The giant impact hypothesis is the most widely supported theory for how the moon was formed, with research in 2014 adding support to this theory over other possibilities. Now UCLA-led research reconstructs a massive crash that took place 4.5 billion years ago (abstract, full article paywalled), supporting the theory that the Moon was produced by a head-on collision between Earth and Theia, a forming planet.
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.
Tom Hanks, somewhat of an authority on going to the moon, wrote about it in The New Yorker. (You, too, can write like Tom Hanks!)
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.
I am a staunch believer in leading with the bad news, so let me get straight to the point. Earth, our anchor and our solitary haven in a hostile universe, is in a precarious situation. The solar system around us is rife with instability.[more inside]
35 years ago today, Voyager 1 transmitted three images which NASA processed into a single frame of Earth and its moon. [more inside]
What if other planets in the Solar System orbited Earth at the same distance as the Moon? (SLVimeo) Full screen highly recommended.
From grainy stills to gorgeous high-resolution portraits, from intimate pairings to stark contrasts, and from old standbys to little-known surprises, The Planetary Society's Earth galleries offer a rich collection of stunning photography and video footage of our world as seen from both planetary spacecraft and geostationary satellites. It is a vista that has inspired many a deep thought in the lucky few that have seen it firsthand [previously]. Oh, and the rest of the Solar System is pretty neat, too.
How to blow up the Earth (with a coffee can), and why we should, along with some discussion of how it is done in fiction. Blowing up the moon (and how the US nearly did in 1958, with the help of Carl Sagan), and lots of reasons why, including one in song [YouTube]. How to blow up a star. How we might accidentally blow up the universe in November. [prev. discussion of Earth destruction]
Pale Blue Dot: The Earth and Moon as photographed from Mars. Just in case you needed a bit of perspective.
From the Earth to the Moon by Jules Verne: A capital idea. Why did we not fasten a thread to our projectile, and we could have exchanged telegrams with the earth?. Bad idea, said Jules. Great idea, says NASA.
If you want to try playing with little planets or images of them, try visiting these websites...
Webearth -- builds a LIVE vrml model of the Earth as it is right now. It draws from current composite satellite photos. Or you can play with a VRML Moon, Venus, Mars or Jupiter, if you'd prefer. (Note: this site does require a VRML 2.0 compatible plug-in, like Parallel Graphics Cortona VRML Viewer.)
Here's an oldie, but a goodie... Same concept, just not live. Earth and Moon Viewer uses various static composite satellite images from many different points of view, and it lets you zoom in and out ... (to a certain extent).
Webwide World lets you zoom in on an earth-like planet... not quite the same thrill, but the images the site produces are beautifully gem-like. And the planet it produces is huge. You'll be able explore islands off the coasts of islands off the coasts of islands.
And for more satellite image zooming pleasure, you can't beat Microsoft's Terra Server.