The Universe, space, and time, is a difficult concept to comprehend due to its vast and infinite size. That is why the Lightyear was created, which is the distance that light travels in 1 year or just under 6 trillion miles (5,878,625 million miles). The “year” contains measurements of both time and distance, where time is calculated on the Julian scale, where 1 year is equal to 365.25 days. Because light takes time to travel from one place to another, we can therefore look farther back through time through telescopes. We see objects not as they are now but as they were at the time when they released the light that has traveled across the universe to Earth. That is what fascinates me about Astronomy and why I started the hobby of Astrophotography.
Take the image above, for example. We are looking at the NGC 3395 and 3396 galaxies as they were 85 million years ago because the distance that these objects are in space are 85 Million Lightyears from Earth. So what was happening on Earth 85 million years ago? Earth was in the Cretaceous Period, defined by following characteristics:
“Flowering plants proliferate, along with new types of insects. More modern teleost fish begin to appear. Ammonoidea, belemnites, rudistbivalves, echinoids and sponges all common. Many new types of dinosaurs (e.g. Tyrannosaurs, Titanosaurs, duck bills, and horned dinosaurs) evolve on land, as do Eusuchia (modern crocodilians); and mosasaurs and modern sharks appear in the sea. Primitive birds gradually replace pterosaurs. Monotremes, marsupials and placental mammals appear. Break up of Gondwana. Beginning of Laramide and Sevier Orogenies of the Rocky Mountains. Atmospheric CO2 close to present-day levels (source: wikipedia).”