The signal the mothership is sending, the so called beacon that times the arrival of all the ships over all their target sites, makes no sense. Why would you need that as the captain of one of the smaller ships? If the order is given: be there at that time, why would you not be there? You're driving this big mother of a ship, you certainly can make it in time.

And why bother waiting for the signal anyway? Why not enter the atmosphere guns blazing? Who is going to stop you? You just kill anything that moves. They certainly had the fire power.

Why fire at the cities? Stupid, unnecessary mistake. First, from deep space, you make a detailed map of the planetary surface, then you fry all the cropland. You don't need to kill anybody (save the odd unlucky farmer) and you wait for society to destabilize. You can have whatever stores you want, they will not last a year.

Why bother with the land? have them form a neat line over the oceans and turn them into water vapor. The heat those beams produced must certainly have been sufficient (weapons grade and all). You wait for the  clouds to block the sun and winter sets in. After a time, you just come down and harvest what you want.

More exotic: Those ships were big, I mean REALLY big. Why not fly a formation way out into space, and form a physical barrier before the sun, following the earth's orbit? You induce arctic conditions overnight. You just do that and wait until earth is all neatly frozen over. There will be massive extinction of species on a planetary scale, and after a while you just clean up and get what you want. What do these aliens want anyway? If it's resources, there must be limitless amounts in the asteroids and on planetary moons. If it's "lebensraum" their technology must be sufficient for terraforming (or their equivalent). Why bother with earth?

Updated 29/5/98 by JWES