Hong Kong police arrested hundreds of demonstrators at a pro-democracy sit-in early Wednesday morning.

Tuesday marked the 17th anniversary of Britain handing over Hong Kong to China, and tens of thousands of protesters marched through the streets to demand full electoral freedom. Following what the BBC termed "the city's largest democracy rally in a decade," hundreds of protesters staged the sit-in in Hong Kong's business district. Police deemed the sit-in "unauthorized," leading to the arrests.

BBC News reports that a total of 511 people were arrested for "illegal assembly and obstructing police officers."

"All of us here fight for democracy, fight for universal suffrage," protester Edward Fung told BBC News. Beijing has promised to introduce universal suffrage for Hong Kong's 2017 election — but says it needs to approve every candidate first.

Russian officials announced Wednesday that "North Korea's leader" will make his first official visit to Russia in May. He will attend a commemorative ceremony in Moscow to mark the 70th anniversary of the Soviet Union's victory in World War II.

South Korea's Yonhap News Agency reported the news, adding that the Kremlin had invited Kim Jong Un, along with 20 other "state leaders," to attend the ceremony.

Officials in South Korea are skeptical that Kim Jong Un will make the trip, though. They suggested that North Korea may send Kim Yong-nam, president of the Presidium of the North Korean Supreme People's Assembly and the nominal head of state for foreign relations, to Russia in Kim Jong Un's place.

The Kremlin stated that "North Korea's leader" would attend the event, and while most people took that to mean Kim Jong Un would visit, South Korean officials told the Yonhap News Agency that the phrase could also refer to Kim Yong-nam.

Physicist Charles Townes, who shared the 1964 Nobel Prize in physics for his work inventing the laser and maser, died on Tuesday at age 99. U.C. Berkeley, where Townes had been a professor since 1967, said he had been in poor health and died on the way to the hospital. He had visited campus daily until last year.

Townes was 35 in 1951 when he conceived the idea for the maser (microwave amplification by stimulated emission of radiation), an instrument that concentrated microwaves instead of optical light. He built the first maser in 1954, then developed the idea for the laser (light amplification by the stimulated emission of radiation) four years later with future Nobel laureate Arthur Schawlow, his brother-in-law. Townes later pioneered the use of laser and masers in astronomy.

Along with his Nobel Prize, Towns was awarded the Templeton Prize for Progress Toward Research or Discoveries about Spiritual Realities in 2005 — Mother Teresa is the only other person to win both a Nobel and Templeton prize. He is survived by his wife, Frances Hildreth Townes (whom he married in 1941), four daughters, six grandkids, and two great-grandchildren.

In an interview with AFP, Bill Gates has warned that health officials needs to learn from the fight against Ebola — and fast. 

"A more difficult pathogen [than Ebola] could come along, a form of flu, a form of SARS or some type of virus that we haven't seen before," Gates said. "We don't know it will happen, but it's a high enough chance that one of the lessons of Ebola should be to ask ourselves: Are we as ready for that as we should be? A good comparison is that we prepare ourselves for war — we have planes and training and we practice."

During a Berlin conference of the Global Alliance for Vaccines and Immunization, which delivers vaccines to poor countries, Gates said it is "reckless" not to act now," AFP reports. His plan includes having teams of volunteers who can "mobilize quickly in a public health emergency," AFP notes, in a similar fashion to how workers responded to Ebola in Guinea, Liberia, and Sierra Leone.

Despite lackluster conditions in New York City, Boston and the surrounding parts of New England received plenty of snowfall on Tuesday — some parts of the region received almost three feet of snow.

At midnight on Wednesday, Massachusetts Gov. Charlie Baker lifted the state travel ban, and Boston's MBTA transit system has resumed service. Boston Mayor Marty Walsh said he hoped the city's major roads would be cleared on Wednesday morning so the snow emergency could be lifted.

After the storm, New England will still experience bitter cold, though: The low in Boston is expected to be 10 degrees Fahrenheit on Wednesday, with a wind chill of minus five degrees Fahrenheit. Forecasters predict Boston temperatures won't be above freezing in the next week.

On Tuesday, Indiana Gov. Mike Pence (R) announced that his state will accept the Affordable Care Act's expansion of Medicaid, after gaining some concessions from the Obama administration. Under the deal, all new Medicaid enrollees will have to pay for part of their monthly premium, from $1 to $26 for single adults, depending on income, and they'll lose coverage for six months if they fall behind. Beneficiaries who inappropriately overuse the emergency room will also face copays of up to $25.

The Indiana waivers are "the latest example of how the GOP is trying to broaden its reach by appealing to lower earners," as well as "a growing willingness by the Obama administration to cut deals with states in order to expand insurance coverage under the 2010 health law after the Supreme Court hampered that effort," The Wall Street Journal explains. The deal could pave the way for a handful of on-the-fence GOP-led states to expand Medicaid, too — and prompt states that already adopted the ObamaCare expansion to seek similar waivers.

On Wednesday, Jordan said it has offered to hand convicted terrorist Sajida al-Rishawi to Islamic State in exchange for a Jordanian air force pilot captured by ISIS, First Lt. Moaz al-Kasasbeh. ISIS had threatened to kill Kasasbeh and a Japanese journalist today if their demands weren't met. Jordan's statement didn't mention the Japanese hostage, Kenji Goto. Earlier Wednesday, Kasasbeh's father had angrily urged Jordan's King Abdullah II to make the exchange.

Hezbollah is claiming responsibility for an attack Wednesday against an Israeli military convoy near the Israel-Lebanon border. After the attack — in which an anti-tank missile hit a vehicle, injuring four Israeli soldiers, a military source tells Reuters — Israel sent helicopters and fired at least 35 artillery shells into Lebanon, according to Lebanese security officials.

The attacks follow weeks of rising tensions in the Lebanon-Syria-Israel border area. Earlier Wednesday, Israeli jets hit Syrian military artillery posts, apparently in retaliation for Tuesday's Syrian rocket attack into the Israeli-occupied Golan Heights. An Israeli airstrike on Jan. 18 killed a Hezbollah commander and a general in Iran's Revolutionary Guards; Iran is a primary sponsor of both Hezbollah and the Syrian government.

When Dr. Ghofran Ageely received the X-ray of his 16-month-old patient, he was not expecting to see SpongeBob SquarePants looking back at him.

The radiology resident at King Abdulaziz University Hospital in Jeddah, Saudi Arabia, was caught off guard when he saw the cartoon character clearly show up in the image. "I thought it was just a pin," Ageely told ABC News in an email. "But when I opened the front view I was shocked to see SpongeBob looking at me with a big smile. Its angle and rotation are just perfect."

The tiny figure appeared to be a pendant, and it was safely removed from the child through a scope.

Patriots coach Bill Belichick acknowledged that he's "not a scientist" when he floated the theory that "atmospheric conditions" and not human meddling was behind New England's under-inflated footballs in their Super Bowl–clinching win against the Indianapolis Colts. So the National Football League is hiring actual scientists — the Columbia University physic department, in fact — to help the league understand how weather and temperature affect football pressure, The New York Times reports.

Lorin Reisner, a partner in law firm the NFL hired to look into "deflategate," called the Columbia physic department on Monday requesting "to consult with a physicist on matters relating to gas physics," according to notes taken by an administrative manager and a follow-up email, both seen by The Times.

There has actually been a fairly heated debate over Belichick's espoused theory, though it should be noted that team loyalties may be clouding judgments: Some of the high-profile scientists siding with Belichick are from the Boston area (a.k.a Patriots central), while Bill Nye ("the Science Guy"), who pooh-poohed the explanation on TV, is from Seattle, home to New England's rival Seahawks in the upcoming Super Bowl. For what it's worth, NFL football maker Wilson Sporting Goods Co. calls Belichick's nature-did-it excuse "BS."

Luckily, the NFL isn't relying entirely on science: It has hired investigators from Renaissance Associates to look over video and other electronic evidence.

Do you compare your tweets to a summer day? If so, a new website can help you turn your 140-character prose into a sonnet (possibly) worthy of Shakespeare.

Poetweet was developed by the Brazil Contemporary Art Center (b_arco) in San Paolo, which says the poems "are made by combining all user tweets and finding rhymes between them, creating curious results and sometimes surreal." The process is simple: Go to the site, enter your Twitter handle, and then choose between a sonnet (14 lines), rondel (4 lines, 4 lines, 5 lines) or an indriso (eight verses).

In mere moments, Poetweet scans your profile and gives you a poem based on your musings. Results will vary, of course, depending on what you've tweeted about — Carolyn Kellogg from the Los Angeles Times said her poem turned out "pretty awful" — but who knows, it could show you're the next Dickinson or Frost.