The Universe everything we can touch, feel, sense, measure or detect. includes living things, planets, stars, galaxies, dust clouds, light, and even time. Before the birth of the Universe, time, space and matter did not exist.. Cited from: https://www.esa.int/esaKIDSen/SEMX4EBE8JG_OurUniverse_0.html

The space between the stars and galaxies is largely empty. contains billions of galaxies, which contain millions/billions of stars. The space between the stars and galaxies is largely empty. Space is also filled with radiation (e.g. light and heat), magnetic fields & high energy particles (e.g. cosmic rays). Cited from: https://www.esa.int/esaKIDSen/SEMX4EBE8JG_OurUniverse_0.html

the visible Universe is at least 93 billion light years across. A light year is the distance light travels in one year (about 9 trillion km). Travelling at the speed of light (300,000 km per second), it would take 100,000 years to cross our Milky Way galaxy alone. Cited from: https://www.esa.int/esaKIDSen/SEMX4EBE8JG_OurUniverse_0.html

The Big Bang Theory

Time begins The universe begins ~13.7 Billion years ago (= age of oldest stars)

In 1927, the Belgian priest Georges Lemaître was the first to propose that the universe began as a single point, a singularity, that stretched, expanded, & continues to expand = Big Bang Theory It is the leading scientific explanation as to how the Universe began.

The universe begins smaller than the size of a single atom It was hotter and denser than anything we can imagine. The universe began as a violent expansion All matter and space were created from a single point of pure energy in an instant there was NO explosion