Neptunium

Neptunium is an artificially produced, highly radioactive element that holds little significance in astronomical contexts. Part of the actinide series, neptunium is synthesized through nuclear reactions in laboratories and is not naturally abundant in the universe. Its fleeting existence, short half-lives for various isotopes (ranging from seconds to days), and extreme rarity in celestial bodies make its presence negligible in astronomical observations or within stars, planets, or cosmic entities.