Observing the Phases of the Moon Moon Orbit

Observing the Phases of the Moon

Moon Orbit • Moon orbits Earth every 27. 3 days • As it revolves it also rotates on its axis • Therefore, the same side of the Moon faces Earth at all times

The Earth, Moon & Sun Moon Sun Earth

Lunar Phases • When we see the Moon, we see the light from the Sun reflected off its surface – The illuminated side does not always face Earth – We see different amounts of the lit side as the Moon orbits Earth

Why does the moon not look the same every night? • Different phases of the moon

The Far Side of the Moon • The full view of the far side of the moon is never visible from Earth • The far side was first photographed by the Soviet Luna 3 orbiter in 1959

Naming the phases of the moon.

Terminology for Moon Phases: • Crescent – phases where the moon is less than half illuminated. • Gibbous - phases where the moon is more than half illuminated. • Waxing - "growing" or expanding in illumination • Waning - "shrinking" or decreasing in illumination.

Phases

Phases in Motion

Waxing Gibbous

Waxing Cresent

Last Quarter

New Moon

Full Moon

Waning Cresent

Eclipses • The Moon's orbit around Earth is tilted relative to Earth's orbit around the sun. • Lunar Eclipses occur only at the time of the full moon. • Solar Eclipses occur only at the time of the new moon. • An eclipse can only happen when the sun, moon and Earth are in a nearly perfect straight line.

What happens more often, solar or lunar eclipses? • Solar eclipses are fairly numerous, about 2 - 5 per year, but the area on the ground covered by totality is only a few km wide. • In any given location on Earth, a total eclipse happens only once every 360 years. • Eclipses of the Moon by the Earth's shadow are actually less numerous than solar eclipses; however, each eclipse covers about 1/2 the surface of the Earth. At any given location, you can have up to 3 lunar eclipses per year, but some years there may be none. • In any one calendar year, the maximum number of eclipses is 4 solar and 3 lunar.

Lunar Eclipse • When the Earth is directly between the Sun and the Moon • Total Eclipse - the entire moon passes through the Earth’s shadow • Partial Eclipse - only part of the moon passes through the Earth’s shadow

Lunar Eclipse http: //www. youtube. com/watch? v=wuh. NZej. He. Bg

Solar Eclipse • When the moon is between the Sun and Earth • Only possible when there is a new Moon • Only the Corona of the Sun is visible

Solar Eclipse

Solar Eclipse

Tides & Tidal Force • Gravity of moon and sun pull the Earth’s water toward them. • This causes tides: – The rising and falling of the surface of large bodies of water

• This results in TWO high tides and TWO lows tides on Earth each day. The time between low and high tide is approximately SIX hours.

Tide

Tidal Force • The side of the planet/moon closest to the other body experiences a tidal pull due to the force of gravity. • When Sun and Moon are aligned then the effect on the tides is increased. • When the Sun and Moon are perpendicular to one another the two gravitational pulls counteract each other and there are weaker tides formed.