Well this is fun: My friend Henry Reich of Minute Physics made a short video with my friend Randall Munroe of xkcd and what if, explaining how Hubble Space Telescope can look at Earth.

You may recognize the stick figure shown 15 seconds in!

This video is based on a question Randall answered in his what if series a while back. It cracks me up that he references something I wrote back in 2000. Hubble takes images of Earth all the time, to calibrate some of its cameras. It still does, in fact. I describe why and how in that link.

Not all astronomy photos are jaw-dropping shots filled with incredible beauty and awe-inspiring structures. But sometimes what they tell us is still very, very cool.

For example, here is the most sensitive radio-wavelength image ever taken of the globular cluster 47 Tucanae:

I know, not much to look at, right? But it’s deep: That’s a total of 450 hours of observations using the Australia Telescope Compact Array, a collection of six 22-meter radio antennae in New South Wales [link to research paper]. It’s the deepest (that is, most sensitive, so seeing the faintest objects) radio image ever taken of a globular cluster. And it’s very, very interesting indeed…

Globulars are collections of hundreds of thousands of stars packed into tight balls usually only a few dozen light-years wide. 160 or so orbit the Milky Way, and 47 Tuc is one of the closest, easily visible to the naked eye from the southern hemisphere. Here’s what it looks like using Hubble:

Yeah, I know, right? This is one reasons they’re one of my favorite kinds of objects in the sky. Like a humming beehive.

Globulars are pretty old, with many stars 10 – 12 billion years old. They have a complicated formation history, but essentially all the most massive stars (roughly the same as the Sun and heftier) are long dead. Ones like the Sun swelled into red giants, blew off their outer layers, and are now dim white dwarfs. More massive ones exploded as supernovae, leaving behind dense neutron stars or black holes.

And this is where things get interesting.

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