The Hajj pilgrimage draws millions of Muslims from around the world every year to Mecca, the birthplace of the Prophet Muhammad, Islam's holiest place. Saudi Arabia expects to host perhaps three million people in a ritual journey that every able-bodied Muslim who can afford it must make at least once in their lifetime. It is the largest annual gathering of humanity anywhere. Timed to the Muslim lunar calendar, the Hajj is followed by the celebrations of the three-day festival of Eid al-Adha, or the Feast of Sacrifice, which symbolizes Abraham's willingness to sacrifice his son. Collected here are photographs of the Hajj in Mecca, Saudi Arabia, as well as images of preparations for the Hajj and Eid al-Adha in many other parts of the Muslim world. -- Lane Turner (42 photos total)

The growing population of the world, now estimated to be over 7 billion, marks a global milestone and presents obvious challenges for the planet.� There are extremely densely populated cities and sparsely populated countries.� China is the most populous country with India following closely behind. This post brings together some disparate illustrations of our world as it grows, including scenes from Mong Kok district in Hong Kong, which has the highest population density in the world, with 130,000 per one square kilometer. In Mongolia, the world's least densely populated country,� 2.7 million people are spread across an area three times the size of France.� Then there's Out Skerries, a tiny outcropping of rocks off the east coast of Scotland where the population is just 65.� And doing what he can to contribute to that 7 billion global milestone is Ziona, the head of a religious sect called "Chana." �He has 39 wives, 94 children, and 33 grandchildren. The world is an interesting place. -- Paula Nelson� (41 photos total)

The 16th Pan American Games wrapped up with closing ceremonies this past weekend in Guadalajara, Mexico. Over 6,000 athletes from 42 nations in the Western Hemisphere competed for gold, silver, and bronze medals in many of the same events that will be seen during the Olympic Games next summer in London. Athletes were also vying for Olympic qualifying berths in many of the events. The 2015 edition of the games will be held in Toronto. -- Lloyd Young (35 photos total)

Flood waters inundating Thailand north of Bangkok since July have made the journey south and reached the capital. The disaster is responsible for 400 deaths in Thailand and neighboring Cambodia and Vietnam. Thailand is the world's biggest rice exporter, but the floods have wiped out over a quarter of the country's crop. The government has declared a five-day holiday for the capital to allow residents time to evacuate. Damages could top six billion dollars in Thailand's worst flooding in 50 years. Collected here are images of the water as it moves south to Bangkok, and how residents there are dealing with the disaster. -- Lane Turner (43 photos total)

On October 31, 2011, the United Nations is expected to announce a projected world population figure of 7 billion. This global milestone presents both an opportunity and a challenge for the planet. While more people are living longer and healthier lives, says the U.N., gaps between rich and poor are widening and more people than ever are vulnerable to food insecurity and water shortages. Because censuses are infrequent and incomplete, no one knows the precise date that we will hit the 7 billion mark - the Census Bureau puts it somewhere next March. In the last 50 years, humanity has more than doubled. What could the next decade mean for our numbers and the planet? In this post, we focus on births, but we'll be back with population-related content including it's affect on the environment and our food supply. -- Paula Nelson (47 photos total)

The effort to save any remaining earthquake victims continues around the clock in the eastern province of Van in Turkey after an earthquake reduced many of its buildings to rubble on Sunday, Oct. 23. A two-week old baby girl, her mother and grandmother were rescued in Ercis on Tuesday, but most teams are finding only bodies among the ruins. The 7.2 magnitude quake has reportedly killed at least 450 people as of Tuesday night and damaged more than 2,000 structures. Survivors live on the streets and in tents provided by the government. -- Lloyd Young (28 photos total)

Do not adjust your monitor. You're looking at 3D photographs by Jason Hawkes of sites around the UK. You'll need some 3D glasses, and fortunately, they're easy to make yourself. Jason shares some tips for shooting from a helicopter, as well as making images in 3D: "I�normally fly in a Eurocopter AS355 which is a five seater machine. I�sit in the back wearing a harness and we usually take off the doors�before flight. I shoot on Nikon D3X and D3S using lenses from 14mm up�to 300mm. (3D) Rigs on helicopters are a nightmare, especially as I might use three�different types of helicopters in a week. In the end I found with a�little trial and error its just as easy to shoot with a single camera�as long as you get the timings spot on. Once you have the images you just use some standard Anaglyph software�to integrate the shots and you end up with these stereoscopic images.�When viewed with chromatically opposite lenses you perceive the images�as having three dimensions." -- Lane Turner (18 photos total)

Sukkot, or Feast of Tabernacles, is a Biblical holiday celebrated in late September to late October. The holiday lasts seven days. The Sukkah is a walled structure covered with plant material - built for the celebration - and is intended to be a reminiscence of the type of dwelling in which the Israelites stayed during their 40 years of travel in the desert after the exodus from slavery in Egypt. Throughout the holiday, meals are eaten inside the Sukkah and many sleep there as well. On each day of the holiday, members of the household recite a blessing over the lulav and etrog (four species). The four species include the lulav (a ripe green, closed frond from a date palm tree), the hadass (boughs with leaves from the myrtle tree), the aravah (branches with leaves from the willow tree) and the etrog (the fruit of a citron tree.) -- Paula Nelson (29 photos total)

After being held captive by the Palestinian group Hamas for five years, Israeli soldier Gilad Schalit returned to his home in Mitzpe Hila, northern Israel. As his family and friends were celebrating his freedom, 477 of an eventual 1,027 Palestinians held in Israeli prisons were released to mass celebrations in the West Bank and Gaza Strip, part of the deal with Hamas. Schalit, a tank crewman who is now 25, was captured in June of 2006 near the Gaza border. -- Lloyd Young (19 photos total)

Global protests against economic injustice gripped cities over the weekend, predominantly on Saturday, October 15. Solidarity with Spain's "Indignants" and New York's "Occupy Wall Street" protesters brought demonstrations over the concentration of wealth in the hands of a few and the worldwide economic crisis to cities from Hong Kong to Tulsa. Hundreds of thousands joined the mostly peaceful demonstrations, although arrests were made in many cities, and clashes with police in Rome became particularly violent. The movement shows no signs of slowing. Gathered here are images from cities large and small. -- Lane Turner (40 photos total)

Often in the Big Picture we feature "slice of life" photography originating from around the world, brought to us by photographers based in those countries who work for the Associated Press, Reuters and Getty Images. The photographs are often simple and show daily life in many places that we might not be able to experience in any other way except through those photographers' documentation. The images themselves are somewhat universal - they show us where people live and how people live, sometimes not so differently than we do ourselves. -- Paula Nelson (35 photos total)

What started in NewYork City in mid September, a call to "flood lower Manhattan, set up tents, kitchens, peaceful barricades and occupy Wall Street," has continued to feed similar groups around the United States taking up the name and cause. Groups have gathered to bring attention to many issues, with a central focus on the economic hardships and inequality they say many Americans face. -- Lloyd Young (35 photos total)