If you don't have enough to worry about, here's more.
The latest SKY & TELESCOPE magazine issue, August/2008, has a
brief news item on page 16, titled:
Is Mercury's Orbit Unstable?
The gist of the news item is that computer simulation shows
that there is a 1-2 percent chance that within 7-billion years
Jupiter's gravity will elongate Mercury's orbit to the point
where it may intersect Earth's orbit, crashing into our
planet.
Sweet dreams.
IMHO I think this planet is in greater danger of being fried and roasted
by a hitherto unknown cosmic event within the next 10,000 years;
which is pure speculation of course.