U.S. President Barack Obama and First Lady Michelle Obama hug after delivering remarks during a campaign event at the Alliant Energy Amphitheater in Dubuque, Iowa, on Aug. 15. The Obama campaign posted the photo on Twitter under the words "Four more years" shortly before the president delivered his victory speech on Election Day in November. With more than 800,000 retweets, it is now the most retweeted post in Twitter history.
JIM WATSON/AFP/Getty Images
Addressing the United Nations General Assembly on Sept. 27 in New York City, Israeli Prime Minister Benjamin Netanyahu points to a red line he drew on a graphic of a bomb to illustrate the stage at which preemptive military action against Iranian nuclear facilities would be necessary. Netanyahu pressed the United States to establish "red lines" for Iran's nuclear program during the country's presidential election.
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Chinese dissident Chen Guangcheng (right), who escaped from house arrest in April and took refuge in the U.S. Embassy in Beijing, looks on as U.S. Ambassador to China Gary Locke (left) talks on the phone on May 2 in the Chinese capital. After several days of tense negotiations, the United States struck a deal with China under which Chen was permitted to travel to the United States to study.
U.S. Embassy Beijing Press via Getty Images
An armed man waves his rifle as buildings and cars are engulfed in flames inside the U.S. mission in Benghazi on Sept. 11. The terrorist attack on the compound killed Ambassador Christopher Stevens and three other Americans.
In a cemetery in Aleppo on Oct. 13, a Free Syrian Army fighter illuminates the body of an unknown man killed by the Syrian Army's artillery shelling before burying the corpse in a common grave. More than 44,000 have died from the violence in Syria since March 2011, according to the Syrian Observatory for Human Rights.
Henry Terifay and his sister, fourth-grader Kelly Terifay, wait in shock outside
Sandy Hook Elementary School after Adam Lanza opened fire at the school in Newtown, Conn. on Dec. 14, fatally shooting 20 children and six adults before killing himself.
Former CIA Director Gen. Davis Petraeus shakes hands with biographer Paula Broadwell, co-author of All In: The Education of General David Petraeus, on July 13, 2011. Petraeus, who popularized counterinsurgency strategy while overseeing the wars in Iraq and Afghanistan, resigned from his post at the intelligence agency on Nov. 9 over an extramarital affair with Broadwell. The FBI began an investigation after it was tipped off by Jill Kelley, a friend of the Petraeus family who received threatening emails from Broadwell.
ISAF via Getty Images
North Korean leader Kim Jong Un smokes a cigarette at the General Satellite Control and Command Center on Dec. 12 after the country's successful launch of a long-range Unha-3 rocket carrying a satellite. Japan, South Korea, and the United States accused North Korea, which staged a failed rocket launch in April, of testing missile technology that could deliver a nuclear warhead.
KCNA via REUTERS
Rising water brought on by Hurricane Sandy rushes into a subterranean parking garage on Oct. 29 in New York City's Financial District. The massive hurricane left more than 250 people dead across several countries and caused at least $65 billion in damage.
Andrew Burton/Getty Images
Water shoots out from the Three Gorges Dam on the Yangtze river in China's Hubei province on July 24 after heavy downpours in the upper reaches of the dam caused the highest flood peak of the year. Nearly 80 people died in the worst flooding in Beijing in six decades, according to Chinese authorities.
Venezuelan President Hugo Chávez waves a Venezuelan flag while speaking to supporters after receiving news of his reelection in Caracas on Oct. 7. Chávez, who has been battling cancer, defeated opposition candidate Henrique Capriles Radonski.
JUAN BARRETO/AFP/Getty Images
Tens of thousands of mourners gather in Addis Ababa's Meskel square on Aug. 30 for a candlelight vigil dedicated to former Prime Minister Meles Zenawi, who died from an infection on Aug. 20 at the age of 57.
CARL DE SOUZA/AFP/Getty Images
Demonstrators throw fire bombs at riot police during violent protests in Athens on Feb. 12, as the Greek parliament prepared to vote on an EU/IMF austerity deal to secure a 130 billion euro bailout and save Greece from bankruptcy.
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A Pakistani girl sits amid candles and portraits of Malala Yousafzai as people pray for the 15-year-old in Lahore, Pakistan, on Oct. 10. A Taliban gunman shot Yousafzai, a prominent advocate for girls' education, on a school bus a day earlier in Pakistan's Swat Valley, but the young Pakistani activist survived the attack.
Jamaica's Usain Bolt celebrates after winning a gold medal in the men's 100-meter final on Aug. 5 during London's Olympic Games.
Julia Vynokurova/Getty Images
NASA's Curiosity rover, tasked with exploring the Gale Crater on Mars, uses its Mars Hand Lens Imager (MAHLI) on Oct. 31 to capture a set of 55 high-resolution images, which were stitched together to create this self-portrait. The image shows the rover at Rocknest, the spot in Gale Crater where Curious scooped its first soil samples to analyze. Four scoop scars are visible in front of the rover.
NASA/JPL-Caltech/Malin Space Science Systems
The Austrian skydiver Felix Baumgartner prepares to jump from an altitude of nearly 97,000 feet above Roswell, N.M. on July 25 as part of his Red Bull Stratos project. After jumping from more than 128,000 feet above New Mexico on Oct. 14, Baumgartner became the first skydiver to break the sound barrier and secured the world record for the highest ever freefall.
Jay Nemeth/Red Bull Content Pool
The South Korean singer PSY, whose "Gangnam Style" music video is now YouTube's most-viewed clip of all time, performs during the 2012 MTV European Music Awards at the Festhalle in Frankfurt am Main, Germany, on Nov. 11.
DANIEL ROLAND/AFP/Getty Images
Members of the punk band Pussy Riot (left to right) Yekaterina Samutsevich, Maria Alyokhina, and Nadezhda Tolokonnikova sit in a glass-walled cage in a court in Moscow on Oct. 10. A Russian appeals court ordered the release of Samutsevich but sentenced Alyokhina and Tolokonnikova to two years in prison camps for the "punk prayer" they staged at a Moscow cathedral, in a case that came to symbolize the clash between the Kremlin and a reinvigorated opposition.
NATALIA KOLESNIKOVA/AFP/Getty Images
The stricken Costa Concordia cruiseship lies in the harbor of the Tuscan island of Giglio after hitting underwater rocks on Jan. 13. Thirty people died when the 60,000-ton Italian luxury liner -- the largest passenger ship ever to capsize -- crashed.
FILIPPO MONTEFORTE/AFP/Getty Images
Above is a screenshot from Invisible Children's Kony 2012 video campaign to arrest Ugandan warlord Joseph Kony for war crimes -- including the recruitment of child soldiers -- by the end of 2012. The film generated heated controversy and has been viewed more than 95 million times on YouTube, but Kony remains at large the year draws to a close despite a Ugandan-led and U.S.-supported mission to bring the leader of the Lord's Resistance Army to justice.
Russia's President Vladimir Putin enters Andreyevsky (St. Andrew's ) Hall at the Great Kremlin Palace in Moscow on May 7 during his inauguration ceremony. Putin is serving a third term as president after four years as prime minister.
ALEXEY DRUZHININ/AFP/Getty Images
Vladimir Putin pilots a motorized hang glider while flying with cranes as he takes part in a scientific experiment as part of the Flight of Hope, which aims to preserve a rare species of cranes, on Sept. 5. Putin made three flights -- the first to get familiar with the process, and two others with the birds.
ALEXEY DRUZHININ/AFP/Getty Images
Wearing a sombrero, Pope Benedict XVI arrives at Bicentennial Park in his Popemobile in the Mexican city of Silao, where he celebrated an open-air mass on March 25 during a trip that also included a visit to Cuba.
Ronaldo Schemidt/AFP/Getty Images
Iranian Air Force soldiers carry a cardboard cutout of Ayatollah Ruhollah Khomeini, the founder of the Islamic Republic, down the stairs of a passenger plane at Merhrabad airport on Feb. 1 during a ceremony to re-enact his return to Iran from exile in 1979.
RUHOLLAH YAZDANI/AFP/Getty Images
Ousted Egyptian President Hosni Mubarak sits inside a cage in a courtroom during his verdict hearing in Cairo on June 2. A judge sentenced Mubarak to life in prison after convicting him of involvement in the murder of protesters during the uprising that removed him from power in 2011.
Workers erect a giant photograph of Queen Elizabeth II and the Duke of Edinburgh on a building along the River Thames on May 25 in London, England. Constructed to celebrate the queen's Diamond Jubilee, the image shows the royal family on the balcony of Buckingham Palace during Silver Jubilee celebrations in 1977.
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Actor Clint Eastwood speaks to an empty chair representing Barack Obama during the final day of the Republican National Convention Aug. 30 in Tampa, Fla.
Mark Wilson/Getty Images
Former Chinese Presidents Hu Jintao (center left) and Jiang Zemin (center right) raise their hands along with other Chinese officials during the closing ceremony of the Communist Party Congress at the Great Hall of the People in Beijing on Nov. 14 ahead of a once-in-a-decade leadership transition. The next day, the Communist Party unveiled the new members of its Politburo Standing Committee and the country's new leader, Xi Jinping.
MARK RALSTON/AFP/Getty Images
Egyptians celebrate the election of Mohamed Morsy as president in Cairo's Tahrir Square on June 24. Five months later, Egyptians returned to the square to protest a decree granting the president broad powers, which Morsy has since repealed.
Daniel Berehulak/Getty Images
A boy plays on the gun of a charred Syrian army tank partially covered in the rubble of a destroyed mosque outside the city of Aleppo on Aug. 2.
AHMAD GHARABLI/AFP/Getty Images
News Corp. chief Rupert Murdoch looks at his wife, Wendi Deng Murdoch, on April 26 as they are driven from the Royal Courts of Justice in London after he gave evidence to the Leveson Inquiry, an investigation into the culture, practice, and ethics of the press in the United Kingdom established in the wake of the phone-hacking scandal that forced Murdoch to shutter the News of The World in 2011.
Peter Macdiarmid/Getty Images
U.S Republican presidential candidate Mitt Romney visits the Western Wall on July 29 in Jerusalem during an overseas tour that also included stops in Poland and Britain.
Lior Mizrahi/Getty Images
Members of Ansar Dine are pictured during the release of a Swiss hostage on April 24, near Timbuktu, Mali, which the al Qaeda-linked group helped rebels seize early that month. Special forces from Burkina Faso swept into rebel-held northern Mali aboard a helicopter and whisked the hostage to safety in a pre-arranged handover by the Islamist rebels.
ROMARIC OLLO HIEN/AFP/Getty Images
Smoke billows after Israeli airstrikes near smuggling tunnels between the southern Gaza Strip and Egypt on Nov. 21. A week-long Israeli operation to degrade militant groups and halt rocket attacks from Gaza -- one that included the deployment of Israel's Iron Dome missile defense system and the killing of Hamas military commander Ahmad Jabari -- left more than 150 Palestinians and five Israelis dead.
SAID KHATIB/AFP/Getty Images
A Japanese coast guard vessel (right) sprays water at Taiwanese fishing boats on Sept. 25 while a Taiwanese coast guard ship (left) also sprays water in the East China Sea near what the Japanese call the Senkaku Islands and the Chinese call the Diaoyu Islands. The water-cannon duel occurred after dozens of Taiwanese boats escorted by patrol ships sailed into waters around the disputed Tokyo-controlled islands.
YOMIURI SHIMBUN/AFP/Getty Images
Space Shuttle Enterprise is carried by barge underneath the Verrazano-Narrows Bridge on June 3 in New York City en route to the Intrepid Sea, Air and Space Museum, where it has been put on permanent display.
Michael Nagle/Getty Images
A Tibetan exile runs after self-immolating in New Delhi on March 26 during a protest against former Chinese President Hu Jintao's visit to India. Nearly 100 Tibetans have set themselves on fire since 2009.
An Afghan villager cries over the bodies of Afghan civilians who were allegedly shot by Staff Sgt. Robert Bales as they are loaded into the back of a truck in Kandahar province. The U.S. Army is seeking the death penalty against the American soldier, who is accused of killing 16 civilians in two villages on March 11 before returning to his military base and surrendering.
Myanmar's opposition leader Aung San Suu Kyi waves to a crowd as she leaves the National League for Democracy headquarters in Yangon on April 2 -- a day after she and her party claimed major victories in landmark by-elections held amid a series of reforms in the country.
CHRISTOPHE ARCHAMBAULT/AFP/Getty Images
This photo of U.S. Marine Sgt. Brandon Morgan kissing his partner Dalan Wells upon returning home, which was posted to the Gay Marines Facebook page on Feb. 25, went viral, generating more than 40,000 Likes and 10,000 comments to date. The military's "don't ask, don't tell" policy ended in September 2011.