Gaia Sky lets you explore our galaxy, the Milky Way. Gaia Sky is a real-time, 3D, astronomy visualisation software that runs on Windows, Linux and macOS.
https://zah.uni-heidelberg.de/institutes/ari/gaia/outreach/gaiasky/
IsThatABigNumber.com is about extending our number sense. We make comparisons that are (mostly) down-to-earth: populations of people and animals, national budgets, river lengths and so on.
But when we leave behind everyday experience and look at the kind of numbers you find in astronomy and in combinatorics, we come across vastly bigger numbers.
One strategy to grasp these numbers is to break them down into a series of levels, to see them as stupidly big aggregations of things that are themselves stupidly big aggregations of … Here are some good clips illustrating this:
Jules Verne sent Phileas Fogg around the world in 80 days, but how far is that anyway? How fast would he have had to travel? How long would it take today to go around the world?
http://www.andrewcaelliott.com/explorations/2017/3/21/around-the-world-in-how-long