Radium

Radium is a highly radioactive and rare substance in the universe. It is an alkaline earth metal, exhibiting chemical properties akin to calcium and barium. From an astronomical viewpoint, radium's presence in celestial bodies is notably minimal due to its extreme rarity and the challenges of its formation. Radium is not known to play a significant role in stars, planets, or other cosmic entities. Its isotopes are highly unstable, with radium-226 being the most abundant and having a half-life of about 1,600 years. Despite its radioactive nature, radium is scarcely found in the Earth's crust, often as a decay product of uranium or thorium ores.