DAILY CURRENT AFFAIRS: 18 February 2025

The solar system planets information

The solar system refers to the combination of the Sun and various celestial bodies. At its center lies the Sun, around which all the planets orbit. Our solar system consists of eight planets, along with numerous asteroids, comets, and meteors. The gravitational pull between the Sun and these celestial objects ensures that the planets continue their orbit around the Sun.

UNIVERSE

The Universe includes everything that exists, from the vast Galactic Mega clusters to the smallest subatomic particles.

• Age of the Universe: As of 2015, scientists estimate the Universe to be approximately 13.79 billion years old.
• Galaxies: The Universe is made up of numerous galaxies. Optical and radio telescope studies suggest there are around 100 billion galaxies in the observable universe.
• Origin: The Big Bang Theory is the most widely accepted explanation for the Universe’s origin.

🌌 GALAXY

A galaxy is a vast collection of millions or billions of stars and planets, all held together by gravitational pull. 🌠

• Milky Way: The Milky Way is the galaxy that contains Earth. 🌍 It appears as a river of milky light flowing across the sky, giving it its name. ✨
• Shape: The Milky Way has a spiral shape and is called “Akash Ganga” in India. 🌀
• Nearest Galaxy: The closest galaxy to the Milky Way is Andromeda, a spiral galaxy located about 2.5 million light-years away. 🌠🔭

⭐ STARS

Stars are luminous celestial bodies that emit their own light and radiant energy. 💫

• Composition: They are composed of extremely hot, burning gases. 🔥

Color and Temperature:

Stars’ colors reflect their temperatures:

• Red: Low temperature 🌡️
• Yellow: Higher temperature 🌕
• Blue: Very high temperature 🔵

⭐ Star: Birth to Death

• Formation (Nebula): A star begins its life as a cloud of dust and gas called a Nebula. 🌫️
• ProtoStar: As the Nebula contracts, it forms a dense region known as a ProtoStar. 🌟
• Star Formation: The ProtoStar condenses further until nuclear fusion starts, marking the birth of a star. ⚛️
• Hydrogen to Helium Fusion: The star fuses hydrogen into helium. When the hydrogen is depleted, helium fuses into carbon. At a certain point, energy production stops, and the star’s core contracts. 🌞
• White Dwarf: After its core contracts, the star becomes a White Dwarf—a dense, dead star that shines by radiating stored heat. ❄️ If the mass is below 1.44 times the Sun’s mass (Chandrasekhar Limiting Mass), the star cools and becomes a Black Dwarf. ⚫
• Supergiants and Supernova: Larger stars expand into Red Supergiants after consuming hydrogen and helium. Eventually, they may explode as a Supernova or turn into a Neutron Star or Black Hole. 🌠
• Nearest Stars: The closest star to Earth is the Sun, followed by Proxima Centauri and Alpha Centauri, located 4.35 light-years away. 🌞

🌟 Constellations

A constellation is a group of stars forming an imaginary shape or pattern in the night sky. 🌠

• Navigation Aid: Constellations help navigate sea vessels at night, as they appear in fixed directions during specific times of the year. 🚢✨

Examples of Constellations: Some well-known constellations include:

• Orion (Mriga): Visible in the late evening during winter ❄️
• Cassiopeia: Seen in the Northern sky during winter 🌌
• Great Bear: Consists of Ursa Minor (Laghu Saptarishi) and Ursa Major (Vrihat Saptarishi), visible in the early night during summer ☀️

🌞 Sun

• Composition: The Sun is a star composed mainly of hydrogen (70%), helium (26.5%), and other gases (3.5%). It is 109 times larger than Earth and weighs 2 × 10²⁷ tonnes, making up 99.83% of the solar system’s mass. ✨
• Distance from Earth: The Sun is 150 million km away, and sunlight takes about 8 minutes to reach Earth. 🚀
• Gravitational Pull: Its immense gravitational force keeps the planets in orbit around it. 🌌
• Energy Emission: The Sun emits energy in various forms, including visible light, infrared, ultraviolet, X-rays, gamma rays, radio waves, and plasma gas. 🌈
• Solar Flares: Solar flares are sudden, bright flashes near the Sun’s surface caused by magnetic energy release. They can disrupt satellite communication. ⚡🌠
• Nuclear Fusion: In the Sun’s core, hydrogen atoms fuse under intense pressure to form helium, releasing immense energy that radiates outward. ⚛️

Zones of the Sun:

• Core: Site of nuclear fusion. 🔥
• Convection Zone: Surrounding the core, where temperatures drop to 2 million °C. 🌡️
• Photosphere: The Sun’s surface, with a temperature of 6,000°C. ☀️
• Sun’s Atmosphere: The atmosphere consists of the chromosphere and corona. The corona is visible through spectral lines and consists of ionized elements, increasing its temperature. 🌌🔭
• Solar Wind: A stream of charged particles from the Sun’s corona that interacts with Earth’s magnetic field, creating auroras. 🌬️

Auroras:

• Aurora Borealis: Northern lights. 🌌✨
• Aurora Australis: Southern lights. 🌌🌠
• Sunspots: Dark, cooler areas on the photosphere from which solar flares originate. They follow an 11-year cycle known as the Sunspot Cycle, marked by solar maximum (high sunspot activity) and solar minimum (low activity).🌑
• Solar Wind and Storms: The solar wind, composed of electrons, protons, and alpha particles, can cause solar storms that affect space weather and result in geomagnetic storms on Earth, impacting communication and technology. ⚡

🌍 Planets

The term “planet” means “wanderer.” There are eight planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. 🌌

• Orbit: All planets orbit the Sun in an elongated (elliptical) path. 🌞🔄
• Dwarf Planets: The International Astronomical Union (IAU) recognizes five dwarf planets: Ceres, Pluto, Haumea, Makemake, and Eris. 🌠

Planet Classification:

• Terrestrial Planets: These are dense, rocky bodies, often referred to as Earth-like planets. They include Mercury, Venus, Earth, and Mars. They are also known as inner planets. 🌍🪐
• Jovian Planets: These are the outer planets, which are large, gaseous, and have significant satellite systems. They are similar in features to Jupiter, thus called Jupiter-like planets. They include Jupiter, Saturn, Uranus, and Neptune. 🌌🌠

🪐 Pluto: The Dwarf Planet

• Historical Status: Pluto was once considered the smallest planet in the solar system and the ninth planet from the Sun. 🌟
• Current Classification: Pluto is now classified as a “dwarf planet.” 🌌
• Distance from the Sun: On average, Pluto is more than 3.6 billion miles away from the Sun. 🌞🚀
• Location: Pluto resides in a region known as the Kuiper Belt. 🌠
• Day Length: A day on Pluto is approximately 6.5 Earth days. 🕰️

Moons: Pluto has five known moons:

• Charon (the largest) 🌕
• Kerberos 🪐
• Styx 🌟
• Nix 🌠
• Hydra 🌌