Comet 2014 UN271 the largest ever observed

by Bob Yirka ,

Comet 2014 UN271 the largest ever observed
Fig. 1. Recentered 233 GHz total image of 2014 UN271 merging data from the two SB and the four spectral windows. The synthesized beam, shown in white, is 0.067”× 0.062”. The scale of the color bar is in mJy. Credit:

A team of researchers with the Paris observatory and Instituto de Astrofísica de Andalucía-CSIC, has confirmed that comet 2014 UN271 is the largest comet ever observed. They published a paper describing their findings on the arXiv preprint server, and it has been accepted for publication in Astronomy and Astrophysics Letters.

Comet 2014 UN271, also known as Bernardinelli-Bernstein, was first sighted in 2014; hence, the initial part of its name. Researchers determined at the time that it had originated in the Oort Cloud. It was observed during the search for solar system objects during the Dark Energy Survey. Back then, the comet was still as far away as Neptune, and astronomers had no idea of its size. Seven years later, as it drew closer, it became clear that it was bigger than most comets. Researchers at the time suggested it was likely 100 to 370 kilometers across.

In this new effort, using data from the Atacama Large Millimeter Array, the team studied the wavelengths of light bouncing off the comet to learn more about its size (most other measurements of comet size have involved measuring how much of the sky they cover). More specifically, the researchers focused on those wavelengths of its microwave radiation that were not represented by the dust given off by the comet, noting that the comparative brightness of the wavelengths reflected from the comet were fairly typical. Their calculations showed that for the comet to be reflecting so much light, it had to be approximately 137 kilometers across, nearly in the minor planet category. The previous record holder was Hale-Bopp, which was measured at approximately 74 kilometers across.

The researchers also point out that their measurement of Comet 2014 UN271 was the most distant measurement of a comet’s reflectivity (albedo) ever performed. They note that measuring a comet at such a distance will allow researchers to measure its size in detail as it loses ice on approach to the sun. They expect it to be just half its current size once it begins its return trip.

Explore further

The biggest comet ever seen will get as close as Saturn in 2031

Largest collection of free-floating planets found in the Milky Way

by Association of Universities for Research in Astronomy (AURA)

Largest collection of free-floating planets found in the Milky Way
An artist’s impression of a free-floating planet. Using observations and archival data from several of NSF’s NOIRLab’s observatories, together with observations from telescopes around the world and in orbit, astronomers have discovered at least 70 new free-floating planets — planets that wander through space without a parent star — in a nearby region of the Milky Way known as Upper Scorpius OB stellar association. Credit: NOIRLab/NSF/AURA/J. da Silva

Using observations and archival data from several of NSF’s NOIRLab’s observatories, together with observations from telescopes around the world and in orbit, astronomers have discovered at least 70 new free-floating planets—planets that wander through space without a parent star—in a nearby region of the Milky Way. This is the largest sample of such planets found in a single group and it nearly doubles the number known over the entire sky.

Researchers have discovered a group of free-floating planets—planets not orbiting a star—in a nearby region of the Milky Way known as the Upper Scorpius OB stellar association. At least 70, and as many as 170 of these Jupiter-sized planets have been found by examining data from over 20 years of observations. The first free-floating planets were discovered in the 1990s, but the latest findings have almost doubled the total number known.

To find these planets, the study’s first author, Núria Miret-Roig of the Laboratoire d’Astrophysique de Bordeaux, at the University of Bordeaux in France, with a team of astronomers, used observations and archival data from a number of large observatories, including facilities from NSF’s NOIRLab, telescopes of the European Southern Observatory, the Canada-France-Hawaii Telescope, and the Subaru Telescope, amounting to 80,000 wide-field images over 20 years of observations.Play00:0001:16MuteSettingsPIPEnter fullscreenPlayUsing observations and archival data from several of NSF’s NOIRLab’s observatories, together with observations from telescopes around the world and in orbit, astronomers have discovered at least 70 new free-floating planets — planets that wander through space without a parent star — in a nearby region of the Milky Way. This is the largest sample of such planets found in a single group and it nearly doubles the number known over the entire sky. Credit: NOIRLab/NSF/AURA/J. da Silva/ESO/L. Calçada/N. Risinger ( et al./M. Kornmesser/H.Bouy/COSMIC-DANCE team/T. van de Zalm/M. Attard.Image Processing: M. ZamaniMusic: Stellardrone – Airglow

Hervé Bouy, an astronomer at the Laboratoire d’Astrophysique de Bordeaux, and project leader of the research, says that the discovery of so many free-floating planets would not have been feasible without access to NOIRLab’s Astro Data Archive and Astro Data Lab Science Platform operated at the Community Science and Data Center (CSDC).

The data include 247 images from the NEWFIRM extremely wide-field infrared imager at Kitt Peak National Observatory (KPNO) in Arizona, 1348 images from the same NEWFIRM instrument after it was relocated to the Cerro Tololo Inter-American Observatory (CTIO) in Chile, 2214 images from the Infrared Side Port Imager that was previously operating on the Víctor M. Blanco 4-meter Telescope at CTIO, and 3744 images from the Dark Energy Camera.

“The treasure trove available in the NOIRLab Astro Data Archive has been fundamental to this study,” Bouy says. “We needed very deep and wide-field images in both the optical and near-infrared, spanning a long time baseline. So the Dark Energy Camera and NEWFIRM were very appealing for our project because they are among the most sensitive wide-field cameras in the world.”

One of the highest-performance, wide-field CCD imagers in the world, the Dark Energy Camera was designed for the Dark Energy Survey funded by the Department of Energy (DOE). It was built and tested at DOE’s Fermilab, and was operated by the DOE and National Science Foundation (NSF) between 2013 and 2019. At present the Dark Energy Camera is used for programs covering a huge range of science. The analysis of data from the Dark Energy Survey is supported by the DOE and the NSF.

Largest collection of free-floating planets found in the Milky Way
This image shows the locations of 115 potential free-floating planets recently discovered by a team of astronomers in the direction of the Upper Scorpius and Ophiuchus constellations, highlighted with red circles. Free-floating planets have masses comparable to those of the planets in our Solar System, but do not orbit a star and instead roam freely on their own.The exact number of free-floating planets found by the team is between 70 and 170, depending on the age assumed for the study region. This image was created assuming an intermediate age, resulting in a number of planet candidates in between the two extremes of the study. Credit: ESO/N. Risinger (

“This project illustrates the incredible importance of providing access to archival data from different telescopes, not just throughout the US, but worldwide,” says Chris Davis, Program Officer at the National Science Foundation for NSF’s NOIRLab. “This is something NOIRLab and specifically the CSDC has been working hard to enable over a number of years, and continues to do so with support from NSF.”×280&!1&btvi=1&fsb=1&xpc=9PeAqYTwvr&p=https%3A//

The free-floating planets lie in the Upper Scorpius OB association, which is 420 light-years away from Earth. This region contains a number of the most famous nebulae, including the Rho Ophiuchi cloud, the Pipe Nebula, Barnard 68, and the Coalsack.

Free-floating planets have mostly been discovered via microlensing surveys, in which astronomers watch for a brief chance alignment between an exoplanet and a background star. However, microlensing events only happen once, meaning follow-up observations are impossible.

These new planets were discovered using a different method. These planets, lurking far away from any star illuminating them, would normally be impossible to image. However, Miret-Roig and her team took advantage of the fact that, in the few million years after their formation, these planets are still hot enough to glow, making them directly detectable by sensitive cameras on large telescopes. Miret-Roig’s team used the 80,000 observations to measure the light of all the members of the association across a wide range of optical and near-infrared wavelengths and combined them with measurements of how they appear to move across the sky.

“We measured the tiny motions, the colors and luminosities of tens of millions of sources in a large area of the sky,” explains Miret-Roig. “These measurements allowed us to securely identify the faintest objects in this region.”

The discovery also sheds light on the origin of free-floating planets. Some scientists believe these planets can form from the collapse of a gas cloud that is too small to lead to the formation of a star, or that they could have been kicked out from their parent system. But which is the actual mechanism remains unknown.

The ejection model suggests that there could be even greater numbers of free-floating planets that are Earth-sized. “The free-floating Jupiter-mass planets are the most difficult to eject, meaning that there might even be more free-floating Earth-mass planets wandering the galaxy,” says Miret-Roig.

It is expected that Vera C. Rubin Observatory could find many more free-floating planets when it begins scientific operations this decade.

Explore furtherAstronomers uncover largest group of rogue planets yet

Astronomers Have Discovered Why The Solar System Might Be Shaped Like a Croissant

The possible croissant-like shape of the Solar System. (M. Opher)SPACE


The Solar System exists in a bubble.

Wind and radiation from the Sun stream outwards, pushing out into interstellar space. This creates a boundary of solar influence, within which the objects in the Solar System are sheltered from powerful cosmic radiation.

It’s called the heliosphere, and understanding how it works is an important part of understanding our Solar System, and perhaps even how we, and all life on Earth, are able to be here.

“How is this relevant for society? The bubble that surrounds us, produced by the Sun, offers protection from galactic cosmic rays, and the shape of it can affect how those rays get into the heliosphere,” says astrophysicist James Drake of the University of Maryland.

“There’s lots of theories but, of course, the way that galactic cosmic rays can get in can be impacted by the structure of the heliosphere – does it have wrinkles and folds and that sort of thing?”

Since we’re inside the heliosphere, and its boundary is not actually visible, figuring out its shape is not exactly easy. But it’s not impossible. The two Voyager probes and New Horizons are three spacecraft that have traveled to the far reaches of the Solar System; in fact, the Voyager probes have even traversed the boundary of the heliosphere, and are currently making their way through interstellar space.

With data from these probes, scientists determined last year that the heliosphere could be shaped a bit like a weird cosmic croissant. Now, they have figured out how: neutral hydrogen particles streaming into the Solar System from interstellar space likely play a crucial role in sculpting the shape of the heliosphere.

The team set out to investigate the heliospheric jets. These are twin jets of material that emanate from the Sun’s poles, shaped by the interaction of the solar magnetic field with the interstellar magnetic field. Rather than shooting straight out, though, they curve around, pushed by the interstellar flow – like the points of a croissant. These are the Solar System’s tails.

turbulence solar jetsA reconstruction of the heliosphere showing the jets. (M. Opher/AAS)

These are similar to other astrophysical jets observed in space, and like those other jets, the Sun’s jets are unstable. And the heliosphere, shaped by the Sun, also appears to be unstable. The researchers wanted to know why.

“We see these jets projecting as irregular columns, and [astrophysicists] have been wondering for years why these shapes present instabilities,” explains astrophysicist Merav Opher of Boston University (BU), who led the research.

The team performed computational modeling, focusing on neutral hydrogen atoms – those that carry no charge. We know these stream through the Universe, but not what effect they could have on the heliosphere. When the researchers took the neutral atoms out of their model, suddenly the solar jets became stable. Then they put them back.

“When I put them back in, things start bending, the center axis starts wiggling, and that means that something inside the heliospheric jets is becoming very unstable,” Opher says.

According to the team’s analysis, this occurs because of the interaction of the neutral hydrogen with the ionized matter in the heliosheath – the outer region of the heliosphere. This generates a Rayleigh-Taylor instability, or an instability that occurs at the interface between two fluids of different densities when the lighter fluid pushes into the heavier one. In turn, this produces large-scale turbulence in the tails of the heliosphere.

It’s a clear and elegant explanation for the shape of the heliosphere, and one that could have implications for our understanding of the way galactic cosmic rays enter the Solar System. In turn, this could help us to better understand the radiation environment of the Solar System, outside Earth’s protective magnetic field and atmosphere.

“The Universe is not quiet. Our BU model doesn’t try to cut out the chaos, which has allowed me to pinpoint the cause [of the heliosphere’s instability]…. The neutral hydrogen particles,” Opher says.

“This finding is a really major breakthrough, it’s really set us in a direction of discovering why our model gets its distinct croissant-shaped heliosphere and why other models don’t.”

The research has been published in The Astrophysical Journal.

Asteroid As Large As A Mountain Will Fly Near Earth This Weekend

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Asteroid As Large As A Mountain Will Fly Near Earth This Weekend


By Dr Alfredo Carpineti

20 AUG 2021, 10:54

On Saturday, August 21, a potentially hazardous asteroid will safely fly past Earth at a distance of just 3.4 million kilometers (2.1 million miles), the closest approach for several decades. That’s just 8.9 times the distance between the Earth and the Moon.

Asteroid 2016 AJ193 is larger than 99 percent of all known Near-Earth objects and so it is good to keep an eye on it.

The space rock measures 1.37 kilometers (0.85 miles) according to measurements from NASA’s spacecraft NEOWISE. It is also surprisingly dark, reflecting very little light back making this close (and safe) approach an important chance to better study the object.

It was discovered by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) facility – located at Haleakala Observatory, Hawaii in January 2016. It is important to stress that an asteroid with the potential to devastate our planet was only discovered five years ago.

The asteroid orbits around the Sun every 5.9 years going far beyond the orbit of Jupiter and then as far as the orbit of Venus, with quite the inclination with respect to the plane of the solar system. Its next really close passage to Earth will be August 19, 2080, where the asteroid will be at about twice the distance that it will be on Saturday.

The orbital path of 2016 AJ193 around the Sun. Image Credit: NASA/JPL-Caltech

Professional astronomers will study this object using the Goldstone Observatory in California together with observatories in Spain, Germany, Italy, and Russia. The observations will cover the period August 20 to August 24, roughly the time that it is observable for them.

But if you are passionate about astronomy and you have a telescope, you to can look for it in the sky. Despite its dimness, astronomers expect that it should brighten to at least the 14th magnitude during its close approach.

Telescopes of 20 centimeters (8 inches) or larger should be able to spot it. It will appear in the constellation of Lepus, near the Mu Leporis star. Better watch it just before dawn.

“Not only is 2016 AJ193 a near-Earth asteroid, but it is too classified as a Potentially Hazardous Asteroid. The flyby from a roughly 1-mile (~1.4 kilometers) large body does not only require specific attention, but it is also a clear reminder of the importance of building a community of observers capable of observing the sky from everywhere and all the time,” Franck Marchis, chief scientific officer at Unistellar, told IFLScience.

Asteroid the size of the Great Pyramid of Giza to fly (safely) by Earth Sunday

By Jeanna Bryner – Live Science Editor-in-Chief about 2 hours ago

3D illustration of an asteroid flying past Earth. (Image credit: Aleksandra Sova via Shutterstock)

An asteroid about as long as the Great Pyramid of Giza is tall will make a “close” approach with Earth on Sunday (July 25), according to NASA calculations.

There is no worry that the space rock poses any threat to Earth, but NASA monitors such rocks to both learn more about the early solar system — asteroids are rocky fragments from that time — and because if their orbits were to change, the asteroid could pose a future risk to Earth.

Related: Top 10 ways to destroy Earth

On its closest approach, the near-Earth asteroid, called 2008 GO20, will swing within 2.8 million miles (4.5 million kilometers) of our blue marble. It will be trekking at a whopping 18,000 mph (nearly 29,000 km/h), according to news reports. RECOMMENDED VIDEOS FOR YOU…

The rock is estimated to be anywhere from 318 to 720 feet (97 to 220 meters) across. (The Great Pyramid of Giza stands at 450 feet, or 138 m, tall.) Any space rock larger than about 490 feet (150 m) across that is expected to make a shave with Earth within 4.6 million miles (7.5 million km) is considered a potentially hazardous asteroid (PHA); NASA’s Center for Near Earth Object Studies monitors all PHAs. For comparison, that distance is 19.5 times the span between Earth and the moon.

And in reality, that distance doesn’t hold a candle to the closest known flyby by an asteroid (at least one that didn’t smash into us), which occurred on Aug. 16, 2020, when 2020 QG zipped just 1,830 miles (2,950 kilometers) above the Indian Ocean, Live Science sister site reported. Such little space rocks pose no danger to life on Earth.RELATED CONTENT

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On the other hand, 2008 GO20 is “potentially hazardous” because over time the gravitational tug of the planets could change the object’s orbital path so that it crosses Earth’s orbit. If that were to happen, a future collision with our planet is possible, NASA said.

This isn’t the first time 2008 GO20 has visited Earth’s quarters. It made its closest approach on Aug. 4, 1901, when the asteroid swung to 806,856 miles (1.3 million km) of our planet, according to NASA records. Its next closest flyby happened on July 31, 1935 at a distance of 1.15 million miles (1.85 million km) of Earth. When it next flies by Earth, on July 24, 20342008 GO20 will get as close as 3.1 million miles (5 million km).

Bezos’s Space Stunt Got Almost as Much TV Time as Climate Crisis in All of 2020

Jeff Bezos laughs as he speaks about his flight on Blue Origin’s New Shepard during a press conference on July 20, 2021, in Van Horn, Texas.
Jeff Bezos laughs as he speaks about his flight on Blue Origin’s New Shepard during a press conference on July 20, 2021, in Van Horn, Texas.

BYSharon ZhangTruthoutPUBLISHEDJuly 21, 2021SHAREShare via FacebookShare via TwitterShare via Email

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READING LISTECONOMY & LABORPoverty Wages and Tax Dodging Funded Bezos’s Ridiculous Space TripPOLITICS & ELECTIONSTrump Has Convinced His Followers He’s About to Return to Office This SummerWAR & PEACEBiden Promised Diplomacy, But He’s Overseeing Military Buildup Against ChinaPOLITICS & ELECTIONSInvestigating Trump Is “Absolutely” a Possibility, Says Jan 6 Commission ChairPOLITICS & ELECTIONSAOC Calls GOP Refusal to Advance Infrastructure Bill Tactics for “Killing Time”IMMIGRATIONLet’s Call the “Border Crisis” What It Is: Another Big Lie From the Right

Broadcast news networks are notoriously bad at covering the climate crisis, dedicating a vanishingly small amount of airtime — year after year — to the grave existential threat despite the many potential stories they could be running about it.

Their neglect of the climate crisis is on stark display in a new statistic: According to Media Matters for America, morning TV shows spent nearly as much time on Jeff Bezos’s space launch on July 20, 2021 as they did on the climate crisis in all of 2020.

The morning shows on broadcast networks combined spent 212 minutes covering Bezos’s space trip just on Tuesday alone, Media Matters researchers found. Meanwhile, in the entirety of last year, the shows spent a combined 267 minutes on the climate crisis.

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Bezos’s space trip was 11 minutes long. By contrast, the climate crisis has been ongoing for decades and daily threatens the fabric of our society and the continued existence of our species, if it continues unabated.

Further, Bezos’s trip to space was largely a PR stunt, meant to garner excitement around the billionaire and his space company while also buying fawning coverage from news outlets. It comes at a time when billionaires have come under increased scrutiny for paying zero or fewer taxes than ordinary working people and progressives put forward the argument that nobody should be allowed to accrue as much wealth as people like the Amazon CEO.

As progressives argue, the space trip was wasteful and almost insulting to the Amazon workers, who, under Bezos, suffer terrible work conditions. “Amazon workers did pay for this — with lower wages, union busting, a frenzied and inhumane workplace, and delivery drivers not having health insurance during a pandemic,” wrote Rep. Alexandria Ocasio-Cortez on Twitter.

And yet, judging by the amount of coverage that the morning broadcast shows dedicated to the Bezos flight versus the climate crisis, it would almost seem as though they’re of equivalent importance.

In fact, CNN recently bumped climate scientist Katharine Hayhoe, who was slated to discuss the climate crisis as Death Valley was hitting record high temperatures, in order to cover the other recent billionaire space stunt — businessman Richard Branson’s brief jaunt to the edge of space.

CNN’s decision to bump Hayhoe for Branson’s stunt “shows that cable news, and TV news as a whole, still largely continues to fail at grasping the climate crisis as the existential threat it is,” wrote Earther’s Molly Taft. “Instead, coverage prioritizes entertainment and sensationalism that keeps people watching the commercial breaks.”

What makes it especially frustrating too, Taft writes, is that TV news networks appear to be reaching a breakthrough with covering climate this year. Networks linked recent heat waves in the American West to climate change in 27 percent of segmentsMedia Matters research showed, and have improved coverage in recent months.

Mentioning the climate crisis in 27 percent of segments on the heat wave is still quite low, especially when researchers have found that it was almost certainly brought on and worsened by climate change.

Indeed, climate advocates have expressed frustration for years that broadcast news as a whole largely ignores the climate crisis. In 2019, according to Media Matters, broadcast news shows dedicated less than 1 percent of their reporting to the climate crisis.

That’s despite the fact that 2019 was a landmark year for the climate crisis as the second warmest year on record at the time. It’s now been bumped to third place, with 2020 tying for first place with 2016. And 2019 was even an improvement on 2018’s coverage, with networks having spent a combined 238 minutes on climate in 2019 versus only 142 minutes the year before.

Media analysts and climate communication researchers argue that broadcast news — and media at large — can make a difference with more urgent and frequent climate coverage. The American public is growing more and more concerned about the climate crisis despite a dearth of coverage from corporate news outlets, and that impact could be even higher if the networks dedicate the time and effort to cover it.

The largest comet ever discovered in modern times is zooming toward the sun

Doyle RiceUSA TODAY0:001:14

  • “We have the privilege of having discovered perhaps the largest comet ever seen.”
  • It has not visited the solar system in more than 3 million years.
  • People here on Earth will likely need to rely on telescopes to capture photographs of it.

This is a big one.

A giant comet – which scientists say is arguably the largest comet discovered in modern times – is on its way toward the sun and will make its closest approach to Earth in 2031.

“We have the privilege of having discovered perhaps the largest comet ever seen – or at least larger than any well-studied one – and caught it early enough for people to watch it evolve as it approaches and warms up,” said University of Pennsylvania astronomer Gary Bernstein, a co-discoverer of the object.

It is the most distant comet to be discovered on its incoming path, giving us years to watch it evolve as it approaches the sun, the National Science Foundation said. 

The comet is also an infrequent visitor to our neck of the woods: “It has not visited the solar system in more than 3 million years,” Bernstein said in a statement.

The comet, which is estimated to be 60 to 120 miles across, or about 10 times the diameter of most comets, is an icy relic flung out of the solar system by the migrating giant planets in the early history of the solar system.

This comet is quite unlike any other seen before, the National Science Foundation said, and the huge size estimate is based on how much sunlight it reflects. 

This illustration shows the distant Comet Bernardinelli-Bernstein as it might look in the outer solar system. Comet Bernardinelli-Bernstein is estimated to be about 1,000 times more massive than a typical comet, making it arguably the largest comet discovered in modern times.

At its current pace, the comet will travel from its current point just past Neptune’s orbit to nearly reach Saturn’s orbit in 2031, Smithsonian magazine said.

The object probably will only be about as bright as Pluto’s moon Charon at that point, according to New Atlas, so people here on Earth will likely need to rely on telescopes to capture photographs of it. Then it will head back into distant space from where it came.

Comet Neowise:7 awe-inspiring photos show Comet Neowise light up the sky

The comet probably came from the Oort Cloud, which is believed to be a giant spherical shell that surrounds the solar system, according to NASA. Most long-period comets such as this one come from the Oort Cloud, NASA said.

It could be the largest object from the Oort Cloud ever detected, and it is the first comet on an incoming path to be detected so far away.

Astronomers suspect that there may be many more undiscovered comets of this size waiting in the Oort Cloud. These giant comets are thought to have been scattered to the far reaches of the solar system by the migration of Jupiter, Saturn, Uranus and Neptune early in their history.

The comet is dubbed Bernardinelli-Bernstein after the two astronomers who discovered it: Pedro Bernardinelli (also from the University of Pennsylvania) and Gary Bernstein. Its official name is 2014 UN271.

Scientists identify 29 planets where aliens could observe Earth

Astronomers estimate 29 habitable planets are positioned to see Earth transit and intercept human broadcasts

The scientists identified 1,715 star systems where alien observers could have discovered Earth in the past 5,000 years by watching it ‘transit’ across the face of the sun. Photograph: c/o Cornell

Ian Sample Science editor@iansampleWed 23 Jun 2021 11.00 EDT

For centuries, Earthlings have gazed at the heavens and wondered about life among the stars. But as humans hunted for little green men, the extraterrestrials might have been watching us back.

In new research, astronomers have drawn up a shortlist of nearby star systems where any inquisitive inhabitants on orbiting planets would be well placed to spot life on Earth.

The scientists identified 1,715 star systems in our cosmic neighbourhood where alien observers could have discovered Earth in the past 5,000 years by watching it “transit” across the face of the sun.

Among those in the right position to observe an Earth transit, 46 star systems are close enough for their planets to intercept a clear signal of human existence – the radio and TV broadcasts which started about 100 years ago.Advertisement

The researchers estimate that 29 potentially habitable planets are well positioned to witness an Earth transit, and eavesdrop on human radio and television transmissions, allowing any observers to infer perhaps a modicum of intelligence. Whether the broadcasts would compel an advanced civilisation to make contact is a moot point.

“One way we find planets is if they block out part of the light from their host star,” said Lisa Kaltenegger, professor of astronomy and director of the Carl Sagan Institute at Cornell University in New York. “We asked, ‘Who would we be the aliens for if somebody else was looking?’ There is this tiny sliver in the sky where other star systems have a cosmic front seat to find Earth as a transiting planet.”

Earthly astronomers have detected thousands of planets beyond the solar system. About 70% are spotted when alien worlds pass in front of their host stars and block some of the light that reaches scientists’ telescopes. Future observatories, such as Nasa’s James Webb Space Telescope due to launch this year, will look for signs of life on “exoplanets” by analysing the composition of their atmospheres.

To work out which nearby star systems are well placed to observe an Earth transit, Kaltenegger and Dr Jackie Faherty, an astrophysicist at the American Museum of Natural History, turned to the European Space Agency’s Gaia catalogue of star positions and motions. From this they identified 2,034 star systems within 100 parsecs (326 light years) that could spot an Earth transit any time from 5,000 years ago to 5,000 years in the future.

One star known as Ross 128, a red dwarf in the Virgo constellation, is about 11 light years away – close enough to receive Earth broadcasts – and has a planet nearly twice the size of Earth. Any suitably equipped life on the planet could have spotted an Earth transit for more than 2,000 years, but lost the vantage point 900 years ago. If there is intelligent life on any of the two known planets orbiting Teegarden’s star, 12.5 light years away, it will be in a prime position to watch Earth transits in 29 years’ time.

At 45 light years away, another star called Trappist-1 is also close enough to eavesdrop on human broadcasts. The star hosts at least seven planets, four of them in the temperate, habitable zone, but they will not be in position to witness an Earth transit for another 1,642 years, the scientists write in Nature.

The findings come as the US government prepares to publish a hotly anticipated report on unidentified flying objects (UFOs). The report from the Pentagon’s Unidentified Aerial Phenomena Task Force, which was set up to gain insights into the nature and origins of unknown aircraft, is not expected to reveal evidence of alien antics, or rule it out.

Prof Beth Biller at Edinburgh University’s Institute for Astronomy, who was not involved in the Nature study, said the work could change how scientists approach Seti, the search for extraterrestrial life. “What was striking to me was how few of the stars within 100 parsecs could have viewed a transiting Earth,” she said.

“The transit method requires a very precise alignment between the transiting planet, its star, and the sun for a given planet to be detectable, so this result is not surprising. Now I am curious about what fraction of the stars in the Gaia catalogue of nearby stars have the right vantage point to detect the Earth via other exoplanet detection methods, such as the radial velocity method or direct imaging!”

An enormous ‘mega comet’ is flying into our solar system

SPACE 21 June 2021

By Jonathan O’Callaghan

New Scientist Default Image
A large object in the outer solar system may be a “mega comet”MARK GARLICK/Getty Images/Science Photo Library RF

Astronomers have discovered a huge and previously unknown object entering our solar system that will reach the orbit of Saturn in 2031. It is possibly the largest body from the outer reaches of our solar system ever found to make such a close approach to the sun.

Known as 2014 UN271, it is estimated to be between 100 and 370 kilometres across. The object was spotted by the Dark Energy Survey (DES), a project using the Victor …

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The surface of Venus is geologically active

22 June 2021/

Amalyah Hart

New study of the ‘hellish’ planet reveals tectonic activity, disproves solid lithosphere theory.

A 1,100 km-wide, false-color radar view of Lavinia Planitia, one of the lowland regions on Venus where the lithosphere has fragmented into blocks (purple) delineated by belts of tectonic structures (yellow). Image credit:NC State University based upon NASA/JCL imagery

Venus’ surface is not a single, solid “lithosphere”, as once thought, but a patchwork of tectonic plates with similar activity to – but not the same as – those here on Earth, according to a new study out today in Proceedings of the National Academy of Sciences. 

The study shows that these tectonic plates jostle and bump against one another like pack ice on a frozen lake, suggesting Venus is still geologically active.

“We’ve identified a previously unrecognised pattern of tectonic deformation on Venus, one that is driven by interior motion just like on Earth,” says Paul Byrne, associate professor of planetary science at North Carolina State University, the lead and co-corresponding author of the work. “Although different from the tectonics we currently see on Earth, it is still evidence of interior motion being expressed at the planet’s surface.”

Byrne and an international team of researchers used radar images from NASA’s Magellan spacecraft, which imaged the entire surface of Venus before plunging into the Venusian atmosphere in the summer of 1993 and breaking apart. Looking at the extensive Venusian lowlands, the team saw areas where large blocks of the lithosphere appeared to have moved, some pulling apart, others pushing together, and others sliding past one another.

By creating a computer model of this deformation, the team found that sluggish motion in the planet’s interior explains the more gentle tectonic activity occurring on Venus – as opposed to the violent tectonic motions on Earth, which can create huge mountain ranges or vast subduction systems.

The find is significant because Venus was once thought to have a motionless, solid surface just like Mars or the Moon, rather than a geologically active, moving surface.

“We know that much of Venus has been volcanically resurfaced over time, so some parts of the planet might be really young, geologically speaking,” Byrne says. “But several of the jostling blocks have formed in and deformed these young lava plains, which means that the lithosphere fragmented after those plains were laid down. This gives us reason to think that some of these blocks may have moved geologically very recently – perhaps even up to today.”

The new “pack ice” pattern identified on our furnace-hot neighbour may offer clues about the deformation of tectonic plates on planets outside the solar system, as well as the geological formation of early Earth.

“The thickness of a planet’s lithosphere depends mainly upon how hot it is, both in the interior and on the surface,” Byrne says. “Heat flow from the young Earth’s interior was up to three times greater than it is now, so its lithosphere may have been similar to what we see on Venus today: not thick enough to form plates that subduct, but thick enough to have fragmented into blocks that pushed, pulled, and jostled.”

The new study is part of a renaissance in interest surrounding our neighbouring planet. Both NASA and the European Space Agency recently approved three new missions to Venus that will observe the planet’s surface and assess whether it once held oceans – and potentially life.

“It’s great to see renewed interest in the exploration of Venus, and I’m particularly excited that these missions will be able to test our key finding that the planet’s lowlands have fragmented into jostling crustal blocks,” Byrne says.