Moons Phases and Tides, Exams of Astronomy

Download Moons Phases and Tides and more Exams Astronomy in PDF only on Docsity! Moon’s Phases and Tides Moon Phases  Half of the Moon is always lit up by the sun.  As the Moon orbits the Earth, we see different parts of the lighted area.  From Earth, the lit portion we see of the moon waxes (grows) and wanes (shrinks). The revolution of the Moon around the Earth makes the Moon look as if it is changing shape in the sky  The Moon passes through four major shapes during a cycle that repeats itself every 29.5 days.  The phases always follow one another in the same order: New moon Waxing Crescent First quarter Waxing Gibbous Full moon Waning Gibbous Third (last) Quarter Waning Crescent • IF LIT FROM THE RIGHT, IT IS WAXING OR GROWING • IF DARKENING FROM THE RIGHT, IT IS WANING (SHRINKING) Tides • The Moon's gravitational pull on the Earth cause the seas and oceans to rise and fall in an endless cycle of low and high tides. • Much of the Earth's shoreline life depends on the tides. – Crabs, starfish, mussels, barnacles, etc. – Tides caused by the Moon • The Earth's tides are caused by the gravitational pull of the Moon. • The Earth bulges slightly both toward and away from the Moon. -As the Earth rotates daily, the bulges move across the Earth. • The moon pulls strongly on the water on the side of Earth closest to the moon, causing the water to bulge. Neap Tide Moderate tidal range Description of tides • High water: a water level maximum ("high tide") • Low water: a water level minimum ("low tide") • Tidal range: the difference between high and low tide • Spring Tide: full moon and new moon (14.77 days) • Neap Tide: 1st quarter and 3rd quarter (14.77 days) • How many high tides occur daily? – Two • How many weekly? – Fourteen • How many in 30 days? – Sixty Intertidal Zone zone High tide Low tide