We know space is big, but trying to understand how big is tricky. Say you stare up at the sky and identify stars and constellations in a virtual planetarium, you can't quite fathom how far away all those stars are (previously, twice). Even if you could change your point of view and zoom around in space to really see 100,000 nearby stars (autoplaying ambient music, and there are actually 119,617 stars mapped in 3D space), it's still difficult to get a sense of scale. There's this static image of various items mapped on a log scale from XKCD (previously), and an interactive horizontal journey down from the sun to the heliosphere with OMG Space (previously). You can get a bit more dynamic with this interactive Scale of the Universe webpage (also available in with some variants, if you want the sequel [ previously, twice], the swirly, gravity-optional version that takes some time to load, and the wrong version [previously]), but that's just for the scale of objects, not of space itself. If you want to get spaced out, imagine if If the Moon Were Only 1 Pixel, and travel from there (previously). This past March, BBC Future put out a really big infographic, which also takes a moment to load, but then you can see all sorts of things, from the surface of Earth out to the edge of our solar system.
If the Moon Were Only 1 Pixel is a tediously accurate model of the Solar System that Josh Worth made to explain to his daughter just how difficult it is to go on holiday to Mars.
What lives where in the Solar System. Fantastic Adventure covers from 1939/40 depicting the kind of lifeforms they think each planet can support. [more inside]
The United Stated Geological Survey has finished a six-year effort to map the surface of Jupiter's moon Io. [more inside]
NASA's MESSENGER team (previously: 1, 2, 3), with help from the U.S. Geological Survey, released yesterday the first global map of the planet Mercury. [more inside]
Tvashtar in Motion. Awesome five-frame GIF of fountaining sulfuric lava on Io courtesy New Horizons as it swung by Jupiter earlier this year. Found via Planetary Society Blog (Thank you, Emily). More on Tvashtar.
Space volcano. The New Horizons space probe, en route to Pluto and the Kuiper Belt, captures an amazing image of the Tvashtar volcano on Jupiter's moon Io.