthusiasm this election cycle could lead to lower voter turnout than occurred for President Obama's election, The Associated Press reports. Four in 10 Iowans voted early in 2012, and this year Democrats hope that number will be even higher, as more Republicans tend to turn up for the polls in November.

While early voting is now open in a handful of states, Iowa is the first battleground state to open voting. At this time, Donald Trump leads the state in the RealClearPolitics average, with 43 percent to Clinton's 38 percent in a four-way race. Jeva Lange

America's millionaire class is expanding rapidly. In just five years, the number of households whose investable assets totaled more than $1 million jumped 41.5 percent, from 4,797,879 millionaires in 2010 to 6,789,666 millionaires in 2015. Moreover, the growth spreads out across every level of the wealth pyramid, Barron's reports. For example, the number of households that crossed the $20 million mark soared a remarkable 64 percent in that time frame. And in a historical first, more than 1 million Americans can be considered penta millionaires, meaning their assets surpass $5 million total. Kelly Gonsalves