I didn't receive your question until May 8, so the best evidence against the astrological beliefs you mention is simple: we're still here!
In general, planetary alignments, or "conjunctions", are interesting, but have no significant effects on the Earth or any of the other planets. Some people think the gravitational effects of the other planets might shift the Earth's orbit, or "knock it out of orbit" altogether. This is quite impossible. You can calculate the strength of the other planets' gravitational pull on the Earth, compared to the Sun's pull. Jupiter pulls the Earth with a maximum force only 54 millionths as large as the Sun's pull. Venus's pull is at most 32 millionths of the Sun's. The other planets exert even smaller forces. It's hard to see how such tiny forces could cause the earth-shattering effects some people are predicting.
Second, events like this have occurred before, many times in Earth's history. A recent roughly similar case occurred in early August, 1861: then, the planets and the moon about as lined up as they are today. Nothing happened. This sort of arrangement has occurred countless times before, with no effect.
Conjunctions are harmless, but sometimes pretty. It's nice see to several members of the solar system family all hovering in one spot in the sky. Unfortunately, this time the planets are all hidden by the sun's glare, so we can't see them. The next really good multi-planet conjunction will be in April, 2020. On the morning of April 1, 2020, Mars, Jupiter, and Saturn will be visible in the sky, so close together you could cover all three with a fist held at arm's length. On April 15, they'll be a little farther apart (a spread handsbreadth), but will be joined by the Moon. It will be quite beautiful to see!
Try the links in the MadSci Library for more information on Earth Sciences.
