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Earth and Space - The Solar System and Planetary Motion

Grade 4IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

The Solar System is composed of a central star, the Sun, and 88 major planets orbiting it: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Rotation refers to Earth spinning on its imaginary axis. One full rotation takes approximately 2424 hours, which creates the cycle of day and night.

Revolution is the movement of Earth around the Sun in an elliptical path called an orbit. One complete revolution takes approximately 365.25365.25 days, defining 11 year.

Earth is tilted on its axis at an angle of approximately 23.523.5^\circ. This tilt, combined with the revolution around the Sun, is responsible for the changing seasons (SpringSpring, SummerSummer, AutumnAutumn, WinterWinter).

The Moon is Earth's only natural satellite. It revolves around the Earth approximately every 27.327.3 days, leading to the different lunar phases we see from Earth.

Gravity is the force of attraction that keeps planets in their orbits around the Sun and the Moon in orbit around the Earth.

📐Formulae

1 Day=24 Hours1 \text{ Day} = 24 \text{ Hours}

1 Year365.25 Days1 \text{ Year} \approx 365.25 \text{ Days}

1 Leap Year=366 Days1 \text{ Leap Year} = 366 \text{ Days}

Earth’s Axial Tilt23.5\text{Earth's Axial Tilt} \approx 23.5^\circ

💡Examples

Problem 1:

If the Earth takes 365.25365.25 days to orbit the Sun once, how many days will have passed after 44 complete orbits?

Solution:

365.25×4=1461365.25 \times 4 = 1461 days.

Explanation:

To find the total days, multiply the time for one revolution (365.25365.25) by the number of orbits (44). This extra 0.250.25 day every year is why we add a 'Leap Day' to the calendar every 44 years.

Problem 2:

Identify which movement causes day and night and how long it takes in minutes.

Solution:

24×60=144024 \times 60 = 1440 minutes.

Explanation:

Day and night are caused by Earth's rotation on its axis. Since one rotation takes 2424 hours and there are 6060 minutes in an hour, the total time is 14401440 minutes.

Problem 3:

Why does the Moon appear to change shape over the course of a month?

Solution:

The Moon's phases change based on its position relative to the Earth and the Sun.

Explanation:

As the Moon orbits the Earth, different portions of its sunlit side become visible to us. We call these stages phases, such as the NewMoonNew Moon, FirstQuarterFirst Quarter, FullMoonFull Moon, and ThirdQuarterThird Quarter.

The Solar System and Planetary Motion - Revision Notes & Key Formulas | IB Grade 4 Science