ESA/Rosetta/NAVCAM via Flickr // CC BY-SA IGO 3.0
ESA/Rosetta/NAVCAM via Flickr // CC BY-SA IGO 3.0

Comet 67P Transformed as It Approached the Sun

ESA/Rosetta/NAVCAM via Flickr // CC BY-SA IGO 3.0
ESA/Rosetta/NAVCAM via Flickr // CC BY-SA IGO 3.0

Comet 67P/Churyumov-Gerasimenko underwent some fantastic transformations as it approached the Sun, according to a new study of Rosetta data published this week in Science. Fractures grew, cliffs collapsed, and boulders rolled on the comet, among other geologic happenings. 

At the 48th Lunar and Planetary Science Conference in The Woodlands, Texas, Ramy El-Maarry of the University of Colorado, Boulder, revealed stunning images of the comet’s transformation as it approached perihelion, or the closest it gets to the Sun during its orbit. This is the first time scientists have observed in detail the punishment comets sustain this close to the Sun.

“This is the first mission that we’ve been able to have such a huge set of high-resolution images while at the same time having the longevity of a mission where we were able to look at a comet and study how it evolved through more than two years as it journeyed through the inner solar system,” El-Maarry said at the conference. He is a member of the U.S. Rosetta science team and lead author of the study.

From August 2014 through September 2016, Rosetta orbited 67P, its scientific instruments trained on the comet. Then the team attempted to land—and most likely crashed—the orbiter into the comet. Rosetta's fate remains unknown. But the data it sent back to Earth is not.

For the current study, the researchers focused on observations made between December 2014 and June 2016. Among the most striking phenomena they found is a collapsed cliff face, whose volume is the equivalent of nine Olympic-sized swimming pools.

A cliff collapse the researchers observed. Image Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

It fell not in a few giant pieces, but essentially crumbled apart, much in the way the White Cliffs of Dover in the United Kingdom sometimes fall. “It would have been like watching a slow-motion video,” El-Maarry told mental_floss. “If you saw the cliff starting to fall, and you’re on the comet, you would have had time to take out your phone, open the camera, start the video and keep recording for 20 or 30 minutes as the event unfolds.”

The collapse revealed bright, fresh, icy comet interior. It's the first time we've observed this process.

At the comet’s nucleus, outbursts caused by increased sunlight moved a 282-million-pound, 100-foot-wide boulder the distance of one and a half football fields. In a cometary day on 67P, an hour and half of perpendicular illumination can cause chaos. In the span of 20 minutes, temperatures swing from -140°C to 50°C. Interior ice sublimates―changes from solid to gas without bothering to become water―and blasts into space. Increased temperatures as the comet approached the Sun also caused Empire State Building–sized fractures along the neck of the rubber duck–shaped body.

Two images showing the boulder's movement. In the right image, the dotted circle outlines the original location of the boulder for reference. Image Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

These Rosetta data are the first direct link between outbursts and crumbling cometary material, and suggest that thermal gradients are fundamental drivers of geologic processes on comets, which include weathering and erosion, sublimation of water ice, and mechanical stresses arising from the comet's spin.

If you were to stand on the surface of 67P and witness the cliff face collapse, it would be quite an experience. “If you’re in the northern hemisphere, it might be a lot of fun,” said El-Maarry. “You’re seeing a lot of things happening in slow motion. You might be able to see dust coming from the southern hemisphere and falling like volcanic ash on top of you in the north. It would have also had a spectacular view of space because you don’t have an atmosphere.”

In the extremely long term, the processes responsible for fractures on the duck’s neck will cause the comet to split in two―temporarily. “What we can say with a degree of certainty is that it’s not going to explode. It’s going to break,” he described. “And because it’s going to break and separate, the two bodies still have enough gravity to pull themselves together to reattach.”

The next step, El-Maarry says, is to locate more bodies just entering the solar system, as opposed to objects that have been here for dozens of orbits. “What our work implies is that most of the activity seems to happen just as you enter the inner solar system in an inner configuration,” he said. He is interested in the findings from the New Horizons mission after it visits an object in the Kuiper Belt on January 1, 2019. That region is a source of comets, and New Horizons offers a chance at a pristine body before being subjected to heat or sublimation.

“It will be really cool to see what is the topography you’re seeing there. Are you seeing something that’s just a ball of dust and ice as we thought of comets before going to 67P,” El-Maarry wondered, “or are we going to see all this complex geology? This is going to be really very exciting. When you look at New Horizons, no one really thought that Pluto would look as amazing as it did in picture. And that’s what happens with space missions. They just keep surprising us and opening up new frontiers.” 

Today's Wine Glasses Are Almost Seven Times Larger Than They Were in 1700

Holiday party season (a.k.a. hangover season) is in full swing. While you likely have no one to blame but yourself for drinking that second (or third) pour at the office soiree, your glassware isn't doing you any favors—especially if you live in the UK. Vino vessels in England are nearly seven times larger today than they were in 1700, according to a new study spotted by Live Science. These findings were recently published in the English medical journal The BMJ.

Researchers at the University of Cambridge measured more than 400 wineglasses from the past three centuries to gauge whether glass size affects how much we drink. They dug deep into the history of parties past, perusing both the collections of the Ashmolean Museum of Art and Archaeology at the University of Oxford and the Royal Household's assemblage of glassware (a new set is commissioned for each monarch). They also scoured a vintage catalog, a modern department store, and eBay for examples.

After measuring these cups, researchers concluded that the average wineglass in 1700 held just 2.2 fluid ounces. For comparison's sake, that's the size of a double shot at a bar. Glasses today hold an average of 15.2 fluid ounces, even though a standard single serving size of wine is just 5 ounces.

BMJ infographic detailing increases in wine glass size from 1700 to 2017
BMJ Publishing group Ltd.

Advances in technology and manufacturing are partly to blame for this increase, as is the wine industry. Marketing campaigns promoted the beverage as it increasingly became more affordable and available for purchase, which in turn prompted aficionados to opt for larger pours. Perhaps not surprisingly, this bigger-is-better mindset was also compounded by American drinking habits: Extra-large wineglasses became popular in the U.S. in the 1990s, prompting overseas manufacturers to follow suit.

Wine consumption in both England and America has risen dramatically since the 1960s [PDF]. Cambridge researchers noted that their study doesn't necessarily prove that the rise of super-sized glassware has led to this increase. But their findings do fit a larger trend: previous studies have found that larger plate size can increase food consumption. This might be because they skew our sense of perception, making us think we're consuming less than we actually are. And in the case of wine, in particular, oversized glasses could also heighten our sensory enjoyment, as they might release more of the drink's aroma.

“We cannot infer that the increase in glass size and the rise in wine consumption in England are causally linked,” the study's authors wrote. “Nor can we infer that reducing glass size would cut drinking. Our observation of increasing size does, however, draw attention to wine glass size as an area to investigate further in the context of population health.”

[h/t Live Science]

Researchers Pore Over the Physics Behind the Layered Latte

The layered latte isn't the most widely known espresso drink on coffee-shop menus, but it is a scientific curiosity. Instead of a traditional latte, where steamed milk is poured into a shot (or several) of espresso, the layered latte is made by pouring the espresso into a glass of hot milk. The result is an Instagram-friendly drink that features a gradient of milky coffee colors from pure white on the bottom to dark brown on the top. The effect is odd enough that Princeton University researchers decided to explore the fluid dynamics that make it happen, as The New York Times reports.

In a new study in Nature Communications, Princeton engineering professor Howard Stone and his team explore just what creates the distinct horizontal layers pattern of layered latte. To find out, they injected warm, dyed water into a tank filled with warm salt water, mimicking the process of pouring low-density espresso into higher-density steamed milk.

Four different images of a latte forming layers over time
Xue et al., Nature Communications (2017)

According to the study, the layered look of the latte forms over the course of minutes, and can last for "tens of minutes, or even several hours" if the drink isn't stirred. When the espresso-like dyed water was injected into the salt brine, the downward jet of the dyed water floated up to the top of the tank, because the buoyant force of the low-density liquid encountering the higher-density brine forced it upward. The layers become more visible when the hot drink cools down.

The New York Times explains it succinctly:

When the liquids try to mix, layered patterns form as gradients in temperature cause a portion of the liquid to heat up, become lighter and rise, while another, denser portion sinks. This gives rise to convection cells that trap mixtures of similar densities within layers.

This structure can withstand gentle movement, such as a light stirring or sipping, and can stay stable for as long as a day or more. The layers don't disappear until the liquids cool down to room temperature.

But before you go trying to experiment with layering your own lattes, know that it can be trickier than the study—which refers to the process as "haphazardly pouring espresso into a glass of warm milk"—makes it sound. You may need to experiment several times with the speed and height of your pour and the ratio of espresso to milk before you get the look just right.

[h/t The New York Times]


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