🌊 TIDES & THE MOON
PAGE 1 OF 5 — MOON PULL
GRAVITY TUG
THE MOON LIFTS WATER
Stand on a beach and you can watch the sea level rise and fall. Tides are mainly caused by the Moon's gravity pulling on Earth. The pull is strongest on the side of Earth facing the Moon. Ocean water heaps up into a bulge there. Earth and the Moon are a linked system moving through space together. The Moon does not just pull Earth. It pulls the oceans hardest on the near side.
🌙 PULL
The Moon's gravity tugs on Earth's oceans. The near side feels the strongest pull, creating a tidal bulge.
TIDES!
OCEAN
🌊 Water responds to gravity
🏖️ Beaches flood and drain
🏖️ Beaches flood and drain
MOON
🌙 Main driver of daily tides
🔗 Earth-Moon system moves together
🔗 Earth-Moon system moves together
PAGE 2 OF 5 — TWO BULGES
OPPOSITE SIDE
WHY TWO HIGH TIDES
High tide is not only on the side facing the Moon. There is also a bulge on the opposite side of Earth. The Moon pulls Earth itself a little toward it, but water on the far side is pulled less strongly and piles up there too. As Earth rotates through these two bulges, most places get roughly two high tides and two low tides about every 24 hours and 50 minutes.
🌊 TWO
Earth rotates through two tidal bulges, so most coasts see high tide about twice each day.
BULGE!
NEAR
🌙 Strongest pull on near ocean
⬆️ Water swells toward Moon
⬆️ Water swells toward Moon
FAR
🌍 Far side bulges too
🔄 Spin brings two highs daily
🔄 Spin brings two highs daily
TIMING
⏱️ About 24 hours 50 minutes
🌊 Two highs, two lows daily
🌊 Two highs, two lows daily
PAGE 3 OF 5 — SUN HELPS TOO
ALIGN
☀️ Sun plus Moon pull together
📈 Higher highs, lower lows
📈 Higher highs, lower lows
NEAP
🌗 Quarter moons weaken the combo
📉 Smaller tidal range
📉 Smaller tidal range
EXTRA TUG
SUNLIGHT AND TIDES
The Sun also pulls on Earth's oceans, but it is farther away so its tidal effect is smaller than the Moon's. When the Sun, Moon, and Earth line up at new moon or full moon, their pulls combine. That makes extra-high high tides and extra-low low tides called spring tides. The name has nothing to do with the spring season. It comes from the idea of the waters springing higher.
🌕 SPRING
Spring tides occur at new and full moon when the Sun and Moon pull together on Earth's oceans.
SPRING!
PAGE 4 OF 5 — NEAP TIDES
RIGHT ANGLES
WHEN PULLS CANCEL PARTLY
At first quarter and third quarter moon, the Sun and Moon pull at right angles to each other. Their tidal forces partly cancel. The result is neap tides, with a smaller difference between high and low water. Neap tides are gentler for boats and beaches. Spring and neap tides repeat in a cycle of about two weeks as the Moon orbits Earth and changes phase.
🌗 NEAP
Neap tides happen when the Sun and Moon pull at right angles, producing a smaller tidal range.
NEAP!
GENTLE
🌊 Smaller rise and fall
⛵ Calmer coastal waters
⛵ Calmer coastal waters
CYCLE
🔄 About two weeks spring to spring
🌙 Moon phase sets the pattern
🌙 Moon phase sets the pattern
QUARTER
🌗 First and third quarter moons
📉 Pulls partly cancel out
📉 Pulls partly cancel out
PAGE 5 OF 5 — TIDE FACTS
WRAP UP
THE MOON MOVES THE SEA
The Moon's gravity pulls Earth's oceans into bulges. One bulge faces the Moon, and another forms on the opposite side. Most places get high tide about twice a day. When the Sun and Moon align, spring tides bring bigger swings. At quarter moons, neap tides are gentler. Watch the beach and you are seeing the Moon's gravity at work.
TIDES!
WATCH
🌊 Tide tables predict highs and lows
🌙 Moon phase changes the range
🌙 Moon phase changes the range
REMEMBER
🪐 KEY FACTS
The Moon's gravity drives tides. Two bulges mean two highs daily. Spring tides come when Sun and Moon align. Neap tides come at quarter moons.
🌙 Moon gravity pulls ocean water
🌊 Two bulges, two highs per day roughly
🌕 Spring and neap tides cycle with Moon phase
🌊 Two bulges, two highs per day roughly
🌕 Spring and neap tides cycle with Moon phase
🧠 QUIZ TIME!
TIDES & THE MOON · 5 QUESTIONS
QUESTION 01
What mainly causes ocean tides on Earth?
QUESTION 02
Why are there two high tides each day in most places?
QUESTION 03
When do spring tides occur?
QUESTION 04
What are neap tides?
QUESTION 05
Does the Sun affect tides?
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