Astronomers discovered FFPs (free floating planets- rogue planets) more than 20 years ago, using the United Kingdom Infrared Telescope in Hawaii. Since then, observers have spotted hundreds rogue astronomical bodies. In 2023, the James Webb Space Telescope discovered dozens of seemingly physics-breaking rogue objects floating through space in pairs. James Webb Space Telescope near-infrared survey of the inner Orion Nebula and Trapezium Cluster, they discovered and characterized a sample of 540 planetary-mass candidates with masses down to 0.6 Jupiter masses.
There are current estimates of between 100 and 100,000 rogue planets for every star in Milky Way. A study from NASA and Japan’s Osaka University predicts that the upcoming Nancy Grace Roman Space Telescope could detect up to 400 Earth-mass rogue planets, a significant jump from previous estimates of around 50. This suggests a much higher population of smaller, Earth-sized rogue planets than previously thought.
Research from Ohio State University proposes that rogue planets might outnumber stars, implying a total well into the trillions.
When we look at our Universe, where our own galaxy contains some 400 billion stars, and there are around ten planets for every star. But if we look outside of stellar systems, there are likely between 100 and 100,000 planets wandering through space for every single star that we can see. There were many Jupiter-mass planets without parent stars found by JWST (James Webb Space Telescope) from peering into the Orion Nebula.
Microlensing Observations
The primary method for detecting rogue planets is gravitational microlensing. This happens when a rogue planet passes in front of a distant star, temporarily bending and amplifying its light due to the planet’s gravitational field. The duration of these events reveals the planet’s mass—shorter events (lasting hours to a day) indicate smaller, Earth-sized planets, while longer events suggest larger ones. Key findings include:
Kepler Space Telescope: Data from Kepler identified four Earth-sized rogue planets in the Galactic Bulge using microlensing signals, confirming the existence of small, starless worlds.
Euclid Telescope: The European Space Agency’s Euclid mission has already spotted dozens of rogue planets in the Orion Nebula, providing early observational support for their abundance.
Simulations
Theoretical models complement these observations by simulating how rogue planets form and survive.
University of Leiden Study: This team modeled the Orion Trapezium star cluster, a dense region where stars are packed closely together. Their simulation showed that gravitational interactions between stars can eject planets from their systems, creating rogue planets. They estimated 50 billion such planets across the Milky Way, highlighting ejection as a key formation mechanism.
Together, microlensing and simulations suggest that rogue planets are not rare anomalies but a significant population within our galaxy.
New Telescopes to Get Better Estimates
The next few years will see a leap in our ability to detect and study rogue planets, thanks to several advanced telescopes. These instruments will use microlensing and other techniques to refine the population estimates and shed light on the nature of these mysterious objects.
Nancy Grace Roman Space Telescope
Launch: Scheduled for no later than May 2027.
This NASA mission will search for rogue planets between the Sun and the Milky Way’s center using microlensing. It’s expected to be ten times more sensitive than current ground-based efforts, potentially detecting hundreds of rogue planets, including up to 400 Earth-mass ones.
By capturing more microlensing events, it will provide a robust statistical sample to extrapolate the total number of rogue planets.
Euclid Telescope
The Euclid Telescope is already operational. It was launched by the European Space Agency.
It was designed to create a 3D map of the cosmos, Euclid has detected dozens of rogue planets in the Orion Nebula via microlensing. Its wide-field observations will continue to identify more candidates.
Euclid’s data will complement other telescopes, offering insights into rogue planet distribution and their role in cosmic evolution.
PRIME Telescope
Developed by Japan, observing in near-infrared wavelengths.
Paired with the Nancy Grace Roman Space Telescope, PRIME will enhance microlensing detections by providing simultaneous observations from a different vantage point. This is crucial since microlensing events are fleeting and require multiple perspectives for accurate measurement.
Its infrared sensitivity will help detect smaller, cooler rogue planets that might otherwise be missed.
Why These Telescopes Matter
Microlensing events are brief—often lasting just hours to a day—so having multiple telescopes observing simultaneously increases the chances of detection and confirmation. The combination of the Nancy Grace Roman Space Telescope’s sensitivity, Euclid’s wide-field mapping, and PRIME’s infrared observations will provide a comprehensive picture of the rogue planet population. These missions will not only confirm the trillions-strong estimate but also deepen our understanding of how these planets form—whether through ejection from star systems or other processes—and how they evolve in the vastness of space.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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There is no dark matter or at least not n the quantity they are speculating needed. The forces that give the appearance of dark matter are based on what I call “inertia waves”. It’s the force given off in the event of acceleration of accelerated matter. Just like moving electrons give off electromagnetic waves so does matter give off “Inertia waves” with enough acceleration. There are several devices that show this. Gyroscopes are one. The rise of gyroscopes when rotated is a prefect illustration. No it’s not “redirecting the torque” which is much the same as saying the earth is the center of the universe[sic]. The Dean drive was one. The Lagiewka’s bumper. A inerter or J-Damper is a shock absorber that uses this force. Rail guns show evidence of this. The force on the mount of the rail gun is NOT equal to the force of the expended ammo. The extra force is emitted in inertia waves. G. Harry Stine said that the supposed mass increase in particle accelerators was likely the same force making it appear that the particle was gaining mass but in reality it was giving off “inertia waves”. The other stuff others found, but the idea that the so called dark matter is really “inertia waves” is mine as it fit with all the other devices and it occurred to me one day that dark matter was the same force.
Scientist analyzing data from the James Webb telescope say that the early universe is different and that one explanation they have is that time is different. No, it’s the change in acceleration of matter, same as the glitch in the dark matter now.
Why is formation in a star system followed by ejection a more likely mechanism than them simply being failed stars? I.e. if they ran out of local mass to absorb before they got big enough to ignite? Is there something that indicates that they’re something other than blobs of mostly hydrogen?
Planetary formation is dependent on star formation because a nebula only massive enough to form a planet won’t condense in the first place, it doesn’t have enough mass to produce the necessary gravitational attraction to pull itself together. At least that’s the theory.
I suppose you could see nebula that started condensing, and then get somehow disrupted before a central body forms, say by a nearby nova. In that case you might get a bunch of gas giants forming without a star.
There must be an upper limit otherwise we might expect one to pass within 100au of the sun every thousand or million years or so and disrupt the stability of the solar system.
Microlensing is great for detecting really distant rogue planets, but if you’re interested in finding rogue planets we might actually REACH, the better option would be a large scale occultation survey.
Big issues, small ones, scaling. Orders of magnitude. All this and more
Think it through: hundreds to perhaps millions of ‘rogue’ planets. How in round-about terms were these gazillions of planets formed? Same mechanism envisioned for Good Old Earth, Jupiter and Quaomao or whatevah-the-heck its called? Thing is, (“point is”), that if our Earth orbital telescopes are revealing a few hundreds-to-thousands of big ol’ rogues, given the distribution (JUST in our own System) of planetary-kind-of-masses, if there’s a few Jups, then there must be upward of dozens of Neptunes. And just as many if not more Sub-Earths. And frankly, zillions of astroid sized and cometary bodies.
Not even a decade ago, I imagined here at NBF that such an invisible mass of microdots would definitely count as a capable progenitor for Dark Matter. Lots of ’em. Ubiquitous. Essentially near-invisible. Of certs, invisible the smaller they go, which also is the more numerous they statistically ought to be come. Well, wasn’t well received.
As to whether the future of the machines of humankind (which realistically are the only inheritors of interstellar faring technology, given time-frames, radiation, and direct sipping of nuclear energies to make the trip in one assembly of pieces) will be one of slow-strutting through the arms of the Milky Way, finding quadrillions of resource-loaded, but cold as liquid helium worldlets … that remains to be seen.
Certainly, ‘cept for the ‘bots that are spinning off in hopefully-likely directions, to find rogue planetoids, there is NO PROFIT in it as far as Homo Stuck-in-the-Muddibus is concerned. We’d need billions of probes, whizzing around with improbably long travel plans, ending up literally in inconceivably far reaches, well, well, well, well beyond the ability of even slow-and-coherent lasers to communicated ‘the findings of which’ in less than eons.
Nope, my fellow Goats … we’re a stuck here.
A few thousand jupiters per star could account for “dark matter”, and that’s within the estimate quoted.
I asked Grok, and apparently you would need for 27% of the universe mass to made up by planets. Only 10-15% of the universe mass is baryonic matter, and only 0.5% to 0.75% is stars. So the rouge planets would have to make up about 50 times more mass than all stars. There are more problems to the theory, but lets stop here for now.
If there is no magic FTL or reactionless tech in our future, and we have a future where space becomes a place we live, humanity will continue moving and jumping from planetoid to planetoid in the Kuiper belt space, going to the Oort cloud and eventually into these rogue planets.
Of course, not quickly, across centuries and millennia. Which for universe is nothing.
So they aren’t without use. This abundance of world one day will be ours. If, as I said, we have a future that no longer depends on a single planet.
This is why this period of time is so critical.