Quick note: this week’s live chat will be tomorrow, SATURDAY, July 19 at 3:00 Mountain time (21:00 UT). I have to do some stuff Sunday, and won’t be here at the usual time, so I’ve moved it up a day.

I’ll have a new post up an hour or two beforehand with the video feed embedded and all that as usual. See you there!

Regular readers know I am deeply impressed with astronomical imagery, and I tend to be a little over-the-top on occasion when describing it.

However, having said that, let me be very clear: the following is just about the coolest thing I have ever seen.

First, the setup. The Deep Impact spacecraft was the one that smacked a chunk of copper into a comet so that we could see what materials were below the surface. After the impact, the spacecraft kept going (with the mission renamed EPOXI), and it’s being used to do all sorts of interesting observations.

In late May, 2008, it turned its cameras back to Earth and observed us over the course of a several hours. During this time, from EPOXI’s point of view, the Moon passed directly in front of the Earth! The images were put together (by my old boss, Don Lindler!) into, well, one of the most astonishing animations I have ever watched. Ever.

Now below is the same view, but this time the "red" you see is actually infrared; note that land masses which are warm, appear really red since they are emitting lots of IR compared to the oceans: appear bright in the IR due to vegetation and the ground being good reflectors (see note at bottom of post):

To my knowledge, nothing like this has ever been seen before. These are incredible. Higher-res versions of these videos can be found on the NASA EPOXI press release page.

Take a look at that, folks. It’s us, seen from 50 million kilometers away. I’ve seen many images of the Earth and Moon together as taken by distant spacecraft, but this, seeing them in motion, really brings home — if I may use that highly ironic term — just where we are: a planetary system, an astronomical body, a blue orb hanging in space orbited by a desolate moon. This is a view that is literally impossible from the ground. Only a spacefaring race gets the privilege of this view from a height.

While there is science galore in these animations, I think their real impact is the visceral one from simply seeing them. As Carl Sagan once said: everyone you have ever met, every human who has lived and died, lived out their lives on that blue ball. And yet here we are, in the 21st century, plains apes allowed to evolve and satiate their curiosity, now with the ability to lob metal proxies into deep space, look back, and see ourselves.

Science. I love this stuff.

A very big tip o’ the solar panel to Don Lindler, for alerting me about these animations.

And oops: I originally said that the land is warm, and thus bright in the IR. That’s wrong, at least in this case! That would be true if these were far (thermal) IR images, but they’re actually near-IR, just outside the range seen by the human eye. At those wavelengths, plant and other objects are pretty good reflectors, so they appear bright. My thanks to R Simmons in the comments below for pointing this out.

This is a common question: what is the nearest star to the Earth that can explode as a supernova? Most people say Betelgeuse, a red supergiant in Orion, but there are several stars that are closer.

In the video below I answered this question as part of my weekly live video chat.

If you have an astronomy question you want answered, tune in to the live chat, which I usually do on Sundays at 15:00 Mountain time (21:00 UT). I might make a video of your Q&A!

Some notes: the image of Spica is used under the Creative Commons license, and is from fdecomite’s Flickr set. The awesome white dwarf illustration is from my friend the artist David Hardy (and PPARC), who gave me permission to use that in my book, so hopefully he won’t mind if I plug him here.

When I was in Canada, it was really cool to see everyone using the metric system. But what made me a little nuts was how everyone pronounced the word kilometer. Is it kil-AW-meter or KILL-o-meter?

I make my case for the latter in the video below. If you disagree with me, then I can state quite objectively and maturely that you are wrong wrong wrong.

When I was giving my first talk in Canada I actually mentioned this, and got a lot of applause from right-thinking people. The others were strangely (ominously?) silent. Perhaps they were tuning up their kill-o-meters.

Note: in the video I use the spelling decameter. I have seen it as dekameter as well, and in some dictionaries it says decameter is the old way to spell it. Well, maybe. I still like it, so I used it. If I can rant about pronunciation, I can rant about spelling, too.

I’ll be holding a live video chat right here on this very blog post at 15:00 Mountain time (21:00 UT). All you need to do is go down to the embedded video player below and click play (the little curly arrow at the bottom left). As usual, I encourage y’all to go to my UStream video page so you can participate in the chat room. You can change your name by typing "/nick Davros" (or whatever) so you can be listed with an actual name, and not an anonymous one. If you have some chat software you prefer to use (like mIRC or Colloquy) then the server is chat1.ustream.tv and the room is #bad-astronomy.

Oh — I’m going to see a movie in a few minutes as a I write this (WALL-E if you care) and I expect to be back in plenty of time to start the chat. If I’m not, don’t panic; I’ll be back as soon as I can.

I’ll be doing another live video chat on Sunday at 15:00 Mountain Time (21:00 UT). I’ll have it all set up an hour or two before hand with a new post, so I’ll just leave you with the countdown clock for now:

To the unaided eye, Saturn doesn’t look like much. It appears to be just another "star" — brighter than most, but still just starlike. In fact, you can see for yourself: over the next few days, go outside right after sunset and look west. You’ll see two of these "stars" very close together. One is Mars, the other Saturn. It’s hard to tell which is which: from a few hundred million kilometers away, Saturn’s signature rings are invisible with just your eye.

That’s too bad. Saturn’s ring system is magnificent, and amazing. But if we can’t go to Saturn to see the rings, the least I can do is bring the rings here to you.

And so I present the fourth in the series of short astronomy videos I’ve been making with director Tom Lucas. Saturn, Lord of the Rings is now up in high-definition goodness on Hulu.com (if you’re in the US), and we’ve also simulposted it on YouTube. I’ve even embedded it here, like Pandora and Prometheus in the F Ring:

This one was fun to make. We filmed it at the Denver Museum of Nature and Science — which is also the place that managed the making of the black hole planetarium show, which Tom produced and directed and on which I served as Science Consultant. So it was nifty to go back and see the place again. They have an incredible planetarium, and that image of Saturn you see behind me in the video was actually being projected in real time on the dome as we shot it. It was a fully controllable 3D rendering, so we could spin it, zoom in, revolve around it, everything. Very cool stuff. If you’re in the area, treat yourself to the DMNS. They do good work… and Splendid Elles is there too for a bonus!