Considering how much we don’t yet know about the world and the universe, it is amusing how much the mind gets perplexed and frustrated when it encounters a mystery. Whether you are a historian, a geologist, an astronomer, or just someone with no particular specialty, mysteries are equally appealing and solving them is the only way to appease the mind.

Many an enthusiast throughout the history has worked years, decades, or even a lifetime to solve them and they still do. We have listed some of these solved mysteries that we are sure you would find interesting.

1 Launched in the 1970s, the Pioneer spacecraft appeared to slow down by one kilometer per hour, more than expected due to Sun’s gravity after reaching outer Solar System. Decades later in 2012, they found the reason to be thermal recoil which caused an extremely small deceleration of 0.000000000874 m/s². 

The Pioneer 10 space probe was launched in 1972 and in 1973, it became the first of the five artificial objects with the escape velocity to leave the Solar System. It was also the first to take pictures of Jupiter. The next space probe was Pioneer 11 which was launched in 1973 to study the asteroid belt and the environment around Jupiter and Saturn.

Scientists first noticed their anomalous accelerations as early as 1980, but serious investigations did not start until 1994. Though radio communications ceased from Pioneer 10 in 2003 and Pioneer 11 in 1995, research into the data they sent up to that point continued, including their deviations from predicted trajectories.

Suggestions that the effects of their thermal coil were underestimated when first made in 1998. By 2012, several papers by various groups reanalyzed the thermal radiation pressure forces inherent in the spacecraft. One paper published by physicist Slava Turyshev et al. stated that “once the thermal recoil force is properly accounted for, no anomalous acceleration remains.” (source)

2 The burial place of British monarch Richard III who was killed in 1485 during the Battle of Bosworth Field and hastily buried remained unknown for centuries until 2012 when his remains were found under a parking lot.

Fought on August 22, 1485, the Battle of Bosworth Field was the last battle of the War of the Roses fought between the Houses of Lancaster and York. It is estimated that the royal army of Richard III had 8,000 men while Henry Tudor’s army had 5,000. However, Lord Stanley, the fourth husband of Henry Tudor’s mother, Sir William Stanley, and Henry Percy abandoned Richard leading to his defeat and death.

According to Burgundian chronicler Jean Molinet, a Welshman used a halberd to strike a blow with such force that Richard’s helmet was driven into his skull. Early sources suggest that his naked body was tied to a horse and taken to the Collegiate of Church of the Annunciation of Our Lady of the Newarke where it was displayed before burying him at Greyfriars Church in Leicester.

Other sources also suggested that his body was thrown into the River Soar. There is also evidence that a memorial stone which King Henry paid £50 (equivalent to £37,713 in 2016) for, was visible in 1612 in the Greyfriars’ garden. The site was, however, lost due to 400 years of development in the area until in September 2012, archaeological investigations lead to its discovery. Following the examination and confirmation of his remains, they were reburied on March 26, 2015, in Leicester Cathedral. (source)

3 There was a Pennsylvanian urban legend about someone called “The Green Man” or “Charlie No-Face” about a strange-looking creature wandering the streets at night. It was, in fact, a real man named Raymond Robinson whose face was severely disfigured due to an accident with a power line. 

When Robinson was nine years old, he was severely injured on the Morado Bridge near Beaver Falls which had electrical lines of both 1,200 volts and 22,000 volts that claimed the life of another boy the previous year. Though doctors were not optimistic about Robinson, he made it through but suffered severe disfigurement. He lost his eyes, nose, and his right arm.

Robinson lived in the borough of Koppel at his relatives’ home and made doormats, wallets, and belts for a living. Not wanting to create panic in public, he was always stayed indoors during the day and went for long walks in the night along the State Route 351.

His walks aroused the curiosity of locals who would gather to find him. While some showed friendly curiosity and would trade cigarettes or beer in exchange for a conversation or a photograph with him, others were cruel. He was even struck by cars a few times.

Nothing stopped Robinson from taking his nightly walks, feeling his way with a walking stick along the road. He became a myth and an urban legend which many generations in Pennsylvania grew up with.

Exaggerations about him, such as the green color of his skin which resulted from electrocution or that he hides in an abandoned house, persist. The fact that he actually existed and was liked by his family and neighbors often comes as a surprise to many who only know the urban legend. (source)

4 First documented in 1915, the sailing stones are a geological phenomenon where rocks move and inscribe long tracks along a smooth valley floor. No one knew how it happened until 2009 when technological developments allowed researchers to observe the stones using time-lapse cameras.

Aptly named, the Racetrack Playa, or simply “The Racetrack,” is a dry lake located above the northwestern side of the Death Valley, California. It is 3,714 feet (1,132 meters) above sea level and is exceptionally flat with very fine sediment that is often seen as firm, hexagonal, mud cracks.

Most of the sailing stones are found in the southern portion of the playa and measure between 15 to 46 centimeters (six to 19 inches) in diameter. The tracks they leave are often up to 100 meters (330 feet) long, between eight to 30 centimeters (three to 12 inches) wide, and usually less than 2.5 centimeters (one inch) deep.

Study of the rocks began in 1900, but all that researchers could get was hypotheses and no confirmations. Research continued throughout the 20th century, but without knowing when or under what conditions the movement occurred, it was impossible to solve the mystery. In 2009, the development of inexpensive time-lapse cameras allowed researchers to capture their movement.

In 2014, a time-lapse video was published clearly showing what happens. When there is water in the lake, thin ice sheets a few millimeters thick form on the surface during cold nights. During sunny days, the sheets break up. The winds move the ice sheets and the rocks along with them at up to five meters per minute leaving tracks in the fine sediment. Some rock movements lasted up to 16 minutes. (source)

5 In the 1970s, several US submarines were forced back to base to repair damage, fearing they were being attacked by an unknown weapon. Later, they found out it was cookiecutter sharks that were biting chunks off the neoprene on sonar domes, impairing navigation.

The cookiecutter shark, also known as “cigar shark,” is a small species of shark reaching just 42 to 56 centimeters (16.5 to 22 inches) in length. They are commonly found in warm oceanic waters throughout the world. Their name refers to the way they feed by gouging out round pieces of flesh off larger animals, like whales, seals, sharks, stingrays, and bony fishes.

They are even known to attack submarines, underwater cables, fishing nets, and, in rare instances, humans. They have lips that work as suction cups and bandsaw-like teeth that help them latch onto the prey and cut off a chunk of flesh.

The attacks on US submarines resulted in the sound-transmitting oil to leak, impairing navigation. In the 1980s, around 30 submarines were attacked by cookiecutter sharks damaging the rubber-sheathed electric cable connected to the sounding probe that ensures safety when surfacing in shipping zones.

In both cases, the material was covered by a fiberglass coating. Apart from submarines, oceanographic equipment, and telecommunications cables also suffer attacks from them. (source)