Astronomy

NASA's Parker Solar Probe is the spacecraft currently studying the sun up close, designed to gather data about the sun's outer atmosphere and solar wind.

The heliopause is the boundary in the solar system where the solar wind's pressure balances the pressure from the interstellar medium, marking the outer edge of the heliosphere.

Jupiter has the maximum number of moons in the solar system, with over 90 confirmed moons, surpassing Saturn, Uranus, and Venus (which has none).

Voyager 1 is the first human-made object to enter interstellar space, having crossed the heliopause in 2012. Apollo 1 and Apollo II were manned lunar missions, and Sputnik was the first artificial satellite but did not leave the solar system.

The moon's surface is constantly bombarded by meteoroids, which are small rocky or metallic bodies traveling through space. Comets are much less frequent, and UV light is radiation, not a physical bombardment. Therefore, meteoroids are the correct answer.

The solar wind originates from the Sun's corona, which is the outermost layer of the Sun's atmosphere. The high temperature and pressure in the corona cause particles to escape into space as solar wind.

The Sun is the star at the center of the solar system, around which all the planets, including Earth, Mercury, and Venus, orbit.

Terrestrial planets in the solar system, such as Earth, Mars, Venus, and Mercury, are composed primarily of rock and metal. Therefore, both metal and rock are correct components of their composition.

The Moon completes one rotation on its axis approximately every 27.3 days, which is why the same side of the Moon always faces the Earth. This period is known as the sidereal rotation period of the Moon.

Venus and Uranus rotate in the opposite direction (retrograde rotation) compared to most other planets in the solar system, which rotate prograde (in the same direction as their orbit around the Sun).

The sun's surface is called the photosphere, which is the visible surface layer from which light is emitted. The other options refer to different atmospheric layers of the sun or Earth and are incorrect in this context.

Comets revolve around the Sun as they orbit it in elliptical paths, just like planets, but often with more elongated orbits. This is why option A is correct.

According to the Big Bang Theory, the Universe began approximately 13.8 billion years ago, which falls within the range of 10–20 billion years. This makes option A the correct choice.

Venus is the brightest planet visible from Earth and is easily seen with the naked eye, often called the 'Evening Star' or 'Morning Star'. It is more visible than Mercury, Mars, or Jupiter under normal conditions.

Mercury is the closest planet to the Sun, so it has the highest orbital speed according to Kepler's laws of planetary motion. Therefore, Mercury moves around the Sun faster than any other planet.

The planets visible to the naked eye without a telescope are Mercury, Venus, Mars, Jupiter, and Saturn, totaling five planets. Hence, option C is correct.

Mercury completes one orbit around the Sun in approximately 88 Earth days, making option A correct. The other options represent incorrect orbital periods for Mercury.

Comets generally have highly elliptical orbits, which bring them close to the Sun and then far out into the outer solar system. This distinguishes them from planets, which have more circular orbits.

Venus is the nearest planet to Earth on average because it orbits closer to Earth than Mercury or Mars. The Moon is not a planet, so it cannot be the correct answer.

Nicolas Copernicus is considered the founder of modern astronomy because he proposed the heliocentric model, which placed the Sun at the center of the solar system, revolutionizing previous geocentric views.

Halley's Comet is known to have an orbital period of approximately 76 years. It last appeared in 1986, so its next appearance is predicted around 2061, making option B correct.

The Giant Magellan Telescope (GMT), expected to be completed around 2029, will be one of the most powerful ground-based telescopes, surpassing current telescopes in light-gathering and resolution capabilities. The James Webb Space Telescope is already launched (2021), and the Hubble Space Telescope 2.0 does not exist as a named project. The Vainu Bappu Telescope is smaller and less powerful.

A total solar eclipse occurs when the Moon completely covers the Sun as seen from Earth. The reason total eclipses are rare and sometimes absent is due to the Moon's elliptical orbit around Earth, which causes variations in its apparent size. When the Moon is farther away, it appears smaller and cannot fully cover the Sun, resulting in an annular eclipse instead of a total one.

The Great Red Spot is a giant storm located on the planet Jupiter, making option D the correct answer.

Jupiter is known as the 'bodyguard' of Earth because its strong gravitational field attracts or deflects many comets and asteroids, reducing the number that reach Earth.