Which one of the following statements about planet Earth is false, when compared with the other planets of the solar system?

Introduction / Context:
Basic astronomy and general science questions frequently ask about key facts related to Earth and its position in the solar system. This question focuses on identifying which of several statements about Earth is false. To answer correctly, you need to know Earth's relative size, density, orbital position, and common nicknames used in astronomy. Recognising that the description red planet belongs to Mars rather than Earth is the key idea being tested here.

Given Data / Assumptions:
– The planet under discussion is Earth, our home planet.
– Four statements are provided about Earth regarding density, size rank, nickname, and distance from the Sun.
– Only one of these statements is false, while the others are essentially correct as per standard astronomy data.
– We assume basic knowledge of the names and simple characteristics of planets in the solar system.

Concept / Approach:
Earth is the third planet from the Sun after Mercury and Venus. By volume and diameter, Earth is the fifth largest planet in the solar system, after Jupiter, Saturn, Uranus, and Neptune. Because it has a large iron core and a relatively compact structure, Earth is also the densest planet. However, the phrase red planet is firmly associated with Mars due to its reddish appearance caused by iron oxide on its surface. Earth is sometimes called the blue planet because of its abundant liquid water and cloud cover. Therefore, the statement that Earth is also known as the red planet is clearly false, while the other statements correctly describe important characteristics of Earth.

Step-by-Step Solution:
Step 1: Check the orbital position of Earth and confirm that it is the third planet from the Sun, which matches a true statement. Step 2: Recall that Earth is smaller than the four giant planets but larger than Mercury, Mars, and Venus, making it the fifth largest planet by size, which is also true. Step 3: Remember that Earth has a high average density and is listed as the densest planet in standard data tables, so that statement is correct. Step 4: Identify the nickname red planet as belonging to Mars, not Earth, which makes the statement calling Earth the red planet false.

Verification / Alternative check:
Astronomy reference books and educational posters commonly show Earth as the third planet from the Sun and label it as the blue planet. They rank planets by size and list Earth as the fifth largest. Data tables of mean density confirm that Earth has the highest average density among the planets. Mars is shown with a reddish surface and is labelled the red planet. These independent sources consistently assign the red planet nickname to Mars rather than to Earth, verifying that this is the incorrect statement in the question.

Why Other Options Are Wrong (meaning not the false one):
It is the densest planet in the solar system: This is essentially correct for Earth and therefore not the false statement being tested here.
It is the fifth largest planet by size: This correctly describes Earth's size ranking and is not the incorrect option.
It is the third planet from the Sun: This is a basic and accurate positional fact about Earth, so it is also not the false statement.

Common Pitfalls:
A common error is to answer too quickly and not notice that the question is specifically asking for the false statement. Some students also confuse nicknames and may loosely remember that some planet is called red without recalling that it is Mars. Others may be unsure about the exact size ranking of Earth and incorrectly doubt the correct statements. To avoid these mistakes, carefully read whether the question is asking for a true or false statement and firmly associate Mars with the red planet and Earth with the blue planet in your memory.

Final Answer:
The false statement about Earth is that it is also known as the red planet, because that description belongs to Mars, not to Earth.