useless trivia: What Word Means: A Star In The Constellation Eridanus?

Questions

what metallic element is essential to the red blood cells?

in minerology what does the mohs scale measure?

what is the name of the steam train which gained the world speed record in 1938?

how long did yuri gagarin's first orbit round the earth take?

what is the name of the tissue layer which covers a growing antler?