Here's the 'superalignment' I'm referring to:
We've all heard the stories about 'mystical planetary alignments' that will increase/decrease the effective surface gravity experienced on Earth (one debunked here on snopes), sometimes referred to as 'Zero G Day'.
What I'm wondering is: what would be the maximum possible effect on a given weight (ratio of 'normal' weight to 'alignment' weight)?
- Noon at a new moon, Venus and Mercury between the Earth and the Sun, Mars, Jupiter, Saturn, Uranus and Neptune across the sun in roughly a straight line (maximum lightness).
- Midnight during the same alignment (maximum heaviness - almost the same ratio, but 2 Earth radii further away from the planets and sun).
Also, how often (if ever) could this happen?
I have calculated the resulting effects of this 'superalignment':
The result is that with the planets and our moon aligned as much as they can be to have their forces be additive, their gravity culminates in a $\pm0.06\%$ difference. Since I weigh 90kg, I would weigh 89.94 kg at noon and 90.05 kg at midnight.
Now, the last part of this question remains - would this superalignment, or something approximating this superalignment, ever occur, and if so would it be on a repetition and how often?