Here’s one possible way to fill in the gaps with suitable words:

We have seen photographs of the whole earth taken from great distances in outer space. This is the first time, the (1) **very** first time, in man's long history that such pictures have been possible. (2) **For** many years most people have believed that the earth was ball-shaped. A few thought it was round and (3) **flat**, like a coin. Now we know, beyond doubt, that those few were (4) **wrong**. The photographs show a ball-shaped (5) **object**, bright and beautiful. In colour photographs of the earth, the sky is as (6) **black** as coal. The (7) **ocean** looks much bluer than it usually does to us. All our grey (8) **clouds** are a perfect white in colour; because, of course, the (9) **sun** is for ever shining on them. We are (10) **fortunate** to live on the beautiful earth.