Exploring the Cosmos: Space Physics in GCSE The Life Cycle of Stars Stars are born from massive, rotating clouds of gas and dust called nebulae . Gravity causes...
Stars are born from massive, rotating clouds of gas and dust called nebulae. Gravity causes these clouds to contract, and as the material compresses, the core heats up due to increased pressure. Once the core reaches a critical temperature, nuclear fusion begins, converting hydrogen into helium and releasing vast amounts of energy. This marks the birth of a new star.
Over billions of years, a star's life cycle progresses through various stages, determined by its initial mass:
The Big Bang Theory proposes that the universe began as an incredibly hot and dense singularity, which expanded rapidly in a cosmic event known as the Big Bang. Evidence for this theory comes from the cosmic microwave background radiation (CMBR), which is the residual thermal radiation from the initial expansion, and the redshift of distant galaxies, indicating that the universe is expanding.
The concept of dark matter, which exerts gravitational forces but does not interact with electromagnetic radiation, and dark energy, which drives the accelerated expansion of the universe, are also integral parts of the Big Bang Theory.
Our Solar System formed approximately 4.6 billion years ago from a giant, rotating cloud of gas and dust. Gravity caused this cloud to contract, and as it spun faster, it flattened into a protoplanetary disk. Within this disk, smaller clumps of matter collided and grew, eventually forming the planets, moons, asteroids, and other objects orbiting the central Sun.
The planets and other objects in our Solar System orbit the Sun due to the balance between gravitational forces and centrifugal forces. Similarly, moons orbit planets due to the same principles. Artificial satellites, like the International Space Station, are also in orbit around Earth.
Recent observations have confirmed the existence of exoplanets, planets orbiting stars other than our Sun. These discoveries have expanded our understanding of planetary systems and the potential for life elsewhere in the universe.
Problem: A satellite with a mass of 1,000 kg orbits Earth at an altitude of 500 km above the surface. Calculate its orbital speed, given Earth's mass is 5.97 × 10^24 kg and radius is 6,371 km.
Solution: