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World

UK breaks its record for highest temperature as heat builds

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LONDON (AP) — Britain shattered its record for highest temperature ever registered Tuesday, with a provisional reading of 39.1 degrees Celsius (102.4 degrees Fahrenheit), according to the country’s weather office — and the heat was only expected to rise.

The highest temperature previously recorded in Britain was 38.7 C (101.7 F), a record set in 2019. Tuesday’s record was in Charlwood, England.

“Temperatures are likely to rise further through today,” the forecaster said.

The high Tuesday came as the country sweltered in heat that also scorched mainland Europe for the past week. Travel, health care and schools were disrupted in a country not prepared for such extremes.

A huge chunk of England, from London in the south to Manchester and Leeds in the north, remained under the country’s first warning of “extreme” heat Tuesday, meaning there is danger of death even for healthy people.

Britain’s Supreme Court closed to visitors after a problem with the air conditioning forced it to move hearings online. The British Museum planned to close early. Many public buildings, including hospitals don’t have air conditioning, a reflection of how unusual such extreme heat is in the country better known for rain and mild temperatures.

Unusually hot, dry weather has gripped large swaths of the continent since last week, triggering wildfires from Portugal to the Balkans and leading to hundreds of heat-related deaths. Images of flames racing toward a French beach and Britons sweltering — even at the seaside — have driven home concerns about climate change.

The U.K.’s Met Office weather agency also reported that provisional figures showed the temperature remained above 25 C (77 F) overnight in parts of the country for the first time.

Many people coped with the heat wave by staying put. Road traffic was down from its usual levels on Monday. Trains ran at low speed out of concern rails could buckle, or did not run at all. London’s Kings Cross Station, one of the country’s busiest rail hubs, was empty on Tuesday, with no trains on the busy east coast line connecting the capital to the north and Scotland. London’s Luton Airport had to close its runway because of heat damage.

Transport Secretary Grant Shapps said Britain’s transport infrastructure, some of it dating from Victorian times, “just wasn’t built to withstand this type of temperature — and it will be many years before we can replace infrastructure with the kind of infrastructure that could.”

At least five people were reported to have drowned across the U.K. in rivers, lakes and reservoirs while trying to cool off.

Climate experts warn that global warming has increased the frequency of extreme weather events, with studies showing that the likelihood of temperatures in the U.K. reaching 40 C (104 F) is now 10 times higher than in the pre-industrial era. Drought and heat waves tied to climate change have also made wildfires harder to fight.

The dangers of extreme heat were on display in southern Europe. At least 748 heat-related deaths have been reported in the heat wave in Spain and neighboring Portugal, where temperatures reached 47 C (117 F) earlier this month.

In the Gironde region of southwestern France, ferocious wildfires continued to spread through tinder-dry pines forests, frustrating firefighting efforts by more than 2,000 firefighters and water-bombing planes.

More than 37,000 people have been evacuated from homes and summer vacation spots since the fires broke out July 12 and burned through 190 square kilometers (more than 70 square miles) of forests and vegetation, Gironde authorities said.

A smaller third fire broke out late Monday in the Medoc wine region north of Bordeaux, further taxing firefighting resources. Five camping sites went up in flames in the Atlantic coast beach zone where blazes raged, around the Arcachon maritime basin famous for its oysters and resorts.

But weather forecasts offered some consolation, with heat-wave temperatures expected to ease along the Atlantic seaboard Tuesday and the possibility of rains rolling in late in the day.

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Associated Press Writer John Leicester in Le Pecq, France contributed to this story.

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Follow AP’s climate coverage at https://apnews.com/hub/climate-and-environment

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World

UK issues “Red Extreme” heat warning, braces for temperature surge  

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An office worker carries a large fan in central London on July 12, 2022. On Friday, the Met Office issued a Red Extreme heat warning for parts of the country.

Yui Mok | PA Images | Getty Images

The U.K. on Friday issued a “Red Extreme” heat warning, with authorities saying temperatures could potentially hit 40 degrees Celsius (104 Fahrenheit) next week.

In a statement, the Met Office said the warning would cover parts of eastern, southeastern, central and northern England on July 18 and 19.

“Exceptional, perhaps record-breaking temperatures are likely early next week, quite widely across the red warning area on Monday, and focused a little more east and north on Tuesday,” Paul Gundersen, chief meteorologist at the Met Office, said.

“Currently there is a 50% chance we could see temperatures top 40°C and 80% we will see a new maximum temperature reached,” Gundersen said.

Friday’s new heat warning came on the same day the U.K. Health Security Agency issued a Level 4 Heat-Health Warning for England. The warning runs between midnight on Monday and midnight on Wednesday next week.

According to the Met Office, Level 4 denotes a national emergency and takes place “when a heatwave is so severe and/or prolonged that its effects extend outside the health and social care system.”

“At this level, illness and death may occur among the fit and healthy, and not just in high-risk groups,” it adds.

People are being advised to take a number of actions to cope with the heat. These include:

  • Looking out for young children and babies, older people, and people with underlying health conditions.
  • Closing curtains in rooms facing the sun.
  • Dressing appropriately in relation to the weather.
  • Avoiding excess alcohol.
  • And drinking “plenty of fluids.”

The U.K.’s record high temperature stands at 38.7 degrees Celsius. That was reached on July 25, 2019, in Cambridge.

Parts of the U.K. have experienced uncomfortably hot weather in recent days, with an Amber Extreme heat warning already issued between July 17 and 19 for a significant chunk of England and Wales.

“Temperatures are expected to start to return closer to normal for the time of year from the middle of next week onwards as cooler air pushes across the country from the west,” the Met Office said.

In January 2022, the World Meteorological Organization said 2021 had been “one of the seven warmest years on record.” The WMO based its finding on the consolidation of six international datasets.

In a statement at the time, the WMO said global warming and what it called “other long-term climate change trends” were “expected to continue as a result of record levels of heat-trapping greenhouse gases in the atmosphere.”

Back in the U.K., Nikos Christidis, climate attribution scientist at the Met Office, said climate change had “already influenced the likelihood of temperature extremes in the UK.”

“The chances of seeing 40°C days in the UK could be as much as 10 times more likely in the current climate than under a natural climate unaffected by human influence,” Christidis added.

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Science

How cold is space? Physics behind the universe’s temperature

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Though sci-fi movies would have us believe that space is incredibly cold — even freezing — space itself isn’t exactly cold. In fact, it doesn’t actually have a temperature at all. 

Temperature is a measurement of the speed at which particles are moving, and heat is how much energy the particles of an object have. So in a truly empty region space, there would be no particles and radiation, meaning there’s also no temperature. 

Of course, space is full of particles and radiation to produce heat and a temperature. So how cold is space, is there any region that is truly empty, and is there anywhere that the temperature drops to absolute zero?

Related: What is the coldest place in the universe?

How stars are heating up space

The hottest regions of space are immediately around stars, which contain all the  conditions to kick start nuclear fusion.

Things really warm up when radiation from a star reaches a spot in space with a lot of particles. This gives the radiation from stars like the sun something to actually act upon.

That’s why Earth is a lot warmer than the region between our planet and its star. The heat comes from particles in our atmosphere vibrating with solar energy and then bumping into each other distributing this energy. 

Proximity to our star and possessing particles are no guarantee of warmth, though. Mercury — closest to the sun — is blisteringly hot during the day and frigidly cold at night. Its temperatures drop to a low of 95 Kelvins (-288 ⁰Fahrenheit/-178 ⁰Celsius ). 

A false color composite image of the the surface temperature changes on the surface of Uranus, taken by Voyager 2.  (Image credit: NASA)

Temperatures dip to -371 ⁰F (-224 ⁰C) on Uranus, making it even colder than on the furthest planet from the sun, Neptune, which has a still incredibly cold surface temperature of -353 ⁰F (-214 ⁰C ). 

This is a result of a collision with an Earth-sized object early in its existence causing Uranus to orbit the sun on an extreme tilt, making it unable to hang on to its interior heat. 

Far away from stars particles are so spread out that heat transfer via anything but radiation is impossible, meaning temperatures radically drop. This region is called the interstellar medium. 

The coldest and densest molecular gas clouds in the interstellar medium can have temperatures of 10 K (-505 ⁰F/-263 ⁰C or ) while less dense clouds can have temperatures as high as 100 K (-279 ⁰F/-173 ⁰C).

What is cosmic background radiation?

An image of the cosmic microwave background radiation that fills the universe with a temperature of 2.725 K (-450° F/-270 ⁰C). (Image credit: European Space Agency)

The universe is so vast and filled with such a multitude of objects, some blisteringly hot, others unimaginably frigid, that it should be impossible to give space a single temperature.

Yet, there is something that permeates the entirety of our universe with a temperature that is uniform to 1 part in 100,000. In fact, the difference is so insignificant that the change between a hot spot and a cold spot is just 0.000018 K.

This is known as the cosmic microwave background (CMB) and it has a uniform temperature of 2.7 K (-45⁰F/-270⁰C). As 0 K is absolute zero this is a temperature just 2.725 degrees above absolute zero. 

The CMB is a remnant leftover from an event that occurred just 400,000 after the Big Bang called the last scattering. This was the point when the universe ceased to be opaque after electrons bonded to protons forming hydrogen atoms, which stopped electrons from endlessly scattering light and enabling photons to freely travel. 

As such this fossil relic “frozen in” to the universe represents the last point when matter and photons were aligned in terms of temperature. 

The photons that make up the CMB weren’t always so cold, taking around 13.8 billion years to reach us, the expansion of the Universe has redshifted these photons to lower energy levels. 

Originating when the universe was much denser and hotter than it is now, the starting temperature of the radiation that makes up the CMB is estimated to have been around 3,000 K (5,000° F/2,726⁰C). 

As the universe continues to expand, that means space is colder now than it’s ever been and it’s getting colder. 

What would happen if you were exposed to space?

If an astronaut were left to drift alone in space then exposure to the near-vacuum of space couldn’t freeze an astronaut as often depicted in science fiction. 

There are three ways for heat to transfer, conduction, which occurs through touch, convection which happens when fluids transfer heat, and radiative which occurs via radiation.

Conduction and convection can’t happen in empty space due to the lack of matter and heat transfer occurs slowly by radiative processes alone. This means that heat doesn’t transfer quickly in space. 

As freezing requires heat transfer, an exposed astronaut — losing heat via radiative processes alone — would die of decompression due to the lack of atmosphere much more rapidly than they freeze to death.

Additional resources

For more information about the properties of space, check out “Astrophysics for People in a Hurry (opens in new tab)” by Neil deGrasse Tyson and “Origins of the Universe: The Cosmic Microwave Background and the Search for Quantum Gravity (opens in new tab)” by Keith Cooper.

Bibliography

  • Harvard University, “The human body in space: Distinguishing facts from fiction (opens in new tab)“, July 2013. 
  • NASA, “Fluctuations in the Cosmic Microwave Background (opens in new tab)“, accessed July 2022. 
  • NASA, “Cosmic Microwave Background (opens in new tab)“, July 2022. 
  • NASA, “Eta Carinae (opens in new tab)“, September 2020
  • Paul Sutter, “You Will Not Freeze To Death In Space (opens in new tab)“, Forbes, April 2019. 

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Science

Physicists Are Startled by This Magnetic Material That ‘Freezes’ When Heated

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When disordered magnetic materials are cooled to just the right temperature, something interesting happens. The spins of their atoms ‘freeze’ and lock into place in a static pattern, exhibiting cooperative behavior not usually displayed.

 

Now for the first time, physicists have seen the opposite. When fractionally heated, the naturally occurring magnetic element neodymium freezes, turning all our expectations topsy turvy.

“The magnetic behavior in neodymium that we observed is actually the opposite of what ‘normally’ happens,” said physicist Alexander Khajetoorians of Radboud University in the Netherlands.

“It’s quite counterintuitive, like water that becomes an ice cube when it’s heated up.”

In a conventional ferromagnetic material, such as iron, the magnetic spins of the atoms all align in the same direction; that is, their north and south magnetic poles are oriented the same way in three-dimensional space.

But in some materials, such as some alloys of copper and iron, the spins are instead quite random. This state is what is known as a spin glass.

You might be thinking “but neodymium is well known for making excellent magnets” and you’d be right… but it has to be mixed with iron in order for the spins to align. Pure neodymium doesn’t behave like other magnets; it was only two years ago that physicists determined this material is, in fact, best described as a self-induced spin glass.

 

Now, it seems, neodymium is even stranger than we thought.

When you heat a material, the rise in temperature increases the energy in that material. In the case of magnets, this increases the motion of the spins. But the opposite also occurs: When you cool down a magnet, the spins slow.

For spin glasses, freezing temperature is the point at which the spin glass behaves more like a conventional ferromagnet.

Led by physicist Benjamin Verlhac of Radboud University, a team of scientists wanted to probe how neodymium behaves under changing temperatures. Interestingly, they found that raising the temperature of neodymium from -268 degrees Celsius to -265 degrees Celsius (-450.4 to -445 Fahrenheit) induced the freeze state usually seen when cooling a spin glass.

When the scientists cooled the neodymium back down, the spins once again fell into disarray.

It’s unclear why this occurs, since it’s very rare that a natural material behaves in the ‘wrong’ way, contrary to how all the other materials of its kind behave. However, the scientists believe that it may have to do with a phenomenon called frustration.

 

This is when a material is unable to attain an ordered state, resulting in a disordered ground state, such as we see in spin glasses.

It’s possible, the researchers said, that neodymium has certain correlations in its spin glass state that are dependent on temperature. Raising the temperature weakens these, and also therefore the frustration, allowing the spins to settle into an alignment.

Further investigation could reveal the mechanism behind this odd behavior in which order emerges from disorder with the addition of energy; the researchers note this has implications ranging far beyond physics.

“This ‘freezing’ of the pattern does not normally occur in magnetic material,” Khajetoorians  explained.

“If we ultimately can model how these materials behave, this could also be extrapolated to the behavior of a wide range of other materials.”

The research has been published in Nature Physics.

 

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Technology

AirPods Pro 2 No Longer Expected to Feature Built-In Heart Rate or Body Temperature Sensor

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While past rumors have indicated the upcoming second-generation AirPods Pro will feature a built-in heart rate and body temperature sensor, Bloomberg’s Mark Gurman has cast doubt on those rumors turning out to be true, saying instead such a feature is unlikely to come anytime soon.

“Over the past few months, there have been rumors about this year’s model gaining the ability to determine a wearer’s heart rate or body temperature. I’m told that neither feature is likely to arrive in the 2022 upgrade,” Gurman writes in his latest Power On newsletter. Gurman adds that both features have been explored within Apple and could arrive someday.

Just last month, a rumor from 52Audio said that the ‌AirPods Pro‌ 2 would be able to measure heart rate and body temperature from within the ear. That same report said the ‌AirPods Pro‌ 2 would feature USB-C, an updated H1 chip, and Find My functionality. It remains to be seen if other aspects of the report will turn out to be accurate.

Apple has not given the ‌AirPods Pro‌ any updates since its launch in 2019 other than a new MagSafe charging case last fall. Apple is widely expected to announce a new version of the ‌AirPods Pro‌ later this year, possibly around the time it launches the iPhone 14 and new Apple Watch models this fall.

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Science

James Webb Space Telescope’s mirrors are cooling to deep space temperature

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NASA’s massive new space telescope just keeps getting colder.

While the James Webb Space Telescope’s slow cooling process is nearing its end, NASA officials wrote in an update, there’s no firm timeline on when all the observatory components will meet their operating temperatures. That’s because much of this stage of the telescope’s months-long commissioning period comes down to physics, as mission managers wait for the mirrors to naturally cool to a temperature to allow alignment to continue.

All of the observatory’s instruments are at their final temperature, including the Mid-Infrared Instrument (MIRI), which is super-sensitive to heat and gets some help from a cryocooler to stay around 7 degrees Kelvin (minus 447 degrees Fahrenheit or minus 226 degrees Celsius). Webb needs to retain such ultracool temperatures to detect infrared light in heat-emitting wavelengths.

The mirrors, however, “are not quite there yet,” Jonathan Gardner, Webb deputy senior project scientist, said in the update, which was posted on Thursday (April 21).

Live updates: NASA’s James Webb Space Telescope mission
Related: How the James Webb Space Telescope works in pictures

That’s because the 18 hexagonal segments of the primary mirror, as well as the secondary mirror, are all made of beryllium and coated with gold. “At cryogenic temperatures, beryllium has a long thermal time constant, which means that it takes a long time to cool or to heat up,” Gardner explained.

The $10 billion telescope has been cooling ever since its launch on Dec. 25, 2021, and it’s making good progress so far, Gardner said. All of the primary mirror segments are below the mark of 55 Kelvin (minus 360 F or minus 218 C) necessary for MIRI to operate. Further cooling “will only enhance its performance,” Gardner said.

Of the 18 primary mirror segments, just four of them are above the 50 Kelvin (minus 370 F or minus 223 C) mark. Since these segments all have some mid-infrared light that reaches MIRI detectors, the agency stated, officials would prefer to see them cool by an additional 0.5 to 2 Kelvins each before starting the next phase of alignment.

These temperatures are all subject to fluctuation, Gardner noted. The telescope and sunshield operate together when the telescope is aimed at something. There is a “tiny amount of residual heat,” he says, that can move through the five-layer sunshield to the primary mirror depending on the angle the sunshield presents to the sun, or the attitude.

“Since the mirror segment temperatures change very slowly, their temperatures depend on the attitude averaged over multiple days,” he said. In fact, Webb has been spending most of the commissioning period pointing at the poles of the ecliptic, or the plane upon which solar system planets orbit the sun. 

This polar attitude, Gardner said, “is a comparatively hot attitude.” But that’s temporary, he added. “During science operations, starting this summer, the telescope will have a much more even distribution of pointings over the sky. The average thermal input to the warmest mirror segments is expected to go down a bit, and the mirrors will cool a bit more.”

A little later in commissioning, Gardner added, the team plans to test Webb’s ability to transition from a “hot attitude” to a “cold attitude.” This thermal slew process “will inform us how long it takes for the mirrors to cool down or heat up when the observatory is at these positions for any given amount of time.”

Webb still should be finished its commissioning in about June, Gardner said. “Is Webb at its final temperature? The answer is almost,” he concluded.

Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook. 



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Science

Webb Space Telescope’s Coldest Instrument Reaches Operating Temperature Below Minus 447° F

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In this illustration, the multilayered sunshield on NASA’s James Webb Space Telescope stretches out beneath the observatory’s honeycomb mirror. The sunshield is the first step in cooling down Webb’s infrared instruments, but the Mid-Infrared Instrument (MIRI) requires additional help to reach its operating temperature. Credit: NASA GSFC/CIL/Adriana Manrique Gutierrez

The beam of light coming from the telescope enters MIRI through the pick-off mirror located at the top of the instrument and acting like a periscope. Then, a series of mirrors redirect the light toward the bottom of the instruments where a set of 4 spectroscopic modules are located. Once there, the beam of light is divided by optical elements called dichroics in 4 beams corresponding to different parts of the mid-infrared region. Each beam enters its own integral field unit; these components split and reformat the light from the whole field of view, ready to be dispersed into spectra. This requires the light to be folded, bounced, and split many times, making this probably one of Webb’s most complex light paths. To finish this amazing voyage, the light of each beam is dispersed by gratings, creating spectra that then projects on 2 MIRI detectors (2 beams per detector). An amazing feat of engineering! Credit: ESA/ATG medialab

The low temperature is necessary because all four of Webb’s instruments detect infrared light – wavelengths slightly longer than those that human eyes can see. Distant galaxies, stars hidden in cocoons of dust, and planets outside our solar system all emit infrared light. But so do other warm objects, including Webb’s own electronics and optics hardware. Cooling down the four instruments’ detectors and the surrounding hardware suppresses those infrared emissions. MIRI detects longer infrared wavelengths than the other three instruments, which means it needs to be even colder.

Another reason Webb’s detectors need to be cold is to suppress something called dark current, or electric current created by the vibration of atoms in the detectors themselves. Dark current mimics a true signal in the detectors, giving the false impression that they have been hit by light from an external source. Those false signals can drown out the real signals astronomers want to find. Since temperature is a measurement of how fast the atoms in the detector are vibrating, reducing the temperature means less vibration, which in turn means less dark current.

MIRI’s ability to detect longer infrared wavelengths also makes it more sensitive to dark current, so it needs to be colder than the other instruments to fully remove that effect. For every degree the instrument temperature goes up, the dark current goes up by a factor of about 10.

NASA testing the Webb telescope’s MIRI thermal shield in a thermal vacuum chamber at NASA’s Goddard Space Flight Center in Greenbelt, MD. Credit: NASA

Once MIRI reached a frigid 6.4 kelvins, scientists began a series of checks to make sure the detectors were operating as expected. Like a doctor searching for any sign of illness, the MIRI team looks at data describing the instrument’s health, then gives the instrument a series of commands to see if it can execute tasks correctly. This milestone is the culmination of work by scientists and engineers at multiple institutions in addition to

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Science

Scientists Baffled by Neptune’s Temperature Swings

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(Newser)
–
Neptune’s southern hemisphere has spent the last 17 years in its summer season, yet global temperatures have plummeted. It’s a head-scratching finding that leaves astronomers with more questions than answers. “Since we have been observing Neptune during its early southern summer, we would expect temperatures to be slowly growing warmer, not colder,” says Michael Roman, a postdoctoral research associate at the University of Leicester and lead author of the study published Monday in the Planetary Science Journal, in a statement. It’s based on observations of the ice giant’s thermal-infrared brightness, an indication of heat in the atmosphere, over nearly two decades—about half the length of the 40-year summer, per Space.com.

Researchers observed “a decline in Neptune’s thermal brightness since reliable thermal imaging began in 2003, indicating that globally averaged temperatures in Neptune’s stratosphere—the layer of the atmosphere just above its active weather layer—have dropped by roughly 8 degrees Celsius (14 degrees Fahrenheit) between 2003 and 2018,” according to a release. Strangely, observations of Neptune’s south pole suggest the polar stratosphere warmed by roughly 11 degrees Celsius, or 20 degrees Fahrenheit, in just two years between 2018 and 2020, “reversing the previous globally averaged cooling trend,” per the release. It adds “such polar warming has never been observed on Neptune before.”

Researchers actually know very little about Neptune’s seasons, taking place over its 165-year orbit of the sun. They say the temperature variations could be linked to seasonal changes in Neptune’s atmospheric chemistry. As the paper notes, per ScienceAlert, “photochemically produced hydrocarbons—primarily ethane and acetylene—are powerful infrared emitters that serve to cool the stratosphere.” But the changes observed between 2018 and 2020 “appear surprisingly swift for seasonal response.” According to Roman, “random variability in weather patterns or even a response to the 11-year solar activity cycle” may play a role, per the release. Researchers hope to learn more through observations powered by the James Webb Space Telescope later this year. (Read more Neptune stories.)

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Science

Neptune just experienced an unexplained temperature shift

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Astronomers observing Neptune for the past 17 years with multiple ground-based telescopes tracked a surprising drop in the ice giant’s global temperatures, which was then followed by a dramatic warming trend at the planet’s south pole.

Neptune, which orbits the sun at a distance of 2.8 billion miles (4.5 billion kilometers), experiences seasons like Earth does — they just last much longer. One year on Neptune lasts for about 165 Earth years, so a single season can last around 40 years. It’s been summertime in Neptune’s southern hemisphere since 2005.

Astronomers decided to track the planet’s atmospheric temperatures once the southern summer solstice occurred that year.

Nearly 100 thermal images of Neptune taken since then showed that much of Neptune gradually cooled, dropping by 14 degrees Fahrenheit (8 degrees Celsius) between 2003 and 2018.

A study on the phenomenon published Monday in the Planetary Science Journal.

“This change was unexpected,” said lead study author Michael Roman, a postdoctoral research associate at the University of Leicester, in a statement. “Since we have been observing Neptune during its early southern summer, we expected temperatures to be slowly growing warmer, not colder.”

Then, a dramatic warming event occurred at Neptune’s south pole between 2018 and 2020 and temperatures rose by 20 degrees Fahrenheit (11 degrees Celsius). This warm polar vortex completely reversed any cooling that occurred before.

This kind of polar warming has never been seen on Neptune until now.

“Our data cover less than half of a Neptune season, so no one was expecting to see large and rapid changes,” said study coauthor Glenn Orton, senior research scientist at NASA’s Jet Propulsion Laboratory, in a statement.

Images were taken using the European Southern Observatory’s Very Large Telescope and Gemini South telescope in Chile, along with Hawaii’s Subaru Telescope, Keck Telescope and the Gemini North telescope, as well as data from NASA’s now-retired Spitzer Space Telescope. The infrared light emitted by Neptune’s stratosphere, or the atmospheric band above the active weather layer, helped astronomers detect the temperature fluctuations.

Frosty Neptune has an average of negative 340 degrees Fahrenheit (negative 220 degrees Celsius), and astronomers still don’t know what caused these temperature shifts.

For now, they have considered that the unexpected changes could be due to a number of factors.

“Temperature variations may be related to seasonal changes in Neptune’s atmospheric chemistry, which can alter how effectively the atmosphere cools,” Roman said. “But random variability in weather patterns or even a response to the 11-year solar activity cycle may also have an effect.”

More observations will be needed to truly explore these possibilities. The James Webb Space Telescope will observe Uranus and Neptune later this year. The space observatory’s mid-infrared instrument can map the chemistry and temperatures in Neptune’s atmosphere and could identify what caused the shift.

Neptune is more than 30 times as far from the sun as Earth, and it’s the only planet in our solar system that isn’t visible to the naked eye from Earth. So far, only NASA’s Voyager 2 spacecraft has flown by Neptune up close, which occurred in 1989.

“I think Neptune is itself very intriguing to many of us because we still know so little about it,” Roman said. “This all points towards a more complicated picture of Neptune’s atmosphere and how it changes with time.”

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Unexpected Atmospheric Temperature Changes Detected on Neptune

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Observed changes in Neptune’s thermal-infrared brightness, a measure of temperature in Neptune’s atmosphere. The plot shows the relative change in the thermal-infrared brightness from Neptune’s stratosphere with time for all existing images taken by ground-based telescopes. Brighter images are interpreted as warmer. Corresponding thermal-infrared images (top) at wavelengths of ~12 µm show Neptune’s appearance in 2006, 2009, 2018 (observed by the European Southern Observatory’s Very Large Telescope’s VISIR instrument), and 2020 (observed by Subaru’s COMICS instrument). The south pole appears to have become dramatically warmer in just the past few years. Credit: Michael Roman/NASA/JPL/Voyager-ISS/Justin Cowart

Neptune Is Cooler Than We Thought

New research led by space scientists at the University of Leicester has revealed how temperatures in

Neptune as seen in visible light (centre) and thermal-infrared wavelengths (right), in 2020. The centre image combines multiple images from the Hubble Space Telescope, while the thermal-infrared image on the right was taken from the Subaru Telescope on Maunakea, Hawai’i. In the thermal-infrared, Neptune’s warm south pole glows more brightly than ever seen before. Credit: Michael Roman/NASA/ESA/STSci/M.H. Wong/L.A. Sromovsky/P.M. Fry

By analyzing the data, the researchers were able to reveal a more complete picture of trends in Neptune’s temperatures than ever before.

But to the researchers’ surprise, these collective datasets show a decline in Neptune’s thermal brightness since reliable thermal imaging began in 2003, indicating that globally-averaged temperatures in Neptune’s stratosphere – the layer of the atmosphere just above its active weather layer – have dropped by roughly 8 degrees

Voyager 2 view of Neptune, captured in August 1989. Credit: NASA/JPL-Caltech/Kevin M. Gill

Yet, at Neptune’s south pole, the data reveal a different and surprisingly dramatic change. A combination of observations from Gemini North in 2019 and Subaru in 2020 reveal that Neptune’s polar stratosphere warmed by roughly 11°C (~20°F) between 2018 and 2020, reversing the previous globally-averaged cooling trend. Such polar warming has never been observed on Neptune before.

The cause of these unexpected stratospheric temperature changes is currently unknown, and the results challenge scientists’ understanding of Neptune’s atmospheric variability.

Dr. Roman continued:

“Temperature variations may be related to seasonal changes in Neptune’s atmospheric chemistry, which can alter how effectively the atmosphere cools.

“But random variability in weather patterns or even a response to the 11-year solar activity cycle may also have an effect.”

The 11-year solar cycle (marked by periodic variation in the Sun’s activity and sunspots) has been previously suggested to affect Neptune’s visible brightness, and the new study reveals a possible, but tentative, correlation between the solar activity, stratospheric temperatures, and the number of bright clouds seen on Neptune.

Follow-up observations of the temperature and cloud patterns are needed to further assess any possible connection in the years ahead.

Answers to these mysteries and more will come from the

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