Regional Science Centre, Tirupati

The visible part of the Sun is called the photosphere. It is the outermost layer of the Sun's surface that emits the visible light that we see. The photosphere has a temperature of around 5,500 degrees Celsius and is composed mainly of hydrogen gas. It is the layer where sunspots, solar flares, and other solar phenomena occur.

The nucleus of a comet is indeed made up of ice and dust. Comets are composed of a solid core, called the nucleus, which is primarily made up of ice, such as frozen water, carbon dioxide, methane, and ammonia. This icy nucleus is also mixed with dust particles, including rock, metal, and organic compounds. As a comet approaches the sun, the heat causes the ice to vaporize, creating a glowing coma and tail. Therefore, the statement "The nucleus of the comet is made up of ice & dust" is true.

The acceleration of gravity at Earth's surface is 9.8 metres (32 feet) per second per second. This value represents the rate at which an object falls towards the Earth due to gravity. It means that for every second an object falls, its speed increases by 9.8 meters per second. This value is considered constant near the Earth's surface and is used in various calculations related to motion and gravity.

The day on which the Sun's direct rays cross the celestial equator is called the Equinox. During the equinox, the length of day and night is approximately equal all over the world. This occurs twice a year, in March and September, marking the beginning of spring and autumn respectively. It is a significant event in terms of the Earth's tilt and its position in relation to the Sun. The equinox is an important astronomical phenomenon and is used to determine the changing of seasons.

The image is described as a high-resolution image of a celestial object in our solar system. The answer provided is "SUN," which is a correct identification of the object in the image.

The statement is true. The sun constitutes 99.8% of the entire Solar System. This means that it contains almost all of the mass in our Solar System, with the remaining 0.2% being made up of planets, moons, asteroids, comets, and other celestial bodies. The sun's immense size and gravitational pull are what hold the Solar System together and govern the movements of the planets around it.

Kepler discovered the laws of planetary motion. Johannes Kepler was a German mathematician, astronomer, and astrologer who made significant contributions to the field of astronomy. He formulated three laws of planetary motion, known as Kepler's laws, which describe the motion and behavior of planets around the sun. These laws revolutionized our understanding of the solar system and laid the foundation for Isaac Newton's laws of motion.

Halley's Comet is a periodic comet that orbits the Sun approximately every 76 years. The last time it was visible from Earth was in 1986, so if we add 76 years to that, we get the year 2062. However, since the comet is usually visible for several weeks or months, it is often referred to as returning in the year before. Therefore, Halley's Comet is expected to return to the solar system in 2061.

A planet is classified as a dwarf planet based on its shape and size. Unlike regular planets, dwarf planets have not cleared their orbits of other debris and are not large enough to have achieved hydrostatic equilibrium, meaning they have not become spherical due to their own gravity. Therefore, both shape and size are important factors in determining whether a celestial body is classified as a dwarf planet.

The statement is false because constellations in the Southern Hemisphere are not the same as those in the Northern Hemisphere. Due to the Earth's tilt and rotation, the view of the night sky is different depending on one's location. In the Southern Hemisphere, different constellations are visible, such as the Southern Cross and the Magellanic Clouds, which cannot be seen from the Northern Hemisphere.

Chandrasekhar Limit refers to the mass over which a star will become a black hole. This limit was discovered by the Indian astrophysicist Subrahmanyan Chandrasekhar in 1930. According to his calculations, when a star's mass exceeds 1.4 times the mass of the Sun, it will no longer be able to support itself against gravity and will collapse into a black hole. This limit is important in understanding the life cycle of stars and the formation of black holes.

The orbits of all planets in the solar system do not lie exactly in the same plane, but they are relatively close. This is because the solar system formed from a rotating disk of gas and dust, which caused most of the planets to form in a similar plane known as the ecliptic. However, there are slight variations in the inclinations of the planets' orbits, causing them to be slightly tilted or "all over the place" compared to a perfectly flat plane.

ISRO launched India's first lunar probe Chandrayaan-1 in October 2008.

Syzygy is the correct answer because it is the term used to describe the alignment of three celestial bodies. This alignment can occur between the Earth, Moon, and Sun, or between other celestial bodies. Syzygy is commonly used in astronomy to explain phenomena such as eclipses and planetary conjunctions.

Uranus is the correct answer because its axis is almost parallel to its orbital plane, causing it to spin nearly on its side. This unique characteristic sets Uranus apart from the other planets, whose axes are more aligned with their orbital planes. This axial tilt results in extreme seasons on Uranus, with long periods of sunlight and darkness.

The doughnut-shaped zones of highly energetic charged particles trapped at high altitudes in the magnetic field of Earth are known as the Van Allen radiation belt. These belts were discovered by scientist James Van Allen in 1958 and are named after him. The Van Allen radiation belts are made up of charged particles, mainly electrons and protons, that are trapped by the Earth's magnetic field. They extend from about 1,000 to 60,000 kilometers above the Earth's surface and play a crucial role in protecting the Earth from harmful solar radiation.

Scintillation is the correct answer because it refers to the twinkling of stars. When starlight passes through the Earth's atmosphere, it gets refracted or bent due to the varying densities of air. This causes the star's light to twinkle or scintillate when observed from the Earth's surface. Parallax is the apparent shift in the position of an object when viewed from different angles, and it is not related to the twinkling of stars. Refraction is the bending of light as it passes through different mediums. Albedo refers to the reflectivity of an object's surface and is not related to the twinkling of stars.

Georges Lemaître formulated the modern big bang theory. Lemaître was a Belgian astronomer and Catholic priest who proposed the theory in the 1920s. He suggested that the universe originated from a primeval atom, which later expanded and gave rise to the current state of the universe. Lemaître's theory was based on the observations of redshift in distant galaxies, indicating that the universe is expanding. His work laid the foundation for the understanding of the origin and evolution of the universe.

Hans Lippershey is credited with inventing the telescope. He was a Dutch eyeglass maker who applied for a patent for his device in 1608. Lippershey's telescope consisted of a convex objective lens and a concave eyepiece lens, allowing for magnification of distant objects. Although Galileo is often associated with the telescope, he actually improved upon Lippershey's design and used it for his astronomical observations.

NASA quarantined the astronauts who landed on the moon when they returned to Earth because they wanted to prevent any potential contamination from moon germs. As the moon is a completely different environment with its own unique organisms, there was a concern that these organisms could pose a risk to Earth's biosphere. Quarantining the astronauts allowed NASA to study them and ensure that they were not carrying any harmful lunar microorganisms that could potentially harm life on Earth.

The Space Age began in 1957. This was the year when the Soviet Union launched the world's first artificial satellite, Sputnik 1, into space. This event marked the beginning of human exploration and technological advancements in outer space.

In 1992, the first exoplanet was discovered. This marked a significant milestone in astronomy as it confirmed the existence of planets beyond our solar system. Prior to this discovery, scientists could only speculate about the existence of exoplanets, but now they had concrete evidence. This discovery opened up a new field of research and led to the subsequent detection of thousands of exoplanets in the following years.

Pisces is the correct answer because it is a zodiac constellation. In astrology, the zodiac is divided into twelve constellations, and Pisces is one of them. It is represented by two fish swimming in opposite directions. People born between February 19 and March 20 are considered to have Pisces as their zodiac sign.

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ASTROSAT is the correct answer because it is a satellite that was developed and launched by ISRO (Indian Space Research Organisation). ASTROSAT is India's first dedicated multi-wavelength space observatory and it is designed to study celestial sources in X-ray, UV, optical, and near-infrared wavelengths simultaneously. It was launched on September 28, 2015, and it has been instrumental in conducting various astronomical observations and research.

The International Astronomical Union is responsible for naming constellations. This organization, consisting of professional astronomers from around the world, has the authority to officially designate names for celestial objects and features, including constellations. They follow a systematic and collaborative process to ensure that the names are scientifically accurate and widely accepted within the astronomical community. This helps in standardizing the naming conventions and facilitating communication among astronomers and researchers globally.

The correct answer is Himalayan Chandra Telescope. This telescope is developed and operated by the Indian Institute of Astrophysics. It is located in the Indian state of Himachal Pradesh in the Himalayan region. The telescope is named after the famous Indian astrophysicist Subrahmanyan Chandrasekhar, who won the Nobel Prize in Physics in 1983. The Himalayan Chandra Telescope is an important research facility for studying various astronomical phenomena and conducting observations in the visible and infrared regions of the electromagnetic spectrum.

Satellites that are positioned at an altitude of exactly 42,164 kilometers from the center of the Earth, which is approximately 36,000 kilometers from Earth's surface, are called geostationary or geosynchronous satellites. These satellites have an orbit that matches the rotation of the Earth, allowing them to remain fixed in a specific position relative to the Earth's surface. This characteristic makes them ideal for applications such as telecommunications, weather monitoring, and navigation systems.

The picture depicts a halo of dust and gas surrounding a massive black hole located in the Messier 87 galaxy, which is situated 55 million light-years away from Earth.

CATOSAT 1 is the correct answer because it was the first mapping satellite launched by India. It was launched on May 5, 2005, and was primarily used for cartographic applications, urban and rural infrastructure development, and monitoring of developmental projects. CATOSAT 1 played a crucial role in providing high-resolution satellite images for various mapping and surveying purposes, contributing to India's space program and technological advancements in the field of remote sensing.