The Fermi Paradox refers to a simple question that has eluded us all for decades: If aliens exist, then why haven’t we seen any yet? Billions of Earth-like planets exist in the Milky Way alone, and if life is a fraction as common as we believe it to be, our galaxy should be filled with alien civilizations in various points of development. Obviously, this is not the case, so the question the Fermi Paradox poses is “what went wrong?” Most people agree that there are only two likely answers. Either the development of life is significantly rarer than we previously believed, and we are truly the only intelligent beings thus far in our local pocket of the universe’s history, or there is some sort of “Great Filter” that kills off the majority of species. I’m going to explore both of these possibilities and then share my thoughts on them.
Although we are aware of most of our evolutionary history, the likelihoods of some of these processes occurring remains unknown. For example, abiogenesis, or the process of life emerging from non life like we believe it did on Earth, might be exceedingly uncommon. It is possible that the factors that allowed for this have only lined up once, and it happened here on earth. Other stages of our evolution also have the potential to be far rarer than expected. The evolution of eukaryotes(cells with nuclei), which are essential to multicellular life, only happened once on Earth. Multicellularity arose precious few times as well. And, of course, out of the millions of species that roamed Earth, intelligent life only appeared in one of them(us). If these processes are exceedingly rare on their own, and Earth has the optimal environment to encourage them, other planets that might have less ideal conditions than ours could be incapable of developing intelligent life, as multiple processes could keep their native species locked in an inferior stage of development. The evolutionary argument is widely regarded as the most likely explanation for the Fermi Paradox, but others propose a more ominous one: the Great Filter.
Some experts posit that throughout a species’ development, it encounters several “filters” or major obstacles that prevent it from progressing to the next stage of life. The Great Filter refers to the largest of these filters, the one that typically holds a species back. This filter may be something behind us, such as the attainment of intelligence or abiogenesis, which shines a brighter prospect on our future. However, it could just as well be something that lies ahead of us, whether it be nuclear war, AI, or environmental catastrophe. If it lies ahead, some argue, it could be the answer to why there are no visible spacefaring civilizations in our universe. Perhaps none of them were able to break past this filter, and they were forever doomed to the confines of their planet or even extinguished entirely.
Now that I’ve laid out the two main theories, I want to talk about what I think. Of course, there is some overlap in both, but most supporters of the Great Filter seem to think it lies ahead of us, so I think it’s safe to consider these separate arguments. I personally believe the evolutionary perspective is far more logical and likely. In my opinion, it is a mistake to believe that we would possess even an inkling of an idea of the motivations and psychology of an alien species. There is no guarantee that a species with our intelligence level will develop the exact same technologies on the same level. One species might shut down the idea of nuclear weapons before they ever come to fruition. Another might do the same with AI. A third could recognize the collapse of its environment due to industry and rush to fix the problem. Others might never explore these possibilities at all. Because civilizations could take such different developmental paths, I find it unlikely that there is a single universal filter that wipes out nearly all of them. On the flip side, the evolutionary argument shows us just how much we don’t know about our own ascension to intelligence. Without thorough simulations to ascertain the exact probabilities of abiogenesis or other processes, any one of them could be the secret to the Fermi Paradox. Regardless of which viewpoint you support, however, one thing is true: For now, we are alone in this universe.
Birds become shrouded in confusion, sunflowers twist in uncertainty, yet I gaze in awe. The sky plunges into darkness, so fast it makes you question the possibility of a cosmic light switch. This infamous phenomenon is known as a solar eclipse.
It was a typical summer morning. After packing my bag, I headed out to summer camp. For weeks, my counselors had told me to mark my calendar for this very day, August 21st, because a solar eclipse was coming. I had read about eclipses before, but experiencing one was not something my nine-year-old brain could truly comprehend.
After arriving, the wait seemed to never end. I was filled with excitement you only experience a handful of times in life. My ears awaited the announcement from the camp director, and when it finally came, I struggled to refrain from tugging on the counselors and other campers to get there faster. After the classic warning not to look at the eclipse until totality, I was ready. I quickly grabbed my eclipse goggles and looked at the Sun patiently. A black spot started to engulf the light, my heart raced. Gradually the Sun was eclipsed and adrenaline coursed through my veins. Once totality was confirmed, I lifted off my goggles and it felt like my whole life led up to this moment. I was only reminded that the passage of time continued by the cold, surreal breeze grazing my skin.
I could almost smell the disruption in the Earth’s natural flow. A solar eclipse defies all things nature is accustomed to.
It dawned on me though: if the Sun was completely blocked, why was it not night time? Obviously it was just sun rays peeking through, right? I was puzzled by this question ever since totality, but I forgot temporarily as everyone started to clap and cheer. Once it was over, the call for the cosmos rang in my head stronger than ever before. Going home after was disappointing, but it meant I got to revisit my question. I ran to my trusty tablet as soon as I got home and began to research.
My previous assumption was far from the truth. Every solar eclipse, a typically forgotten aspect of the Sun shines instead. The corona, a hazy cloud of million-degree plasma, is usually invisible because the Sun’s rays overshadow it. But during totality, it finally has its chance to show the world its beautiful halo around the Moon’s darkness.
Total solar eclipse showing the Sun’s corona, Oregon, August 21, 2017. Credit: NASA / Aubrey Gemignani
Once the corona stepped off stage, nature resumed. Birds began to sing again, the chatter of campers grew louder, and the warmth rushed back to my skin. But the image of the eclipse was engraved in my mind. While uncovering the answers, I realized eclipses were not just spectacles of cosmic nature but doors leading to mysteries science has been trying to solve. I was oblivious to it at the time, but that day a seed of curiosity for the cosmos was planted in me.
Eight years later I cherish this moment as one of the biggest sparks in my journey toward becoming an astronomer. The universe is an endless sea of knowledge, and though the sky’s light switch has long been flipped back on, my curiosity has stayed lit ever since.
Something Very Tiny Is Following Earth Around the Sun The Earth stands alone in the solar system as a habitable world, as far as we know. But that doesn’t mean we don’t get visitors, most often in the form of (usually harmless) asteroids. Some even choose to stick around for a while, gaining a moonlike status….more
-NYT
A Forgotten Cosmic Impact Was Hidden in a Museum’s Glass Shards Every few million years, give or take, a sizable asteroid slams into our planet. Researchers have now found evidence of such a cataclysm roughly 11 million years ago, thanks to shards from a more recent Earthly encounter with a giant space rock…more
-NYT
What a Signal in a Failed Star’s Clouds Means for the Search for Life On a brown dwarf dozens of light years from Earth, astronomers have detected trace amounts of phosphine, a molecule that on this planet is produced by living things. This discovery is not life, the astronomers say. Any life as we know it would be impossible to sustain in such an environment…..more
-NYT
A Defender of Darkness in the Darkest Place on Earth When night falls in the Atacama Desert, in northern Chile, brilliant constellations shine down on the dry plains. So perfect was the inky blackness that the Indigenous people who live here believed they could make out the forms of animals in the dark spaces between the bright stars…..more
-NASA
What is Betelgeuse? Inside the Strange, Volatile Star A blazing red supergiant shining brilliantly in the night sky, Betelgeuse is a star that has captured humanity’s awe and attention for centuries. The “right shoulder” in the constellation Orion (or left shoulder, as seen from Earth), Betelgeuse (or Alpha Orionis) is one of the brightest stars in the night sky and one of the largest stars ever discovered. But there is more to this ultra-bright stellar monster than meets the eye…..more
-NYT
In a Rock on Mars, NASA Sees ‘Clearest Sign of Life’ So Far Life, especially the microbes too small to see, has left an indelible mark on rocks on Earth, creating minerals that would otherwise not be there. If some of those minerals turn up in rocks on Mars, is that not good evidence that life once existed there, too?….more
-NYT
Happy Birthday, LIGO. Now Drop Dead. The space around It’s been 10 years since astronomers first felt the universe tremble. At 4 a.m. on Sept. 14, 2015, in both the desert of eastern Washington State and the backwoods of Louisiana, two beams of light began quivering in distant synchrony as the space through which they were traveling stretched and shrank at a rate of 250 times a second….more
-NYT
Hopeful Hint of an Earthlike Atmosphere on a Distant Planet Around 40 light-years from Earth, seven rocky worlds orbit a cool, red star named Trappist-1. Some of these planets may be habitable to life as we know it, which has led astronomers to point the James Webb Space Telescope at each member of the septuplet. To date, they have been left disappointed: Several of the planets appear to be bare rocks exposed to the horrific void of space….more
-NASA
NASA’s Hubble Uncovers Rare White Dwarf Merger Remnant An international team of astronomers has discovered a cosmic rarity: an ultra-massive white dwarf star resulting from a white dwarf merging with another star, rather than through the evolution of a single star. This discovery, made by NASA’s Hubble Space Telescope’s sensitive ultraviolet observations, suggests these rare white dwarfs may be more common than previously suspected…more
-NASA
NASA’s Apollo Samples, LRO Help Scientists Forecast Moonquakes As NASA prepares to send astronauts to the surface of the Moon’s south polar region for the first time ever during the Artemis III mission, scientists are working on methods to determine the frequency of moonquakes along active faults there. Faults are cracks in the Moon’s crust that indicate that the Moon is slowly shrinking as its interior cools over time. The contraction from shrinking causes the faults to move suddenly,….more
Science and science fiction writer Arthur C. Clarke famously speculated, “Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying.” September’s guest speaker argues for the first terrifying possibility. The evening’s guest speaker is Edwin L. Turner, Emeritus Professor of Astrophysical Sciences at Princeton University. The September, 2025 meeting of the AAAP will take place in Peyton Hall on the campus of Princeton University on Tuesday, September 9th at 7:30 PM. As usual, the meeting is open to AAAP members and the public. Participants can join the meeting in-person at Peyton Hall or log in to the Zoom session as early as 7:00 pm to chat informally before the meeting begins.
Options for Attending the Meeting
You may choose to attend the meeting in person or participate via Zoom or YouTube as we’ve been doing for the past few years. (See How to Participate below for details). Due to security concerns, if you log in before the host has set up internet connectivity in Peyton Hall, you may need to wait in the Waiting Room for a few minutes until the host is prepared to admit you into the meeting. You’ll need to unmute yourself to make comments or ask questions. It’s polite, though not required, for you to enable your camera so other participants can see you. The meeting will be recorded and edited for posting to our club’s YouTube channel.
Meet the Speaker Dinner Prof. Turner will join us for the traditional “meet the speaker” dinner at Winberie’s Bar and Restaurant prior to the meeting. Our reservation is for 5:45 pm. Please contact the Program Chair if you plan to attend.
Here’s the anticipated agenda for September 2025’s monthly meeting of the AAAP:
(Times are approximate)
Getting to Peyton Hall The parking lots across the street (Ivy Lane) from Peyton Hall are now construction sites, unavailable for parking. We’ve been advised by the administration of the astrophysics department that we should park in the new enclosed parking garage off Fitzrandolph street and walk around the stadium and athletic fields. Here’s a map of the campus and walking routes from the parking garage to Peyton Hall. The map shows the recently completed East Garage. Not shown is an access road Sweet Gum that connects from Faculty Road to an entrance at the lower left corner of the garage. Stadium Road connects from Fitzrandolph Road to another entrance at the opposite corner (and higher level) of the garage. It’s about a 10-15 minute walk from the parking garage to Peyton Hall.
Featured Speaker: Edwin L. Turner elt@astro.princeton.edu
Professor Emeritus of Astrophysical Sciences Princeton University
“An Observable Universe Devoid of Extraterrestrial Life, Intelligence, and Technological Civilizations Is Plausible”
The two most common and apparently compelling arguments for the existence of extraterrestrial life, intelligence and technological civilizations are the (probable) extremely large number of exoplanetary environments similar to the Earth’s and the application of the Copernican Principle to abiogenesis, evolution, and sociology. On closer examination both of these lines of reasoning are shown to have fundamental flaws. Thus, it remains plausible that the Earth is unique in the observable universe as a home to any or all three of these astro-biological phenomena. The discussion will also illuminate a major unresolved question in our understanding of nature which deserves serious attention independent of the specific context considered in this presentation.
Edwin L. Turner Edwin L. Turner is Professor of Astrophysical Sciences at Princeton University. He also serves as Co-Chair of the NAOJ-Princeton Astrophysics Collaboration Council (N-PACC). After receiving an S. B. in Physics at MIT (’71) and a Ph. D. in Astronomy from Caltech (’75), he spent brief periods at the Institute for Advanced Study and on the astronomy faculty at Harvard University before joining the Princeton faculty in 1978. Since 2008 he has also held an Affiliate Scientist appointment at the University of Tokyo’s Kavli Institute for the Physics and Mathematics of the Universe. He has carried out extensive astronomical observations at Mt. Palomar Observatory, Kitt Peak National Observatory, NRAO’s Very Large Array, Apache Point Observatory, the National Astronomical Observatory of Japan’s (NAOJ’s) Subaru Telescope and with the Hubble Space Telescope. Turner has served on a variety of national professional committees, including nine years each on the Board of Directors of the Association of Universities for Research in Astronomy and the Space Telescope Institute Council (which he chaired for 3 of those years). He also served as Director of the Apache Point Observatory 3.5-meter Telescope for nine years and on the Board of Governors of the Astrophysical Research Consortium for an additional 8 years. His sabbatical leaves have taken him to Caltech, Harvard, MIT, the National Astronomical Observatory of Japan, the University of Melbourne and the University of Tokyo. Working extensively in both theoretical and observational astrophysics, he has published more than 240 research papers with particular concentrations on topics including binary galaxies, groups of galaxies, large scale structure, dark matter, quasar populations, gravitational lensing, the cosmic x-ray background, the cosmological constant, exoplanets, astrobiology and the origin of life, frequently in all of these areas with an emphasis on statistical analyses. His recent teaching activities at Princeton include courses in cosmology, in astrobiology and in media coverage of science, and he has been a member of the University’s Committee for Statistical Studies since 1992. Recently he has been an active participant in the Breakthrough Starshot Initiative and in the organization of YHouse, Inc. project.
How to Participate (Links) Zoom& YouTube Live Amateur Astronomers Association of Princeton is inviting you to a scheduled Zoom meeting.
Topic: September 2025 AAAP Meeting-Edwin Turner, Emeritus Professor of Astrophysical Sciences, Princeton University Time: September 9, 2025 07:00 PM Eastern Time (US and Canada) Join Zoom Meeting
Prof. Phillipson is an astrophysicist who leverages statistics, nonlinear dynamics, and machine learning to study the explosive and highly variable characteristics of exotic astrophysical objects such as black holes and neutron stars.
Thanks to Bill Thomas for suggesting this speaker.
Also: Eklavya Doegar and members of the Unistellar Student Group will show images they acquired with the club scope and discuss their experiences using this recently donated smart telescope
Nov. 11, 2025
Romain Teyssier Professor of Astrophysical Sciences and Applied and Computational Mathematics Princeton University teyssier@princeton.edu
Prof. Teyssier’s main research activity is to perform simulations of cosmic structure using supercomputers in order to understand the origins of stars and galaxies.
Discovery of Dwarf Planet Candidate in an Extremely Wide Orbit
Dr. Cheng and colleagues discovered in publicly available data from the Dark Energy Camera a dwarf planet candidate, 2017 OF201, currently located at a distance of 90.5 au. Its orbit is extremely wide and extends to the inner Oort cloud, with a semi-major axis of 838 au and a perihelion of 44.9 au precisely determined from 19 observations over seven years. Assuming a typical albedo of 0.15, they estimate a diameter about 700 km, making it the second-largest known object in this dynamical population and a likely dwarf planet.
Thanks to Nick Mellis for suggesting these speakers.
Jan. 12, 2026
Not Yet Scheduled
Feb. 12, 2026
John Bochanski Associate Professor and Chair, Department of Computer Science and Physics Rider University
Dr. Bochanski has been connected to the Legacy Survey of Space and Time Discovery Alliance since his graduate studies more than 15 years ago. Rider University is part of the global effort using the Vera C. Rubin Observatory to map the optical sky. The Rubin observatory (formerly the Large Synoptic Survey Telescope, LSST) will capture more information about our Universe than all other optical telescopes throughout history combined. The observatory released its first images this past June. Prof. Bochanski will discuss the project’s history and discoveries.
Thanks to Nick Mellis for suggesting this speaker.
Mr. Horgan will discuss his controversial 1996 book The End of Science, in which he argues that pure science, defined as “the primordial human quest to understand the universe and our place in it,” may be coming to an end. Horgan claims that science will not achieve insights into nature as profound as evolution by natural selection, the double helix, the Big Bang, relativity theory or quantum mechanics. In the future, he suggests, scientists will refine, extend and apply this pre-existing knowledge but will not achieve any more great “revolutions or revelations.” Shades of Auguste Comte, perhaps?
We expect to have copies of his book(s) for sale for the author to sign at the conclusion of his presentation.
As usual, the June meeting will take place in the planetarium at the NJ State Museum in Trenton. There will be no streaming of this live-only sky show and PowerPoint presentation. Topic to be announced.
As always, members’ comments and suggestions are gratefully accepted and much appreciated. Thanks to Ira Polans and Dave Skitt for setting up the online links and connecting the meeting to the world outside Peyton Hall.
Astroimagers, Environmentalists, and Fellow Stewards of our Planet,
It has come to my attention by the AAS in regard to the plans and seeking FAA approval by Reflect Orbital to light up our night sky by an additional 4 hours.
The AAS policy team is requesting input from the community regarding the potential impacts of Reflect Orbital’s proposed reflector satellites on astronomical research and night sky visibility. Reflect Orbital is a satellite company that plans to deliver sunlight at night by building a constellation of reflectors in low Earth orbit beginning in 2026, with the goal of 4,000 satellites in orbit by 2030. Each satellite is expected to reflect ~0.8 lux (4-5x the brightness of the full Moon) to a ~5 km diameter beamon Earth’s surface.
Needless to say this is of extreme concern. I have posted a survey by AAAS below. We need to fight this as well as gather others in this fight.
We are used to sending our spacecraft to nearby astronomical bodies like the moon, the asteroids and the planets in our solar system. What is new over the last few years is the passage of transiting astronomical objects passing through our solar system. Like an out of town visitor driving through the main street of our town and going out without any stops. The most recent one was given the name of 3I/ATLAS. The third such object since we started tracking such extraneous objects.
3I stands for third interstellar object (dubbed as ISO). While ATLAS stands for the detection system which spotted it – Asteroid Terrestrial-impact Last Alert System. We know that it is an interstellar object by the trajectory it takes. Almost all other intra solar system objects move in circles or ellipses around the sun, however elongated the orbit may be. The picture below, courtesy NASA, shows the trajectory of 3I/ATLAS in blue which is cutting across our solar system. The speed is about 200,000 kmph. Such a fast moving almost straight trajectory would be an interstellar object. Its path is very close to the plane of our solar system which seems to be a coincidence.
Avi Loeb, the scientist who postulated that such objects are alien probes coming in to take a peek at our solar system, thinks that the chances of a random visitor happening to line up so neatly with our planetary plane is very low. It also has a flight path very close to Venus, Mars, and Jupiter. Such a flyby can be expected from a NASA spacecraft or the one by an alien design! However, It has frozen carbon dioxide which is becoming a gas as it gets closer to the Sun. The outgassing indicates that 3I/ATLAS is a comet. Not a spacecraft.
Like our solar system which is confined to a plane, our galaxy the Milky Way is also a disk which is thick at the center and tapers as one goes away from the center. Our solar system is in the thin part of our galactic plane. If we move sufficient distance away from our solar system or our galaxy, we can see the essential disk structure !
We had two ISOs before the current one. First was 1I/Oumuamua and the second one 2I/Borisov. Investigators reveal that all the 3 ISOs originated from different regions in our galaxy Milky Way and at different times. Their ages range in age from one to several billion years. 3I/ATLAS is the oldest of the three, with an estimated age of 4.6 billion years, and originated from the Milky Way’s thick disk (closer to the center of the galaxy). It is also the largest of the three ISOs, at about twenty km in diameter. This region of our galaxy is populated by older, lower metallicity stars. In astronomy, anything other than Hydrogen and Helium are considered as metals !
1I/Oumuamua is about 1 billion years old and originated from the thin disk where new stars are still forming. 2I/Borisov is approximately 1.7 billion years old, and originated from the thin disk as well.
Asteroids and comets are material leftover from the formation of planetary systems. We have our own asteroid belt between Mars and Jupiter and comets at the end of our solar system. Every one of them orbiting the Sun. Presumably other planetary systems also have similar bodies. Some bodies may get ejected and travel in interstellar space and may occasionally travel through other planetary systems like ours.
It is possible some bodies from our solar system may have broken loose, or got ejected, and ventured into interstellar space and possibly other planetary systems. Gravitational scattering could be one reason why objects get ejected from the host planetary systems. Or other unknown dynamic processes. It is not just asteroids or comets which can get out from their parents’ home. Sometimes planets can do so. We do have single planets without a parent star. But none came to visit us so far !
Planetary systems are not the same. They vary in terms of the sizes of the stars, number and sizes of planets, number of moons etc. Studying ISOs gives us an indication of the planetary system where they originate. Instead of us going on interstellar journeys, the objects are coming to us so that we can study them.
While we need to keep an open mind on the possibility that any of the earlier two ISOs could have been alien spacecraft, since they could not prove to be comets, extraordinary claims need extraordinary evidence. We don’t have evidence one way or the other. More such visitors in the future could give us opportunities for further studies.
If the event is cancelled due to weather, we will use the 9/20/25 rain date. I will email you directly (usually the night before), so watch your emails!
If you have any questions or comments, please contact me via email or by phone (see below).
Michael Franzyshen, NJAA Open House Coordinator 908-256-2918
Amateur Astronomers Association of Princeton 