A Rare Celestial Treat On the Winter Solstice (Planetary Science)

Four tips and takeaways from astronomer Cullen Blake on the upcoming alignment of Jupiter and Saturn and how to best catch a glimpse of the ‘great conjunction.’

During the past several weeks, Jupiter and Saturn’s orbits have been slowly approaching one another in the early evening sky. On the night of the winter solstice, the two gas giants will appear closer to one another than they have been for the past 400 years. Known as the “great conjunction,” this bright planetary alignment will be easily visible just after sunset.

Saturn (top) and Jupiter visible just after sunset at Shenandoah National Park on December 13th. On the winter solstice, December 21st, the two gas giants will appear a tenth of a degree apart from one another. (Image: NASA/Bill Ingalls)

To learn more about this rare event and how to best catch a glimpse of the great conjunction, Penn Today spoke with astronomer Cullen Blake, who shares four tips and takeaways for making the most of this end-of-the-year celestial spectacle.

What is a planetary conjunction?

A conjunction happens when two planets in the same solar system appear to pass extremely close to one another in the sky. “From our perspective, we’re closer to the sun than Jupiter and Saturn. That means when we look out at the night sky every few hundred years, these two planets align and will be located in the same part of the sky,” says Blake.

The orbits of the planets can be thought of as a racetrack, he says, with Earth circling the Sun more quickly on an inside lane while Jupiter and Saturn move more slowly in the outer lanes. A conjunction happens as Jupiter begins to “pass” Saturn on the inside and overtakes the slower-moving planet, which happens on the night of the solstice.

Because each planet in the solar system has its own orbital period—the time it takes to complete its rotation around the sun—the orbits of individual planets don’t coincide with each other very often. “Our moon comes back to the same position every 28 to 29 days, while Jupiter is going around the sun within a period of 12 years and Saturn of 29.5 years,” Blake says. “If you have two things going in orbit at that period, they only line up quite rarely.”

On the night of the winter solstice, Jupiter and Saturn can be found low in the southwestern section of the horizon in the hour just after sunset. (Image: NASA/JPL-Caltech)

According to NASA, it has been nearly 400 years since Jupiter and Saturn were this close to one another, but that event, in 1623, wasn’t visible in the night sky, so it’s now been nearly 800 years, in 1226, since the great conjunction has been as visible as it is this year.

How close is ‘close’?

For stargazers on Earth, the angle in the sky will be incredibly small—about 0.1 of a degree. “If you hold up your little finger at arm’s length, it will cover both planets,” says Blake of the level of closeness as perceived here on Earth.

In terms of actual distance, on the night of the solstice Jupiter and Saturn will be around 4 astronomical units (AUs) apart. That’s four times the distance between Earth and the sun, or around 400 million miles. When Jupiter and Saturn are on opposite sides of the solar system from one another, they are around 14 AUs apart.

No fancy telescope needed, just good timing, clear weather, and a pair of binoculars

To get the best glimpse of the great conjunction, Blake suggests finding a place with a clear line of sight towards the southwestern sky right at sunset. “During the hour after the sun goes down, it will be easy to see and very bright; you might even think it’s a plane,” he says. “It’s surprising how quickly after sunset you can start to see it.”

A clear evening makes for the best viewing, but even under thin clouds the conjunction should still be visible. There might also be a long enough break in the clouds to catch a glimpse—colloquially referred to by astronomers as a “sucker hole”—but, if not, Blake suggests trying again after the solstice on a clearer night. “It should be amazing for the next few days,” he says. “You will be able to see them separating after the solstice, so it will still look neat.”

There’s also no advanced astronomical equipment needed. Because of how large and bright the two plants are, a standard pair of binoculars will do just fine, says Blake. “Even with the kind of binoculars you have at home, looking at Jupiter and Saturn is awe-inspiring in terms of how much detail and color you can see,” he says.

Be sure to take advantage of this rare celestial opportunity

Blake hopes that people take the time to get out, while staying warm and socially distanced, to see this rare event. “It’s a great opportunity, especially when it’s easy to catch a glimpse of something neat in sky, and I hope that it makes people excited about astronomy,” he says.

Cullen Blake is an associate professor in the Department of Physics & Astronomy in the School of Arts & Sciences at the University of Pennsylvania.

Provided by Penn Today

Jupiter, Saturn will look like double planet for First Time Since Middle Ages (Planetary Science)

Just after sunset on the evening of Dec. 21, Jupiter and Saturn will appear closer together in Earth’s night sky than they have been since the Middle Ages, offering people the world over a celestial treat to ring in the winter solstice.

“Alignments between these two planets are rather rare, occurring once every 20 years or so, but this conjunction is exceptionally rare because of how close the planets will appear to one another,” said Rice University astronomer Patrick Hartigan. “You’d have to go all the way back to just before dawn on March 4, 1226, to see a closer alignment between these objects visible in the night sky.”

Jupiter and Saturn have been approaching one another in Earth’s sky since the summer. From Dec. 16-25, the two will be separated by less than the diameter of a full moon.

“On the evening of closest approach on Dec 21 they will look like a double planet, separated by only 1/5th the diameter of the full moon,” said Hartigan, a professor of physics and astronomy. “For most telescope viewers, each planet and several of their largest moons will be visible in the same field of view that evening.”

Though the best viewing conditions will be near the equator, the event will be observable anywhere on Earth, weather-permitting. Hartigan said the planetary duo will appear low in the western sky for about an hour after sunset each evening.

A view showing how the Jupiter-Saturn conjunction will appear in a telescope pointed toward the western horizon at 6 p.m. CST, Dec. 21, 2020. The image is adapted from graphics by open-source planetarium software Stellarium. (This work, “jupsat1,” is adapted from Stellarium by Patrick Hartigan, used under GPL-2.0, and provided under CC BY 4.0 courtesy of Patrick Hartigan)

“The further north a viewer is, the less time they’ll have to catch a glimpse of the conjunction before the planets sink below the horizon,” he said. Fortunately, the planets will be bright enough to be viewed in twilight, which may be the best time for many U.S. viewers to observe the conjunction.

“By the time skies are fully dark in Houston, for example, the conjunction will be just 9 degrees above the horizon,” Hartigan said. “Viewing that would be manageable if the weather cooperates and you have an unobstructed view to the southwest.”

But an hour after sunset, people looking skyward in New York or London will find the planets even closer to the horizon, about 7.5 degrees and 5.3 degrees respectively. Viewers there, and in similar latitudes, would do well to catch a glimpse of the rare astronomical sight as soon after sunset as possible, he said.

Those who prefer to wait and see Jupiter and Saturn this close together and higher in the night sky will need to stick around until March 15, 2080, Hartigan said. After that, the pair won’t make such an appearance until sometime after the year 2400.

Provided by Rice University

Seasonal Affective Disorder: Winter Is Coming (Neuroscience)

The temperatures are dropping, the leaves are changing, and the days are becoming shorter—all of these changes from summer to fall means that winter is just around the corner. Many individuals look forward to winter because of the holidays and the beauty of the snowfall. For others, the change from summer to fall can be trigger depression. The “winter blues” can be just around the corner.

What is SAD?

Seasonal affective disorder (SAD) or seasonal depression is a type of depression that comes with the seasons. Seasonal affective disorder is most common during the winter months, but oddly enough, it also appears in the summer, just not nearly as prevalent. According to research, “A small share of people with SAD show the reverse pattern, being sensitive to summer’s longer days. The very existence of opposite winter-summer patterns suggested to researchers that this mood disorder stems from a problem in adapting to the physical environment”.

Individuals with seasonal affective disorder must meet major depressive disorder criteria with symptoms coinciding with the specific seasons and lasting for at least two years.

Who is at risk for developing SAD?

Researchers believed that SAD’s typical appearance in the winter had a high correlation with the lower exposure to light. The obvious next step was to lengthen exposure to light intensity to mimic the outdoors. By 1998, researchers were studying light treatment variations as a treatment for SAD.

Individuals who live further from the Equator are more at risk for developing seasonal affective disorder than individuals who live closer to the Equator. One percent of individuals who live in Florida have SAD, whereas nine percent of individuals who live in Alaska have SAD. Females are more at risk of developing SAD compared to males, and individuals who have a history of depression or bipolar disorder are also at an increased risk for developing SAD. Individuals who have an increased level of melatonin and decreased serotonin and vitamin D levels are also at a higher risk for developing SAD.

“Sunlight plays a critical role in the decreased serotonin activity, increased melatonin production, disrupted circadian rhythms, and low levels of Vitamin D associated with symptoms of SAD,” according to a study published in Depression Resistant Treatment.

Light therapy to treat seasonal depression

Not any type of bright light is known to treat individuals with SAD. There are certain light therapy boxes, which filter out UV light that are used to treat SAD. Lightboxes that have UV rays are used to treat certain skin disorders. Below are key points to keep in mind when using phototherapy to treat your seasonal affective depression.

• Use a lightbox that is 10,000 lux, which is 20 times the strength of typical indoor lighting.
• You can order a lightbox online.
• Use a lightbox that blocks out 99% of UV rays.
• Position the lightbox above your head to mimic natural outdoor lighting.
• Use the lightbox in the morning for 20 to 60 minutes.
• Use the lightbox daily from early fall through winter.
• Ask your doctor about using your lightbox if you are on certain medications that cause photosensitivity.
• Monitor your mood weekly by journaling about your emotions to assess whether light therapy is working.
• Phototherapy should also be combined with other therapeutic approaches such as cognitive behavioral therapy and anti-depressants if you do not see an improvement in your mood.

This article is originally written by Kristen Fuller, M.D., is a physician and a clinical mental health writer for Center For Discovery. 

Human Biology Registers Two Seasons, Not Four (Biology)

A Stanford Medicine study finds that changes in molecular patterns in Californians correspond with two nontraditional “seasons.”

As kids, we learn there are four seasons, but researchers at the Stanford School of Medicine have found evidence to suggest that the human body doesn’t see it this way.

“We’re taught that the four seasons — winter, spring, summer and fall — are broken into roughly equal parts throughout the year, and I thought, ‘Well, who says?’” Michael Snyder, PhD, professor and chair of genetics, said. “It didn’t seem likely that human biology adheres to those rules. So we conducted a study guided by people’s molecular compositions to let the biology tell us how many seasons there are.”

Four years of molecular data from more than 100 participants indicate that the human body does experience predictable patterns of change, but they don’t track with any of Mother Nature’s traditional signals. Overall, Snyder and his team saw more than 1,000 molecules ebb and flow on an annual basis, with two pivotal time periods: late spring-early summer and late fall-early winter. These are key transition periods when change is afoot — both in the air and in the body, said Snyder, who is the Stanford W. Ascherman, MD, FACS, Professor in Genetics.

“You might say, ‘Well, sure, there are really only two seasons in California anyway: cold and hot,” Snyder said. “That’s true, but even so, our data doesn’t exactly map to the weather transitions either. It’s more complicated than that.”

Snyder hopes that observations from this study — of higher levels of inflammatory markers in the late spring, or of increased markers of hypertension in early winter, for example — can provide a better foundation for precision health and even help guide the design of future clinical drug trials.

One caveat, Snyder said, is that the team conducted the research with participants in Northern and Southern California, and it’s likely that the molecular patterns of individuals in other parts of the country would differ, depending on atmospheric and environmental variations.

The study was published online Oct. 1 in Nature Communications. Snyder is the senior author. Postdoctoral scholars Reza Sailani, PhD, and Ahmed Metwally, PhD, share lead authorship.

Spring-ish and winter-ish

The study was conducted in 105 individuals who ranged in age from 25 to 75. About half were insulin resistant, meaning their bodies don’t process glucose normally. About four times a year, the participants provided blood samples, which the scientists analyzed for molecular information about immunity, inflammation, cardiovascular health, metabolism, the microbiome and much more. The scientists also tracked the exercise and dietary habits of all participants.

Over the span of four years, data showed that the late-spring period coincided with a rise in inflammatory biomarkers known to play a role in allergies, as well as a spike in molecules involved in rheumatoid arthritis and osteoarthritis. They also saw that a form of hemoglobin called HbAc1, a protein that signals risk for Type 2 diabetes, peaked during this time, and that the gene PER1, which is known to be highly involved in regulating the sleep-wake cycle, was also at its highest.

In some cases, Snyder said, it’s relatively obvious why levels of molecules increased. Inflammatory markers probably spike due to high pollen counts, for instance. But in other cases, it’s less obvious. Snyder and his team suspect that HbA1c levels are high in the late spring because of the often indulgent eating that accompanies the holidays — HbA1c levels reflect dietary habits from about three months before measurements are taken — as well as a general waning of exercise in the winter months.

As Snyder and his team followed the data into early winter, they saw an increase in immune molecules known to help fight viral infection and spikes of molecules involved in acne development. Signatures of hypertension, or high blood pressure, were also higher in the winter.

The data also showed that there were some unexpected differences in the microbiomes of individuals who were insulin resistant and those of individuals who processed glucose normally. Veillonella, a type of bacteria involved in lactic acid fermentation and the processing of glucose, was shown to be higher in insulin-resistant individuals throughout the year, except during mid-March through late June.

Parsing seasonality

“Many of these findings open up space to investigate so many other things,” Sailani said. “Take allergies, for instance. We can track which pollens are circulating at specific times and pair that with personalized readouts of molecular patterns to see exactly what a person is allergic to.”

The hope is that more information about a person’s molecular ups and downs will allow them to better understand the context of their body’s biological swings and will enable them to use that information to proactively manage their health.

“If, for instance, your HbA1C levels are measured during the spring and they seem abnormally high, you can contextualize that result and know that this molecule tends to run high during spring,” Snyder said. “Or, you could see it as a sort of kick in the pants, so to speak, to exercise more during the winter in an effort to keep some of these measurements down.”

Even more broadly speaking, these findings could also help inform the design of drug trials. For example, if researchers are hoping to test a new drug for hypertension, they would likely benefit from knowing that because hypertension seems to spike in the early winter months, trials that started in winter versus spring would likely have different outcomes.

Other Stanford authors of the paper are former postdoctoral scholars Wenyu Zhou, PhD, Sara Ahadi, PhD, Tejaswini Mishra, PhD, and Lukasz Kidzinski, PhD; instructor of genetics Sophia Miryam Rose, MD, PhD; life science researcher Kevin Contrepois, PhD; graduate student Martin Zhang; and adjunct clinical assistant professor of pediatrics Theodore Chu, MD.

This study was funded by the National Institutes of Health (grants U54DK102556, R01 DK110186-03, R01HG008164, NIH S10OD020141, UL1 TR001085 and P30DK116074).

References: Sailani, M.R., Metwally, A.A., Zhou, W. et al. Deep longitudinal multiomics profiling reveals two biological seasonal patterns in California. Nat Commun 11, 4933 (2020). https://doi.org/10.1038/s41467-020-18758-1 link: https://www.nature.com/articles/s41467-020-18758-1

Provided by Stanford School Of Medicine

Many Ventilation Systems May Increase Risk Of COVID-19 Exposure (Medicine)

Ventilation systems in many modern office buildings, which are designed to keep temperatures comfortable and increase energy efficiency, may increase the risk of exposure to the coronavirus, particularly during the coming winter, according to research published in the Journal of Fluid Mechanics.

A team from the University of Cambridge found that widely-used ‘mixing ventilation’ systems, which are designed to keep conditions uniform in all parts of the room, disperse airborne contaminants evenly throughout the space. These contaminants may include droplets and aerosols, potentially containing viruses.

The research has highlighted the importance of good ventilation and mask-wearing in keeping the contaminant concentration to a minimum level and hence mitigating the risk of transmission of SARS-CoV-2, the virus that causes COVID-19.

The evidence increasingly indicates that the virus is spread primarily through larger droplets and smaller aerosols, which are expelled when we cough, sneeze, laugh, talk or breathe. In addition, the data available so far indicate that indoor transmission is far more common than outdoor transmission, which is likely due to increased exposure times and decreased dispersion rates for droplets and aerosols.

“As winter approaches in the northern hemisphere and people start spending more time inside, understanding the role of ventilation is critical to estimating the risk of contracting the virus and helping slow its spread,” said Professor Paul Linden from Cambridge’s Department of Applied Mathematics and Theoretical Physics (DAMTP), who led the research.

“While direct monitoring of droplets and aerosols in indoor spaces is difficult, we exhale carbon dioxide that can easily be measured and used as an indicator of the risk of infection. Small respiratory aerosols containing the virus are transported along with the carbon dioxide produced by breathing, and are carried around a room by ventilation flows. Insufficient ventilation can lead to high carbon dioxide concentration, which in turn could increase the risk of exposure to the virus.”

The team showed that airflow in rooms is complex and depends on the placement of vents, windows and doors, and on convective flows generated by heat emitted by people and equipment in a building. Other variables, such as people moving or talking, doors opening or closing, or changes in outdoor conditions for naturally ventilated buildings, affect these flows and consequently influence the risk of exposure to the virus.

Ventilation, whether driven by wind or heat generated within the building or by mechanical systems, works in one of two main modes. Mixing ventilation is the most common, where vents are placed to keep the air in a space well mixed so that temperature and contaminant concentrations are kept uniform throughout the space.

The second mode, displacement ventilation, has vents placed at the bottom and the top of a room, creating a cooler lower zone and a warmer upper zone, and warm air is extracted through the top part of the room. As our exhaled breath is also warm, most of it accumulates in the upper zone. Provided the interface between the zones is high enough, contaminated air can be extracted by the ventilation system rather than breathed in by someone else. The study suggests that when designed properly, displacement ventilation could reduce the risk of mixing and cross-contamination of breath, thereby mitigating the risk of exposure.

As climate change has accelerated since the middle of the last century, buildings have been built with energy efficiency in mind. Along with improved construction standards, this has led to buildings that are more airtight and more comfortable for the occupants. In the past few years however, reducing indoor air pollution levels has become the primary concern for designers of ventilation systems.

“These two concerns are related, but different, and there is tension between them, which has been highlighted during the pandemic,” said Dr Rajesh Bhagat, also from DAMTP. “Maximising ventilation, while at the same time keeping temperatures at a comfortable level without excessive energy consumption is a difficult balance to strike.”

In light of this, the Cambridge researchers took some of their earlier work on ventilation for efficiency and reinterpreted it for air quality, in order to determine the effects of ventilation on the distribution of airborne contaminants in a space.

“In order to model how the coronavirus or similar viruses spread indoors, you need to know where people’s breath goes when they exhale, and how that changes depending on ventilation,” said Linden. “Using these data, we can estimate the risk of catching the virus while indoors.”

The researchers explored a range of different modes of exhalation: nasal breathing, speaking and laughing, each both with and without a mask. By imaging the heat associated with the exhaled breath, they could see how it moves through the space in each case. If the person was moving around the room, the distribution of exhaled breath was markedly different as it became captured in their wake.

“You can see the change in temperature and density when someone breathes out warm air – it refracts the light and you can measure it,” said Bhagat. “When sitting still, humans give off heat, and since hot air rises, when you exhale, the breath rises and accumulates near the ceiling.”

Their results show that room flows are turbulent and can change dramatically depending on the movement of the occupants, the type of ventilation, the opening and closing of doors and, for naturally ventilated spaces, changes in outdoor conditions.

The researchers found that masks are effective at reducing the spread of exhaled breath, and therefore droplets.

“One thing we could clearly see is that one of the ways that masks work is by stopping the breath’s momentum,” said Linden. “While pretty much all masks will have a certain amount of leakage through the top and sides, it doesn’t matter that much, because slowing the momentum of any exhaled contaminants reduces the chance of any direct exchange of aerosols and droplets as the breath remains in the body’s thermal plume and is carried upwards towards the ceiling. Additionally, masks stop larger droplets, and a three-layered mask decreases the amount of those contaminants that are recirculated through the room by ventilation.”

The researchers found that laughing, in particular, creates a large disturbance, suggesting that if an infected person without a mask was laughing indoors, it would greatly increase the risk of transmission.

“Keep windows open and wear a mask appears to be the best advice,” said Linden. “Clearly that’s less of a problem in the summer months, but it’s a cause for concern in the winter months.”

The team are now working with the Department for Transport looking at the impacts of ventilation on aerosol transport in trains and with the Department for Education to assess risks in schools this coming winter.

References: Rajesh K. Bhagat et al. ‘Effects of ventilation on the indoor spread of COVID-19.’ Journal of Fluid Mechanics (2020). DOI: 10.1017/jfm.2020.720.

Provided by University Of Cambridge

Kaindy Lake Is A Ghostly Underwater Forest (Amazing Places)

You’ve seen forests, and you’ve seen lakes. But when you see one inside the other, things start to feel pretty eerie. That’s the essence of Kaindy Lake in Saty, Kazakhstan. A landslide a century ago created the lake atop a spruce forest — leading to some bizarre scenery.

In 1911, an earthquake ripped through the Tian Shan Mountains, causing a large landslide that blocked a gorge and formed a natural dam. Over the course of time, rainfall filled the area, submerging the forest of spruce trees and forming 1,300-foot (400-meter) long Kaindy Lake. Today, the spruce trees are dead, their roots drowned deep beneath the water’s surface, but their top halves tower over the water’s in an even speckling that looks a bit like ghostly ships masts or giant spears. The eeriness is made all the more palpable when a light fog is cast over the water or when the lake is frozen over in the dead of winter when the trees have transitioned from navigational beacons to something for fishermen to lean on.

The most striking view of this forest is under the water. There, the tree trunks have resisted decomposition, leaving perfectly preserved needles on their branches even after all this time. This interesting feature is thanks to the lake’s frigid temperatures, which rarely exceed 43 degrees Fahrenheit (6 degrees Celsius), even in summertime. Luckily, you don’t need to take a dip to catch a glimpse of this marvel — the water is so clear that you can see far down into its depths from safety on the shore.

If you do find yourself at Kaindy in the winter, though, know that the lake freezes over and its icy waters become popular for trout fishing and ice diving. Adventurous travelers and locals choose ice fishing for a glimpse of Kaindy’s surreal landscape from under the frozen, crystal-clear waters.

Surprisingly, this unique lake sees few visitors. Although located close to Almaty, the country’s largest city of 1.5 million people, Kaindy is overshadowed by the more famous and nearby Bolshoe Almatinskoe Lake and the Kolsay Lakes, which are easier to access. Located in a canyon off a dirt road, accessing Kaindy requires a utility vehicle designed for rough terrain, but it’s not impossible.

Whether you plan to visit this lake less-traveled in the summer or the winter, you’re bound to be stunned by an idyllic scene like no other. Personally, we’d prefer enjoying Kaindy’s beauty from above the ice, but to each his own.

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