Smithsonian.com

If you don't want to show an misformed Moon on a Christmas card, a full moon is a safe option (courtesy of flickr user sally_monster)

You probably don’t pay too much attention to the imagery on the Christmas cards you receive or the paper wrapping your presents. You probably care more about the card’s message or the attractiveness of the gift wrap. And it’s probably just as well, since a new study in the journal Communicating Astronomy With the Public has found that depictions of the Moon on Christmas cards and gift wrap and in children’s Christmas books are often wrong.

Peter Barthel, an astronomer at the University of Groningen in the Netherlands, was spurred to look into this issue after seeing a Unicef Christmas card in 2010 and a popular animated Advent e-calendar that year that both showed an unlikely Moon. The card depicted children decorating a Christmas tree beneath a waning crescent moon (one with its left-hand side lit) while the calendar scene showed people caroling, also under a waning Moon. The problem here is that the waning Moon doesn’t rise until 3 a.m. While it’s not impossible that these scenes could take place in the early morning hours, “it’s unlikely,” Barthel writes.

And so Barthel began to examine Christmas scenes on wrapping paper and cards and in books in both the Netherlands and the United States, two countries that have done much to shape our modern view of Santa Claus and Christmas. He found that 40 percent of the pictures in Dutch Christmas books and 65 percent of the Dutch gift wrap samples incorrectly showed the waning Moon. And this wasn’t a modern problem–six out of nine samples from a collection of older Dutch gift wrap also depicted, wrongly, the waning Moon.

American Christmas artists did better at showing a believable Moon in their images, but simply because they more often draw a full Moon in Christmas scenes. (The full Moon rises at sunset and shines over evening holiday scenes naturally.) That said, Barthel did find examples of incorrect waning Moon scenes. One booklet even showed a full Moon and a waning Moon in the same night.

Should we care? Barthel says yes:

The errors are innocent, somewhat comparable to incorrectly drawn rainbows, with the colour at the inside of the arc. Now watching beautiful phenomena like rainbows and moon crescents is one thing, but understanding them makes them all the lot more interesting. Moreover, understanding leads to knowledge which lasts.

And I don’t think it’s too much to ask for artists, especially ones drawing for children, to pay a little attention to accuracy in something like this. After all, if artists like Vincent Van Gogh and Edvard Munch could take the time to use real moons and stars in their paintings, surely modern artists could as well.

Reindeer have a few strategies for keeping cool (courtesy of flickr user much ado about nothing)

You might not think that keeping cool is a problem for reindeer. After all, they live in cold northern regions, like Norway, Alaska and Siberia (and, of course, at least mythologically, the North Pole). But when they’re really active–running from a predator, say, or pulling Santa’s sleigh–then their nice, warm fur coat becomes a liability. They need a way to cool down their bodies, and especially their brains, before they overheat.

To find out how reindeer keep their cool, a group of researchers in Norway trained reindeer to trot on a treadmill at a speed of about 5 1/2 miles per hour (the scientists say that the animals appeared to enjoy the experience). While the animals were on the treadmill, the researchers varied the ambient temperature from 50 to 86 degrees Fahrenheit and measured the animals’ physiological responses, including respiration and blood flow. (The results of the study appear in the Journal of Experimental Biology.)

The researchers found that the reindeer employed three different tactics to cool down during their exercise. In the first stage, the reindeer increased their rate of breathing, from 7 breaths per minute to 260 breaths per minute, inhaling plenty of cool air through their noses. As the air passed through their nasal passages, water evaporated from their mucous membranes and cooled the blood in their noses. That cooled blood then passed into the reindeer’s body through its jugular vein and helped cool it down.

In the second stage, as the reindeer continued their trot and needed to get rid of more heat, they started to pant like dogs, opening their mouths and letting their tongues go floppy. “The tongue is large, vascularized and well circulated,” says the study’s lead author, Arnoldus Schytte Blix of the University of Tromsø. “They moisturize the tongue so you have evaporation which also takes heat away from the blood.”

It’s not until the reindeer’s brain reaches 102 degrees Fahrenheit that the animal employs stage three. At that point, cooled blood from the nose is diverted away from the body and into the head where a network of blood vessels act as heat exhangers, pulling out heat from the brain and into the blood and protecting the brain from dangerous overheating.

Which is a really good thing, because no one wants to wake up on Christmas morning to find a reindeer with heatstroke on the roof.

A human riding a horse, photo by Patrick Gries (from "Evolution")

Scientists have long used the skeletons of animals to study the relationships among different species. French naturalist Pierre Belon in 1555 included an engraving of a human skeleton beside a bird skeleton in his History of the Nature of Birds to emphasize similarities. Nearly 200 years later another French naturalist, George-Louis Leclerc, Comte de Buffon, compared the skeletons of humans and horses. He wrote in 1753:

Take the skeleton of a man. Tilt the pelvis, shorten the femur, legs, and arms, elongate the feet and hands, fuse the phalanges, elongate the jaws while shortening the frontal bone, and finally elongate the spine, and the skeleton will cease to represent the remains of a man and will be the skeleton of a horse.

Charles Darwin also used skeletons of living species–along with live and taxidermied specimens and fossils–as he developed his theory of natural selection.

It would appear that skeletons, then, would be a great tool for teaching evolutionary theory. But I wasn’t expecting them to be so beautiful.

Evolution, by Jean-Baptiste de Panafieu, photographs by Patrick Gries

The first thing you notice when you see a copy of Evolution by Jean-Baptiste de Panafieu are the photographs. One of my magazine colleagues called these stark black-and-white images of animal skeletons, by Patrick Gries, “science porn.” An artist friend drooled over the beauty in the imagery. (You can see four examples from the book in our photo gallery.) It could be incredibly easy to own this book and never read the text.

But that would be a shame. The book, brilliantly translated by Linda Asher from the original French, is organized into 44 easy-to-read essays about various topics in evolution, from history to modern theory, each illustrated by a set of skeleton photographs. The co-evolution of predator and prey species, for example, includes images of a leopard skeleton attacking a screwhorn antelope, a golden eagle swooping down on a rabbit and a red fox pouncing on a common vole. The text is full of details and stories that will be new even to readers who are familiar with the topic of evolution. But everything is explained well enough that those who have not read much about evolution before will not be lost.

Evolution may seem familiar; in 2007, the book was released in large format and quickly sold out after a selection of its images ran in the science section of the New York Times. This new version is a much more shelf-friendly and reading-friendly size, and it includes a handful of new images. The book would make a great last-minute holiday gift for the science or art lover on your list or just a fine addition to your own library.

(I can hardly bring up the topic of evolution without mentioning Smithsonian magazine’s January issue, now online. With it, we created something called Evotourism–a new type of travel focused on evolution. We’ve started off with 12 destinations, from the Jurassic Coast of England to Australia’s Kangaroo Island. You can learn about evolution by digging for your own fossils, viewing some of the world’s weirdest species ever to evolve, even helping scientists study the co-evolution of a predator and its prey. And if you’ve got your own Evotourism suggestions, we want to hear them.)

Aspen trees in Colorado (courtesy of flickr user Bill Dayton)

Three years ago, Michelle Nijhuis wrote about the phenomenon of sudden aspen decline (SAD) in her story “What’s Killing the Aspen?”

In 2004, foresters noticed that aspen in western Colorado were falling silent. While the trees have always been susceptible to disease and insect attacks, especially in old age, “this was totally different from anything we’d seen before,” says forester Wayne Shepperd. “In the past, you’d maybe see rapid die-off of one stand out of an entire landscape—it wasn’t really a big deal. But now, we’re seeing whole portions of the landscape go.”

By 2006, close to 150,000 acres of Colorado aspen were dead or damaged, according to aerial surveys. By the following year, the grim phenomenon had a name—”sudden aspen decline,” or SAD—and the devastated acreage had more than doubled, with some 13 percent of the state’s aspen showing declines. In many places, patches of bare and dying treetops are as noticeable as missing teeth, and some sickly areas stretch for miles. Aspen declines are also underway in Wyoming, Utah and elsewhere in the Rockies. Surveys of two national forests in Arizona showed that from 2000 to 2007, lower-elevation areas lost 90 percent of their aspen.

At the time, scientists suspected that extreme drought and high temperatures in the West, probably due to climate change, were weakening the trees.

It seems that new stems aren’t growing back after trees die because drought and heat have stressed the trees. During drought, aspen close off microscopic openings in their leaves, a survival measure that slows water loss but also slows the uptake of carbon dioxide, required for photosynthesis. As a result, the trees can’t convert as much sunlight into sugar. [Forest Service plant pathologist Jim] Worrall speculates that the trees absorb stored energy from their own roots, eventually killing the roots and preventing the rise of new aspen sprouts. “They basically starve to death,” he says.

But a new study in PNAS has found that it was lack of water, not food, that led to the aspen deaths. Nijhuis explained the findings on the blog The Last Word on Nothing:

When the researchers studied dying aspen in the field in Colorado, and induced drought stress in both potted aspen and full-grown trees, they found that the aspen hung on to plenty of carbohydrates. The problem was that the water-delivery systems in the trees’ roots and branches were blocked with air bubbles, like straws trying to pull water from too-shallow pools. … When trees lose 50 percent of their water-delivery capacity, they start to drop their leaves, no matter the season; the dying aspen in the study had lost 70 to 80 percent. And the more root blockage, the researchers found, the more root death. Aspen are a clonal species, and without healthy roots, they’re slow to resprout and recover.

The weakened trees are more vulnerable to other threats, such as insects and fungal infections, Nijhuis noted both in 2008 and in her recent post.

“Our study provides a snapshot of what future droughts could hold for the emblematic tree of the American West,” says the study’s lead author, William Anderegg of Stanford University. The study holds an even greater lesson, though, when it comes to climate change. As we pump more and more greenhouse gases into the atmosphere, the American West and many other places are expected to get drier. And that lack of water may hurt other tree species, animal species and humans, too.

In this image from December 15, 2011, Comet Lovejoy appeared to be headed towards sure destruction in a collision with the Sun (credit: NASA/SOHO)

Amateur astronomer Terry Lovejoy of Australia discovered a comet in 2007 using nothing more than a digital camera. Comet Lovejoy was a large member of the Kreutz family of comets–fragments of a large comet that broke up hundreds of years ago but still travel in its path, grazing the surface of the Sun and sometimes colliding with it. And yesterday it looked like Comet Lovejoy would meet such a fiery end.

But that didn’t happen.

Despite scientists’ predictions that the comet would not survive its encounter with the Sun, Comet Lovejoy lives on. The Associated Press reports:

The comet came within 75,000 miles of the sun. For a small object often described as a dirty snowball, that brush with the sun should have been fatal.

Astronomers say it probably wasn’t deadly because the comet was larger than they thought.

Comet Lovejoy’s near-fatal journey was well-watched by scientists who have a fleet of satellites pointed at our Sun. You can watch the comet streak through the Sun’s atmosphere in the video below, taken by NASA’s Solar Dynamics Observatory, or see the comet’s path around the Sun in the animated gif (below the video), created with images from the NASA satellite SOHO.

Comet Lovejoy survived its close encounter with the Sun (credit: NASA/SOHO)