Science 101 Universal

Its gravity holds the Solar System together, influencing the orbits of planets, moons, comets, and asteroids. This stellar giant is primarily composed of hydrogen and helium, undergoing nuclear fusion in its core, where hydrogen atoms combine to form helium, releasing a tremendous amount of energy. This process is the source of the Sun's light and heat, essential for life on Earth.

Predicted by Albert Einstein in 1916 as a consequence of his General Theory of Relativity, these waves propagate at the speed of light, carrying with them information about their cataclysmic origins and about the nature of gravity. Unlike electromagnetic waves, which travel through space, gravitational waves actually travel through spacetime itself, making them a unique messenger in the realm of astrophysics.

According to this theory, the universe began from an extremely dense and hot state approximately 13.8 billion years ago and has been expanding ever since. This initial explosion not only created the majority of matter but also the physical laws that govern our cosmos.



Initially, the universe was in a state of extreme heat and density. Within the first few moments, it began expanding rapidly—a phase known as cosmic inflation. This expansion helped to smooth out any irregularities or anisotropies in the nascent universe, laying the groundwork for a more uniform distribution of energy and matter. As the universe expanded, it also began to cool, allowing for the formation of subatomic particles, and later simple atoms.

It was formed approximately 4.6 billion years ago from the gravitational collapse of a region within a large molecular cloud most commonly found in the Milky Way galaxy. Over millions of years, the collapsing material formed a spinning disk, with the Sun coalescing at its center, growing hot and dense enough to initiate nuclear fusion.

Nestled within the Orion Nebula, which itself is a part of the larger Orion Molecular Cloud Complex, the cluster is a vivid laboratory for the study of young stars and their development. This cluster is relatively close to Earth, situated approximately 1,300 light-years away, in the constellation of Orion, making it an accessible and invaluable resource for astronomers.

Stretching about 100,000 light-years in diameter, it is a part of a larger group of galaxies known as the Local Group. This majestic galaxy, seen from Earth as a milky band of light arching across the night sky, contains a complex structure of spiral arms wrapped around a dense central bulge, which is believed to harbor a supermassive black hole known as Sagittarius A*.