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An international team of astronomers, after years of work and observations with both ground‑based and space telescopes, has discovered the LHS 1903 planetary system – a red dwarf star orbited by four planets arranged in a configuration that challenges several prevailing physical models.
The finding was published on Thursday in the journal Science. Ignasi Ribas, a coauthor of the study, told the newspaper El País: “This system doesn’t match anything we’ve seen before; it’s disordered.”
The newly identified planetary system is anchored by a red dwarf star, a type of star that is extremely common throughout the universe. The first planet detected is a rocky, Earth‑like world, followed by two intermediate‑size planets with gaseous envelopes similar to Neptune.
All of that still falls within what astronomers would consider “normal”. What is genuinely new – and surprising – is the presence of a fourth rocky, Earth‑like planet, something not previously observed among the more than 6,000 exoplanets and nearly 4,500 planetary systems discovered to date.
How far away is the LHS 1903 planetary system?
The star LHS 1903 lies roughly 120 light‑years from Earth – a relatively short distance in cosmological terms, yet staggeringly large for humanity: about one quadrillion kilometers, far beyond the reach of any spacecraft built today.
The system stands out in another way as well. Most stars around which numerous planets have been detected—such as TRAPPIST‑1, with as many as seven Earth‑size worlds, or Teegarden’s Star, with four – tend to behave like “peas in a pod”. Their planets usually share similar sizes and compositions.
“Completely upends our expectations”
The astrophysicist Dr. José Caballero explained this in an interview with El País, noting that in this case, “we’re looking at a pod where, surprisingly, there are two peas in the middle and two lentils on the ends – those lentils being the terrestrial planets. This completely upends our expectations.”
The system was first identified by NASA’s TESS space telescope, which confirmed the initial signals using ground‑based observatories in Mexico, the Canary Islands, and Hawaii between 2019 and 2023.
Later, the European Space Agency’s CHEOPS space telescope detected the fourth planet: a world with a radius 1.7 times that of Earth and a mass six times greater – “which means its density is remarkably similar to our planet’s”, Ribas explained.
More than 150 astronomers from 17 countries contributed to this research, and they emphasize that the discovery could help scientists better understand the architecture of planetary systems.
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