Burntcoat Head, Nova Scotia flow back out. Each day the tides times will change approximately by one hour. The reason why the tides fills and empties the Bay of Fundy each day is due to gravitational pull of the moon and the sun on the earth, as well as earths rotation. Spring tides happen twice a month when the sun, moon, and earth are aligned. During this alignment the tides rise higher than average. Neap tides occur during the first and third quarter moon. During this time the high tides heights are lower than average. At low tide the ocean floor becomes exposed allowing
Frozen orbit propellant. For most spacecraft, changes to orbits are caused by the oblateness of the Earth, gravitational attraction from the sun and moon, solar radiation pressure, and air drag. These are called "perturbing forces". They must be counteracted by maneuvers to keep the spacecraft in the desired orbit. For a geostationary spacecraft, correction maneuvers on the order of 40–50 m/s per year are required to counteract the gravitational forces from the sun and moon which move the orbital plane away from the equatorial plane of the Earth. For sun-synchronous spacecraft, intentional shifting of the orbit plane (called "precession") can be used