Which of the following planets is popularly known as the "Blue Planet"?

Introduction / Context:
This question lies in the basic astronomy and general science portion of general knowledge. Examinations often ask about the popular nicknames of planets in our solar system, such as "Red Planet" for Mars or "Blue Planet" for Earth. Knowing these nicknames helps students quickly identify key characteristics associated with each planet.

Given Data / Assumptions:
- The question asks specifically for the planet known as the "Blue Planet".
- Options include Jupiter, Mars, Earth, Saturn and Venus, all major planets in the solar system.
- The nickname is based on the appearance of the planet when viewed from space.
- We assume standard school-level planetary science as the reference.

Concept / Approach:
The colour-based nicknames of planets are derived from the way each planet reflects sunlight and the composition of its atmosphere and surface. Earth is called the "Blue Planet" because a large portion of its surface is covered by liquid water in oceans and seas, which appear blue from space. The presence of a relatively clear atmosphere also allows this blue colour to dominate the view. In contrast, Mars looks reddish due to iron oxides, Jupiter and Saturn have banded cloud patterns, and Venus appears bright white-yellow due to thick clouds of sulphuric acid and carbon dioxide.

Step-by-Step Solution:
Step 1: Recall the common planetary nicknames: Mars is the "Red Planet", Earth is the "Blue Planet".Step 2: Think about the visual appearance of Earth from space with its blue oceans and white clouds standing out against the darkness.Step 3: Compare with other options. Jupiter is known mainly for its Great Red Spot and cloud bands, not for an overall blue colour.Step 4: Saturn is recognised for its rings and pale yellowish tint, while Venus appears bright and yellowish-white.Step 5: Therefore, the planet whose dominant colour is blue and is widely called the "Blue Planet" is Earth.

Verification / Alternative check:
Images from space agencies show Earth as a beautiful blue and white marble, due to the huge coverage of oceans and the scattering of sunlight in the atmosphere. School textbooks, encyclopedias and documentaries all repeat the phrase "Earth, the Blue Planet", which makes this association very strong. No other planet is consistently described with this nickname in mainstream education resources, so this confirms that Earth is the correct answer.

Why Other Options Are Wrong:
Jupiter: A gas giant with multicoloured cloud bands and the Great Red Spot, not an overall blue appearance.
Mars: Known as the "Red Planet" because its iron-rich surface soils give it a reddish colour.
Saturn: Famous for its rings and pale yellowish hue, not blue dominance.
Venus: Appears bright yellowish-white due to dense clouds and is often called Earth's twin in size, but not the "Blue Planet".

Common Pitfalls:
Some learners may overthink and try to associate blue with gas giants or outer planets without recalling the standard nicknames taught in school. Another mistake is mixing up the colours of Earth and Neptune, since Neptune can also look bluish due to methane in its atmosphere, but is not commonly called the "Blue Planet" in basic GK contexts. Remembering that oceans and life-supporting water give Earth its distinctive blue look helps fix this fact firmly.

Final Answer:
Earth