The hunt for the first stars formed in the universe is on. There have been some promising candidates but no confirmations yet. The first batch of stars called the population III stars were formed when the universe was in its infancy. They consist of the primordial hydrogen and helium soon after the big bang.
Population III stars are metal free. In astronomy anything other than hydrogen and helium are called metals. These stars are posited to be very massive, very hot and also short lived. Heavier stars, 10-1000 solar masses, burn fuel very rapidly, generating a lot of luminosity. At the end of their short lives, with all the hydrogen converted to helium, they churn out heavier elements like carbon, oxygen and nitrogen in their burnt out cores. These form the seeds for the next generation of stars – the population II stars.
Population II stars are low metallicity stars. Recent stars which are the population I stars are high in metals. Our Sun is considered as a population I star. Our discoveries to date have centred around population I and II stars. Population III stars are the real challenge.
Firstly, all of them died within a few million years of their formation, which is in the distant past. There would be none in our vicinity for sure. The distant ones are dead as well. But the light from those stars could still be travelling towards us. The further we look into space, the older the objects are. Watching distant objects is like going into the past on a journey using time travel. We could be seeing objects which do not exist “now”.
Secondly, we cannot see objects further away without any intervening objects blocking our line of sight. For example, assuming that the earth were flat and we had a powerful telescope, we still cannot see Los Angeles from Jacksonville. Because of some intervening town or city blocking our view. However, if we go higher into space, we can see. In astronomy, we don’t have the luxury of flying higher into space. Our solar system is essentially in a plane and so is our galaxy the Milky Way confined to the galactic plane. Any attempt to go beyond the solar and galactic planes needs a lot of rocket fuel. It is not a practical proposition to move out to a vantage point to make observations. All the spacecraft and telescopes launched to date are confined to our planes with very little deviation in the vertical dimension.
Fortunately in astronomy, even if there is an obstructing object in between, we still can see objects behind using a concept called gravitational lensing. If the obstructing object is massive enough, the radiation (including light) coming from the hidden object gets bent by the gravitation force exerted by the obstructing object. As a result of this bending, the image of the hidden object appears as a distorted ring or as part of a ring around the obstructing object.
Another factor is that the earlier universe was very compact and dense. As the universe expanded, objects moved away from each other very rapidly. The population III stars moved away as well, resulting in redshifting of the radiation coming from those stars. A promising candidate named “Earendel” (named for a character in JRR Tolkien’s novel meaning “morning star”) is the closest we have come to observing population III stars. It was spotted by the Hubble telescope in 2022. It later proved to be a cluster of stars, but not a population III star.
One of James Webb Space Telescope’s goals is to detect population III stars. And the hunt goes on.
by Veer Bedi, Eighth Grade, Princeton Middle School
The night sky is full of wonders. You can see stars, planets, constellations, star clusters, and even the occasional shooting star. Go out on a clear, moonless night in a place with low light, and the beauty of the night sky will truly unfold before you.
I often go to Princeton Battlefield State Park for stargazing. Being in a place where a major battle was fought more than two centuries ago makes me wonder: in the past, did stargazing—and knowledge of the night sky—help armies win battles?
Let’s look at some historical examples.
On the night of January 2, 1777, General George Washington marched approximately 4,500 soldiers from Trenton toward Princeton in a bold move to outmaneuver British General Charles Cornwallis. The Battle of Princeton took place on January 3, 1777, where Washington’s forces defeated British troops under General Charles Mawhood. This victory proved pivotal in boosting American morale during the Revolutionary War. The battle occurred right here at what is now Princeton Battlefield State Park. Could Washington and his soldiers have used the stars to help guide their nighttime march and arrive at Princeton in time?
There are other examples of celestial navigation in military history. During World War II, U.S. Army Air Forces bombers used bubble sextants to observe celestial objects and determine their position during long-range missions. Around the same time, the British Long Range Desert Group (LRDG) conducted deep desert patrols behind Axis lines in North Africa. Operating in the vast Sahara—with no roads, landmarks, or radio beacons—they relied on Polaris, star altitude measurements, and sextants to determine their location and direction, according to the National Army Museum.
Even the Roman armies are believed to have used the stars at night to help maintain direction during long marches.
Returning to Princeton and my own stargazing experiences, the constellation Perseus is visible these days—or rather, at night—weather gods permitting. Perseus, the mythological Greek hero and son of Zeus, was also a great warrior in legend. Perhaps, in the stories told about him, he too looked up at the stars for guidance on his epic quests!
This Comet Stopped Spinning. Then It Started Rotating Backward. If you were standing on the surface of Comet 41P/Tuttle-Giacobini-Kresák nine years ago as it was getting closer to the sun, you might have been in for a shock. First, each day on the comet would have gotten drastically longer over a period of weeks, until the object’s rotation stopped dead — and then started going backward…more
-space.com
Real NASA space telescope data creates soundtracks for Jupiter, Saturn and Uranus NASA’s Chandra X-ray Observatory has transformed new telescope views of Jupiter, Saturn and Uranus from this month’s “planetary parade” into striking soundscapes — capturing everything from Jupiter’s crackling auroras to the sweeping arc of Saturn’s rings…more
-space.com
Could these weird stars just be overgrown planets? Many astronomical objects play by clear rules and fit into neat categories, but brown dwarfs (celestial objects too massive to be mere planets, but too small to be real stars) continue to refuse to cooperate. Astronomers recently studied a sample of 70 objects, ranging from Jupiter-mass planets to brown dwarfs that are right on the brink of stardom…more
-NASA
Young ‘Sun’ Caught Blowing Bubbles by NASA’s Chandra For the first time, a much younger version of the Sun has been caught red-handed blowing bubbles in the galaxy, by astronomers using NASA’s Chandra X-ray Observatory. The bubble – called an “astrosphere” – completely surrounds the juvenile star. Winds from the star’s surface are blowing up the bubble and filling it with hot gas as it expands…more
-NASA
Citizen Scientist Finds Ancient White Dwarf Star Encircled by Puzzling Rings Since the Sun is so hot, how can it contain oxygen, carbon, and other elements without destroying them? If you were to take a random blob of gas and heat it to solar temperatures (roughly 10,000 degrees Fahrenheit [5,500 degrees Celsius] at the surface or over 27 million F [15 million C] in the core), two things would happen. …more
-NASA
Elusive Planet Reshapes a Ring Around Neighboring Star NASA Hubble Space Telescope’s most detailed visible-light image ever taken of a narrow, dusty ring around the nearby star Fomalhaut (HD 216956), offers the strongest evidence yet that an unruly and unseen planet may be gravitationally tugging on the ring. Hubble unequivocally shows that the center of the ring is a whopping 1.4 billion miles (15 astronomical units) away from the star….more
-NASA
Straight Shot: Hubble Investigates Galaxy with Nine Rings NASA’s Hubble Space Telescope has captured a cosmic bullseye! The gargantuan galaxy LEDA 1313424 is rippling with nine star-filled rings after an “arrow” — a far smaller blue dwarf galaxy — shot through its heart. Astronomers using Hubble identified eight visible rings, more than previously detected by any telescope in any galaxy, and confirmed…more
-NASA
16-Year-Old Cosmic Mystery Solved, Revealing Stellar Missing LinkThe Blue Ring Nebula, which perplexed scientists for over a decade, appears to be the youngest known example of two stars merged into one. In 2004, scientists with NASA’s space-based Galaxy Evolution Explorer (GALEX) spotted an object unlike any they’d seen before in our Milky Way galaxy: a large, faint blob of gas with a star at its center. In the GALEX images, the blob appeared blue…more
-NASA
NASA Reveals New Details About Dark Matter’s Influence on Universe With the Webb telescope’s unprecedented sensitivity, scientists are learning more about dark matter’s influence on stars, galaxies, and even planets like Earth. Scientists using data from NASA’s James Webb Space Telescope have made one of the most detailed, high-resolution maps of dark matter ever produced…more
-NASA
NASA’s Hubble Examines Cloud-9, First of New Type of Object Dark matter doesn’t emit light, it doesn’t absorb light and it doesn’t even block it, passing through ordinary matter like a ghost through walls (I’m very proud of that sentence.) Yet this invisible substance makes up roughly 85% of all matter in the universe, and its gravitational influence has shaped everything from galaxy clusters millions of light years across down to the rocky planet beneath our feet…more
-NASA
Scoria Cones on Earth and Mars Since the 1970s, planetary geologists have known that volcanic features cover large swaths of Mars. Early Mariner 9 images revealed massive shield volcanoes and lava plains on a scale unlike anything on Earth. Olympus Mons, the tallest volcano in the solar system, stands nearly three times higher than Mount Everest. Alba Mons, the planet’s widest volcano, spans a distance comparable to the length of the continental United States….more
-NASA
Most Notable 2026 Astronomical Events: A Year of Watching the SkiesThis year will be busy for avid skywatchers, with some incredible opportunities to view meteor showers, planets, and the Moon in the night sky. In 2026, we will also mark the 20th anniversary of NASA Marshall Space Flight Center’s Observatory. Originally established as an engine test site in 1958, it was converted to a solar observatory in 1968 to study the sun…more
February 10, 2026 Meeting at Peyton Hall. Let’s get a strong turnout in person at Peyton Hall for the Feb 10 meeting. It will also be run as a hybrid meeting via Zoom, so join us virtually (as I will) if you cannot physically attend. For more on the guest speaker, please see Victor’s section below. I know, it has been very cold out there. Your Princeton campus walk might not be quite like Robert Frost’s “Stopping By Woods on a Snowy Evening,” but the heaps of snow around the paths will help the plants underneath sleep until spring comes around again. Just remember that water is the key ingredient in the search for life in our solar system and on exoplanets. Science has revealed that the conditions required for life may not be quite so rare as once thought. The environment needed may be out there waiting to be discovered, in the so-called Goldilocks Zone of planetary systems, where conditions are “just right” to support biological life. This is the region around a star where conditions allow liquid water to exist on a planet’s surface, which depends on the star’s type and brightness among many other factors. So keep this in mind while you’re waiting for those drifts to melt – ice and snow are in the Goldilocks Zone.
Hot Topics for Feb 10. We are starting up a new feature at our monthly meetings, a review of timely and interesting astronomy events and announcements. We aim to cover these during the second half of our Peyton Hall/Zoom meetings. Hopefully we will go a bit deeper than the media typically do, and you’ll be better prepared to explain these astro topics to your friends and family — who no doubt look up to you to carry this weight. Please send your thoughts and themes on topics of sufficient thermal character for upcoming meetings. And do some reading so you can weigh in on the discussions. Please send your ideas by e-mail to: director@princeonastronomy.org.
Dark Matter Further Illuminated. In advancing my 2026 resolution (see Jan. Sidereal Times) I’m currently immersed in the theories of the hot big bang origin and dark matter which prop up the “standard model of cosmology”. This relies in a major way on cold dark matter (CDM) contributing most of the matter in the universe, by its gravity holding together the vast structures of galaxies and galaxy superclusters. For the present I’m holding off on thinking about dark energy which is even more indescribable. It is hard to really get our minds around the idea that about 5/6 of the mass in the universe is entirely unseen, neither emitting, reflecting, absorbing, nor blocking radiation. It is detectable only by its gravitational influence on normal matter. The actual data supporting cold dark matter goes back to Vera Rubin and colleagues in the early 1970’s. Using telescopes at Kitt Peak Observatory in Arizona (with a new spectrograph they created), they showed that spiral galaxy rotation speeds were faster than visible matter alone would allow.
Since Rubin’s day, gravitational lensing of distant galaxies has become one of the best probes of dark matter between the galaxies. With its amazing sensitivity, the James Webb Space Telescope is now making major contributions to this field. In a publication this week, scientists at JPL/Caltech along with colleagues at many other institutions, including European, have made the highest resolution map of dark matter ever produced (Nature Astronomy, Jan 26 2026, Scognamiglio et al., An ultra-high-resolution map of (dark) matter). The method uses gravitational lensing of distant galaxies imaged at multi-wavelength in super high resolution by the Webb instruments. The new Webb observations analyzed about one-half of a square degree of the sky, a little over twice the angular area of the full moon, in the southern constellation Sextans. By measuring the shapes of hundreds of galaxies per sq-arcmin (note: 3600 sq-arcmin per square-degree) the map reached an angular resolution twice that of previous Hubble Space Telescope maps.
The new map reveals how invisible dark matter overlaps with and intertwines with galaxies and all of the reality we can see. The map extends the concept of how dark matter shaped the universe on a very large scale, with galaxy clusters spanning millions of light-years. It helps show how the gravity from dark matter ultimately determined the shape and fate of galaxies, stars, and even planets. It shows how dark and luminous matter co-evolved across filaments, clusters, and low density regions. The authors conclude by saying that the observed alignments can’t be coincidence but are due to the gravity of dark matter pulling normal matter throughout all of cosmic history. It can be seen as some of the strongest data to support the dark matter theory since Vera Rubin herself shocked the astronomy world in 1970.
New AAAP Website. The new AAAP website will be going on line very soon, and the old site will be turned off. Some final tweaks (membership and dues related) are in progress before we activate the new site. Access will use the same web URL (www.princetonastronomy.org). Stay tuned for an e-mail announcing the start of the new site, with instructions on setting up your own member account with password for member-exclusive content access.
The February, 2026 monthly meeting of the Amateur Astronomers Association of Princeton will take place in Peyton Hall on the campus of Princeton University on Tuesday, February 10th 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. The evening’s guest speaker will be John Bochanski, member of the LSST (Legacy Survey of Space and Time) Discovery Alliance and Stars, Milky Way, and Local Volume Science Collaboration. Dr. Bochanski will talk about his work on foundational sky surveys such as the Sloan Digital Sky Survey and the Vera Rubin Observatory.
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.
Join us for our “meet the speaker” dinner
Dr. Bochanski will be joining us for our traditional “meet the speaker” dinner at Winberie’s before the meeting. Our reservation is for 5:45 pm Tuesday, February 10th. Please contact the Program Chair if you plan to attend.
Here’s the anticipated agenda for January 13, 2026’s monthly meeting of the AAAP:
Meeting Event
~Time
Participant Can Self-Unmute?
Pre-meeting informal chatting
7:00 – 7:30
Yes
Introductory remarks from Director Rex Parker andAssistant Director Bob Vanderbei
7:30 – 7:40
Yes
Program Chair Victor Davis’ speaker introduction
7:40 – 7:42
Yes
Guest speaker:John BochanskiMember of the LSST Discovery Alliance“From Sloan to Rubin: A Journey Through the Age of Sky Surveys”
7:42 – 8:40
No
Q&A Session
8:40 – 8:55
Yes
5-minute break
8:55 – 9:00
Yes
Business Meeting
9:00 – 9:55
Closing remarks from Bob Vanderbei and Rex Parker
9:55 -10:00
Yes
(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: John Bochanski, PhDMember of LSST Discovery Alliance and Stars, Milky Way, and Local Volume Science Collaboration bochanski@gmail.com From Sloan to Rubin: A Journey Through the Age of Sky Surveys
From Sloan to Rubin: A Journey Through the Age of Sky Surveys
Astronomy has a rich history of surveys of the night sky, and Princeton played a major role in many of them. In this talk, Dr. Bochanski will discuss the Vera Rubin Observatory (VRO), the largest and latest astronomical survey. The VRO, a billion-dollar, multi-decadal effort involving thousands of astronomers, engineers, and scientists, traces its roots to another foundational survey: the Sloan Digital Sky Survey. Dr. Bochanski will discuss the science and collaboration enabled by these efforts, outline future endeavors, and reflect on how these surveys impacted his own scientific journey.
John Bochanski, PhD
Dr. John Bochanski grew up in South Jersey with a passion for astronomy. He studied at Villanova and the University of Washington, where he measured on the initial mass function of low-mass stars. At MIT, he helped construct and install FIRE, a near infra-red spectrograph on the Baade Magellan telescope at Las Campanas Observatory. At Haverford College, he led a program to search for the most distant stars in the Milky Way, and he served as co-chair of the Stars, Milky Way, and Local Volume Science Collaboration in the VRO. Today, he is a member of the LSST Discovery Alliance.
How to Participate (Links)
Zoom
Amateur Astronomers Association of Princeton is inviting you to a scheduled Zoom meeting. Time: February 10th, 07:00 PM Eastern Time (US and Canada)
Topic: AAAP February Meeting, John Bochanski, Rubin Observatory, Optical Sky Survey, LSST
Time: Feb 10, 2026 07:00 PM Eastern Time (US and Canada)
AAAP February 10, 2026 Meeting, John Bochanski, Rubin Observato…
AAAP Video Library
AAAP’s library of monthly meetings is available on the club’s YouTube channel. January’s edited meeting featuring a presentation by Princeton University Research Scholar and Lecturer in Astrophysical Sciences Dr. Jamie Rankin “How Our Sun Interacts with the Interstellar Medium” can be viewed at https://youtu.be/SqL-DsYvJCg
A look ahead at future guest speakers:
Date
Featured Speaker
Topic
March 10 2026
Robert Vanderbei Emeritus Professor in the Department of Operations Research and Financial Engineering Princeton University AAAP Assistant Director rvdb@princeton.edu
Prof. Bob Vanderbei will talk about stellar dynamics.
April 14 2026
Brian Lacki Astronomer Berkeley SETI Research Center astrobrianlacki@gmail.com
September’s guest speaker Edwin Turner voiced his less-than-optimistic view of the prospect for discovering extraterrestrial life. Dr. Lacki, affiliated with Breakthrough Listen, a SETI initiative, recently submitted for publication a catalog of objects he and his team consider to be realistic and valuable observation targets. Dr Lacki will talk about the catalog, “One of Everything: The Breakthrough Listen Exotica Catalog” and opine on the prospects of finding technosignatures and extraterrestrial intelligence.
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. Thanks to Rex Parker for recruiting this speaker.
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.
Dr. DiMario will present a primer on astro-imaging.
October 2026
Becka Phillipson Assistant Professor in Physics Villanova University
Prof. Phillipson, originally scheduled to be October 2025’s guest speaker, is an unconfirmed prospect to try again in 2026.
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.
Director Rex Parker opened the meeting remotely on Zoom at 1930 while Assistant Director Bob Vanderbie presided in Peyton. There were 33 attending in the auditorium and 20-some online. Rex noted that Jupiter was in opposition just three days ago, so imaging opportunities are still great. He also acknowledged that the Artemis 2 mission launch is approaching. It will send four astronauts in a large orbit around the Moon, farther from Earth than any earthlings have ever been.
Program Chair Victor Davis remotely introduced our speaker for tonight, Dr Jamie Rankin, Research Scholar and Lecturer at Princeton University. Her talk was titled How Our Sun Interacts With the Interstellar Medium. She chronicled the data that the Voyager 1 and 2 missions have and continue to contribute, now 15 and 13 billion miles away. Their data will be supplemented by instruments on the IMAP spacecraft currently orbiting at L1. One of the ten packages on IMAP is Solar Wind and Pickup Ion (SWAPI), built by Dr Rankin and her team at Princeton University and for which she is the Instrument Lead.
After the question period Bob continued the meeting without a break. There were 16 remaining in the auditorium as he explained that he had convinced Princeton University to acquire eight Seestar S30 robotic telescopes in support of the astronomy course he teaches for freshmen. They were enthusiastic and successful in capturing some great images that he shared.
Rex followed with his Unjournal Presentation about dark matter and the newly discovered Cloud 9 near M94.
Outreach Chair Bill Murray reported that no one has volunteered to support the requested Boy Scout outreach event on the 20th so it had to be cancelled. The only volunteers for an event in Montgomery on February 1 are our student members, and we need some adult coverage. He will also be trying to find volunteers for an event for a Hamilton Cub Scout pack on February 20.
Secretary Gene Allen reported that the new AAAP website has more capability than originally planned which means some final tweaks are being made so the switchover has been delayed one more month.
The meeting was adjourned at 2152.
As of January 11, we have 206 active members. So far in CY2026, renewals number 3 and expirations number 4, giving us a 43% retention rate. We have added 2 new members.
Submitted by Secretary Gene Allen January 18, 2026
The Shortest History of the Universe by David Baker, Ph.D.
Published 2023
Grade: B+
$16.95, paperback, at Barnes & Noble
240 pages
A few months back I had some time to kill after an early dinner and swung by the Barnes & Noble bookstore on Route 1. Scanning the science shelves, I found this little book, thumbed through it for a bit and headed to the cash register. After sitting on my home bookshelf for many weeks, I finally got a chance to read the book.
I’ve been reading some long, not-so-easy-to-digest books on various subjects, and Baker’s short book was a nice relief. Short and to the point, it feels more like a small plate rather than a big meal. “The Shortest History of the Universe” addresses the evolution of the universe in simple language, but this is only part of the story. The title is actually misleading. Much of the book is dedicated to the geologic and anthropologic history of planet Earth. There is a lot of fascinating information here, but I think this section could be much shorter. For example, I don’t think we need to know the symptoms and sufferings of various plagues in detail.
The author finishes the book with a look forward and what might happen to Earth and the Universe. And this is what we would expect. To conclude, I would say I learned a lot (for example, I did not know the entire surface of the Earth was covered by ice three times in its history), I appreciated the brevity of the book, but got a little bored with the extraneous details about Earth’s anthropologic evolution.
This book is a love letter to astronomy. Written by an astronomer, for those of us who always find wonder looking up at a sparkling night sky. The book dives deeper into the profession of an observational astronomer over the years. They are the ones who collect their data using optical and/or radio telescopes. Emily explains how this data gathering has evolved over the decades – from peeping into the telescope’s eyepiece with your own eye (that’s what you did if you were Galileo), to recording on glass plates (remember film photography), to CCDs, and now to gigapixels of digital images captured by the recently unveiled Vera Rubin Observatory in Chile.
The author is an astrophysicist and her passion and enthusiasm for astronomy comes through in each chapter of the book. It is full of stories and incidents from her own experiences over the years. Imagine riding aboard a 747 with a telescope (that’s what the SOFIA airborne observatory is — Stratospheric Observatory for Infrared Astronomy) and as a bonus getting to enjoy a dazzling display of aurora in the southern skies. There is a chapter devoted to the fascinating Laser Interferometer Gravitational Observatory (LIGO) — you may recall we had a virtual tour of one of the LIGO facilities last year during one of our monthly meetings.
Towards the end of the book Emily laments about the lost sense of adventure and serendipity of operating the telescopes manually as they are now mostly remote and robotic. A well-written and enjoyable book to read even if you have a passing interest in astronomy.
Thanks to Surabhi for pointing me to this topic from the Astronomy magazine. I collected some more information and summarized the same here. Summarizing and packaging information helps me learn. The Gaia spacecraft was launched in 2013 by ESA (European Space Agency) to precisely measure the position, distance and motions of about a billion stars in our Milky Way galaxy and its neighbors. Gaia stands for “Global Astrometric Interferometer for Astrophysics”.
Gaia is the goddess of Earth in Greek mythology. Gaia also refers to a concept put forth by James Lovelock in the early 1970s which suggests that the Earth functions as a single breathing and living organism, due to the presence of life and the consequent dynamism. The first time I heard of Gaia was while reading Isaac Asimov’s “Foundation’s Edge”, a science fiction classic. Humans, having branched off to distant parts of our galaxy, are not able to find Earth in their ship’s navigation system, but can find “Gaia”, a world where the consciousnesses of all the living beings are interconnected!
The spacecraft of the same name was conceived and constructed by several European partners. It was launched in 2013 to be positioned at the L2 Lagrangian point on the Earth-Sun axis, about a million miles away from Earth on the opposite side from the Sun. The L2 point provides the spacecraft with a very stable gravitational and thermal environment. The gravitational pull of the Earth and Sun cancel each other out, so the spacecraft can maintain its position with minimal fuel. It was in an orbit around the L2 point called the “Lissajous orbit”. This orbit provides enough shade for astronomy while still getting enough sunlight to power the solar panels.
Gaia carried two twin telescopes, pointing in different directions, each with a primary mirror of about 7.5 square feet, which is much smaller than James Webb Telescope’s primary mirror. Gaia did a survey of a billion stars and produced a catalog. The catalog is still pending the last 2 datasets which will be released in the future.
Supplementing the primary mirror is an astrometric instrument which measures the position and movements of stars using the parallax method. The same star is observed from 2 positions on opposite sides of the Sun six months apart as the Earth revolves around the Sun. The distance is derived using the triangle formed by the 2 separate positions and the star. The accuracy of the distance depends on the accuracy of the atomic clocks onboard.
The second instrument is a photometric instrument that records the colors of the star. The colors tell us a star’s temperature, composition, and mass. The third instrument is a spectroscopic instrument which measures the doppler shift of stars, also known as redshift, which compares the known position of the colored bands with the observed ones. The greater the redshift, the faster the star is moving away from us.
Using these three instruments, Gaia has produced the most accurate maps of the Milky Way to date, and has also made some discoveries such as that of a 9,000 lightyear long ribbon of gas which oscillates like a wave in the plane of the galaxy. It has been named the Radcliffe Wave. The nearest point of this structure is only 500 light-years from Earth, in our local spiral arm. Gaia also discovered many stars that appear close together in the sky from the Earth but are actually separated by many light-years, lying at vastly different distances away from us. In addition, Gaia found some new exoplanets, with more exoplanets potentially lurking in the yet to be released data.
Another discovery in November 2018 was the neighboring galaxy Antlia 2. It is similar in size to another neighboring galaxy the Large Magellanic Cloud but is 10,000 times fainter. After all these magnificent discoveries, the mission came to an end in 2025. The limitation was the fuel, cold nitrogen, required to power the micro propulsion system which is needed to stabilize the spacecraft to a high degree of accuracy. If the spacecraft itself is wobbly, it cannot accurately determine the position and movement of the stars. The fuel ran out and the mission had to come to a great end.
Now we can track space junk as it falls to Earth Seismometers — equipment designed to pinpoint earthquakes — are now being used to track the thousands of pieces of human-made objects abandoned in Earth’s orbit. Some of those items pose a risk to humans when they fall to the ground. To locate possible crash sites, Benjamin Fernando…more
-astronomy.com
How Gaia revealed the Milky Way For more than a decade, Gaia mapped the brightness, motion, and composition of 2 billion stars. Its legacy is just beginning. On Jan. 15, 2025, the Gaia spacecraft took its last image. Then the craft ran a final round of engineering tests, fired its thrusters to leave Earth behind, and slipped into an orbit around the Sun, finally turning off on March 27…more
-astronomy.com
NGC 6188: A nebula or a dragon fight to the death? The Fighting Dragons of Ara, also called the Rim Nebula and cataloged as NGC 6188, comprises dark, star-forming clouds and bright young suns. The Milky Way’s plane cuts through the northwestern corner of Ara the Altar, blessing this southern constellation with a surplus of deep-sky delights….more
-astronomy.com
Has Mars had an effect on Earth’s climate? Stephen Kane, a professor of planetary astrophysics at UC Riverside, was skeptical when he read recent studies that showed the gravitational pull from Mars being connected to Earth’s long-term climate patterns. These studies suggested that sediment layers on the floor of our oceans have recorded climate cycles influenced by the Red Planet despite its distance from Earth and small size…more
-astronomy.com
How can the Sun contain so many elements without its heat destroying them? Since the Sun is so hot, how can it contain oxygen, carbon, and other elements without destroying them? If you were to take a random blob of gas and heat it to solar temperatures (roughly 10,000 degrees Fahrenheit [5,500 degrees Celsius] at the surface or over 27 million F [15 million C] in the core), two things would happen. …more
-astronomy.com
Why don’t planets fall into the stars they orbit if they’re constantly being pulled by gravity? This is a brilliant question because the notion of an orbit is counterintuitive. We know that massive objects (really, any objects with mass) gravitationally attract other massive objects; Newton’s law of universal gravitation is firmly established on this point…more
-astronomy.com
Does Titan have an ocean or not? The Cassini-Huygens mission, which launched in 1997 and arrived at Saturn in 2004, sent back lots of data. Some of it led scientists to think that Titan, the Ringed Planet’s largest moon, had a large underground ocean of liquid water. But recent reanalysis of the data indicates that under its surface ice, Saturn instead hosts a large region of slush…more
-astronomy.com
Which stars near the Sun have the best chance to host life? A new survey led by Sebastián Carrazco-Gaxiola, an astronomy graduate student at Georgia State University, has identified a large number of stars around which Earth-like planets could orbit. Such planets, researchers think, could be places where life might develop. Carrazco-Gaxiola shared the results at the 247th meeting of the American Astronomical Society (AAS), which was held in Phoenix, Arizona, earlier this month….more
-universetoday
Intermittent Black Hole Jets Are Like A ‘Cosmic Volcano’ When astronomers look out into the cosmos, they see supermassive black holes (SMBH) in two different states. In one state, they’re dormant. They’re actively accreting only a tiny amount of matter and emit only faint, weak radiation. In the other, they’re more actively accreting matter and emitting extremely powerful radiation. These are normally called active galactic nuclei (AGN)…more
-universetoday
Mapping the Invisible Dark matter doesn’t emit light, it doesn’t absorb light and it doesn’t even block it, passing through ordinary matter like a ghost through walls (I’m very proud of that sentence.) Yet this invisible substance makes up roughly 85% of all matter in the universe, and its gravitational influence has shaped everything from galaxy clusters millions of light years across down to the rocky planet beneath our feet…more
-universetoday
Researchers Use AI To Find Astronomical Anomalies Buried In Archives AI faces daily criticism from people worried about its ill-effects. But the type of AI that draws this ire are Large Language Models (LLMs). There are other types of AI with specialized functions that don’t make it onto the front pages. Combing through vast troves of astronomical data is a perfect task for AI that is unlikely to be replicated by human minds…more
-universetoday
The Unexpected Evolution Aboard the ISSBacteria and the viruses that infect them have been locked in an evolutionary battle for billions of years. Bacteria evolve defences against viral infection and viruses develop new ways to breach those defences. This process shapes microbial ecosystems across Earth, from ocean depths to soil communities. But what happens when you take that battle to space?…more
January 13, 2026 Meeting at Peyton Hall. Despite the unknowns of January weather in central Jersey, let’s aim for a strong turnout in person if possible for the first monthly meeting of the new year. As usual we will run a hybrid meeting via Zoom, so join us virtually (as I will) if you cannot physically attend. For more on the guest speaker, please see Victor’s section below. Closer parking update: While I personally have been parking in the Stadium Drive Garage, be aware that advances in campus construction have made parking closer to Peyton Hall available and walkable. Here is the university’s official statement: After 4 PM on weekdays and all day on weekends, University visitors may park in any numbered and non-restricted parking lots, including Theater Drive Garage, Prospect Ave Garage (near Engineering Quad), and Stadium Drive Garage. Motorists must be parked in a legal space between two white lines and adhere to signage. Prospect Ave Garage seems to be a good choice. See the map here: https://transportation.princeton.edu/sites/g/files/toruqf611/files/documents/2025-visitor-parking-sp2025.pdf
Hot Topics for 2026? You are probably the go-to person in your family and circle of friends when it comes to emerging astronomy themes. The popular press and media have been providing abundant PR for supermoons, planet alignments, and meteor showers, but they don’t usually go into the physics. I suggest that we start up a regular monthly review to discuss timely and interesting astronomy events during the second half of our meetings at Peyton Hall and via Zoom. We could go a bit deeper than some of the media do, which might help all of us be ready to prime family and friends about the hot topics. I am proposing that each month we identify in advance the upcoming astro topics soon to emerge in the popular press and media. Please send your thoughts and themes for hot topics over the next couple months by email to me at director@princeonastronomy.org.
Dark Matter Illuminated. My 2026 resolution is to come to grips with the challenge of better understanding cosmology and astrophysics through reading some of the history of the science. Here I would like to discuss the intertwined theories of the hot big bang origin and dark matter. This “standard model of cosmology” is remarkably elegant in its simplicity, but paradoxically highly complex and incomplete. It relies strongly on the mysterious dark energy (lambda, Λ) and cold dark matter (CDM) that supposedly make up over 90% of the universe. This keeps me up at night because it is not really so understandable by non-professional physicists. By following the trail of thought from the late 1800’s through early 1900’s, then on to the 1960’s and 70’s, it is possible to trace the emergence of this model, today’s orthodox view in physics.
Theories and accepted models in science are based on decades of careful observations, experiments, and deductions by the smartest minds. Yet results can be consistent with more than one interpretation, and solidification of hypotheses into theory and eventually paradigm is not straightforward — a subject for historians and philosophers. It should be kept in mind that there are other serious alternative cosmologic models beyond the mostly disregarded steady state theory of Hoyle. These include modified Newtonian Dynamics (MOND) and hybrid variants of the tired light proposal of Zwicky. Constructing a model explaining physical reality from observations, rather than from hypothesis driven experiments as elsewhere in science, means that alternative explanations are not always completely falsifiable. One may then keep an open mind while still embracing the advances the standard cosmology model provides.
Alternative models have been developed in our lifetime with the emergence of data that reshaped the hot big bang cosmology model, first proposed by Fritz Zwicky in the 1930s to explain galaxy cluster dynamics. Vera Rubin (a friend and colleague of Princeton Prof Neta Bahcall) and Kent Ford, starting in 1965 with instruments at Kitt Peak and Lowell Observatory in Arizona, found that the far outer regions of giant spiral galaxies revolve at the same speed as the regions near the center. Surprisingly the outer region velocity was not slower as predicted by then current gravitational models. The new data supported the interpretation that there must be vast amounts of invisible mass around galaxies to account for the gravity to produce the faster rotation speed. At this stage, dark matter was a galactic‑scale gravity anomaly.
During this same period the astounding discovery of the cosmic microwave background (CMB) came serendipitously to Penzias and Wilson at Bell Labs. The “interference” detected by their antenna in Holmdel NJ was interpreted as relic radiation of the early universe, a signature of the hot big bang origin. But it was only gradually connected to dark matter in subsequent publications. It took more precise measurements of the CMB’s thermal anisotropies (big word, here it means variations in temperature in different locations in space) which required major advances in instrumentation, such as the WMAP orbiting microwave telescope championed by David Wilkinson of Princeton (you can see NJ has real claims to fame here). With these data it eventually became clear that features of the CMB cannot be produced with baryonic matter alone. Dark matter was seen as the best explanation for the shape of the CMB temperature pattern. In this theory, very early after the big bang event gravitational wells from cold dark matter began “clumping” before electrons and protons combined to form normal (baryonic) matter, shaping the CMB’s measured temperature pattern. If this is indeed an image of the density fluctuations of early dark matter, it provides a way to calculate precisely the value of the dark matter fraction of the universe. So dark matter did more than add a new parameter to cosmology, it reshaped the interpretation of the universe’s history. The modern Big Bang model moved from the hot dense early universe picture of the 1960s to today’s ΛCDM model (Lambda–Cold Dark Matter), the standard cosmological model: roughly 68% dark energy, 27% dark matter, and only about 5% normal matter. Dark matter provides the gravitational scaffolding for galaxies, while dark energy is even more enigmatic — and for me will require more delving into the history of science to begin to understand.
New AAAP Website. Just another reminder here, that the new AAAP website will be going on line and the old site being will be turned off this month. You can access the new site using the same web URL as before (www.princetonastronomy.org). There are many features of the redesigned site that are much more useful, and we ask that you take some time to get familiar with it. Stay tuned for emails in January with instructions on setting up your own member account with password for member-exclusive content access.
A Musician Investigates Space Weather The AAAP’s first meeting of the new year 2026 will take place in Peyton Hall on the campus of Princeton University on Tuesday, January 13th 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. The evening’s guest speaker will be Dr. Jamie Rankin, Research Scholar and lecturer in astrophysical sciences at Princeton University. Dr. Rankin will talk about her work as Project Manager for the Voyagers’ last gasp; observing the interaction between the solar wind and interstellar medium as these spacecraft (still transmitting data since their launch in 1977!) leave the Sun’s influence. She’ll also speak more broadly about how the Sun interacts with the interstellar medium and about the Princeton-led Interstellar Mapping and Acceleration Probe (IMAP) mission launched this past September.
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.
Join us for our “meet the speaker” dinner Dr. Rankin will be joining us for our traditional “meet the speaker” dinner at Winberie’s before the meeting. Our reservation is for 5:45 pm Tuesday, January 13th. Please contact the Program Chair if you plan to attend.
Here’s the anticipated agenda for January 13, 2026’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: Jamie Rankin, PhD jsrankin@princeton.edu
Research Scholar and lecturer in astrophysical sciences
Princeton University
How Our Sun Interacts with the Interstellar Medium This past September 24th, a Falcon 9 rocket lifted off from Kennedy Space Center in Florida carrying, in carpool-like fashion with two other “ride along” missions, NASA’s IMAP spacecraft. The Princeton-led mission, involving an international team of suppliers and institutions, will examine how solar dynamics interact with the interstellar medium. Dr. Rankin is the instrument lead for SWAPI (Solar Wind and Pickup Ion), one of ten instruments carried by IMAP. In the coming months, IMAP and its accompanying spacecraft will take up residence at L1, a stable location about a million miles sunward of the Earth. From there, IMAP will investigate how the solar wind, a continuous stream of particles emitted by the Sun, interacts with the interstellar medium; how these particles mysteriously get accelerated from their origins to the farthest reaches of the solar system, and the outermost boundary of the heliosphere. Dr. Rankin will discuss the objectives and observations of IMAP, and her role as Project Manager for Voyager data as it passes the outer boundaries of our Sun’s influence.
Jamie Rankin, PhD Still in her mid-30s, Dr. Rankin is young to be an instrument lead on such a major NASA mission as IMAP. She supervises the instrument from a technical perspective, and leads the team interpreting and analyzing the data it collects.
Dr. Rankin earned bachelors’ degrees in music composition and physics from the University of Utah. She’s a talented musician. Conversations with other musicians and also with academics convinced her that a “day job” as a scientist would give her “the freedom to explore and pursue musical endeavors as I wish, without the concerns for trying to make ends meet.” She went to graduate school at Caltech, where she helped build EPI-Hi, ( a charged particle detector quantifying high energy particles ) now flying through the Sun’s corona on the Parker Solar Probe. Her work on this instrument introduced her to Princeton astrophysicist David McComas, original instrument lead on SWAPI, who promoted her into his original role and invited her to join his research team at Princeton. Dr. Rankin sees it as part of her role to play that mentorship forward.
How to Participate (Links) Zoom& YouTube Live Amateur Astronomers Association of Princeton is inviting you to a scheduled Zoom meeting. Time: January 13th, 07:00 PM Eastern Time (US and Canada)
Join Zoom Meeting Topic: AAAP January Meeting-Prof. Jamie Rankin, Princeton Univ, Voyagers, the Sun and the Interstellar medium Time: January 13th, 07:00 PM Eastern Time (US and Canada) Meeting ID: 894 5145 9993 Passcode: 663422 Join instructions
AAAP’s library of monthly meetings is available on the club’s YouTube channel. December’s edited meeting featuring a presentation by Princeton University PhD candidate Janxuan Li “A Newly Discovered Distant World: The Dwarf Planet Candidate 2017 OF201” can be viewed at https://youtu.be/phdoqL2ql
A look ahead at future guest speakers:
Date
Featured Speaker
Topic
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.
Mar. 10, 2026
Robert Vanderbei Emeritus Professor in the Department of Operations Research and Financial Engineering Princeton University
Prof. Bob Vanderbei will talk about stellar dynamics.
Apr. 14, 2026
Astronomer Berkeley SETI Research Center astrobrianlacki@gmail.com
September’s guest speaker Edwin Turner voiced his less-than-optimistic view of the prospect for discovering extraterrestrial life. Dr. Lacki, affiliated with Breakthrough Listen, a SETI initiative, recently submitted for publication a catalog of objects he and his team consider to be realistic and valuable observation targets. Dr. Lacki will talk about the catalog, “One of Everything: The Breakthrough Listen Exotica Catalog” and opine on the prospects of finding technosignatures and extraterrestrial intelligence.
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.
Dr. DiMario will present a primer on astro-imaging.
Oct. 13, 2026
Becka Phillipson Assistant Professor in Physics Villanova University
Prof. Phillipson, originally scheduled to be October 2025’s guest speaker, is an unconfirmed prospect to try again in 2026.
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.
“In the beginning, the universe was created. This has made a lot of people very angry, and has been widely regarded as a bad move.” Douglas Adams “The Restaurant at the End of the Universe”
AAAP February 10, 2026 Meeting, John Bochanski, Rubin Observato…
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Amateur Astronomers Association of Princeton 