GK Questions with Answers - Space

Space science is one of the most fascinating and important topics in general knowledge, especially for students preparing for competitive exams like UPSC, SSC, Banking, Railways, Defence, and State PSCs. Questions related to space research, satellites, space missions, and astronomical discoveries are frequently asked in the general awareness section. Understanding space not only builds scientific awareness but also helps aspirants stay updated with India’s remarkable progress in space technology, led by organizations like ISRO (Indian Space Research Organisation) and other global space agencies such as NASA, ESA, and JAXA.

In this article, we have compiled a detailed collection of Space GK Questions with Answers along with brief explanations to make your preparation more effective. These MCQs cover important topics such as Indian and international space missions, astronauts, space telescopes, launch vehicles, satellites, and recent space discoveries. Practicing these space general knowledge questions and answers 2025 will help you strengthen your science and technology understanding and improve your performance in upcoming competitive exams.

GK Questions with Answers - Space

1. How many planets are there in the solar system?

1. 7
2. 8
3. 9
4. 10

Answer: B) 8

Explanation: The solar system consists of the Sun and all objects that orbit it, including planets, moons, asteroids, comets, and dwarf planets. There are 8 recognized planets in the solar system after Pluto’s reclassification in 2006. They are divided into two groups: 1.Terrestrial (rocky) planets: Mercury, Venus, Earth, Mars 2.Gas and ice giants: Jupiter, Saturn, Uranus, Neptune. Pluto, Ceres, and Eris are classified as dwarf planets, not full planets. The International Astronomical Union (IAU) is the authority for naming and classifying celestial bodies.

2. Which planet is closest to the Sun?

1. Earth
2. Venus
3. Mercury
4. Mars

Answer: C) Mercury

Explanation: Mercury is the closest planet to the Sun. Because of its proximity, it completes one revolution around the Sun in just 88 Earth days, making it the fastest orbiting planet in the solar system. Despite being closest to the Sun, Mercury is not the hottest planet because it has no thick atmosphere to retain heat. It has extreme temperature variations, ranging from about -173°C at night to 427°C during the day.

3. Which is the hottest planet in the solar system?

1. Mercury
2. Mars
3. Jupiter
4. Venus

Answer: D) Venus

Explanation: Venus is the hottest planet in our solar system, with surface temperatures reaching about 465°C. It is the second planet from the Sun, but its thick atmosphere of carbon dioxide and clouds of sulfuric acid trap heat through the greenhouse effect. Venus rotates from east to west, opposite to most planets — a motion known as retrograde rotation. Its atmospheric pressure is about 92 times that of Earth, which would crush most spacecraft.

4. Which is the brightest planet in the solar system?

1. Mars
2. Venus
3. Jupiter
4. Saturn

Answer: B) Venus

Explanation: Venus is the brightest planet in the night sky and is often called the “Morning Star” or “Evening Star”. Its brightness is due to its highly reflective clouds, which reflect about 70% of the sunlight that hits them. Venus is visible to the naked eye and is the third brightest object in the sky after the Sun and the Moon. It has a similar size and composition to Earth, which is why it is often referred to as Earth’s twin.

5. Which is the coldest planet in the solar system?

1. Uranus
2. Neptune
3. Saturn
4. Mars

Answer: A) Uranus

Explanation: Uranus is the coldest planet in the solar system, with an average temperature of about -224°C. Although Neptune is farther from the Sun, Uranus is colder because it emits very little internal heat. Uranus rotates on its side (tilted at about 98°), causing extreme seasonal variations. It is the seventh planet from the Sun and was discovered by William Herschel in 1781.

6. Which is the largest star in the universe (by size)?

1. Sun
2. Sirius
3. Betelgeuse
4. UY Scuti

Answer: D) UY Scuti

Explanation: UY Scuti is currently considered the largest known star by radius in the universe (as of 2025). It is a red supergiant star located in the constellation Scutum, about 9,500 light-years away from Earth. UY Scuti’s radius is estimated to be about 1,700 times larger than the Sun’s radius. If placed at the center of our solar system, its surface would extend beyond the orbit of Jupiter.

7. Which is the largest planet in our solar system?

1. Earth
2. Saturn
3. Jupiter
4. Neptune

Answer: C) Jupiter

Explanation: Jupiter is the largest planet in the solar system. It is a gas giant, mainly composed of hydrogen and helium, and has no solid surface. Jupiter has a strong magnetic field and over 90 known moons (as of 2025). The Great Red Spot, a giant storm larger than Earth, has been raging on Jupiter for over 300 years. Jupiter takes about 12 Earth years to complete one orbit around the Sun.

8. What is the natural satellite of Earth?

1. Sun
2. Moon
3. Mars
4. Jupiter

Answer: B) Moon

Explanation: The Moon is Earth’s only natural satellite and the fifth largest moon in the solar system. It completes one orbit around Earth in 27.3 days and the same time for one rotation, which is why we always see the same side of the Moon from Earth. The Moon has no atmosphere, no liquid water, and very low gravity (about 1/6th of Earth’s).

9. Which planet has the most moons?

1. Saturn
2. Jupiter
3. Uranus
4. Neptune

Answer: A) Saturn

Explanation: As of 2025, Saturn has the most moons in the solar system — at least 145 confirmed moons. Saturn’s largest moon, Titan, is bigger than the planet Mercury and has a thick atmosphere. The planet is also known for its spectacular ring system, made up of ice and rock particles. Saturn is the second-largest planet and a gas giant, mainly composed of hydrogen and helium.

10. What was the name of the first satellite launched by India?

1. Bhaskara
2. INSAT-1A
3. Rohini
4. Aryabhata

Answer: D) Aryabhata

Explanation: Aryabhata was India’s first artificial satellite, launched on 19 April 1975. It was named after the ancient Indian mathematician and astronomer Aryabhata. The satellite was launched by the Soviet Union using a Kosmos-3M launch vehicle from the Kapustin Yar launch site. Aryabhata’s main objectives were to conduct scientific experiments in X-ray astronomy and solar physics. The launch marked the beginning of India’s space journey, led by the Indian Space Research Organisation (ISRO).