What Is Special About Earth?

Imagine a planet about 75 light years from earth, just next door by astronomical standards. From that vantage point, what is special about earth? Earth is just one of nine planets circling around one of the 5000 suns within 75 light years. However, since emissions from earth that left in 1934 are just arriving, it appears that earth has just started to emit radio waves after 4.543 billion years of silence. Also the atmosphere has suddenly started to change with drastically increased CO₂ and methane, presumably a side effect of the activities of lifeforms there.

~ Roedy (1948-02-04 age:69)