There's an old joke about the plantarium lecturer who tells his audience that in 5 billion years the Sun will swell to become a bloated red giant, engulfing the planets Mercury and Venus and eventually perhaps even gobbling up the Earth. Afterward, an anxious member of the audience buttonholes him:
'Excuse me, Doctor, did you say that the Sun will burn up the Earth in 5 billion years?'
'Yes, more or less.'
'Thank God. For a moment I thought you said 5 million.'