Tidal Forces Visualizer
See how the Moon’s gravity creates two tidal bulges on Earth — one on the near side and one on the far side. Toggle the Sun to see spring tides (aligned) and neap tides (perpendicular). Drag the Moon or animate one lunar month to watch the cycle unfold.
Why two bulges?
The tidal force is the difference between the Moon’s gravitational pull at a given point and the pull at Earth’s center. On the near side, the pull is stronger than average, so water is pulled toward the Moon. On the far side, the pull is weaker than average, so water is “left behind” — it bulges away from the Moon. This is why there are two high tides per day, not one.
Spring and neap tides
When the Sun and Moon are aligned (new moon or full moon), their tidal forces add up, producing spring tides with the highest highs and lowest lows. When they are at right angles (first or third quarter), the forces partially cancel, producing neap tides with smaller tidal range.
The tidal force formula
The tidal force scales as F ∝ M / r³, where M is the mass of the attracting body and r is its distance. Despite the Sun being much more massive than the Moon, the Moon is much closer, and the cubic distance dependence makes the Moon’s tidal influence about 2.2 times stronger than the Sun’s.