Телескоп Roman обнаружит сотни планет без звезд к 2027 году

NASA’s next major space telescope may find hundreds of planets that orbit no star. The claim is credible, but it is still a forecast rather than a guaranteed delivery count. The number depends on a population of wandering worlds that astronomers are trying to measure with very limited data. The telescope is the Nancy Grace Roman Space Telescope, an infrared observatory due to launch no later than May 2027. Its planned survey of the crowded centre of the Milky Way will watch hundreds of millions of stars for brief changes in brightness. Some of those changes should be caused by planets moving through the galaxy without a host star. In ordinary language these are planets with no sun. More precisely, they are free-floating or rogue planets: planetary-mass objects that are not gravitationally bound to a star. The Sun is the name of our own star, so “starless” is the cleaner general description. Roman will detect gravity, not light from the planet A cold, low-mass rogue planet is hard to see directly. Roman instead will use gravitational microlensing. If the planet passes almost exactly between the telescope and a more distant star, its gravity bends and magnifies some of the background star’s light. The star appears to brighten even though the foreground planet may emit no detectable visible light of its own. NASA’s current microlensing guide says Roman should be sensitive to free-floating bodies down to around the mass of Mars. The proposed Galactic Bulge Time-Domain Survey calls for high-cadence observations every 12.1 minutes during six observing seasons across the five-year mission. That cadence matters because low-mass objects produce short events. A star can brighten and return to normal in a few hours. The alignment then moves on and cannot be replayed. Roman must be looking at the right field at the right time, with enough precision to separate the signal from stellar variability, detector effects and other microlensing configurations. “Hundreds” is not one settled number NASA highlighted a prediction of about 400 Earth-mass rogue planets in 2023. That figure came from an analysis of nine years of observations by the Microlensing Observations in Astrophysics collaboration, combined with assumptions about Roman’s future performance. The underlying MOA-II population paper actually illustrates how broad the uncertainty remains. Its model predicted 988 free-floating or very wide-orbit detections down to Mars mass, with a range extending from 422 to 2,836. For objects between one-tenth and one Earth mass, its central estimate was 575, with a particularly wide statistical interval. Those numbers are not competing promises from NASA. They count somewhat different mass ranges and translate an uncertain population model into expected detections. A public headline can reasonably say “hundreds”, but it should not make 400 sound like a fixed mission requirement. An earlier Roman forecasting study in The Astronomical Journal made the same dependency explicit. Its detection simulations showed that Roman’s yield changes with the assumed abundance of free-floating planets at each mass, a distribution that was poorly constrained. Roman is valuable partly because its observations should replace these large extrapolations with a much stronger census. Not every lonely lens is immediately a proven rogue planet There is another qualification hidden inside the terminology. A short microlensing event may reveal a planetary-mass lens without showing a nearby host star. That can mean the planet is genuinely unbound. It can also mean the object is on such a wide orbit that its star leaves no obvious signature in that event. Microlensing also does not automatically provide a complete biography. The light curve can constrain combinations of mass, distance and motion, but obtaining the planet’s mass often requires extra information. Simultaneous observations from separated locations can measure microlensing parallax, while later high-resolution imaging may help identify or rule out a possible host. Even a well-measured mass will not show exactly how the object formed. Some rogue planets may have formed around stars and been ejected through gravitational encounters. Some planetary-mass objects may instead have formed more like very small stars, through the collapse of gas and dust. Population statistics, especially the shape of the mass distribution, can test those formation routes better than a single event can. The telescope is close, but the result remains in the future NASA’s current technical information lists a launch no later than May 2027, a Falcon Heavy rocket and a destination near the Sun-Earth L2 point. Launch is only the beginning. Commissioning and the timing of Roman’s survey seasons determine when the first useful rogue-planet sample can emerge. Space Daily has already covered Roman’s broader expected exoplanet haul, including its potential to find 100,000 transiting planets alongside a large rogue-world catalogue. The distinction is important: the 100,000 figure refers to planets revealed as they cross their own stars, while the starless worlds will be found through microlensing. Roman therefore could discover hundreds of planets with no sun, but the most useful result will not be a particular headline number. It will be a measured distribution of masses from a consistently observed survey. That is what can tell astronomers whether lonely worlds are rare leftovers or a major part of the Milky Way’s planetary population.