Twenty-five years ago this week, in the early hours of Dec. 3, 1984, large amounts of water entered a tank at the Union Carbide factory in Bhopal, India. That water reacted with the 42 tons of methyl isocyanate inside, raising temperature and pressure so high that it began venting massive amounts of gas made up of methyl isocyanate, phosgene, hydrogen cyanide and more. The poisonous cloud swept through neighborhoods near the boundary wall, waking sleeping residents with burning throats and eyes, killing about 4,000 people in the first few hours. Over the next few years, the lingering effects increased that toll to about 15,000 dead, according to government estimates. A quarter-century later thousands of people are still grappling with the effects of the world's worst industrial accident and the continued contamination. Union Carbide was bought by Dow Chemical in 2001, and Dow claims the legal case was resolved in 1989, with responsibility for continued cleanup now falling to the local state government. (28 photos total)

Today, November 27th, marks the beginning of 2009's Eid al-Adha, the Muslim "Festival of Sacrifice", commemorating the willingness of Ibrahim (Abraham) to sacrifice his son to God. Muslims around the world will celebrate by slaughtering animals to commemorate God's gift of a ram to substitute for Abraham's son, distributing the meat amongst family, friends and the poor. Eid al-Adha also takes place immediately after the Hajj, a pilgrimage to Mecca that is a pillar of Islamic Faith. Some 2.5 million Muslim faithful from all over the world descended on Mecca this year, many encountering an unusual occurance: heavy flooding due to recent torrential rains. Collected below are photographs from this year's Hajj and observance of Eid al-Adha. (38 photos total)

President Barack Obama recently announced that he was determined to "finish the job" in Afghanistan, and aides signaled to allies that he would send as many as 25,000 to 30,000 additional American troops there. Obama will formally announce his decision in a national address at 8 p.m. Tuesday from the Military Academy at West Point. As casualties mount on both sides, 2009 is shaping up to be the deadliest year yet for coalition troops - twice as deadly as 2008. American and Afghan officials have been encouraged by the recent rise of independent anti-Taliban militias in Afghanistan, even though their emergence is recent and supporting them raises fears of the consequences of arming and training Islamic militants. Collected here are images of the country and conflict over the past month, part of an ongoing monthly series on Afghanistan. (42 photos total)

National Geographic's International Photography Contest attracts thousands of entries from photographers of all skill levels around the world every year. While this year's entry deadline has passed, there is still time to view and vote for your favorites in the Viewer's Choice competition. National Geographic was kind enough to let me choose a few of their entries from 2009 for display here on The Big Picture. Collected below are 25 images from the three categories of People, Places and Nature. Captions were written by the individual photographers. (25 photos total)

The European Organization for Nuclear Research (CERN) says it expects to restart the Large Hadron Collider (LHC) by this weekend after more than a year of repairs. The 27 km (17 mi) particle accelerator was launched last year, but suffered a failure from a faulty electrical connection, damaging 53 of the smasher's 9,300 superconducting magnets. Repairs are now completed, and the plan is to begin injecting protons into the LHC this weekend, on the path to search for particles such as predicted-yet-unobserved Higgs Boson. Collected below are some photographs of the repairs, and of the LHC and some of its experiments in various stages of construction. (30 photos total)

We humans are drawn to the shore, with some 40% of the world's population living within 100 kilometers of a coast. Coastal areas have made recent news with the arrival of several storms, concerns about rising sea levels and other environmental and conservation efforts. Collected here are a handful of photographs from around the world of people and animals at the shoreline, playing, working, struggling or relaxing on the border between land and sea. (36 photos total)

Health officials around the world are stepping up vaccination efforts and are closely tracking the progress of the H1N1/09 virus (often referred to as "swine flu" in the media). World Health Organization officials recently noted that the virus has spread to virtually every country in the world, reaching as far as remote tribes in Venezuela and aboriginal populations in Australia. Although the number of deaths attributed to H1N1 this year (over 7,000 to date) remains low compared to a normal seasonal flu outbreak of several hundred thousand deaths in a year, health officials remain concerned because of the instability of H1N1/09 combined with its tendency to affect younger healthier people. Collected here are photos of people around the world preparing for and dealing with the current H1N1 pandemic. (37 photos total)

Last Wednesday was Armistice Day, when on the "eleventh hour of the eleventh day of the eleventh month", in 1918, the armistice was signed for the cessation of hostilities on the Western Front at the end of World War I. The date is now observed by many of the allied nations from that era as Veterans Day, Armistice Day, Remembrance Day or Poppy Day - a day set aside to commemorate the sacrifices made by those in the armed forces and their families. Collected here are photos of Veterans and Remembrance Day from the United States and several Commonwealth nations. (37 photos total)

Havana, the capital city of the island nation of Cuba is home to nearly 4 million people - 20% of the entire population of Cuba. On November 16th the city will celebrate its 490th anniversary, being founded by the Spanish in 1519. Havana is also the seat of the state-run economy, one that has been faltering more and more in recent years. President Raul Castro has even gone so far as to warn Cubans that their socialist system must change - and to invite (limited) criticism of the state. Cuba's economic woes are compounded by the 50-year-old trade embargo imposed by the United States, a practice recently condemned (again) by the United Nations with a vote of 187-3. Collected here are recent photos from in and around Havana, Cuba. (35 photos total)

Twenty years ago, on the night of November 9, 1989, following weeks of pro-democracy protests, East German authorities suddenly opened their border to West Germany. After 28 years as prisoners of their own country, euphoric East Germans streamed to checkpoints and rushed past bewildered guards, many falling tearfully into the arms of West Germans welcoming them on the other side. Thousands of Germans and world leaders gathered in Berlin yesterday to celebrate the "Mauerfall" - the dismantling of the Berlin Wall and German reunification - and to remember the approximately 100-200 who died attempting to cross the border over the years. Collected here are photographs both historic and recent, from the fall of the Berlin Wall. Be sure to pause on photos 12 - 15, and click them to see a fade effect from before to after. (38 photos total)

Sixty years ago, the Soviet Union detonated its first nuclear weapon, nicknamed "First Lightning", at a test facility on the steppe of northeast Kazakhstan (formerly the Kazakh SSR). The test site, named the Semipalatinsk Polygon, would go on to host 456 atomic explosions over its 40-year existence. Residents in the surrounding area became unwitting guinea pigs, exposed to the aftereffects of the bombs both intentionally and unintentionally. The radiation has silently devastated three generations of people in Kazakhstan - the total number affected is thought to be more than one million - creating health problems ranging from thyroid diseases, cancer, birth defects, deformities, premature aging, and cardiovascular diseases. Life expectancy in the area is seven years less than the national average of Kazakhstan. Photographer Ed Ou has graciously shared with us these photos from the area, with thanks to the excellent Reportage by Getty Images. (25 photos total)

Since 2006, NASA's Mars Reconnaissance Orbiter (MRO) has been orbiting Mars, currently circling approximately 300 km (187 mi) above the Martian surface. On board the MRO is HiRISE, the High Resolution Imaging Science Experiment camera, which has been photographing the planet for several years now at resolutions as fine as mere inches per pixel. Collected here is a group of images from HiRISE over the past few years, in either false color or grayscale, showing intricate details of landscapes both familiar and alien, from the surface of our neighboring planet, Mars. I invite you to take your time looking through these, imagining the settings - very cold, dry and distant, yet real. (35 photos total)

Pushkar Mela (or Pushkar Fair) is an annual five-day camel and livestock fair, held in the town of Pushkar in the state of Rajasthan, India, where over 25,000 camels are traded each year. The fair draws thousands of tourists, camels, camel traders, racers, locals and Hindu faithful who come to bathe in the sanctified Lake Pushkar - until the final day, Kartik Poornima, a Hindu holy day celebrated on the full moon day of the month of Kartik. Collected here are a handful of photographs from Associated Press photographer Kevin Frayer, from his trip to this year's Pushkar Mela. (30 photos total)

From October 31st through November 2nd, a number of festivals, holidays and solemnities take place, all loosely related and revolving around remembrance of the dead. Halloween, Samhain, All Saints' Day, All Souls' Day, the Day of the Dead and other festivals trace their origins back to Celtic, Aztec, Roman and Christian traditions. Halloween is largely a secular observation these days, All Souls and All Saints remain mainly Catholic observations, and the Day of the Dead is still largely a Latin American tradition, its roots in Mexico's Aztec heritage. Collected here are photographs over the past week from the varied observations of the Days of the Dead around the world. (37 photos total)