Why Are There Only 28 Days in February?

iStock
iStock

Thirty days hath September,
April, June, and November.
All the rest have 31,
Except for February,
Which got the short stick because it's cold and no one likes it.  

Well, something to that effect. Some believe February once boasted 29 days and that Augustus Caesar stole a day so he could add it to August, which was named for him. (If there’s a month named after you, why not milk it?) But that’s a myth. Rather, February has 28 days because, to the Romans, the month was an afterthought. In the 8th century BCE, they used the Calendar of Romulus, a 10-month calendar that kicked the year off in March (with the spring equinox) and ended in December. January and February didn’t even exist:

Martius: 31 days
Aprilius: 30 days
Maius: 31 days
Junius: 30 days
Quintilis: 31 days
Sextilis: 30 days
September: 30 days
October: 31 days
November: 30 days
December: 30 days

Tally up those numbers, and you’ll see a problem—the year is only 304 days long. Back then, winter was a nameless, monthless period that no one cared for much. (Planters and harvesters used the calendar as a timetable. To them, winter was useless and wasn’t worth counting.) So for 61 days out of the year, Romans could ask “What month is it?” and you could correctly answer, “None!”

King Numa Pompilius thought that was stupid. Why have a calendar if you’re going to neglect one-sixth of the year? So in 713 BCE, he lined the calendar up with the year’s 12 lunar cycles—a span of about 355 days—and introduced January and February. The months were added to the end of the calendar, making February the last month of the year.

But no Roman calendar would be complete without some good old-fashioned superstition mixed in! The Romans believed even numbers were unlucky, so Numa tried to make each month odd. But to reach the quota of 355, one month had to be even. February ended up pulling the short stick, probably because it was simply the last month on the list. (Or as Cecil Adams puts it, “If there had to be an unlucky month, better make it a short one.”) Numa’s calendar ended up looking like this:

Martius: 31 days
Aprilius: 29 days
Maius: 31 days
Iunius: 29 days
Quintilis: 31 days
Sextilis: 29 days
September: 29 days
October: 31 days
November: 29 days
December: 29 days
Ianuarius: 29 days
Februarius: 28 days

Of course, a 355-day calendar had its bugs. After a few years went by, the seasons and months would fall out of sync. So to keep things straight, the Romans would occasionally insert a 27-day leap month called Mercedonius. The Romans would erase the last couple days of February and start the leap month on February 24—further evidence no one ever cared much for the month.  

This caused headaches everywhere. The leap month was inconsistent, mainly because Rome’s high priests determined when it would arrive. Not only did they insert Mercedonius haphazardly, but the priests (being politicians) abused the power, using it to extend the terms of friends and trim the terms of enemies. By Julius Caesar’s time, the Roman people had no clue what day it was.

So Caesar nixed the leap month and reformed the calendar again. (To get Rome back on track, the year 46 BCE had to be 445 days long!) Caesar aligned the calendar with the sun and added a few days so that everything added up to 365. February, which by now was at the top of the calendar, kept its 28 days. We can only imagine it’s because Caesar, like everyone before and after him, just wanted it to be March already. 

How Is a Sunscreen's SPF Calculated?

Rawpixel/iStock via Getty Images
Rawpixel/iStock via Getty Images

I’m a pale person. A very pale person. Which means that during these hot summer months, I carry sunscreen with me at all times, and apply it liberally. But I’ve never really understood what those SPF numbers meant, so I asked some sun care to break it down for me—and to tell me how to best apply the stuff so that I can make it through the summer without looking like a lobster.

Soaking up the sun ... safely

SPF stands for Sun Protection Factor, and it indicates a sunscreen’s ability to block UVB rays. The concept was pioneered at the Coppertone Solar Research Center in 1972; in 1978, the FDA published an SPF method based on Coppertone’s system, according to Dr. David Leffell, chief of Dermatologic Surgery and Cutaneous Oncology at Yale.

The numbers themselves stand for the approximate measure of time a person who has applied the sunscreen can stay out in the sun without getting burned. Say you get burned after 20 minutes in the sun without sunscreen; if properly applied (and reapplied), SPF 30 will allow you to stay in the sun 30 times longer without burning than if you were wearing no protection at all. So, theoretically, you should have approximately 600 minutes, or 10 hours, in the sun. But it’s not an exact science because the amount of UV light that reaches us depends on a number of factors, including cloud cover, the time of day, and the reflection of UV rays off the ground, so it’s generally recommended that you reapply sunscreen every two hours (or even sooner).

What gives a sunscreen a higher SPF comes down to the product’s formulation. “It’s possible that an SPF 50 might contain slightly more of one or more sunscreen active ingredients to achieve that higher SPF,” Dr. Patricia Agin, president of Agin Suncare Consulting, says. “But it’s also possible that the SPF 50 might contain an additional active ingredient to help boost the SPF performance to SPF 50.”

No matter what SPF your sunscreen is, you’ll still get a burn if it’s not properly applied. So let’s go over how to do that.

How to apply sunscreen

First, make sure you have a water-resistant, broad spectrum sunscreen—which means that it protects against both UVB and UVA radiation—with an SPF of at least 30. “Typically, you don’t have to buy sunscreen that has an SPF higher than that unless you have very sun sensitive skin,” Leffell says. “That’s a very small percentage of the population.” (Redheads, people with light eyes, and those who turn pink after just a few minutes in the sun—you’ll want to load up on SPF above 30.)

Twenty minutes before you go out to the beach or the pool, begin to apply your sunscreen in an even coat. “Don’t apply it like icing on a cake,” Leffell says. “I see these patients and they’ve got the tops of their ears covered with thick, unevenly applied sunscreen, and that’s not a good sign.” Sunscreen sprays will easily give you that even coat you need.

Whether you’re using lotion or a spray, when it comes time to apply, Leffell recommends starting with your scalp and face, even if you plan on wearing a hat. “Make sure you’ve covered the ears and nose and under the eyes,” Leffell says. “Then, I would move down to the shoulders, and make sure that someone can apply the sunscreen on your back beyond the reach of your hands.”

Other areas that are important that you may forget to cover, but shouldn’t, are the tops of your feet, the backs of your hands, and your chest. “We see it all the time now—the v of the chest in women has become a socially and aesthetically huge issue when they are 50 and beyond. Because even though they can treat their faces with all sorts of cosmetics and procedures, the chest is much harder, and they are stuck with the face of a 40-year-old and the chest of a 60-year-old. You want to avoid that using sunscreen.”

Another important thing to keep in mind: Water-resistant doesn’t mean waterproof. “I always tell patients to reapply every couple of hours while you’re active outdoors," Leffell says, "and always reapply when you come out of the water or if you’ve been sweating a lot, regardless of whether the label says water resistant."

Determining whether or not you’ve succeeded in properly applying your sunscreen is easy: “You know you’re applying your sunscreen properly if, after the first time you’ve used it, you haven’t gotten a burn,” Leffell says.

Agin has a caveat, though: "It’s not a good idea to think of sunscreens only as a way to extend your time in the sun," she says. "One must also understand that even before becoming sunburned, your skin is receiving UV exposure that causes other damage to the skin. At the end of the 600 minutes, you will have accrued enough UV to cause a sunburn—one Minimal Erythema Dose or MED—but there is pre-MED damage done to skin cells’ DNA and to the skin’s supporting structure of collagen and elastin that is not visible and happens even before you sunburn. These types of damage can occur without sunburning. So you can’t measure all the damage done to your skin by only being concerned about sunburn."

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

An earlier version of this post ran in 2014.

What's the Difference Between Ice Cream and Gelato?

iStock/Getty Images/zoff-photo
iStock/Getty Images/zoff-photo

'Tis the season for beach reads, tan lines, and ice-cold desserts. You know it's summer when going to the local ice cream or gelato shop becomes part of your daily routine. But, what exactly is the difference between these two frozen treats?

One of the key differences between the two is butterfat. While ice cream's main ingredients include milk, cream, sugar, and egg yolks, the secret to making gelato is to use much less cream and sometimes little to no egg yolk. This leads to a much smaller percentage of butterfat in gelato. The FDA rules say that ice cream cannot contain less than 10 percent milkfat (though it can go as high as 25 percent) while gelato, much like soft serve, stays in the 4- to 9-percent range.

The churning method for both also differs, which affects the treat's density. Ice cream is churned at a much faster pace, leading to more air being whipped into the mixture. Ice cream's higher butterfat content comes into play here—due to all of that milkfat, the mix absorbs the air more readily. Gelato, on the other hand, is churned at a slower pace and absorbs far less air, creating a much denser dessert.

You also might have noticed that the serving style for the two treats aren't the same, either. In order to get those perfectly stacked ice cream scoops on a cone, buckets of ice cream must be stored at around 0°F to maintain its consistency, while the softer gelato is stored at a warmer 10°F to 22°F. Ice cream is then scooped into fairly uniform balls with the round ice cream scooper, whereas a spade or paddle is best for molding gelato into mound in a cup or a cone.

You can't really go wrong with either gelato or ice cream on a sweltering summer day, but there is one more difference to keep in mind while you debate which to get: taste. If you want a bolder flavor, you'll want to go with gelato. Because of the density of the cream and because there's less butterfat to coat your taste buds, gelato can seem to have more intensity to its flavors.

Have you got a Big Question you'd like us to answer? If so, send it to bigquestions@mentalfloss.com.

SECTIONS

arrow
LIVE SMARTER