1. Expanding Universe
The universe has been expanding since the Big Bang, which occurred around 13.8 billion years ago. This expansion is accelerating due to a mysterious force known as dark energy.
2. Dark Matter and Dark Energy
About 85% of the mass of the universe is dark matter, which does not emit light or energy, making it invisible. Additionally, around 70% of the universe's energy density is dark energy, driving the accelerated expansion of the universe.
3. Cosmic Microwave Background Radiation (CMB)
The CMB is the afterglow of the Big Bang, a faint cosmic background radiation filling the universe. It provides a snapshot of the early universe, approximately 380,000 years after the Big Bang.
4. Black Holes
These are regions in space where gravity is so strong that nothing, not even light, can escape from them. The largest known black hole, TON 618, has a mass 66 billion times that of our Sun.
5. Galaxies
There are an estimated two trillion galaxies in the observable universe, each containing millions to billions of stars. Our galaxy, the Milky Way, contains over 100 billion stars and is part of the Local Group of galaxies.
6. Observable Universe
The observable universe is about 93 billion light-years in diameter. This limit is set by the age of the universe and the speed of light, beyond which light hasn't had enough time to reach us.
7. Elements in the Universe
Hydrogen and helium are the most abundant elements in the universe, formed during the Big Bang nucleosynthesis. Heavier elements are formed in the cores of stars and during supernova explosions.
8. Neutron Stars
These are incredibly dense remnants of supernova explosions. A neutron star's mass is typically about 1.4 times that of the Sun, but packed into a sphere with a radius of only about 10 kilometers.
9. Exoplanets
Thousands of exoplanets (planets outside our solar system) have been discovered. These range from gas giants larger than Jupiter to rocky planets similar to Earth, some of which reside in the habitable zones of their stars.
10. Multiverse Theory
Some theories suggest that our universe might be one of many in a larger multiverse, with each universe having its own distinct physical laws and constants.