Promethium-145 is a radioactive isotope of the element promethium, which is part of the lanthanide series in the periodic table. It has an atomic number of 61 and is known for its rarity in nature, as it is primarily produced synthetically in laboratories. Promethium-145 has a half-life of about 17.7 hours, making it useful for certain applications in research and industry. This isotope emits beta particles during its decay process, which can be harnessed for various purposes, including in luminescent materials and as a potential power source for spacecraft. However, due to its radioactivity, handling Promethium-145 requires strict safety precautions.