Explanation: Nebular hypothesis – The planets were formed out of a cloud of material associated with a youthful sun, which was slowly rotating. The theory was developed by Immanuel Kant. But Mathematician Laplace revised it in 1796. Other Hypothesis: Big Bang Theory – Propounded by George Lamaitre related to the origin of the universe .

Explanation: Rocks and metals. Terrestrial Planets – Mercury, Venus (Earth’s sister planet), Earth and Mars. They are categorised into the following: Silicate Planets, Iron Planets, Coreless Planets, Carbon (diamond) Planets. Saturn, Jupiter, Uranus and Neptune are called Jovian Planets because of their large size (Jovian is named after Jupiter) and their hydrogen content.

Explanation: Increasing. In 1929, Edwin Hubble announced that almost all galaxies appeared to be moving away from us. He found that the universe was expanding – with all of the galaxies moving away from each other. This phenomenon was observed as a redshift of a galaxy’s spectrum.

Explanation: Jupiter is the largest planet in the solar system. It is made mostly of hydrogen and helium. Number of Moons – 95. Neptune – It is the only planet in our solar system not visible to the naked eye. It has 14 Moons.

Explanation: Fred Hoyle. Steady-State Theory : It is a theoretical model in which the Universe is constantly expanding but with a fixed average density. The theory was put forward by three scientists (1948) : Sir Hermann Bondi, Thomas Gold, and Sir Fred Hoyle.

Explanation: Pluto. The five dwarf planets are Ceres, Pluto, Makemake, Haumea, and Eris. A dwarf planet is a celestial body that is in orbit around the Sun and has enough mass to be roughly round in shape.

Explanation: Venus – The second planet closest to the sun. It is also called Earth’s twin sister because it is similar in size and density as of the Earth. It is also known as Morning and Evening Star. It rotates from east to west i.e. in clockwise direction. It does not have its own natural satellite.

Explanation: Comets. Meteors are bits of rock and ice that are ejected from comets as they move in their orbits about the Sun. Meteorite – Asteroids after the collision are known as a meteorite. usually originate from the asteroid belt between Mars and Jupiter.

Explanation: Uranus. Neptune is the second coldest planet. Venus is the hottest planet of all eight planets.

Explanation: Neptune – Farthest-known planet from the Sun. Rotation on its axis – 16 hours. Revolution – 165 Earth years. Size – 17 times the mass of Earth. Moons – 14. Natural satellite – Triton (largest moon). Only a planet which is invisible to the naked eye.

Explanation: 27. Moon is the only natural satellite of planet Earth. It takes 27 days, 7 hours and 43 minutes to complete one revolution around the Earth. Earth’s Moon is the fifth largest moon in the solar system (Largest – Ganymede of Jupiter). Distance – 384,400 kilometers from Earth.

Explanation: Titan – The second-largest moon in our solar system. Ganymede (Jupiter’s moon ) is the largest moon in the solar system. Atlas – It is a satellite of Saturn which was discovered by Richard Terrile. Carme – It is one of the moons of Jupiter which was discovered by Seth Barnes Nicholson. Europa – It is the moon of Jupiter.

Explanation: 6371 km. Earth Distance from the Sun (150 million km), Surface area: 510.1 million km², Land area: 149 million km², Gravity: 9.8 m/s².

Explanation: Orion is located on the celestial equator and can be seen throughout the world. It is named after the hunter in Greek. Ursa Major or Great Bear: A constellation in the northern sky. The constellation Leo : Seen in the northern hemisphere in the spring. Cassiopeia : A large constellation located in the northern sky, named after Cassiopeia, the vain and boastful queen in greek. There are 88 constellations.

Explanation: Cosmos (Greek word) meaning both “order” and “world”.

Explanation: 90-93. In 24 hours, the space station makes 16 orbits of Earth, traveling through 16 sunrises and sunsets.

Explanation: 1 day. Rotation time of planets (Approx.): Earth (1 day – 23 hours 56 min), Jupiter (9 hours 56 minutes), Saturn (10 hours 40 minutes), Uranus (17 hours 14 minutes) and Neptune (16 hours).

Explanation: Penumbral (Lunar eclipse). A solar eclipse occurs when the Moon passes between Earth and the Sun. Types of solar eclipse: Total (Completely blocking the face of the Sun), Hybrid (the Moon is farther away from Earth, it appears smaller than the Sun and does not completely cover the Sun) and Annular (when Sun is at or near its farthest point from Earth).

Explanation: 8. Interstellar distance: Distance between any two celestial bodies; measured in astronomical units (AU). Moon: 1.3 light-seconds away from the Earth. Proxima Centauri: 4.2 light-years from Sun. Light – year is the distance light travels in one year. 1 Light year = 63241 AU (approx).

Explanation: Mars and Jupiter. Asteroid Belt separates the inner and outer planets. Jupiter and Saturn, Uranus and Neptune are the Outer planets (Last four from the Sun) and also known as Jovian Planets. The first four planets (Mercury, Venus, Earth and Mars) are known as Inner or Terrestrial planets.

Explanation: Galileo Galilei. He was an Italian astronomer and scientist. He described the rings of Saturn, the phases of Venus, sunsets, and the bumpy lunar surface. The four moons he discovered were: Io, Europa, Ganymede, and Callisto.

Explanation: Christiaan Huygens. His other inventions: pendulum clock, Centrifugal governors and magic lantern.

Explanation: 1. The Moon is Earth’s only natural satellite circling the planet at an average distance of 384,400 kilometers. The Moon’s presence helps stabilize our planet and moderate our climate. A single orbit of our planet takes the Moon 27.3 Earth days – The same amount of time it takes for the satellite to also rotate once on its axis. Huygens is the Moon’s tallest mountain.

Explanation: I, II and III. Celestial bodies (heavenly bodies) include: Planets, Stars, Satellites, Comets, Asteroids, Meteors and Meteorites, Galaxies. Halley’s Comet (1P/Halley) is a short-period comet visible from Earth every 75–79 years.

Explanation: Both I and II. When there are two full moons within a month, the second full moon is called a Blue Moon, When a full moon occurs at its perigee (the moon is closest to the earth) it is called a Supermoon.

Explanation: Ceres is a dwarf planet in the asteroid belt between the orbits of Mars and Jupiter. Eris is the most massive and one of the largest known dwarf planets in the Solar System. Haumea is a dwarf planet located beyond Neptune’s orbit.

Explanation: Van Allen. An aurora is a natural phenomenon which is characterized by a display of a natural-coloured (green, red, yellow or white) light in the sky. Kuiper belt, flat ring of icy small bodies that revolve around the Sun beyond the orbit of the planet Neptune.

Explanation: Pluto. Charon is known as Pluto. It is the largest of the five known natural satellites of the dwarf planet Pluto.

Explanation: Neptune is the eighth and farthest-known Solar planet from the Sun. It is 17 times the mass of Earth. Neptune is dark, cold, and very windy.

Explanation: December/January. The meteor shower named Quadrantids is generally visible from Earth. The Quadrantids can produce over 100 meteors per hour in a moonless sky.

Explanation: April. The radiant point for the Lyrid meteor shower is near the constellation Lyra, which has the bright star Vega in the east.

Explanation: galaxy. IC 1101 is a supergiant elliptical galaxy at the center of the Abell 2029 galaxy cluster and is one of the largest known galaxies.

Explanation: 29.5 days. The time interval between a full moon and the next repetition of the same phase, a synodic month, averages about 29.53 days.

Explanation: 1.74 × 106 m. The distance between the moon and the earth is 384,400 km.

Explanation: 152 million km. Aphelion is the point of the Earth’s orbit that is farthest away from the Sun. Perihelion is the point of the Earth’s orbit that is nearest to the Sun.

Explanation: outer core. On Earth, flowing liquid metal in the outer core of the planet generates electric currents. The rotation of Earth on its axis causes these electric currents to form a magnetic field which extends around the planet.

Explanation: ) Diastrophism. Denudation is the process of wearing away the Earth’s surface by weathering and erosion. Volcanism is the process of molten rock (magma) erupting onto the Earth’s surface.

Explanation: Celestial bodies are objects in space, such as stars, planets, moons, and galaxies.

Explanation: Venus. Lucifer means “Lightbringer”. Other Planet Nickname – Ringed Planet (Saturn), Red Planet (Mars), Giant Planet (Jupiter).

Explanation: lunar exosphere bounded by the emptiness of space and the Moon’s surface , is an atmosphere so thin that atoms really collide. Chandrayaan-2 observed Argon-40 in the lunar exosphere.

Explanation: 15. On its axis, the earth rotates 360 degrees every 24 hours.

Explanation: a, b and d. Intertropical Convergence Zone (ITCZ) – The region that circles the Earth, near the equator, where the trade winds of the Northern and Southern Hemispheres come together. Seasonal shifts in the location of the ITCZ drastically affects rainfall in many equatorial nations, resulting in the wet and dry seasons of the tropics rather than the cold and warm seasons of higher latitudes.

Explanation: South. The position of the rising sun keeps on moving towards the south in the period from 21st June to 22nd December. This period is called Dakshinayan. From 22nd December to 21st June, the sun keeps on moving towards the north. This period is called Uttarayan.

Explanation: Warm – The region between the Tropic of Cancer and the Tropic of Capricorn is characterized by hot temperatures, high humidity, and abundant rainfall.

Explanation: Chhattisgarh. The Tropic of Cancer passes through eight states in India – Gujarat (Jasdan), Rajasthan (Kalinjarh), Madhya Pradesh (Shajapur), Chhattisgarh (Sonhat), Jharkhand (Lohardaga), West Bengal (Krishnanagar), Tripura (Udaipur) and Mizoram (Champhai).

Explanation: 21 March and 23 September. Equinox is the situation when the equator receives the vertical rays of the Sun and day and night are equal. Spring equinox – 21st March, Autumn equinox – 23 September. 21st June (winter solstice in Southern Hemisphere, Summer solstice in Northern hemisphere) – The rays of the sun fall directly on the Tropic of Cancer. 22 December (Summer solstice in Southern hemisphere, winter solstice in Northern Hemisphere) – The rays of the sun fall directly on the Tropic of Capricorn.

Explanation: 3214 km. Extent of India: East to west (2,933 km), land frontier (15,200 km), coastline (7,516.6 km). The westernmost point (Ghuar Moti in Kutch). The easternmost point (Kibithu in Arunachal Pradesh). Indira Col northernmost point). Indira Point (Great Nicobar Island, Andaman sea) is the Southernmost point of India while Kanyakumari is the southernmost point of the Indian Mainland.

Explanation: Frigid zone. The North Frigid Zone, between the North Pole at 90° N and the Arctic Circle at 66°33′48.7″ N, covers 4.12% of Earth’s surface.

Explanation: Sikkim. The 90 degree East Meridian passes through Assam and Meghalaya in India and it crosses Bhutan and Bangladesh.

Explanation: 111 km. This distance decreases marginally as one travels to poles and increases marginally as one goes towards the equator.