Tides

[Leonard James]

Hi all,

 

I'm new here and hope this question is posted on the correct forum.

 

Can somebody explain to me why spring tides occur at full moon? I realise that at new moon the sun and moon are pulling in the same direction and thus cause a spring tide, but at full moon the two gravitational forces are directly opposed, and should affect one another negatively.

 

I'm not a scientist, so would appreciate the explanation in layman's language.

 

Many thanks.

Leonard.

[swansont]

Tides aren't the result of direct gravitational attraction, they are the result of differences in gravitational attraction between two points. The closest point to either the sun or the moon feels a stronger force than the center, so there's a bulge due to that. The far side feels less of a force than the center, so there's a bulge in the opposite direction. That's going to be true when they are on the same side of the earth, or on opposite sides. The effects will add.

 

Here's another take:

http://blog.dotphys.net/2009/08/tides-why-are-they-so-hard/

[Leonard James]

Hi Swansont,

 

Many thanks for that. I'm afraid it's too complicated for me to get my head round ... so I shall just take it as read.