The Life Cycle of Stars Stars are born from massive clouds of gas and dust called nebulae . Gravity causes these clouds to contract, and when the core becomes h...
Stars are born from massive clouds of gas and dust called nebulae. Gravity causes these clouds to contract, and when the core becomes hot and dense enough, nuclear fusion begins. This process converts hydrogen into helium, releasing vast amounts of energy that make stars shine.
As stars age, they go through different stages depending on their initial mass. Low-mass stars like our Sun will eventually become red giants, shedding their outer layers as planetary nebulae. Their cores will become white dwarfs and slowly cool down. Massive stars, however, will explode as supernovae, leaving behind either a neutron star or a black hole.
The Big Bang theory describes the beginning of our universe about 13.8 billion years ago. Evidence for this theory includes the cosmic microwave background radiation (CMBR), a faint glow of radiation that pervades the entire universe. The redshift of distant galaxies, caused by the Doppler effect, also supports the idea of an expanding universe.
Observations have revealed the existence of dark matter and dark energy, which make up a large portion of the universe's total mass and energy. Dark matter provides the gravitational force that holds galaxies together, while dark energy is responsible for the accelerated expansion of the universe.
Our Solar System formed about 4.6 billion years ago from a massive, rotating cloud of gas and dust. Gravity caused the cloud to collapse, forming the Sun at the center and a spinning disk of material that eventually coalesced into planets, moons, asteroids, and comets.
The planets and moons in our Solar System orbit the Sun in elliptical paths governed by Newton's law of gravitation. These orbits are also influenced by the gravitational forces of other bodies, leading to phenomena like tides and eclipses.
Recent discoveries have revealed the existence of exoplanets, planets that orbit stars other than our Sun. These planets exhibit a wide range of characteristics, including rocky Earth-like worlds and gas giants similar to Jupiter.
The motion of planets, moons, and artificial satellites can be explained by Newton's laws of motion and gravitation. Kepler's laws describe the elliptical orbits of planets around the Sun, while the motion of artificial satellites, such as those used for communication and navigation, is governed by similar principles.
Problem: Earth's average distance from the Sun is 1.496 x 10^11 m. Calculate Earth's orbital velocity around the Sun, given the Sun's mass is 1.989 x 10^30 kg.
Solution: