Re: what happen on 05/05/2000?

I assume you are referring to the alleged planetary "alignment."

With respect to this "alignment," nothing much is going to happen. First off, the most of the planets will be on the other side of the Sun, so we won't even get to see the "alignment" itself.

Every fifteen years or so, lots of people get themselves alarmed by the fact that the planets are going to be all in a "line" or on the same side of the Sun. (For a recent example that generated surprisingly little publicity, 1999 March, see APOD.) Much of this alarm is undue.

As the sci.astro FAQ explains:

For starters, the planets only "align" in a very rough fashion. They don't orbit the Sun in the same plane, so it's impossible to get very many of the planets in a straight line. Nevertheless, any time they all get within about 90 degrees of each other, someone will claim they're "aligned." The last time this happened was 1982 when dire predictions were heard about how the "Jupiter effect" would lead to world-wide disaster.

Second, even if they *were* all aligned, the effect on the Earth would be miniscule. It's true that the other planets' gravity does affect the orbit of the Earth, but the effect is small, and lining up all the planets doesn't even come close to making it big enough for anyone to notice. The effect on the Earth is dominated by Jupiter and Venus anyway (Jupiter because it's massive, Venus because it's occasionally very close to us). All the other planets put together only affect us about 10% as much as those two, so the fact that they're all in the same general direction as Jupiter and Venus doesn't make much difference.

Third, even if all the planets could produce a strong gravitational effect on the Earth (which they can't, unless they find a way to increase their mass by a factor of 10--100), it wouldn't result in the "crust spinning over the magma" or some other dire effect, since their gravity would be pulling on every part of the Earth (almost) equally.

The "(almost)" is because the other planets do exert tidal forces on the Earth, which means they pull on different parts of the Earth very slightly differently. However, tidal forces decrease *rapidly* with distance (as the third power), so these forces are very small: The tidal force from Venus at its closest approach to Earth is only 1/17,000th as large as the Moon's, and we seem to survive the Moon's tides well enough twice a day. If the Moon raises tides of 1 meter (three feet) where you live, Venus at its closest will raise tides of 1/20th of a millimeter, or about the thickness of a hair. The other planets have even smaller tidal effects on the Earth than Venus does.

Finally, it's worth remembering that the Earth is about 4.5 billion years old. Whilst these "alignments" may be rare in terms of a human lifetime (occurring once every few decades), they've occurred numerous times during the time that life has existed on this planet, and many, many times in the comparatively brief time that humans have been around. Brian Monson [has] found ten such "alignments" between AD 1000 and AD 2000. Thus, over the history of this planet there have been about 45 million such "alignments." The fact that we're still here to talk about it is proof enough that nothing too terrible happens!