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

When Donald Trump announced he was running for president in 2015, he made a big point about how much smarter China's leaders are than America's presidents. Almost three years later and in the White House, Trump might finally be admitting he underestimated President Xi Jinping, HuffPost's Igor Babic observed Tuesday.

Trump's remarks came during a press conference with South Korean President Moon Jae-in. "I think that President Xi is a world-class poker player," Trump told the press, adding that the North Koreans had "a somewhat different attitude" during negotiations with the U.S. after they met with the Chinese leader. Trump, who admitted that his summit with North Korean Leader Kim Jong Un might be derailed, said of Xi's meeting with North Korea: "I can't say that I'm happy about it."

Compare that with Trump's tone in 2015: "[China's] leaders are much smarter than our leaders, and we can't sustain ourself with that," he said. "There's too much — it's like — it's like take the New England Patriots and Tom Brady and have them play your high school football team. That's the difference between China's leaders and our leaders." Watch below. Jeva Lange

President Trump said it would be "a disgrace" for the United States if there were "spies in my campaign" in remarks Tuesday following a Monday meeting with FBI Director Christopher Wray and Deputy Attorney General Rod Rosenstein.

Trump has demanded that the Justice Department look into whether Obama administration officials coordinated surveillance of his campaign for political reasons following reports that an American academic working as an FBI informant met with several members of his 2016 campaign in the early days of the agency's investigation into Russian election meddling.

"That would be one of the biggest insults that anyone has ever seen," Trump said, although there is no evidence the informant was embedded in his campaign. The president additionally dodged a question about whether he has "confidence" in Rosenstein. Jeva Lange

The chairman and CEO of New York City's transit system is bound to be a busy man: The Metropolitan Transportation Authority carries millions of people every day, often via outdated infrastructure in a constantly-evolving city.

But that man, Joe Lhota, is even busier than one might expect, because he also has a handful of other jobs. Lhota's position as chief of staff at a major hospital network, along with his seats on eight different boards and additional lobbying work on the side make for potential conflicts of interest, The New York Times reported Tuesday.

Lhota has run the MTA since 2017, but delegates much of the work while he juggles his other leadership positions. The Times explains that Lhota's influence in the city has continued to expand, but the amount of time he spends on the troubled subway system has decreased. Lhota is chief of staff at NYU Langone Health, a network of 230 hospitals and clinics. He has reportedly lobbied for NYU Langone while also running the MTA. He is also a paid board member at Madison Square Garden, a major facility tied to MTA decisions about the adjacent Penn Station.

His work at NYU Langone and on eight transportation-related boards earned Lhota $2.5 million last year, while he forfeited his MTA salary to avoid the appearance of conflicts of interest. Lhota vowed to spend 40 hours a week working for the MTA, but records show he has been spending closer to 22 hours. Lhota denied that his multiple jobs represented any conflicts in his role as MTA chief. Read more at The New York Times. Summer Meza

President Trump is tempering expectations ahead of his historic meeting with North Korean Leader Kim Jong Un, telling the press Tuesday that the planned summit in Singapore "may not work out for June 12." Trump went as far as to say, "[we'll] see what happens, whether or not it happens, if it does, that'll be great … and if it doesn't, that's okay too."

Trump made the comments ahead of his meeting with South Korean President Moon Jae-in, and added that "whether or not" the North Korea summit happens, "we'll know soon." Jeva Lange

Facebook — which in March admitted to a data breach of 50 million users — wants your nudes. Understandably, that might not seem like the most appealing idea at this point. But Facebook's policy chief in Ireland, Niamh Sweeney, said that the company is testing zapping photos that violate its terms and conditions by, apparently, inviting users to try to post the images themselves, The New York Times reports.

Facebook has struggled to keep "revenge porn" and embarrassing photos from being shared without users' consent, but it still needs something to test — the reasoning being that Facebook requires a nude photo to teach it to recognize and delete a nude photo. That's where audience participation comes in!

Lawyer Paul Tweed later expressed his disbelief at Facebook's suggestion, however, asking users rhetorically: "Are you gonna?" Jeva Lange

A number of Amazon customers are complaining that they've been banned from the retailer over what the company claims are excessive returns, despite the fact that nowhere in Amazon's return policy does it suggest such a condition, The Wall Street Journal reports.

One customer who spoke with the Journal, Shira Golan, said she spends thousands of dollars a year on Amazon, buying household items and clothes. Golan said that she has on occasion asked for refunds on apparel or shoes when they arrive damaged or are the wrong item, and that the company closed her account permanently without warning, citing "an unusual number of problems."

"If I knew this would happen, I wouldn't buy clothes and shoes on Amazon," Golan said.

Chris McCabe, a former policy enforcement investigator at Amazon, said that people tend to get banned from the retailer when they are "creating a lot of headaches." Yet another customer, Nir Nissim, who lives in Israel, said he had returned just one item this year and four items last year but was nevertheless banned by the company. He was eventually able to get his account reinstated.

Amazon reserves the right to terminate users' accounts at its discretion, but many banned customers said they had no idea the retailer would flag their routine returns as abuse, and that they received no warning before getting the notice. Read more about the company's shadowy policy at The Wall Street Journal. Jeva Lange

Four competitive races in the House of Representatives have shifted, and are more likely to be won by Republicans than they once were, the Cook Political Report predicted on Tuesday, in the latest sign that Democrats' midterm advantage is disappearing.

Democrats are still solidly favored nationally, but the landscape surrounding high-stakes primaries is rapidly changing. And while Democrats still lead Republicans by four percentage points in Real Clear Politics' congressional generic ballot, that lead is a fraction of the 13-point advantage they held in December.

California's 39th and 49th districts have both shifted from "lean Democratic" to "toss up," the Cook Political Report says, as a crowded field of Democratic candidates threaten to splice the share of votes. The open ballot policy in California means it's possible for two Republicans and no Democrats to make it through the primaries to the general election.

In South Carolina's 5th district, ratings shifted from "likely Republican" to "solid Republican." South Carolina's race has been affected by recent allegations that Democrat Archie Parnell assaulted his ex-wife in the 1970s — Parnell has so far opted to stay in the race even though top Democrats and his own staffers have renounced support.

Nebraska's 2nd district went from "toss up" to "lean Republican." After progressive candidate Kara Eastman beat out the Democratic Party's moderate pick in Nebraska's primary, analysts say Eastman may be too liberal for the district as she goes up against incumbent Rep. Don Bacon (R).

Read more analysis at the Cook Political Report. Summer Meza