Composite photo showing difference
in water level during low tide and high tide.
- sea tides are the rise and fall of the water level in the earth’s oceans – they happens twice a day.
- gravitational pull of the Moon and the Sun create the tides on Earth.
- the Moon’s pull creates two bulges in the sea – one below the Moon and one on the opposite side of Earth.
- as the Earth’s spins, the tidal bulges seems to move around the world, creating two high tides every day.
Diagram of neap tides and spring tides
- neap tides – small tides – that happen when the Sun and the Moon are ar the right angles to the Earth and their pulls are weakened by working against one another.
- spring tides – very high tides – that happen when the Sun and Moon are in line, and combine their pull.
- the solid earth has tides too – they are very slight and the Earth only moves about 0.5 metres – this is called Earth Tide or Body Tide.
- tides are also any uplift created by the pull of gravity, as one space object orbits another.
Did you know?
- some moons orbiting large planets – Jupiter’s moon – Io which have stretched so much that its interior is heated enough to create many volcanoes today.
Io’s volcanoes today
- whole galaxies can be affected by tidal pulls – making them stretch as they are tugged by the gravitational pull of other passing galaxies.
NGC 6050/IC 1179 (Arp 272) is a remarkable collision between two spiral galaxies,
NGC 6050 and IC 1179, and is part of the Hercules Galaxy Cluster,
located in the constellation of Hercules.
(Picture: NASA, ESA, the Hubble Heritage Team)