Continuing the planet’s long-term warming trend, global temperatures in 2021 were 1.5 degrees Fahrenheit (0.85 degrees Celsius) above the average for NASA’s baseline period, according to scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York. NASA uses the period from 1951-1980 as a baseline to see how global temperature changes over time.

Collectively, the past eight years are the warmest years since modern recordkeeping began in 1880. This annual temperature data makes up the global temperature record — which tells scientists the planet is warming.

According to NASA’s temperature record, Earth in 2021 was about 1.9 degrees Fahrenheit (or about 1.1 degrees Celsius) warmer than the late 19th century average, the start of the industrial revolution.

“Science leaves no room for doubt: Climate change is the existential threat of our time,” said NASA Administrator Bill Nelson. “Eight of the top 10 warmest years on our planet occurred in the last decade, an indisputable fact that underscores the need for bold action to safeguard the future of our country — and all of humanity. NASA’s scientific research about how Earth is changing and getting warmer will guide communities throughout the world, helping humanity confront climate and mitigate its devastating effects.”

This warming trend around the globe is due to human activities that have increased emissions of carbon dioxide and other greenhouse gases into the atmosphere. The planet is already seeing the effects of global warming: Arctic sea ice is declining, sea levels are rising, wildfires are becoming more severe and animal migration patterns are shifting. Understanding how the planet is changing — and how rapidly that change occurs — is crucial for humanity to prepare for and adapt to a warmer world.

Weather stations, ships, and ocean buoys around the globe record the temperature at Earth’s surface throughout the year. These ground-based measurements of surface temperature are validated with satellite data from the Atmospheric Infrared Sounder (AIRS) on NASA’s Aqua satellite. Scientists analyze these measurements using computer algorithms to deal with uncertainties in the data and quality control to calculate the global average surface temperature difference for every year. NASA compares that global mean temperature to its baseline period of 1951-1980. That baseline includes climate patterns and unusually hot or cold years due to other factors, ensuring that it encompasses natural variations in Earth’s temperature.

Many factors affect the average temperature any given year, such as La Nina and El Nino climate patterns in the tropical Pacific. For example, 2021 was a La Nina year and NASA scientists estimate that it may have cooled global temperatures by about 0.06 degrees Fahrenheit (0.03 degrees Celsius) from what the average would have been.

A separate, independent analysis by NOAA also concluded that the global surface temperature for 2021 was the sixth highest since record keeping began in 1880. NOAA scientists use much of the same raw temperature data in their analysis and have a different baseline period (1901-2000) and methodology.

“The complexity of the various analyses doesn’t matter because the signals are so strong,” said Gavin Schmidt, director of GISS, NASA’s leading center for climate modeling and climate change research. “The trends are all the same because the trends are so large.”

NASA’s full dataset of global surface temperatures for 2021, as well as details of how NASA scientists conducted the analysis, are publicly available from GISS (https://data.giss.nasa.gov/gistemp).

GISS is a NASA laboratory managed by the Earth Sciences Division of the agency’s Goddard Space Flight Center in Greenbelt, Maryland. The laboratory is affiliated with Columbia University’s Earth Institute and School of Engineering and Applied Science in New York.

For more information about NASA’s Earth science missions, visit:

https://www.nasa.gov/earth

Story Source:

Materials provided by NASA. Note: Content may be edited for style and length.

The planet, TOI-2180 b, has the same diameter as Jupiter, but is nearly three times more massive. Researchers also believe it contains 105 times the mass of Earth in elements heavier than helium and hydrogen. Nothing quite like it exists in our solar system.

Details of the finding have been published in the Astronomical Journal and presented at the American Astronomical Society virtual press event on Jan. 13.

“TOI-2180 b is such an exciting planet to have found,” said UCR astronomer Paul Dalba, who helped confirm the planet’s existence. “It hits the trifecta of 1) having a several-hundred-day orbit, 2) being relatively close to Earth (379 lightyears is considered close for an exoplanet), and 3) us being able to see it transit in front of its star. It is very rare for astronomers to discover a planet that checks all three of these boxes.”

Dalba also explained that the planet is special because it takes 261 days to complete a journey around its star, a relatively long time compared to many known gas giants outside our solar system. Its relative proximity to Earth and the brightness of the star it orbits also make it likely astronomers will be able to learn more about it.

In order to locate exoplanets, which orbit stars other than our sun, NASA’s TESS satellite looks at one part of the sky for a month, then moves on. It is searching for dips in brightness that occur when a planet crosses in front of a star.

“The rule of thumb is that we need to see three ‘dips’ or transits before we believe we’ve found a planet,” Dalba said. A single transit event could be caused by a telescope with a jitter, or a star masquerading as a planet. For these reasons, TESS isn’t focused on these single transit events. However, a small group of citizen scientists is.

Looking over TESS data, Tom Jacobs, a group member and former U.S. naval officer, saw light dim from the TOI-2180 star, just once. His group alerted Dalba, who specializes in studying planets that take a long time to orbit their stars.

Using the Lick Observatory’s Automated Planet Finder Telescope, Dalba and his colleagues observed the planet’s gravitational tug on the star, which allowed them to calculate the mass of TOI-2180 b and estimate a range of possibilities for its orbit.

Hoping to observe a second transit event, Dalba organized a campaign using 14 different telescopes across three continents in the northern hemisphere. Over the course of 11 days in August 2021, the effort resulted in 20,000 images of the TOI-2180 star, though none of them detected the planet with confidence.

However, the campaign did lead the group to estimate that TESS will see the planet transit its star again in February, when they’re planning a follow up study. Funding for Dalba’s research is provided by the National Science Foundation’s Astronomy and Astrophysics Postdoctoral Fellowship Program.

The citizen planet hunters’ group takes publicly available data from NASA satellites like TESS and looks for single transit events. While professional astronomers use algorithms to scan a lot of data automatically, the Visual Survey Group uses a program they created to inspect telescope data by eye.

“The effort they put in is really important and impressive, because it’s hard to write code that can identify single transit events reliably,” Dalba said. “This is one area where humans are still beating code.”

Story Source:

Materials provided by University of California – Riverside. Original written by Jules Bernstein. Note: Content may be edited for style and length.

While such intruder-based flyby events have previously been witnessed with some regularity in computer simulations of star formation, few convincing direct observations have ever been made, and until now, the events have remained largely theoretical.

“Observational evidence of flyby events is difficult to obtain because these events happen fast and it is difficult to capture them in action. What we have done with our ALMA Band 6 and VLA observations is equivalent to capturing lightning striking a tree,” said Ruobing Dong, an astronomer at the University of Victoria in Canada and the principal investigator on the new study. “This discovery shows that close encounters between young stars harboring disks do happen in real life, and they are not just theoretical situations seen in computer simulations. Prior observational studies had seen flybys, but hadn’t been able to collect the comprehensive evidence we were able to obtain of the event at Z CMa.”

Perturbations, or disturbances, like those at Z CMa aren’t typically caused by intruders, but rather by sibling stars growing up together in space. Hau-Yu Baobab Liu, an astronomer at the Institute of Astronomy and Astrophysics at Academia Sinica in Taiwan and a co-author on the paper, said, “Most often, stars do not form in isolation. The twins, or even triplets or quadruplets, born together may be gravitationally attracted and, as a result, closely approach each other. During these moments, some material on the stars’ protoplanetary disks may be stripped off to form extended gas streams that provide clues to astronomers about the history of past stellar encounters.”

Nicolás Cuello, an astrophysicist and Marie Curie Fellow at Université Grenoble Alpes in France and a co-author on the paper added that in the case of Z CMa, it was the morphology, or structure, of these streams that helped scientists to identify and pinpoint the intruder. “When a stellar encounter occurs, it causes changes in disk morphology — spirals, warps, shadows, etc. — that could be considered as flyby fingerprints. In this case, by looking very carefully at Z CMa’s disk, we revealed the presence of several flyby fingerprints.”

These fingerprints not only helped scientists to identify the intruder but also led them to consider what these interactions might mean for the future of Z CMa and the baby planets being born in the system, a process that so far has remained a mystery to scientists. “What we now know with this new research is that flyby events do occur in nature and that they have major impacts on the gaseous circumstellar disks, which are the birth cradles of planets, surrounding baby stars,” said Cuello. “Flyby events can dramatically perturb the circumstellar disks around participant stars, as we’ve seen with the production of long streamers around Z CMa.”

Liu added, “These perturbers not only cause gaseous streams but may also impact the thermal history of the involved host stars, like Z CMa. This can lead to such violent events as accretion outbursts, and also impact the development of the overall star system in ways that we haven’t yet observed or defined.”

Dong said that studying the evolution and growth of young star systems throughout the galaxy helps scientists to better understand our own Solar System’s origin. “Studying these types of events gives a window into the past, including what might have happened in the early development of our own Solar System, critical evidence of which is long since gone. Watching these events take place in a newly forming star system provides us with the information needed to say, ‘Ah-ha! This is what may have happened to our own Solar System long ago.’ Right now, VLA and ALMA have given us the first evidence to solve this mystery, and the next generations of these technologies will open windows on the Universe that we have yet only dreamed of.”

Recently, the National Radio Astronomy Observatory (NRAO) received approval for its Central Development Laboratory (CDL) to develop a multi-million dollar upgrade to ALMA’s Band 6 receiver, and the Observatory’s next-generation VLA (ngVLA) received strong support from the astronomical community in the Astro2020 Decadal Survey. Technological advancements for both telescopes will lead to better observations, and a potentially significant increase in the discovery of difficult-to-see objects, like Z CMa’s stellar intruder. Both projects are funded in part by the National Science Foundation (NSF). “These observations highlight the synergy that can come from a newer instrument working in concert with a more seasoned one, and how good a workhorse the ALMA Band 6 receiver is,” said Dr. Joe Pesce, astrophysicist and ALMA Program Director at the NSF. “I look forward to the even-better results the upgraded ALMA Band 6 receiver will enable.”

The discovery, published in Nature Astronomy, was led by David Kipping and his Cool Worlds Lab at Columbia University, which reported the first exomoon candidate in 2017.

“Astronomers have found more than 10,000 exoplanet candidates so far, but exomoons are far more challenging,” said Kipping, who has spent the last decade hunting for exomoons. “They are terra incognita.”

The team spotted the giant exomoon candidate orbiting the planet Kepler 1708b, a world 5,500 light-years from Earth in the direction of the Cygna and Lyra constellations. This new candidate is about a third smaller than the Neptune-sized moon that Kipping and his colleagues earlier found orbiting a similar Jupiter-sized planet, Kepler 1625b.

Both supermoon candidates are likely made of gas that has piled up under the gravitational pull caused by their enormous size, said Kipping. If one astronomer’s hypothesis is correct, the moons may have even started life as planets, only to be pulled into the orbit of an even bigger planet like Kepler 1625b or 1708b.

Both moons are located far from their host star, where there’s less gravity to tug at planets and strip off their moons. In fact, the researchers sought out cold, giant gas planets on wide orbits in their search for exomoons precisely because the analog in our own solar system, Jupiter and Saturn, have more than a hundred moons between them.

If other moons are out there, they will likely be less monstrous, but also harder to spot, said Kipping. “The first detections in any survey will generally be the weirdos,” he said. “The big ones that are simply easiest to detect with our limited sensitivity.”

Exomoons fascinate astronomers for the same reasons that exoplanets do. They have the potential to reveal how and where life may have emerged in the universe. They are also curiosities in their own right, and astronomers want to know how these exomoons form, if they can sustain life, and what role, if any, they play in making their host planets habitable.

In the current study, the researchers looked at the sample of the coldest gas giant planets captured by NASA’s planet-hunting spacecraft, Kepler. After scanning 70 planets in depth, they found just one candidate — Kepler 1708b — with a moon-like signal. “It’s a stubborn signal,” said Kipping. “We threw the kitchen sink at this thing but it just won’t go away.”

Observations from other space telescopes, like Hubble, will be needed to verify the discovery, a process that could take years. Four years later, Kipping’s first exomoon discovery continues to be hotly debated. In a recent paper, he and his colleagues showed how one group of skeptics may have missed Kepler 1625b’s moon in their calculations. Meanwhile, Kipping and colleagues continue to investigate other lines of evidence.

Eric Agol, an astronomy professor at University of Washington, said he’s doubtful that this latest signal will turn out to be real. “It might just be a fluctuation in the data, either due to the star or instrumental noise,” he said.

Others sounded more optimistic. “This is science at its best,” said Michael Hippke, an independent astronomer in Germany. “We find an intriguing object, make a prediction, and either confirm the exomoon candidate or rule it out with future observations.”

“I am very excited to see a second exomoon candidate, although it is unfortunate that only two transits have been observed,” he added. “More data would be very cool.”

Spotting a moon or even a planet hundreds to thousands of light-years from Earth is anything but straightforward. Moons and planets can only be observed indirectly as they pass in front of their host stars, causing the star’s light to intermittently dim. Catching one of these fleeting transit signals with a telescope is tricky, and so is interpreting the light-curve data. Moons are even harder to detect because they’re smaller and block less light.

But the search is worth it, said Kipping, as he recalled how the existence of exoplanets was greeted with the same skepticism as exomoons are today. “Those planets are alien compared to our home system,” he said. “But they have revolutionized our understanding of how planetary systems form.”

Other authors are: Steve Bryson, NASA Ames Research Center; Chris Burke, MIT; Jessie Christiansen and Kevin Hardegree-Ullman, Caltech; Billy Quarles, Valdosta State University; Brad Hansen, University of California, Los Angeles; Judit Szulagyi, ETH Zurich; and Alex Teachey, Columbia.

The scientists, from the University of Cambridge and the Ecole normale supérieure de Lyon, have proposed a new model of crystallisation, where crystals remained suspended in liquid magma over hundreds of millions of years as the lunar ‘slush’ froze and solidified. The results are reported in the journal Geophysical Review Letters.

Over fifty years ago, Apollo 11 astronauts collected samples from the lunar Highlands. These large, pale regions of the Moon — visible to the naked eye — are made up of relatively light rocks called anorthosites. Anorthosites formed early in the history of the Moon, between 4.3 and 4.5 billion years ago.

Similar anorthosites, formed through the crystallisation of magma, can be found in fossilised magma chambers on Earth. Producing the large volumes of anorthosite found on the Moon however, would have required a huge global magma ocean.

Scientists believe that the Moon formed when two protoplanets, or embryonic worlds, collided. The larger of these two protoplanets became the Earth, and the smaller became the Moon. One of the outcomes of this collision was that the Moon was very hot — so hot that its entire mantle was molten magma, or a magma ocean.

“Since the Apollo era, it has been thought that the lunar crust was formed by light anorthite crystals floating at the surface of the liquid magma ocean, with heavier crystals solidifying at the ocean floor,” said co-author Chloé Michaut from Ecole normale supérieure de Lyon. “This ‘flotation’ model explains how the lunar Highlands may have formed.”

However, since the Apollo missions many lunar meteorites have been analysed and the surface of the Moon has been extensively studied. Lunar anorthosites appear more heterogenous in their composition than the original Apollo samples, which contradicts a flotation scenario where the liquid ocean is the common source of all anorthosites.

The range of anorthosite ages — over 200 million years — is difficult to reconcile with an ocean of essentially liquid magma whose characteristic solidification time is close to 100 million years.

“Given the range of ages and compositions of the anorthosites on the Moon, and what we know about how crystals settle in solidifying magma, the lunar crust must have formed through some other mechanism,” said co-author Professor Jerome Neufeld from Cambridge’s Department of Applied Mathematics and Theoretical Physics.

Michaut and Neufeld developed a mathematical model to identify this mechanism.

In the low lunar gravity, the settling of crystal is difficult, particularly when strongly stirred by the convecting magma ocean. If the crystals remain suspended as a crystal slurry, then when the crystal content of the slurry exceeds a critical threshold, the slurry becomes thick and sticky, and the deformation slow.

This increase of crystal content occurs most dramatically near the surface, where the slushy magma ocean is cooled, resulting in a hot, well-mixed slushy interior and a slow-moving, crystal rich lunar ‘lid’.

“We believe it’s in this stagnant ‘lid’ that the lunar crust formed, as lightweight, anorthite-enriched melt percolated up from the convecting crystalline slurry below,” said Neufeld. “We suggest that cooling of the early magma ocean drove such vigorous convection that crystals remained suspended as a slurry, much like the crystals in a slushy machine.”

Enriched lunar surface rocks likely formed in magma chambers within the lid, which explains their diversity. The results suggest that the timescale of lunar crust formation is several hundreds of million years, which corresponds to the observed ages of the lunar anorthosites.

Serial magmatism was initially proposed as a possible mechanism for the formation of lunar anorthosites, but the slushy model ultimately reconciles this idea with that of a global lunar magma ocean.?

The research was supported by the European Research Council.