How Much Does the Moon Weigh?

iStock
iStock

How much does the moon weigh?

C Stuart Hardwick:

Nothing.

Okay, I’m being a bit pedantic. The mass of the moon, which might be what you mean to ask, is approximately 7.3476× 10^22 kilograms.

But the moon doesn’t weigh anything.

Weight is directly related to mass, but it’s not the same thing as mass (even through we call units of weight and mass by the same names). Weight is the force exerted by gravity against a body resting against a larger mass. The moon is in freefall—in orbit—so it doesn’t weigh anything. If it were placed on the surface of the Earth, it would weigh about 7.3476 × 10^22 kilograms—but only for a moment. Then it would collapse under its own weight and become a rather disastrous pimple on the Earth until it broke through the crust.

That would be a bad day.

But fortunately, there is no realistic way that could ever happen. The moon is in orbit, which means it’s falling toward Earth (which is why it doesn’t “feel” our gravity—it’s weightless), but it’s also coasting away into space such that for every meter it falls toward us, it moves far enough for Earth’s surface to curve away one meter. Therefore, like any orbiting body, it goes round and round and round.

This weight versus mass thing confuses a lot of folks because in colloquial English we use pounds and kilograms for both measurements of weight and mass. That is because we figured all this stuff out on Earth, where it was simple and practical to measure mass by measuring weight.

In other words, because we are earthlings, we define units of mass as equal to the observed units of weight as measured on Earth.

If you like science, you might like my free, award-winning sci-fi sampler.

This post originally appeared on Quora. Click here to view.

Why Does Santa Claus Give Coal to Bad Kids?

iStock/bonchan
iStock/bonchan

The tradition of giving misbehaving children lumps of fossil fuel predates the Santa we know, and is also associated with St. Nicholas, Sinterklaas, and Italy’s La Befana. Though there doesn't seem to be one specific legend or history about any of these figures that gives a concrete reason for doling out coal specifically, the common thread between all of them seems to be convenience.

Santa and La Befana both get into people’s homes via the fireplace chimney and leave gifts in stockings hung from the mantel. Sinterklaas’s controversial assistant, Black Pete, also comes down the chimney and places gifts in shoes left out near the fireplace. St. Nick used to come in the window, and then switched to the chimney when they became common in Europe. Like Sinterklaas, his presents are traditionally slipped into shoes sitting by the fire.

So, let’s step into the speculation zone: All of these characters are tied to the fireplace. When filling the stockings or the shoes, the holiday gift givers sometimes run into a kid who doesn’t deserve a present. So to send a message and encourage better behavior next year, they leave something less desirable than the usual toys, money, or candy—and the fireplace would seem to make an easy and obvious source of non-presents. All the individual would need to do is reach down into the fireplace and grab a lump of coal. (While many people think of fireplaces burning wood logs, coal-fired ones were very common during the 19th and early 20th centuries, which is when the American Santa mythos was being established.)

That said, with the exception of Santa, none of these characters limits himself to coal when it comes to bad kids. They’ve also been said to leave bundles of twigs, bags of salt, garlic, and onions, which suggests that they’re less reluctant than Santa to haul their bad kid gifts around all night in addition to the good presents.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

Why Are Poinsettias Associated with Christmas?

iStock
iStock

Certain Christmas traditions never seem to go out of style. Along with wreaths, gingerbread cookies, and reruns of A Christmas Story sits the poinsettia, a red-tinged leafy arrangement that’s become synonymous with the holiday. Upwards of 100 million of them are sold in the six weeks before December 25.

Why do people associate the potted plant with seasonal cheer? Chalk it up to some brilliant marketing.

In 1900, a German immigrant named Albert Ecke was planning to move his family to Fiji. Along the way, they became enamored of the beautiful sights found in Los Angeles—specifically, the wild-growing poinsettia, which was named after Joel Roberts Poinsett, the U.S.-Mexican ambassador who first brought it to the States in 1828. Ecke saw the appeal of the plant’s bright red leaves that blossomed in winter (it’s not actually a flower, despite the common assumption) and began marketing it from roadside stands to local growers as "the Christmas plant."

The response was so strong that poinsettias became the Ecke family business, with their crop making up more than 90 percent of all poinsettias sold throughout most of the 20th century: Ecke, his son Paul, and Paul’s son, Paul Jr., offered a unique single-stem arrangement that stood up to shipping, which their competitors couldn’t duplicate. When Paul III took over the business in the 1960s, he began sending arrangements to television networks for use during their holiday specials. In a priceless bit of advertising, stars like Ronald Reagan, Dinah Shore, and Bob Hope were sharing screen time with the plant, leading millions of Americans to associate it with the holiday.

While the Ecke single-stem secret was eventually cracked by other florists—it involved grafting two stems to make one—and their market share dwindled, their innovative marketing ensured that the poinsettia would forever be linked to Christmas.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

SECTIONS

arrow
LIVE SMARTER