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Why Do Flocks of Geese Fly in a “V” Shape?

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In large swaths of the U.S. this time of year, it seems you can’t get more than a few feet without tripping over a Canada Goose; they come down here from the Great White North for the winter months (or, in some places, hang out year-round). When they’re not lounging about in field and stream, you might see them flying overhead, usually in a large "V" formation, with one bird in the lead and the others trailing behind it in two diverging lines.

Why do they fly in a “V”? Not just because a “Q” would be too hard. Scientists have found that the “V” formation serves two functions that make group travel easier.

Give Me A Lift

One reason—first proposed by aerospace engineers Peter Lissaman and Carl Shollenberger in 1970—is that the shape of the formation makes the birds more energetically efficient flyers than they would be flying alone. As a goose flies, air rushes around its wings, creating circular, rotating patterns of air at the ends of the wings called wingtip vortices. The vortices push air downward and upward in different spots (you can see a pretty clear illustration of this here), and if another goose is flying in one of the spots where the air is getting pushed up, it gets some free lift (the air force that directly opposes the goose’s weight) from the efforts of the first goose.

If geese fly in a group and arrange themselves correctly, then every one behind the leader gets a little extra lift and doesn’t have to flap as much to maintain altitude and forward momentum. The less they flap, the more energy they conserve, and the farther they can fly.

For a long time, scientists only had mathematical models, photos and distant observations of live geese to support this idea. The aerodynamics made sense, and observed birds were almost always in positioned in the formation to gain some advantage, but no one was able to directly measure the energetic benefit, if any, to free-flying birds.

Then, in 2001, French scientists had a unique opportunity to do just that when they crossed paths with a film company that had trained great white pelicans to fly in formation behind motorboats and ultralight planes for movie scenes. Researchers from the Centre d'Etudes Biologiques de Chizé, led by ecologist Henri Weimerskirch, fitted the birds with heart rate monitors and then filmed them in flight. Their data showed that the heart rates of pelicans flying in “V” formation were 11.4–14.5 percent lower than that of any one bird flying alone, and that the birds in formation could afford to flap less and glide more, for energy savings of 11.4–14.0 percent.

Given this, why don’t all birds fly in the “V”? It seems the advantages of the formation only apply to larger birds, like geese and pelicans, and aren’t as pronounced for smaller, lighter birds. But other formations may have their benefits, too. While the “cluster” formations that pigeons fly in, for example, actually cost them energy versus flying alone, they might allow large groups to fly close together and maneuver and turn without mid-air collisions.

An Eye On You

Researchers have noticed something funny with some bird flocks: While the birds usually fly in positions that give them some energy benefit, not every bird is always in the expected optimal position, and therefore they get lower energy savings. Some birds just aren’t making the most of the “V,” which got people thinking that there might be another reason for the formation.

That reason might be that the formation allows the birds to maintain visual contact with each other and to communicate, making it easier to keep the group together and navigate. Taking the angles of the formation and what they know about geese’s field of vision and “blind spots” into account, researchers from the University of Rhode Island hypothesize that a “V” angle of 29 degrees or more would allow every bird in the group to see every other bird. There don't appear to be any studies that directly test this idea.

Just like with the energy conservation idea, though, the birds don’t always take up the optimal spot for clear visual contact. Most fly, instead, in positions that give them some benefit in terms of both energy and flock contact, or in one or the other. Those close-but-no-cigar situations beg the question of whether there's another "V" advantage we're not seeing, or if it's just really hard for birds to find and maintain the best spot in the formation.

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Big Questions
What's the Difference Between Vanilla and French Vanilla Ice Cream?
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While you’re browsing the ice cream aisle, you may find yourself wondering, “What’s so French about French vanilla?” The name may sound a little fancier than just plain ol’ “vanilla,” but it has nothing to do with the origin of the vanilla itself. (Vanilla is a tropical plant that grows near the equator.)

The difference comes down to eggs, as The Kitchn explains. You may have already noticed that French vanilla ice cream tends to have a slightly yellow coloring, while plain vanilla ice cream is more white. That’s because the base of French vanilla ice cream has egg yolks added to it.

The eggs give French vanilla ice cream both a smoother consistency and that subtle yellow color. The taste is a little richer and a little more complex than a regular vanilla, which is made with just milk and cream and is sometimes called “Philadelphia-style vanilla” ice cream.

In an interview with NPR’s All Things Considered in 2010—when Baskin-Robbins decided to eliminate French Vanilla from its ice cream lineup—ice cream industry consultant Bruce Tharp noted that French vanilla ice cream may date back to at least colonial times, when Thomas Jefferson and George Washington both used ice cream recipes that included egg yolks.

Jefferson likely acquired his taste for ice cream during the time he spent in France, and served it to his White House guests several times. His family’s ice cream recipe—which calls for six egg yolks per quart of cream—seems to have originated with his French butler.

But everyone already knew to trust the French with their dairy products, right?

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

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Big Questions
How Many Rings Does Saturn Have?
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NASA/JPL-Caltech/Space Science Institute

Of all the planets surrounded by rings, Saturn is the most famous. These planetary rings are massive enough that Galileo was able to see them using a simple telescope way back in 1610, though it wasn't until half a century later that another scientist was able to figure out what the "arms" Galileo saw actually were. NASA has since called them "the most recognized characteristic of any world in our solar system."

So how many rings does Saturn have, anyway? If you can see them from your backyard, there must be a lot, right?

Scientists don't know for sure exactly how many rings Saturn has. There are eight main, named ring groups that stretch across 175,000 miles, but there are far more than eight rings. These systems are named with letters of the alphabet, in order of their discovery. (Astronomers have known about ring groups A, B, and C since the 17th century, while others are newer discoveries. (The most recent was just discovered in 2009.)

The rings we can see in images of the planet—even high-resolution images—aren't single rings, per se, but are in fact comprised of thousands of smaller ringlets and can differ a lot in appearance, showing irregular ripples, kinks, and spokes. The chunky particles of ice that make up Saturn's rings vary in size from as small as a speck of dust to as large as a mountain.

While the gaps between Saturn's rings are small, the 26-mile-wide Keeler Gap is large enough to contain multiple moons, albeit very small ones. The largest ring system—the one discovered in 2009—starts 3.7 million miles away from Saturn itself and its material extends another 7.4 million miles out, though it's nearly invisible without the help of an infrared camera.

Researchers are still discovering new rings as well as new insights into the features of Saturn's already-known ring systems. In the early 1980s, NASA's Voyager missions took the first high-resolution images of Saturn and its rings, revealing previously unknown kinks in one of the narrower rings, known as the F ring. In 1997, NASA sent the Cassini orbiter to continue the space agency's study of the ringed planet, leading to the discovery of new rings, so faint that they remained unknown until Cassini's arrival in 2006. Before Cassini is sent to burn up in Saturn's atmosphere in September 2017, it's taking 22 dives through the space between the planet and its rings, bringing back new, up-close revelations about the ring system before the spacecraft dives to its death.

Though it's certainly possible to see Saturn's rings without any fancy equipment, using a low-end telescope at your house, that doesn't mean you always can. It depends on the way the planet is tilted; if you're looking at the rings edge-on, they may look like a flat line or, depending on the magnification, you might not be able to see them at all. However, 2017 happens to be a good year to see the sixth planet, so you're in luck.

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

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