Fallacious yet widespread and documented beliefs courtesy of Wikipedia.
It is commonly claimed that the Great Wall of China is the only man-made object visible from the Moon. This is false. None of the Apollo astronauts reported seeing any specific man-made object from the Moon, and even earth-orbiting astronauts can barely see it, but city lights are easily visible on the night side of Earth from orbit. The misconception is believed to have been popularized by Richard Halliburton decades before the first moon landing. Shuttle astronaut Jay Apt has been quoted as saying "…the Great Wall is almost invisible from only 180 miles up."

Fallacious yet widespread and documented beliefs courtesy of Wikipedia.
Black holes, unlike their common image, do not act as "cosmic vacuum cleaners" any more than other stars. The collapse of a star into a black hole is an explosive process, which means, according to Mass–energy equivalence, that the resulting black hole would be of lower mass than its parent object, and actually have a weaker gravitational pull. The source of the confusion comes from the fact that a black hole exists in a space much smaller but orders of magnitude more dense than a star, causing its gravitational pull to be much stronger closer to its surface. But, as an example, were the Sun to be replaced by a black hole of the same mass, the orbits of all the planets surrounding it would be unaffected.

Fallacious yet widespread and documented beliefs courtesy of Wikipedia.
When a meteor lands on Earth (after which it is termed a meteorite), it is not necessarily hot. A meteoroid's great speed during entry is enough to melt or vaporize its outermost layer, but any molten material would probably be quickly blown off (ablated). The interior of the meteoroid probably does not have time to heat up because the hot rocks are poor conductors of heat. Also, atmospheric drag can slow small meteoroids to terminal velocity by the time they hit the ground, giving the surface time to cool down. [page needed]

Fallacious yet widespread and documented beliefs courtesy of Wikipedia.
Seasons are not caused by the Earth being closer to the Sun in the summer than in the winter. In fact, the Earth is actually farther from the Sun when it is summer in the Northern Hemisphere. Seasons are the result of the Earth being tilted on its axis by 23.5 degrees. As the Earth orbits the Sun, different parts of the world receive different amounts of direct sunlight. When an area of the Earth's surface is oriented perpendicular to the incoming sunlight, it will receive more radiation than it will when it is oriented at an angle to the incoming sunlight. In July, the Northern Hemisphere is tilted towards the Sun giving longer days and more direct sunlight; in January, it is tilted away. The seasons are reversed in the Southern Hemisphere, which is tilted towards the Sun in January and away from the Sun in July. In tropical areas of the world, there is no noticeable change in the amount of sunlight.

Fallacious yet widespread and documented beliefs courtesy of Wikipedia.
It is not easier to balance an egg on its end on the first day of spring. In fact, the ease or difficulty of balancing an egg is the same 365 days a year. This myth is said to originate with the egg of Li Chun, an ancient Chinese folk belief that it is easier to balance an egg on Li Chun, the first day of spring in the Chinese calendar. In Chinese Li means setup/erect, Chun spring/egg. Setup spring is a Chinese solar term, literally interpreted as erecting an egg for fun. It was introduced to the western world in a Life article in 1945, and popularized once again by self-titled "urban shaman" Donna Henes, who has hosted an annual egg-balancing ceremony in New York City since the mid-1970s.

Fallacious yet widespread and documented beliefs courtesy of Wikipedia.
The claim that a duck's quack does not echo is false, although the echo may be difficult to hear for humans under some circumstances.

Fallacious yet widespread and documented beliefs courtesy of Wikipedia.
DNA is not made of protein. DNA is instead a nucleic acid. DNA and protein are closely interrelated, however. DNA is always accompanied by proteins in the chromatin of plants and animals. See protein biosynthesis for DNA's involvement in assembling protein. See DNA replication for enzymatic proteins' involvement in assembling DNA.

Fallacious yet widespread and documented beliefs courtesy of Wikipedia.
The notion that goldfish have a memory of only three seconds is false.

Fallacious yet widespread and documented beliefs courtesy of Wikipedia.
Lemmings do not engage in mass suicidal dives off cliffs when migrating. They will, however, occasionally unintentionally fall off cliffs when venturing into unknown territory, with no knowledge of the boundaries of the environment. The misconception is due largely to the Disney film White Wilderness, which shot many of the migration scenes (also staged by using multiple shots of different groups of lemmings) on a large, snow-covered turntable in a studio. Photographers later pushed the lemmings off a cliff. The misconception itself is much older, dating back to at least the late nineteenth century.