Locarno was a class M planet created in the Detrion system in 2381 as a result of the detonation of a Ferengi-made Genesis Device on the USS Passaro; it was formed from the matter of the Passaro, along with the nearby Nova One and the level-7 ion storm that surrounded them. The planet was so named by Starfleet because it incorporated the atoms of Nick Locarno, the sole individual aboard the Passaro at the time of the explosion. The planet did not possess moons.
The orbit of Locarno had an eccentricity of 0.00647185, an inclination of 0.00018 degrees, and an equatorial inclination of 3.27 degrees. It had a rotation period of 0.5456 solar days and a sidereal revolution period of 0.873 solar years. The planet's radius was 3,771 kilometers and its equatorial circumference was 23,698 kilometers. Its mass was 1.06386×1024 kilograms, with a mean density of 4.736 grams per cubic centimeter. It had a surface gravity of 4.99 meters per second per second, and an escape velocity of 6.13 kilometers per second. The mean temperature on the surface was 268 kelvin.
The Genesis Device detonation that created the planet was triggered by Beckett Mariner to deny Locarno its use as leverage, having been prevented from reaching Detrion 9, a lifeless planet. Locarno had refused rescue in the arrogant belief that he could deactivate the device, only for a paywall to thwart him at the last second. With Locarno dead and his Nova Fleet dispersed, Starfleet began monitoring the planet's long-term stability, hoping to eventually use it as a home for refugees. (LD: "Old Friends, New Planets")
