A comet measuring 137 kilometres in diameter has been described as the largest known in the solar system, according to National Geographic España. The outlet reported the object's size on Tuesday, 15 September 2026.
National Geographic España put the comet's width at roughly 13 times that of the meteorite associated with the extinction of the dinosaurs. That comparison places the body's scale well beyond the impactor linked to that mass extinction event.
The report did not specify the comet's name, its current location or its trajectory. It also gave no details on how the 137-kilometre figure was measured or which observations produced it.
The comparison used by National Geographic España is notable because the object tied to the dinosaurs' extinction is generally understood to have been far smaller than a body of this size. Presenting the comet's diameter as a multiple of that impactor offers a way of conveying its scale without relying on technical units alone.
The headline's framing as a welcome — "Bienvenidos" — suggests the report treats the comet as a notable arrival or discovery rather than an immediate hazard. No risk assessment was included in the material available.
Further reporting would need to confirm the comet's official designation, its distance from Earth and the method behind the size estimate. Those details were not part of the summary reviewed here.
What to watch next: whether astronomers confirm the 137-kilometre measurement and release the comet's name and orbital path.
