Seasons
What causes the season on Earth?
What is axis or tilt
What is the name of the moon phase when we see the entire lit side facing Earth?
What is full moon
What is a solar eclipse?
A solar eclipse occurs when the Moon passes between the Sun and Earth and blocks some or all of the Sun from view.
What causes ocean tides on Earth?
Tides are caused mainly by the gravitational pull of the Moon and, to a lesser extent, the Sun on Earth's oceans.
Define "orbit" in one short sentence.
Orbit: the path one object takes around another due to gravity.
During which season in the Northern Hemisphere is the North Pole tilted towards the Sun?
What is Summer?
What phase comes just after new moon as the visible illuminated portion increases?
Waxing crescent (then first quarter follows).
What is a lunar eclipse?
A lunar eclipse occurs when Earth passes between the Sun and Moon and Earth’s shadow falls on the Moon.
What name is given to especially high tides that occur when the Sun, Moon, and Earth are nearly in a straight line?
Spring tides.
What does "axis" mean when talking about Earth?
Axis: an imaginary line through Earth about which it spins (rotates).
Explain why summer in the Northern Hemisphere happens at the Same time as Winter in the Southern Hemisphere.
How many main phases are commonly used to describe the lunar cycle (name them briefly)?
Eight main phases: new, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, last (third) quarter, waning crescent.
Why don’t we have a solar and lunar eclipse every month even though the Moon orbits Earth each month?
Because the Moon's orbit is tilted about 5° relative to Earth's orbit around the Sun, so the three bodies don't line up exactly each month; eclipses only happen when the Moon is near the orbital nodes.
What tidal pattern (two high and two low tides each day) do many coastal areas experience, and why does this happen?
Semidiurnal tides — two high and two low tides each lunar day — because Earth's rotation moves locations through two tidal bulges created mainly by the Moon's gravity and inertia.
Define "waxing" and "waning" when describing moon phases.
Waxing: the illuminated portion is increasing; Waning: the illuminated portion is decreasing.
Describe how day length (hours of daylight) changes from winter to summer for a location in the mid-latitudes.
Day length increases from winter to summer — short days in winter, gradually longer days through spring to longest days in summer.
Explain why we see different moon phases even though the Moon does not produce its own light.
We see phases because sunlight illuminates different portions of the Moon as it orbits Earth; the portion lit that we can see changes.
Distinguish between total and partial solar eclipses in terms of the Moon’s shadow on Earth.
In a total solar eclipse the Moon’s umbra (dark central shadow) reaches Earth and the Sun is fully blocked for observers in a narrow path. In a partial eclipse only the penumbra (lighter outer shadow) reaches an area, so only part of the Sun is covered.
Explain how the Moon’s gravitational pull and Earth’s rotation work together to create a tidal bulge.
The Moon's gravity pulls water toward it, producing a bulge on the near side. Inertia and the system's center-of-mass cause a second bulge on the opposite side. As Earth rotates, different places pass through these bulges, causing tides.
What is "umbra" and how does it differ from "penumbra" during an eclipse?
Umbra: the darkest central part of a shadow where the light source is completely blocked. Penumbra: the lighter outer shadow where the light source is only partly blocked.
The tilt of Earth's axis is about how many degrees? How does that tilt affect the intensity of sunlight received at different latitudes?
About 23.5°. The tilt changes the angle sunlight strikes Earth's surface; higher angles (more direct sunlight) concentrate energy and make warmer seasons, while lower angles spread energy and make cooler seasons.
The lunar cycle (time from new moon to next new moon) is about how many days? Describe one reason this period is not exactly 27 days.
About 29.5 days (synodic month). It's longer than the Moon's sidereal orbital period (~27.3 days) because Earth also moves around the Sun, so the Moon must orbit a bit further to realign with the Sun-Earth line.
Explain how the relative positions of the Sun, Moon, and Earth produce a lunar eclipse and why it can be seen from anywhere on Earth's night side.
A lunar eclipse happens when Earth is between the Sun and Moon so Earth's shadow falls on the Moon. Because the Moon is on the far side of Earth from the Sun, any location on Earth's night side that has the Moon above the horizon can see the eclipse.
Describe how local coastline shape and ocean depth can change the height and timing of tides compared to the simple gravitational model.
Narrow bays or inlets can funnel water and amplify tidal ranges, while shallow seas slow and delay tidal waves; resonances and basin shapes can shift timing and increase or decrease tide heights relative to the basic gravitational prediction.
Define "gravitational force" and explain, in one sentence, how it relates to tides.
Gravitational force: the attraction between masses; it pulls ocean water toward the Moon and Sun and is the main cause of tides.