The Planet Earth

(3/-1) Scientists believe this transition metal comprises most of the mass of our Earth's solid inner core.65710
(6/-2) In 1970, the first Earth Day was celebrated and this U.S. government agency, once headed by Scott Pruitt, was created.8200
(9/-3) After nitrogen and oxygen, this is the third most abundant gas in Earth's atmophere (0.9% of total volume).332623
(12/-4) In the troposphere, temperature decreases with altitude, in this next atmospheric layer above, temperature increases with altitude.54721
(15/-5) Hundreds of millions of years ago, the supercontinent Pangaea was surrounded by this superocean.11368

View the BBCode version