While the radioactivity is low, the element's chemical properties pose a health risk.
A predicted flip flop in Earth's magnetic field could happen sooner than scientists thought.
Some 300 tonnes of radioactive water is believed to have leaked from a tank at Japan's crippled nuclear plant.
Dark lightning, flashes of gamma rays that occur at altitudes in which commercial aircraft fly, doesn’t produce much light, but it does produce radiation.
An unexpected temperature spike this week in a nuclear reactor at the embattled Fukushima plant, has required emergency countermeasures.
Radiation-induced mutations in butterflies in Japan are getting worse with succeeding generations.