Did you know that Niagara Falls is a group of waterfalls rather than a single waterfall? The American Falls, Bridal Veil Falls, and the Canadian Falls, collectively known as Horseshoe Falls, straddle the boundary between Canada and the United States. The Niagara River, from which all three falls flow, gets water from four Great Lakes — Lake Superior, Lake Michigan, Lake Huron, and Lake Erie — before emptying into Lake Ontario.

Thanks to its microscopic budget and major success at the box office, the 2007 film Paranormal Activity, scored a return on investment of 19,758 percent, absolutely blowing away the next most profitable film (2015 horror film Gallows, with an ROI of 6,843 percent). It cost just $60,000 to make and another $400,000 or so to market, yet ultimately brought in more than $89 million.

The Two Fridas is a double self-portrait in oil of two versions of Frida Kahlo seated together. One is dressed in a white European-style Victorian gown, while the other is dressed in a traditional Tehuana gown. After divorcing her husband, fellow artist Diego Rivera, Kahlo created the artwork in 1939. (whom she would later remarry). Many art historians believe that the two figures in the painting represent Frida's dual heritage: her German father and Mexican mother.

Stingrays may appear to be soaring through the water, but a closer look reveals that they are actually moving through with a smooth flapping motion. The majority of species move by undulating their bodies, much like an aquatic wave, however, some prefer to flap their sides like wings. Stingrays in South Africa travelled at a speed of 1.35 kilometres per hour (0.83 miles per hour), and some species made migrations of up to 850 kilometres, according to research by the Save Our Seas Foundation (528 miles).

It is also the biggest meromictic basin in the world. A meromictic lake contains water strata that do not mix together. Regular holomictic lakes, on the other hand, have at least one period every year when the surface and deep waters mix. Although meromictic lakes may be found all over the world, they are extremely uncommon. The proportion of meromictic lakes to holomictic lakes is around one to 1,000.

The Menai Bridge in Anglesey was the world's first suspension bridge built to carry heavy traffic. The bridge, designed by Thomas Telford, was dedicated on January 30, 1826. It was also the longest bridge in the world at the time, measuring 386 metres (1,265 ft).

Adultery is legal in South Korea, as it is in China and Japan, and has been since 2015, as the country believes it is more of a personal matter than a state matter.

MIND THE GAP! That’s the gap between when there was a British Museum tube station and now. The photos above (courtesy of London Transport Museum) show the entrance to the Museum’s underground station in 1921, some gentlemen waiting on the platform in 1903 (with some fabulous hats!), and its construction in 1898. The station opened in 1900 but was closed in September 1933 when the new Holborn station opened, less than 100 yards away.

Sea lampreys suck their victim dry, their keen tongue piercing through the host's skin and scales. Because of the suction-cup capacity of their jaws, they remain connected to their prey. The prey is further rendered immobile by an enzyme secreted by the sea lamprey that serves as an anticoagulant to prevent blood clots and maintain a constant flow.

The brain's structural changes as a result of Alzheimer's disease. As a result of the cerebral cortex and other brain regions shrinking as a result of Alzheimer's disease, the ventricles in the brain can grow. These alterations can make it difficult to detect movement, focus on an object, and change how the pupils respond to light.

The Teutonic Order's Castle at Malbork is the world's largest castle in terms of land area. It is a UNESCO World Heritage Site and was originally erected in the 13th century as a Teutonic castle and stronghold. In that regard, Poland is home to a whopping 15 UNESCO World Heritage Sites!

The same is true for knitting. Your overall health is improved by needlecrafts because they significantly lower your stress and blood pressure. They maintain your flexibility and improve the blood flow to your hands. The simultaneous stimulation of both hemispheres of your brain by using both hands in various ways gives your brain a workout that not many other activities can. You can learn more about this topic here and here.

In Viking law, women had the same rights as males. Despite the traditional expectation that women married who their parents picked for them, they had the right to divorce and remarry. It was also socially acceptable for Viking women to have children outside of marriage. While boys were given precedence over daughters in inheritance, a woman may inherit all of her parents' possessions if she had no brothers. 

Without our brows, where would we be? Evidently emotionless and almost indistinguishable! We adore the eyebrows and eyelashes in addition to the rest of the eye. 

According to the Committee on the Medical Effects of Air Pollutants (COMEAP), outdoor air pollution causes up to 36,000 premature deaths in the UK each year. 29,000 premature deaths per year are caused by fine particle air pollution. The harmful gas nitrogen dioxide's (NO2) impact raises the number to 36,000 every year.

There isn't much wooing before lobster love-making. Females who have recently shed their shells emit a scent to alert males that they are ready. Six to nine months later, eggs appear on her tail, and they hatch after another six to nine months. A female lobster weighing one pound and a half can lay between 8,000 and 12,000 eggs, each roughly the size of a raspberry piece. Females do not have monogamous relationships.

Over the centuries, a few false words have appeared in dictionaries due to human error. Some words, such as phantomnation, which appeared in a Webster's edition in 1864, are the result of missing hyphens. Others are typographical mistakes. Dord was defined as density in a 1934 edition of Webster's New International Dictionary as a result of spacing confusion. To protect their copyright, some dictionary editors have purposefully included fake words, such as equivalence in The New Oxford American Dictionary.

The cornea is one of only two organs in the human body that lacks blood vessels. The cornea is the transparent portion of the eye that protects the pupil and other parts of the eye. According to scientists at the Harvard Department of Ophthalmology's Schepens Eye Research Institute, cartilage and the cornea are the only types of tissue in the human body that lack blood vessels. Your eye also has some unusual characteristics that you probably aren't aware of.

You don't have to use a lot of moisturizers. For the face and neck, a pump or two is plenty. Use just enough cream to hydrate your skin while also allowing it to breathe.

Players were never able to advance the ball. Instead, each player was required to toss it from where he caught it. The first team credited with advancing the ball by dribbling did so at Yale in 1897, and the official allowed for dribbling, initially only one per possession, was implemented four years later. The slam dunk, another major basketball technique, was outlawed from the 1967-1968 season until the 1976-1977 season.

The effects of toxic air are worse for those who are most at risk. The development of a child's lungs is harmed by air pollution. Additionally, it exacerbates pre-existing respiratory and cardiovascular diseases, especially in elderly patients. Because they frequently reside close to major roads, where air pollution is severe, the poorest members of our society suffer more than others. Air pollution has an impact on every motorist. However, especially when using side routes, pedestrians and cyclists are frequently subject to less air pollution than those who travel by car.

Did you know that the word "nectarine" means "sweet like nectar," which is most likely the origin of the name? According to research, nectarines, like peaches, originated in China over 2,000 years ago and were introduced to England in the late 16th or early 17th centuries. Nectarines are high in Vitamin C and A, as well as antioxidants. They help with weight loss, blood pressure regulation, and overall health. They also help to boost immunity and heart health.

The Denmark Strait cataract is the world's highest underwater waterfall, with a drop of 11,500 feet (3,505 metres) in the Atlantic Ocean.

Summer is the time of year with the greatest number of thunderstorms. The glow of summer frequently gives the ideal states of rising air and dampness expected for the production of rainstorms. They are most common in the southeast and East Midlands of the UK.