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By DeepSkyExplorer
Pandora, NASA's latest mission, is diving into the study of exoplanets and their host stars, aiming to clarify how a star's light affects our understanding of exoplanet atmospheres. This is particularly interesting because we’ve had limited insight into the atmospheric make-up of these distant worlds until now. The mission plans to analyze at least 20 exoplanets, specifically looking for key elements like water, clouds, and hazes.
This mission stands out as it utilizes a novel all-aluminum telescope with an 18-inch diameter, a unique feature that allows for simultaneous observations in both visible and infrared light. This approach is crucial because it enables Pandora to gather data over extended periods, which is something flagship missions like the James Webb Space Telescope (JWST) can't always do due to their focus on brief transits.
During these transits, when an exoplanet passes in front of its host star, some of the starlight filters through the planet's atmosphere. This interaction leaves chemical fingerprints in the light that we can analyze. Yet, there’s a complication: the light we receive also includes contributions from the star itself, which isn't uniform in brightness. As noted by Benjamin Rackham from MIT, this means we have to be careful in interpreting the data, as areas of the star can be hotter or cooler, affecting our measurements.
Elisa Quintana, the principal investigator of the mission, pointed out that this study could help us close a significant knowledge gap about exoplanets by giving us a clearer picture of how host stars influence the atmospheres of these planets. It's fascinating to think about how much we still don’t know, especially considering how star variability can throw our measurements off.
I can’t help but think about how this mission might change what we know about potential habitability in these exoplanets. If Pandora finds consistent signatures of water vapor among its targets, it could really shift our understanding of where life might exist beyond Earth. And with this data, future missions using JWST could have a better foundation for interpreting those complex atmospheres that Pandora is now starting to unravel.
Another interesting aspect is how the mission's near-infrared detector is actually a spare originally developed for Webb. It’s like a second chance for that technology, and now it’s contributing to a mission designed to be faster and more cost-effective. This dual-use of technology can be a game changer in how we explore space, don’t you think?
So, now that Pandora is officially in science mode, I’m curious about what specific findings might emerge from its observations. Given that it’s monitoring exoplanets in detail over longer periods, what do you think are the chances we’ll see groundbreaking discoveries about their atmospheres or even signs of habitability? What would you want to know if you were part of the mission team?
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By SpaceObserver
I just came across an intriguing study that really sheds light on how young stars form planets. It centers around research done using the James Webb Space Telescope (JWST), focusing on 72 young, Sun-like stars and their protoplanetary disks. What’s fascinating is how these disks of gas and dust lose their gas over time, which is critical for the formation of gas-rich planets like Jupiter and Saturn. The study was co-authored by Uma Gorti from the SETI Institute and reveals that once the gas is gone, the chance to create gas giants diminishes significantly.
The researchers tracked the winds and gas outflows from these disks at different stages of their development. It’s kind of like watching a time-lapse of how these disks evolve. The study highlights that different types of winds play crucial roles at various stages. This is significant because understanding disk dispersal is essential to grasp how and when planets can form, especially the massive ones that require a solid foundation of gas to build their atmospheres.
I find it remarkable that this research uses archival data from JWST’s Mid-Infrared Instrument (MIRI). The ability to directly observe molecular hydrogen escaping from these disks provides a clearer picture of the mechanisms at play. Previously, scientists had to predict these molecular winds without direct observation. Now, they’ve confirmed those predictions using JWST images, which shows how valuable this telescope is for planetary science.
The implications of this study are profound. If the gas in these disks dissipates too quickly, it limits the time available for massive planets to accumulate the thick atmospheres they need. Given that our own solar system is about 4.5 billion years old, reflecting on its formative years can help us understand similar processes happening in other star systems. This could be crucial for astrobiology and assessing the habitability of exoplanets orbiting young stars.
What do you all think about the findings from this study? Do you believe that understanding gas dispersal in protoplanetary disks will lead to new insights about potential habitability on exoplanets? And how does this shape our perspective on the evolution of planetary systems in general? I’m looking forward to hearing your thoughts!
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By Avi Loeb Medium
Schematic illustration of the progenitor of a supermassive black hole in the form of a supermassive star. After the accretion of gas into the supermassive star ends, the star contracts, ignites hydrogen burning, and re-expands into a late phase of instability. Pulsation-driven mass loss then proceeds through discrete ejection episodes that remove weakly-bound envelope material. Earlier shells expand to large radii, whereas the final pre-collapse ejection remains compact and dense, setting the immediate circumstellar environment which explain Webb telescope data on the observed population of `little red dots’. The ejecta carries a characteristic abundance pattern which is consistent with spectroscopic observations by the Webb telescope. The supermassive star then continues toward collapse through a General Relativistic instability owing to Einstein’s gravity and ultimately ends as a heavy black-hole seed for a quasar. (Image credit: Devesh Nandal et al. 2026)Two new papers today provide evidence for the first generation of stars, made solely from the primordial gas of hydrogen and helium left from the Big Bang. Middle-aged stars like the Sun recycle material that was already processed through nuclear fusion in the interiors of stars. However, the primordial material that made first stars had no heavy elements. As a result, it did not cool efficiently and condensed into massive stars. The first stars with masses exceeding ten solar masses, had a surface temperature of up to 10⁵ degrees and acted as efficient factories of ultraviolet radiation.
This was a theoretical prediction that I derived with my students and postdocs at Harvard University thirty years ago. The earliest publications included a paper, accessible here, that I co-authored with my former postdoc Volker Bromm and Rolf Kudritzki in 2001. Our calculations demonstrated that the ultraviolet radiation from the early stars would break hydrogen and helium atoms in their vicinity, and result in the emission of a distinct spectral line from a singly-charged helium ion at a wavelength of 0.1640 micrometers, labeled He II λ1640. The theoretical predictions from my research were summarized in two textbooks that I published a decade later, titled: “How Did the First Stars and Galaxies Form?” and “The First Galaxies in the Universe”.
Recent spectroscopic observations by the Webb Telescope detected the emission of a strong He II λ1640 spectral line in the vicinity of an early galaxy, labeled GN-z11, at a cosmological redshift of z=10.6. This galaxy existed 13.4 billion years ago, just 400 million years after the Big-Bang. No heavy elements were identified in its spectrum. The properties of the spectral-line source, labeled Hebe, can be explained by a cluster of first-generation stars. A new paper, posted here, studies an alternative source for the ultraviolet radiation in the form of an accreting supermassive black hole. The authors show that a star cluster with a total mass of 10⁵ solar masses can explain the data more naturally. Such a cluster of first generation of stars constitutes the limit of what is expected in theoretical calculations dating back to my work with Bromm and Kudritzki.
My interest in this topic started as early as in 1994, shortly after my arrival as junior faculty at Harvard, when I published a paper — accessible here — with Fred Rasio, suggesting that the progenitors of the first supermassive black holes at the centers of galaxies are supermassive stars. Our model suggested that as a result of inefficient cooling, a clump of primordial gas would generically condense at the center of the first galaxies without fragmenting into low-mass stars. The collapse of this primordial cloud would result in a supermassive star that lives for about a million years and eventually collapses to a seed of a quasar black hole. The early population of quasars are known to be black holes which accrete gas at the center of galaxies. Bright quasars peaked in abundance during the first few billion years after the Big-Bang.
Other observations by the Webb telescope reveal the existence of a population of `little red dots’, compact reddish galactic cores which existed during the era of quasar formation. Could these `little red dots’ be the seeds of quasar black holes? This was indeed the suggestion we made in a paper that I recently published in collaboration with Fabio Pacucci, accessible here.
But there is another new paper that I co-authored today, available here, which was led by my postdoc Devesh Nandal. The paper explains that the spectral properties of `little red dots’ requires dense gas close to the source, yet the physical origin of that cocoon-like structure remains unclear. Our paper shows that late-time episodic mass-loss from supermassive stars leads to the required dense gas cocoons.
After the accretion of gas into the supermassive star ends, the star contracts, ignites hydrogen burning, and re-expands into a late phase of instability. Pulsation-driven mass loss then proceeds through discrete ejection episodes that the remove weakly-bound envelope material. The earlier shells expand to large radii, whereas the final ejection remains compact and dense, setting the immediate circumstellar environment relevant to the `little red dot’ phase. The ejecta carries a characteristic abundance pattern which is consistent with spectroscopic data from the Webb telescope. The supermassive star then continues toward a General Relativistic instability and ultimately collapses into a heavy black-hole seed owing to Einstein’s gravity.
Our paper examines five models with different abundances of heavy elements, all having progenitor masses of order 10⁵ solar masses. We followed the evolution of these supermassive stars after they stop accreting gas with radial pulsations calculations and general relativistic stability diagnostics. Mass loss during the final stages of evolution occurs not as a steady wind, but through discrete strange-mode ejection episodes. In the nearly pristine gas case, there were four late episodes that last 41 to 282 years and eject 10 to 348 solar masses each, for a total loss of 480 to 1,000 solar masses. The final episode alone contributes 73% of the mass-loss, and leaves behind a compact, opaque shell extending out to a light-year that reproduces the dense gas cocoons in `little red dots’.
The final ejecta is dominated by hydrogen and helium but is also rich in nitrogen, as observed in `little red dots’. A supermassive star reaches the General Relativistic instability at an age of about a million years and eventually collapses within a few hours, retaining almost all of its mass.
All in all, these calculations demonstrate that supermassive stars provide a physically motivated origin for the compact cocoon-like structure associated with `little red dots’, while remaining the natural progenitors of massive black hole seeds for quasars.
It took 32 years to confirm my early conjecture with Fred Rasio on this subject, but the journey was definitely worthwhile. I regard 32 years as a discounted wait period. After all, according to the Old Testament, the Israelites spent 40 years wandering in the desert before reaching the promised land.
ABOUT THE AUTHOR
(Image Credit: Chris Michel, National Academy of Sciences, 2023)Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, former director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics (2005–2026), and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
Professional website:
https://lweb.cfa.harvard.edu/~loeb/
Social media:
https://avi-loeb.medium.com/
https://www.youtube.com/@ProfessorAviLoeb
https://open.spotify.com/show/1zhndXkvSY2b8FdjspFpCd
https://x.com/ProfAviLoeb
View the full article
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By Avi Loeb Medium
A photo of Earth from NASA’s livestream of the Artemis II’s Orion spacecraft. (Image credit: NASA)We live through exciting times in a new age of artificial intelligence (AI), a new age of disclosure about alien technologies and a rejuvenated age of space exploration, all led by the United States of America. However, most people did not get the memo as of yet.
The faint response from the general public to the Artemis II renewal of human exploration of the Moon, reminded me of the title of Milan Kundera’s book: “The Unbearable Lightness of Being”. What could be more inspiring than exploring real estate beyond Earth, yet most earthlings were consuming terrestrial content on their digital screens when four astronauts blasted off from the Kennedy Space Flight Center in Florida on April 1, 2026 for a historic 10-day mission to circumnavigate the Moon. This is the first time astronauts return to the vicinity of the moon in 54 years on a trip that goes farther from Earth than any human ever has, breaking the Apollo program’s distance record.
For now, all human journeys to the Moon were round trips. After humans settle there, there would also be one-way trips. So far, we never employed AI in space, but future missions will likely be navigated and guided by AI rather than being `helicopter-parented’ by NASA engineers.
Does the public show fatigue from uninspiring 54 years lacking deep space exploration by humans? Or is it the obsessive distraction brought about by social media and digital screens? Either way, the current state-of-affairs could provide an answer to Enrico Fermi’s question: “where is everybody?” which is: “many of the extraterrestrials are glued to their digital screens and not interested in venturing beyond their home planet where they will perish.”
What could ignite the flame of space exploration here on Earth? My hope is that it will be the discovery of alien technology. If we realize that alien products visit our back yard, we might be intrigued to imitate them and visit the sender’s back yard with our probes.
Yesterday, the brilliant congresswoman Anna Paulina Luna, who chairs the “Task Force on the Declassification of Federal Secrets,” sent a letter to the Secretary of War, Pete Hegseth, requesting 46 video files related to sightings of Unidentified Anomalous Phenomena (UAP). This request was inspired by President Trumps visionary directive to Secretary Hegseth from February 20, 2026 (as discussed here).
Why is the UAP topic not getting full attention within the mainstream of the scientific community, as it should?
What could ignite the flame of UAP research? My hope is that new discoveries from the Galileo Project research team under my leadership could deliver the much-needed change. Stay tuned.
In a Newsmax interview about the Artemis II launch that I had this morning in the program National Report, I had mentioned that the film director Steven Spielberg asked me to let him know if I discover any clue for extraterrestrial artifacts. His film “Disclosure Day” is scheduled to be released on June 12, 2026, and some say that he received undisclosed information from government that inspired this film. I sincerely hope to find clues that will inspire Spielberg’s next film. But most important of all, I hope that insights gained from our cosmic neighbors will inspire us to a prosperous future on Earth and in space.
ABOUT THE AUTHOR
(Image Credit: Chris Michel, National Academy of Sciences, 2023)Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
Professional website:
https://lweb.cfa.harvard.edu/~loeb/
Social media:
https://avi-loeb.medium.com/
https://www.youtube.com/@ProfessorAviLoeb
https://open.spotify.com/show/1zhndXkvSY2b8FdjspFpCd
https://x.com/ProfAviLoeb
View the full article
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By Avi Loeb Medium
The so-called Hertzsprung–Russell diagram of 23,000 stars from the Hipparcos and Gliese catalogues, shows stellar luminosity versus color ranging from hot blue-white stars on the left side to cooler red stars on the right side. Hydrogen-burning stars like the Sun populate a band running from top-left to bottom-right called the Main Sequence. Giant stars clump on the upper-right side. At the lower-left is the band of white dwarfs, the dead cores of old stars that cool slowly over billions of years towards the bottom-right. (Image credit: Wikimedia)In my previous essay, posted here, I suggested that to preserve the habitability of its home planet — an advanced technological civilization might choose to move the planet away from a brightening sun-like star. The preferred planet-star separation would scale as the square root of the evolving star’s luminosity.
If this idea happens to be popular among our siblings in the family of intelligent civilizations within the Milky-Way galaxy, it might lead to an over-abundance of Earth-mass planets in the habitable zone around old Sun-like stars, as these stars evolve along the red giant branch of their Hertzsprung-Russel diagram.
But as the host sun-like star eventually turns to a faint white dwarf, the resident civilization might choose to migrate its planet closer to the dimmed furnace. This would imply an artificial over-abundance of habitable Earth-like planets around white dwarfs.
The graveyard of the Milky-Way galaxy is full of billions of corpses of dead sun-like stars in the form of old white dwarfs, each carrying about 60% of the mass of the Sun. At their typical age of a few billion years, the surface temperature of these white dwarfs is similar to that of the Sun, about 6,000 degrees Kelvin, resulting in white light which is conducive for life-as-we-know-it. The size of a white dwarf is comparable to that of Earth, but the habitable zone around it, is a hundred times bigger — amounting to 1 to 3 times that current radius of the Sun. Closer than a solar radius, the gravitational tide from the white dwarf would destroy a rocky planet.
The fact that the size of the white dwarf is comparable to that of Earth makes transits easy to detect. The probability for a transit is of order 0.6% for a habitable Earth-like planet around a white dwarf. This offers a unique opportunity for probing the composition of the atmospheres of habitable-zone Earth-mass exoplanets that transit white dwarfs.
In 2013, I co-authored a paper with Dani Maoz (published here) which showed that during a transit by an Earth-mass planet across a white dwarf, the transmission spectrum of the planet’s atmosphere would show prominent bio-markers such as molecular oxygen absorption at a wavelength of ∼ 0.76 micrometers. We calculated that a potentially life-sustaining Earth-like planet transiting a white dwarf would be detectable by the Webb telescope in about 5 hours of total exposure time, integrated over 160 two-minute transits.
A follow-up paper that I co-authored in 2014 here with my then undergraduate student Henry Lin (currently a professor at Princeton University), showed that industrial pollution is also detectable in habitable Earth-like planets around a white dwarf. In particular, tetrafluoromethane (CF4) and trichlorofluoromethane (CCl3F) are the easiest to detect chlorofluorocarbons (CFCs) resulting from technological activity. Our paper estimated that a few days of total integration time on the Webb telescope will be necessary to detect the concentration of CCl3F or CF4 for industrial pollution that is ten times higher than the current level on Earth.
The discovery of an over-abundance of habitable Earth-like planets around red giants or white dwarfs can be substantiated as a technological signature by finding industrial pollution in the related planetary atmospheres.
Finding such evidence would provide a useful guide to humanity on how to survive on Earth in the next 10 billion years, both before and after the Sun will turn into a red giant and then a white dwarf in 7.6 billion years (as calculated here).
Based on the census of white dwarfs reported here, most stars formed billions of years before the Sun. Given that we arrived late to the cosmic party, we might have missed numerous tragic incidents involving the extinction of civilizations which did not engage in a cosmic engineering project to save their planet before it lost habitability. We were not around to hear their cry for help. We better be wise to learn the lessons from the surviving civilization by studying habitable planets around red giants and white dwarfs.
As the philosopher George Santayana stated in his 1905 book titled The Life of Reason: Reason in Common Sense: “Those who cannot remember the past are condemned to repeat it.”
ABOUT THE AUTHOR
(Image Credit: Chris Michel, National Academy of Sciences, 2023)Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
Professional website:
https://lweb.cfa.harvard.edu/~loeb/
Social media:
https://avi-loeb.medium.com/
https://www.youtube.com/@ProfessorAviLoeb
https://open.spotify.com/show/1zhndXkvSY2b8FdjspFpCd
https://x.com/ProfAviLoeb
View the full article
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