Scale of the Universe

Someone recently posted an article explaining the scale of the universe via various analogies. We do have a hard time percieving a wide range of scales where distance is involved. However, humans seem to have a perception of time that has a large dynamic range. So, I've found the best way to talk about the size/scale of the universe is in terms of light-travel time. (In other words, how long would it take light to travel that distance).

• to the Moon - ~1.25 seconds
• to the Sun - eight minutes
• to Pluto - about four hours
• to Alpha Centauri - about four years
• to Sirius - about eight years
• to the Orion stellar complex - about 1500 years
• to the center of our Milky Way galaxy - 30,000 years
• Diameter of our Milky Way galaxy (visible arms) - 100,000 years
• To M31 the Andromeda Galaxy - 1.5 million years

Other clusters of galaxies are typically at distances with a light-travel time in the realm of 100 million years. All of these distances are approximate.

Oh, and you can basically ignore any talk of distances to the farthest galaxies, clusters, or talk about the size of the universe or distance to the edge of the universe. Most of those distances are highly model-dependent, and the concept of distance barely applies. After all, everything is moving on cosmological scales, the universe is expanding. That's all another discussion.