Earth and Sky
How does Earth's rotation cause day and night?
Earth rotates on its axis every 24 hours. The side facing the Sun experiences daylight, while the side facing away experiences nighttime.
What causes Earth to experience the four seasons?
Earth's 23.5° axial tilt and its revolution around the Sun.
How did ancient civilizations measure time before modern clocks were invented?
By watching the Sun, Moon, stars, shadows, and the steady flow of water or sand.
What three astronomical movements are used to measure days, months, and years?
Earth's rotation, Moon's phases, and Earth's revolution
Why do we always see nearly the same side of the Moon?
Because the Moon rotates on its axis at the same rate as it revolves around Earth.
What is the purpose of latitude and longitude.
To identify geographic locations on Earth. Latitude measures north and south positions, while longitude measures east and west positions.
At what degree is Earth's axis tilted relative to the perpendicular to its orbital plane?
Earth's axis is tilted approximately 23.5 degrees.
What is the difference between a solar day and a sidereal day?
A solar day measures Earth's rotation relative to the Sun, while a sidereal day measures Earth's rotation relative to distant stars.
Why did the Romans introduce leap years into the Julian calendar?
To add an extra day every 4th year and keep the calendar aligned with Earth's revolution around the Sun.
How does the Moon's gravitational attraction cause high and low tides on Earth?
The Moon's gravitational pull creates two tidal bulges in Earth's oceans, producing high and low tides as Earth rotates.
What is the Prime Meridian and where is it located?
The imaginary line where latitude and longitude intersect at 0 degrees at Greenwich, England.
Why are days longer during summer and shorter during winter?
Earth's tilt causes the Sun to remain above the horizon for longer periods, allowing more sunlight to reach the surface. During winter, the Sun spends less time above the horizon, resulting in shorter days.
Why is a solar day approximately four minutes longer than a sidereal day?
Because Earth moves around the Sun while rotating, it must turn slightly farther for the Sun to return to the same position in the sky.
Why did Pope Gregory introduce the Gregorian calendar in 1582?
To correct errors in the Julian calendar that cause the calendar dates of the seasons to shift.
What is the difference between spring tides and neap tides?
Spring tides occur when the Sun and Moon align, producing stronger tides. Neap tides occur when their gravitational effects partially oppose each other, producing weaker tides.
What is a great circle?
An imaginary circle that divides a sphere into two halves.
Why is Earth's distance from the Sun not the primary reason for the changing seasons?
The seasons are primarily caused by Earth's axial tilt, which changes the angle and duration of sunlight reaching Earth's surface throughout the year
What two movements of Earth influence how astronomers measure time?
Earth's rotation on its axis and its revolution around the Sun.
What causes the Moon to go through different phases throughout the month?
Its orbit around Earth and the changing angles we view
What is the difference between a solar eclipse and a lunar eclipse?
A solar eclipse occurs when the Moon blocks the Sun, while a lunar eclipse occurs when Earth casts its shadow on the Moon.
What is the celestial sphere?
An imaginary sphere surrounding Earth.
Why does the Northern Hemisphere experience warmer temperatures during summer and colder temperatures during winter?
During summer, the Northern Hemisphere tilts toward the Sun, receiving more direct sunlight. During winter, it tilts away, receiving less sunlight.
Why was the mean solar time system developed, and how does it help us measure time today?
To provide a consistent 24-hour day, making timekeeping more accurate and convenient.
How many days does it take for the Moon to complete its cycle of phases?
Approximately 29.5 days.
Why don't solar and lunar eclipses occur every month?
Because the Moon is tilted about 5 degrees, and the Sun, Earth, and Moon do not line up perfectly every month.