Pale Blue Dot, the most distant photograph ever taken of Earth, was created by the Voyager 1 space probe.

Voyager 1 was launched in September 1977 to study the outer Solar System including flybys of Jupiter and Saturn. Having completed the mission for which it had been created in November 1980, the spacecraft was allowed to continue its flight and leave the Solar System.

Carl Sagan, the astronomer and author, was a member of the Voyager imaging team and suggested that Voyager 1 should take a last photograph of Earth before the cameras were deactivated to allow their power to be used for the flight into interstellar space. NASA scientists were concerned that such a photograph, in which the Earth would be relatively close to the sun, could permanently damage Voyager 1’s Imaging Science Subsystem. They consequently held off turning the cameras around until 14 February 1990, by which time the spacecraft was approximately 6 billion kilometres from Earth.

Known as the Family Portrait series of images, Voyager 1 transmitted 60 frames back to Earth where NASA stitched them together to create a mosaic of the Solar System. Three of the images, each taken with a different colour filter, were combined to produce the Pale Blue Dot image, in which the tiny dot of Earth fills less than 1 pixel of the 640,000 pixels that make up the rest of the frame.

Barely visible within the vastness of space, Sagan reflected on the ‘pale blue dot’ at a public lecture at Cornell University and later wrote about it in his book that drew its name from the image.

‘Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.’

Henry Morton Stanley, a Welsh-American journalist and explorer, allegedly greeted the missing Scottish missionary David Livingstone with the phrase, “Dr Livingston, I presume?”

David Livingstone was born in 1813 and, having completed training as a doctor, made his first journey to Africa in 1841. He converted his first and only African eight years later, after which he became convinced that further missionary work could only succeed if Africa’s rivers were mapped to become ‘highways’ to the interior.

Livingstone sent his family back to Britain in 1852 prior to beginning an expedition to explore the Zambezi. Over the course of the next four years he crossed the African continent and mapped almost the entire Zambezi while becoming the first European to see the Mosi-oa-Tunya waterfall, which he renamed Victoria Falls.

Livingstone returned to Britain in 1856, but sailed back to Africa in 1858 with the intention of opening the Zambezi to ‘legitimate’ British trade to combat slavery. After this expedition failed in its aim to find a navigable route to the interior Livingstone again returned to Britain. He began his final journey to Africa in January 1866.

Hoping to find the source of the Nile, the expedition began to fail as Livingstone’s assistants began to desert him. With the outside world having heard nothing of him for over three years, Henry Morton Stanley was sent to find the Scot by the New York Herald newspaper in 1869. He was eventually found on 10 November 1871 in the town of Ujiji. Stanley is alleged to have greeted him with the words “Dr Livingston, I presume?” although this phrase is likely a fabrication since the relevant pages in Stanley’s diary were torn out, and Livingstone himself never mentioned it.

Raleigh had been a favourite of Queen Elizabeth I, who granted him permission to lead three expeditions to the Americas. Although he had inspired the Queen’s fury after secretly marrying one of her ladies-in-waiting, Raleigh had returned to her favour by the time she died in March 1603.

In November, Raleigh was found guilty of treason for his involvement in the Main Plot that sought to depose Elizabeth’s successor James I and replace him with his cousin Arabella Stuart. The King suspended the death sentence and instead imprisoned Raleigh in the Tower of London, where he lived for thirteen years before being pardoned.

Raleigh was freed and granted permission by James to undertake an expedition in search of the fabled city of El Dorado, which began in 1617. In January 1618 a group of his men ignored an order to avoid confrontation with Spanish settlers when Lawrence Keymis, Raleigh’s closest companions, led an attack on the Spanish outpost of Santo Tomé de Guayana on the Orinoco River. This was in direct contravention of peace treaties signed between England and Spain. Raleigh’s son, Walter, was also killed in the attack.

Although Raleigh himself had specifically ordered his men not to attack, he knew that their actions had broken a key condition of his pardon. On his return to England the Spanish ambassador demanded the earlier sentence be reinstated, and King James had little option but to order Raleigh’s execution. He was beheaded in the Old Palace Yard at the Palace of Westminster on 29 October 1618.

At 8am on the 3rd August 1492, Christopher Columbus set sail from the Spanish port of Palos de la Frontera on the voyage that would take him to the Americas. While Columbus captained the Santa María, Palos natives commonly referred to as the Pinzón brothers captained the Pinta and the Santa Clara which is better known by its nickname the Niña. A third Pinzón brother, was the master of the Pinta.

None of the ships belonged to Columbus himself and, despite the voyage officially being supported by the Catholic Monarchs Ferdinand and Isabella, they forced the inhabitants of the port to contribute towards the costs associated with supplying and equipping them. In the case of the Pinta, its owners had even been forced to send the ship on the voyage against their wishes, leading to suspicions of sabotage when the rudder broke after just three days at sea.

The ships sailed first to the Canary Islands, which they reached after six days. Here they repaired the rudder of the Pinta and restocked with provisions for the Atlantic crossing, which they began on the 6th September from the port of San Sebastián de la Gomera.

However, it is Palos de la Frontera that holds the real title as the starting point of Columbus’ transatlantic voyage. The town also played a significant role in the later Christianisation of the New World since it continued to be a departure point for later westward voyages and was the location of the Franciscan Rábida Monastery that sent some of the first missionaries to the Americas.

Often referred to as the ‘lost city of the Incas’, Machu Picchu was constructed in the middle of the 15th century but was abandoned barely a century later in 1572. Believed by modern archaeologists to have been built as a retreat for Incan royalty, the city was never found by the Spanish conquistadors and its existence slowly became known only to those who lived in the local area.

Although there is evidence that the city had been visited by explorers before Bingham, he was the first to conduct an archaeological survey of the area and to secure worldwide publicity for it. He did so as a result of leading the 1911 Yale Peruvian Expedition, having visited the country three years previously on his way home from the First Pan American Scientific Congress.

Bingham’s expedition travelled down the Urubamba River, seeking local information about Inca ruins. Eventually he met Melchor Arteaga who led him up the Huayna Picchu mountain. Here the eleven-year-old Pablito, the son of a farmer, led him to the main Machu Picchu ruins.

Bingham first saw the site on 24 July, but the intricate stonework was covered in vegetation from five hundred years of disuse. Consequently he only conducted preliminary investigations before continuing the expedition along the river. He returned to the mountain the following year to clear the overgrowth and conduct an archaeological excavation with the support of Yale University and National Geographic. Artefacts taken from the site by Bingham have since been returned to Peru, and Machu Picchu continues to be one of the world’s leading tourist sites.

On the 25th June 1876, the Battle of Little Bighorn began when American Lieutenant Colonel George Armstrong Custer led federal troops against the combined forces of the Lakota Sioux, Northern Cheyenne, and Arapaho Plains Indians. Also known as ‘Custer’s Last Stand’, the battle was one of the most significant clashes of the Great Sioux War of 1876.

The Black Hills of South Dakota were sacred to the Plains Indians, and had been recognized as such in the Fort Laramie Treaty of 1868. However, the discovery of gold there six years later led to a gold rush of white settlers in breach of the treaty. Sitting Bull inspired fellow Plains Indians to form an alliance against the invasion of their lands, and by late spring 1876 thousands of warriors had joined him at the Little Bighorn River in an area they referred to as the Greasy Grass.

Determined to drive the natives back to the reservations, the US Army dispatched cavalry to engage them. When Custer, leading the 7th Cavalry Regiment, spotted a Sioux camp on the 25th June he decided to attack it with his 600 men. However, the Indian forces outnumbered his troops and Custer was soon the victim of a pincer movement when Crazy Horse led another group of Sioux to surround him. Within an hour Custer and his men were dead, having been overwhelmed by up to 3,000 warriors. However news of the defeat prompted outrage amongst many white Americans and, over the next year, the Sioux gradually surrendered following continued US Army attacks against their property.

On the 24th April 1916, Sir Ernest Shackleton and five companions set off in the James Caird, a recovered lifeboat, to sail from Elephant Island to South Georgia in the southern Atlantic Ocean.  Their mission was to organize a rescue party for the shipwrecked crew of the Endurance.

The crew had been forced to make their way to Elephant Island after the Endurance sank due to pack ice the previous October.  Having made their way off the ice in the Endeavour’s lifeboats at the start of April, Shackleton decided to take the strongest lifeboat – the James Caird – on the perilous mission across the Southern Ocean to South Georgia.

Despite all the odds stacked against them, the crew of the tiny boat reached South Georgia in 16 days.  A smaller team of three, led by Shackleton, then had to undertake a 17-mile, 36 hour journey by foot across South Georgia’s mountainous interior to reach the whaling station at Stromness where they summoned help.

Historian Carol Alexander has since said that the voyage of the James Caird is one “one of the greatest boat journeys ever accomplished.”  However, the final word on the achievement of the crew must go to Shackleton himself.  In “South: the story of Shackleton’s last expedition 1914-1917” he said this:

“We had suffered, starved and triumphed, grovelled down yet grasped at glory, grown bigger in the bigness of the whole…We had reached the naked soul of man.”

On the 28th February  1525 Cuauhtémoc, the last Aztec Emperor, was executed on the orders of the Spanish conquistador Hernán Cortés. Cuauhtémoc, which means “One who swoops down like an eagle” continues to be a highly regarded in modern-day Mexico as the only Aztec emperor to have survived the Spanish conquest.

Little is known of Cuauhtémoc’s early life and, by the time he was elected leader of Tenochtitlan in 1520, the Aztec city-state had already been invaded by the Spanish and experienced the successive deaths of Moctezuma II and his brother Cuitlahuac. The new ruler attempted to defend the city against the continued Spanish attacks, but was captured on the 13th August 1521 while trying to escape.

Cuauhtémoc surrendered to Cortés and was spared, with contemporary sources claiming that the conquistador initially treated his captive with respect. However, having failed to find large quantities of gold in the city, he tortured Cuauhtémoc by covering his feet in oil and placing them over a fire. Despite this ordeal, Cuauhtémoc allegedly refused to give away the location of his treasures, though a small amount of gold was later found in the house of a noble. Afterwards he was allowed to keep the title of tlatoani but was stripped of his sovereign powers.

In 1525, when Cortés undertook an expedition to Honduras, he took Cuauhtémoc with him. Some suggest that this is because he was concerned the former emperor might lead a revolt in his absence. While they were away Cortés was informed of a rumour that Cuauhtémoc was conspiring to kill him. He was hanged on the 28th February alongside other nobles.

On the 14th December 1911, Norwegian explorer Roald Amundsen led a team of four others to become the first to reach the South Pole. They arrived five weeks ahead of British explorer Robert Falcon Scott, and successfully made it back to their basecamp whereas Scott did not.

Amundsen originally planned to become the first to reach the North Pole, but changed his target to the South Pole after he learned of the now-disputed claim by rival American explorers that they had already reached it. Keeping his new plan secret, even from his crew, his ship departed Norway on the 9th August. He only told them of their destination a month later, shortly before they left their final port on the island of Madeira.

Amundsen’s ship arrived in an Antarctic inland known as the Bay of Whales on the 14th January 1911, where the crew established a base known as Framheim. They then spent the next three months preparing depots across the Ross Ice Shelf, prior to the onset of Antarctic winter.

As soon as the sun returned at the end of August, Amundsen attempted to reach the pole but was forced to turn back due to the harsh conditions. A second attempt that began in mid-October was much more successful, seeing them arrive at the pole almost 2 months later.

As well as being the first expedition leader to reach the South Pole, Amundsen is also the first person to be universally recognised as reaching the North Pole as a result of his 1926 air expedition, making him the first person also to reach both poles.

On the 28th November 1520, Portuguese explorer Ferdinand Magellan led the first European ships from the Atlantic Ocean into the Pacific as part of his planned circumnavigation of the earth. Magellan’s route into the Pacific took him through what we now call the Strait of Magellan. After emerging in calm waters on the other side he called the new ocean Mar Pacifico, or the Pacific Ocean, as the waters were very calm.

Magellan’s voyage was funded by the Spanish king, Charles I, who is better known by his subsequent title of the Holy Roman Emperor Charles V. By the early 1500s it had become evident that Christopher Columbus’ voyages had not found a westward route to the Indies. Consequently the Spanish crown sought to find one, since the eastward route around Africa had been reserved for the Portuguese under the terms of the Treaty of Tordesillas signed in 1498.

Having crossed the Atlantic, Magellan’s fleet searched the South American coast for a channel that would lead them through the land mass. On the 21st October they concluded that they had found the passage at Cape Virgins, and entered it on the 1st November. As a result the channel was first known as the Strait of All Saints.

Three weeks later, Magellan and three ships emerged into the calm waters of the South Pacific. They soon made landfall at the archipelago of Tierra del Fuego, so called due to the fires lit by the inhabitants to ward off the low temperatures. The fleet reached South East Asia the following spring, where Magellan was killed in battle on the 7th April.