The Observable Universe

How far can you see? Everything you can see, and everything you could possibly see, right now, assuming your eyes could detect all types of radiations around you, is the observable universe. The farthest we can see is from the microwave background, which was 13.8 billion years ago. Humans do not yet have the technology to detect the waves that surround us. The image shows the observable universe on an increasingly compact scale, with the Earth and Sun at the center surrounded by our Solar System, nearby stars, nearby galaxies, distant galaxies, and the Cosmic Microwave Background. Our observable universe is assumed to be the nearby part of a larger entity known as the universe where the same physics applies. There are several lines of popular but speculative reasoning that claim that our universe is part of a greater multiverse where either different physical constants occur, different physical laws apply, higher dimensions operate, or slightly different-by-chance versions of our standard universe exist.

Page 2

Explanation: A mere 11 million light-years away, Centaurus A is the closest active galaxy to planet Earth. Spanning over 60,000 light-years, the peculiar elliptical galaxy also known as NGC 5128, is featured in this sharp telescopic view. Centaurus A is apparently the result of a collision of two otherwise normal galaxies resulting in a fantastic jumble of star clusters and imposing dark dust lanes. Near the galaxy's center, leftover cosmic debris is steadily being consumed by a central black hole with a billion times the mass of the Sun. As in other active galaxies, that process likely generates the enormous radio, X-ray, and gamma-ray energy radiated by Centaurus A.