Over time, even facts we consider steadfast truths can change. People used to think doctors could forgo washing their hands before surgery. Knowledge is ever-evolving.
The seven ideas below probably changed since your school days. Re-educate yourself.
THEN: Pluto is a planet
NOW: Pluto isn’t a planet
We’ve known since the late 1800s that a ninth planet, after Uranus, potentially existed. In 1906, Percival Lowell, the founder of the Lowell Observatory in Flagstaff, Arizona, even began a research project intended to locate the mysterious “Planet X.”
Then in 1930, a 23-year-old newbie at the facility found it. The discoverer, Clyde Tombaugh, had been tasked with systematically comparing photographs of the sky taken weeks apart to search for any moving objects. He eventually saw one and submitted his finding to the Harvard College Observatory. After an 11-year-old English girl named the new planet (for the Roman god of the underworld), we started including Pluto as a planet in our solar system.
But in 2003, an astronomer found a larger object beyond Pluto — which he named Eris, according to NASA. The new information caused a bunch of other astronomers to question what really makes a planet a planet, and they decided, based on size and location, that Pluto just didn’t make the cut. Neither did Eris, actually. Pluto was demoted to a dwarf planet.
Needless to say, elementary schools kids were pretty bummed.
But there may be hope. Researchers have recently been debating whether to make Pluto a planet again.’
THEN: Diamond is the hardest substance
NOW: Ultrahard nanotwinned cubic boron nitride is the hardest substance
We’ve known about two substances harder than a diamond since 2009: wurtzite boron nitride and lonsdaleite, according to Scientific American. The first resists indentation with 18% more fortitude than a diamond, and the second — a whopping 58%.