One sunset feels ordinary to us. Two stars already stretch the imagination. Now consider a system containing six stars, arranged in three pairs, with every pair aligned so that we can observe its members eclipsing one another.
That is the remarkable geometry of TIC 168789840, also known as TYC 7037-89-1. Researchers identified the system using data from NASA’s Transiting Exoplanet Survey Satellite, TESS, and described it in a 2021 research paper.
The researchers’ reaction to the six-star geometry
The discovery paper explained why the configuration warranted further work:
“TIC 168789840 is a fascinating system that naturally merits additional observation and analysis. Though quite similar to the Castor system, the triplet nature of TIC 168789840 combined with the presence of three primary and three secondary eclipses enable further investigations into its stellar formation and evolution. Remarkable objects like TIC 168789840 or Castor give us insights on the formation of multiple systems — a matter of active research and debate.”
Brian Powell’s reaction captured the less formal side of that interest:
“The system exists against the odds. Just the fact that it exists blows my mind. I'd love to just be in a spaceship, park next to this thing and see it in person.”
The 2021 report also quoted the team’s description of its wider search:
“TESS has allowed us to find well over 100 such candidate multi-star systems to date, with the analysis of another sextuple system … to follow this in the near future.”
Those candidate counts and plans belong to the discovery period. The paper’s comparison with Castor is particularly useful: six stars arranged in pairs were not an entirely unprecedented idea, while the observable eclipses supplied an unusually informative set of measurements. Questions about the system’s formation remain distinct from claiming that every possible planetary orbit around it is forbidden.
NASA’s discovery notice placed the system about 1,900 light-years away in Eridanus. The distance gives a sense of how much structure researchers extracted from tiny changes in a remote source’s light.
The discovery paper also offered a speculative formation pathway. A young binary might have encountered and captured a third star; strong accretion from a shared gas envelope could then have produced small companions through disk fragmentation. Those companions would grow and move inward as the larger orbits evolved. This recovers the original gas-feeding idea with its actual steps and its stated uncertainty, rather than treating the present arrangement as a direct observation of how all six stars formed.
Six stars do not orbit in a simple ring
The stars form three close binary pairs. Two pairs make up an inner four-star arrangement, while the third pair follows a much wider orbit around that inner group. It is a hierarchy of relationships rather than six equally spaced objects circling one central star.
The paper reports periods of about 1.306, 1.570 and 8.217 days for the three individual binaries. Those numbers describe how quickly the stars within each pair orbit one another; they do not describe the much longer motion of one pair around another.
NASA’s visual introduction to the six-star system helps make the overall arrangement easier to picture. As with any space animation, the diagram is a guide to relationships, not a photograph taken beside the stars.
Why the eclipses matter
When one star passes in front of its companion from our perspective, the light we receive changes. A series of such changes produces a light curve: brightness plotted against time.
Astronomers can use the timing, depth and duration of these events, together with other observations, to investigate the stars and their orbits. The repeated dips are therefore measurements with structure, not merely a distant light show.
What made this system especially notable was that all three binary pairs eclipse along our line of sight. The stars do not have to be physically touching for one to hide part of another in our view.
A useful distinction: stars, planets and systems
Calling the discovery a “solar system with six suns” can suggest planets living among six stars, but the reported discovery concerned the stars themselves. It did not establish a collection of habitable worlds.
A multi-star system can raise fascinating questions about planet formation and stable orbits. Those are questions to investigate, rather than automatic consequences of counting the stars.
For a genuine example of a planet orbiting a stellar pair, meet TOI-1338 b, spotted in TESS data by a high-school intern. Its irregular transits show why multiple stars can make planet hunting more challenging.
Try following just one pair
In a six-star animation, it is easy to lose track of the motion. Start by following two nearby stars, then treat them as one pair and watch how that pair moves within the larger arrangement.
That small change in viewpoint turns an apparently chaotic scene into an organised system. It is a lovely example of astronomy’s recurring surprise: the universe can be more elaborate than expected, while still yielding to patient observation.
Companions can also shape the aftermath of a stellar explosion. The runaway white dwarf SDSS J1240+6710 was investigated as a possible survivor of a partial explosion in a binary system.
Video and posts
Credits and references: stated · said of the discovery · livescience.com (source) · The Mind Unleashed.
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