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🌌 UNIVERSE, BIG BANG, GALAXIES & STARS – ONE-LINER NOTES FOR TELEGRAM 🌌

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🔹 Development of the Concept of Universe

✅ Ptolemy (140 AD) proposed the Geocentric Theory – Earth at the centre of the Universe.

✅ Copernicus (1543 AD) proposed the Heliocentric Theory – Sun at the centre of the Solar System.

✅ William Herschel (1805 AD) stated that the Solar System is only a small part of a galaxy.

✅ Edwin Hubble (1925 AD) proved that the Universe contains numerous galaxies.

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🌠 Theories of Origin of Universe

✅ Big Bang Theory – Georges Lemaître

✅ Steady State Theory – Thomas Gold & Hermann Bondi

✅ Pulsating Universe Theory – Allan Sandage

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💥 Big Bang Theory

✅ Proposed by Georges Lemaître.

✅ The Universe originated from an extremely hot and dense state.

✅ The Universe is continuously expanding.

✅ The increasing distance between galaxies supports the theory.

✅ Present estimated age of the Universe: 13.8 Billion Years.

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⚛️ Higgs Boson (God Particle)

✅ Research conducted at the Large Hadron Collider (LHC).

✅ LHC is operated by CERN near Geneva.

✅ Tunnel length of LHC: 27 km.

✅ Higgs Boson discovery announced on 4 July 2012.

✅ Explains how elementary particles acquire mass.

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🌌 Galaxies

✅ The Universe contains more than 100 billion galaxies.

✅ A galaxy is a huge collection of stars, gas and dust.

✅ Each galaxy contains billions of stars.

✅ The nearest major galaxy to the Milky Way is Andromeda Galaxy.

✅ Distance of Andromeda Galaxy: about 2.2 million light years.

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🌟 Milky Way Galaxy (Mandakini)

✅ Our Solar System is located in the Milky Way Galaxy.

✅ Shape of Milky Way: Spiral.

✅ Diameter: about 100,000 light years.

✅ The Sun takes about 225–250 million years to complete one revolution around the galactic centre.

✅ Orion Nebula is one of the brightest star-forming regions in our galaxy.

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⭐ Important Stars

✅ Sirius (Dog Star) is the brightest star visible in the night sky.

✅ Sirius is about 20 times brighter than the Sun.

✅ Proxima Centauri is the nearest star to the Sun.

✅ Distance of Proxima Centauri: about 4.24 light years.

✅ Kepler-444 is among the oldest known star systems.

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🔭 Astronomy & Telescopes

✅ Galileo first used a telescope for astronomical observations in 1609 AD.

✅ Year 2009 was celebrated as the International Year of Astronomy.

✅ MAST (Multi-Application Solar Telescope) is located at Udaipur, Rajasthan.

✅ FAST in China is the world's largest radio telescope.

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🌟 Life Cycle of a Star

Nebula ➜ Protostar ➜ Main Sequence Star ➜ Red Giant ➜ Supernova ➜ Final Stage

✅ Hydrogen fusion produces helium and releases energy.

✅ Red Giant stage begins after depletion of hydrogen in the core.

✅ Massive stars end with a Supernova explosion.

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⚪ White Dwarf

✅ A star with mass less than 1.4 times the Sun's mass becomes a White Dwarf.

✅ White Dwarf is also called a Fossil Star.

✅ Eventually it becomes a Black Dwarf.

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🌞 Chandrasekhar Limit

✅ Proposed by Subrahmanyan Chandrasekhar.

✅ Value: 1.4 Solar Masses.

✅ Maximum mass limit for a stable White Dwarf.

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🌠 Neutron Star & Pulsar

✅ Massive stars may become Neutron Stars.

✅ A rapidly rotating Neutron Star is called a Pulsar.

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🕳️ Black Hole

✅ Formed by the collapse of very massive stars.

✅ Gravity is so strong that even light cannot escape.

✅ Concept popularized by John Wheeler.

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📌 MOST IMPORTANT EXAM FACTS

🔹 Geocentric Theory → Ptolemy

🔹 Heliocentric Theory → Copernicus

🔹 Big Bang Theory → Georges Lemaître

🔹 Brightest Star → Sirius

🔹 Nearest Star to Sun → Proxima Centauri

🔹 Our Galaxy → Milky Way (Mandakini)

🔹 Nearest Major Galaxy → Andromeda

🔹 God Particle → Higgs Boson

🔹 Largest Particle Accelerator → LHC

🔹 White Dwarf Mass Limit → Chandrasekhar Limit

🔹 First Telescope Astronomer → Galileo

🔹 Rotating Neutron Star → Pulsar

🔹 Object from which light cannot escape → Black Hole

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Topic: Universe, Big Bang, Galaxies & Stars 🌌✨