You might think I’m posting this just because of the awesome title above, but in fact it’s for a video that’s even better. I know!

Here’s the scoop: after WWII, the US government found they had some extra sodium no one wanted, so they disposed of it.

In a lake. Full of water. And by the way, it was ten tons of pure sodium.

So yeah, you wanna see this newsreel footage from the event:

Holy crap.

[UPDATE: By a funny coincidence, I just found out that io9 posted a similar article with 10 videos featuring explosive chemical reactions!]

Sodium is highly reactive. It’s way over on the left side of the periodic table, which means it really wants to give an extra electron to any receptive atom or molecule that happens by. Water will happily accept that electron, but at a cost: the reaction creates sodium hydroxide (NaOH) and hydrogen gas (H₂). It also generates a lot of extra energy in the form of heat. A lot. And there’s hydrogen around. Remember the Hindenburg?

So yeah. Heat + hydrogen = BANG. Especially when you’re dumping that much sodium into a lake! The explosions generated by this were impressive, to say the least.

In high school we did something like this, though on a very small scale. Our teacher took a tiny bit of sodium and put it in a glass with water in it. Sodium is very light, and floats. It reacted with the water, but far more slowly than in this video, rolling around on the surface. As it did, it released the hydrogen, which is lighter than air (and also warm from the reaction) so it rose. The heat ignited it, and so as the ball of shiny metal sodium rolled around on the water’s surface, a tiny blue vertical flame followed it around. It was one of the coolest things I had ever seen, and probably made my nerdy adulthood that much more inevitable.

Oh, and all that surplus WWII sodium? While that would destroy the ecology of a lake, in this case it was already a heavily alkaline lake with no fish in it. While I wouldn’t say this was a great thing to do, at least they thought to minimize the impact. But cripes: don’t try this at home.

Tip o’ the vent hood to Corante.

In this episode of my live Q&BA chat session, I answered a question about how "gravity slingshots" work. This is the process of using the gravity of a planet to accelerate (or decelerate) space probes so they can more easily get to the inner and outer planets. It turns out gravity is not the only process at work here.

This technique is used all the time for spacecraft, and engineers are pretty good about nailing them perfectly, too. Sometimes the probes pass by Earth and take amazing pictures of us, like when Rosetta did in 2009, and in 2007, or when it passed Mars in 2007.

Be sure to check out all my other Q&BA videos!

Sometimes, the images from the Cassini Saturn probe are so cool it’s tempting just to post them and say, "Look at THAT!"

See what I mean? [Click to gigantesenate.]

But of course, I can’t just leave it at that. This image, taken on January 4, 2012, is a bit different than most. Sure, we see Saturn’s magnificent rings, nearly edge on from this perspective. And we’ve seen this icy moon Enceladus many, many times (see Related Posts below for tons more pictures). Look at the bottom of the moon: see those fuzzy streaks? Those are geysers of water spewing from cracks in the moon’s south pole! Cassini has been studying them intently ever since they were discovered; they are proof that liquid water exists under the surface of Enceladus, though it’s still being argued over whether it’s in pockets, like lakes, or the whole moon has an ocean of water under the surface.

Despite all that, I keep getting drawn to the crescent shape itself. We can never see that from Earth. Saturn is much farther out from the Sun than we are, and geometry demands that from home we always see these worlds nearly fully lit by the Sun. The only way to see them like this is to go there.

But also, that giant circular feature is really interesting. It’s big, maybe 200 km (over 100 miles) across, and a bit darker than the surrounding surface. I tried locating it on an atlas of Enceladus, but it wasn’t obvious at all. I thought it might be an impact basin, but a little scrounging online led me to a paper by Cassini imaging team leader Carolyn Porco, which says there are no large impact basins on Enceladus! So what is it?

Well, why not go to Dr. Porco herself? I sent her a note, and she kindly replied. That region is called Diyar Planitia, and it stands out among the surrounding terrain because it’s much smoother. It does have narrow surface features, but they’re too small to be seen at this resolution. At the low angle at which we’re seeing it here, it looks a little bit darker than the rougher terrain around it, so it’s easier to see (which is why on an atlas it’s harder to find). It is roughly circular, but that may simply be coincidence. Enceladus has been massively resurfaced, with some areas much older than others, due to various forces under the surface — looking this all up I learned a new one, called diapirism, where lower density material underneath higher density material can rise up and break through. That’s one process that’s helped change the surface of Enceladus over the eons.

That’s pretty nifty. And think about that! Today I learned of what is to me a new region of the solar system, one that has an interesting and complicated history, molded by vast forces over long-stretched times, one of which was also new to me. How wonderful to get all that from what’s otherwise just a pretty picture!

But of course, in science, there’s no such thing as just a pretty picture. Science is a tapestry, a vast complex fabric interwoven with countless threads. Each of those threads is amazing, each important, and each leads to another. And that’s where the true beauty of science lies.

I caught this video on Geekologie, and it made me laugh. This is a brilliant idea: a woman put a camera on a hula hoop, and then, well, hula’ed:

[WARNING: some folks might feel ill watching this. I will not be blamed if you have to wipe vomit off your keyboard.]

[Note: at the end of the video there are links to other videos like it.]

I found this fascinating. For one thing, the motion is slower than I would’ve expected. I suspect that may be due to an illusion when you watch from the outside as a hula hoop being used; humans are notoriously poor at judging rotating reference frames. After all, people still try to argue with me that centrifugal force isn’t real, when it it quite clearly is.

Even more amazing to me was that I didn’t get ill watching that video. I tend to get a seasick on a kid’s swing or when reading in a car, so the fact I was fine watching this is weird. But I have pretty good 3D spatial reasoning, and have a lot of practice swapping reference frames — trying to figure out when the Moon rises, what configuration planets are in, and how to point a telescope give you a lot of practice there — so maybe that helped. Beats me.

But I wonder what other weird change-of-frames would benefit from using this camera technique? That might make a fun series of videos.

I love science. OK, duh, but I really do. And when I go on vacation, I can’t help but see science everywhere, and in every case it makes the trip more fun for me. Seeing local geology, biology, how the stars might look different at a different latitude… it adds to the vacations, makes it better.

That’s why my wife and I started a company called Science Getaways. We figured there are lots of other folks out there like us who would really enjoy taking a vacation that has bonus science added in. Our first planned trip is to a gorgeous Colorado dude ranch called C Lazy U. Besides the usual amenities of such a place — horseback riding, great food, spectacular views of the Rocky Mountains — we’re adding SCIENCE! And scientists: we have a geologist, a biologist, and an astronomer — hey, me! — who will be on hand to give talks about the local nature scene, and then we’ll take hikes to put that new-found knowledge to practical use. I’ll be running a stargazing session every evening with my new 8" Celestron telescope, and I’m hoping to do some solar observing during the day as well.

IMPORTANT NOTE: We’ve negotiated a special rate — the price we’re offering is actually less than the usual ranch rate. We’re hoping to have the entire ranch for our group, but if we don’t have enough reservations by March 1 we can’t guarantee it. Space is limited, so please book now if you plan to come.

By the way, we’re also on Facebook and Google+ if you’d like to add us.

I hope to see lots of BABloggees there!

Today in America is our most revered holiday: the Superbowl. I am not particularly invested in either team — I had to look up who’s playing, to be honest — but there is something about the game I like: science! Yes, science, of which there is plenty to be had during any sporting event. You just have to look for it.

Last year, during the big game, I tweeted a series of science facts relating to football, and, when the game was over, collected them into a blog post.

I thought it would be fun do it again — this time, I’ll use the hashtag #Sciperbowl — but this year, instead of waiting to collect them, I’ll simply update this post as I add them. That way you don’t have to wait until the end of the game to see them all.

So sit back on your recliner, keep one hand in a bag of chips and another on the refresh button. Let’s see how to really enjoy this game! I’ll start the tweets and start updating this post at the start of the game.

First Quarter

1) Realistically, a football is not a ball. It’s more of a prolate spheroid.

2) Football pads work by absorbing impact as well as spreading it out over a larger area.

3) Pads lower the force of impact by lengthening the time of the collision.

4) Pressure = Force/Area, so increasing the area of the impact reduces pressure and therefore injury.

5) Every time a football is thrown, it’s briefly in orbit… but the Earth gets in the way.

Second Quarter

NOTE: The following info uses air (not ground) speed and neglects air resistance. [Note: the math on these next ones can be found online, for example at the CSU San Bernadino website.]

6) To be thrown 100 yards, a football should leave the quarterback’s hand at a 45 degree angle at 70 mph.

7) The ground speed of that throw is about 50 mph.

8) A ball thrown like that will reach a max height of about 80 feet.

9) A 100 yard throw like that will take about 4.5 seconds to go up and come back down.

Halftime

10) Halftime for the Universe was 6.86 billion years ago (+/- .12 billion).

Third Quarter

11) Because the Moon has 1/6 the Earth’s gravity, lunar football would be pretty different.

12) On the Moon, a football thrown at 70 mph would go 600 yards, take 27 seconds, and reach 500 feet high.

13) Throw a lunar football at 28 mph to get it 100 yards downfield. It’ll take 11 seconds & get 80 feet high.

14) All those throws assumed a 45 degree angle. At higher and lower angles, the ball must be thrown faster.

15) Want the ball to go into Earth orbit? You’ll have to throw it at 5 miles per second.

16) In a black hole, it doesn’t matter how hard you throw the ball. It’s not getting out.

Fourth Quarter

17) During a 4 hour game, the Earth rotates 60 degrees.

18) During a 4 hour game, the Earth spins a total of 3200 miles at the latitude of Indianapolis.

19) During a 4 hour game, the Moon travels over 9000 miles around the Earth.

20) During a 4 hour game, the New Horizons Pluto probe travels 130,000 miles farther from the Sun.

21) Since the starting whistle, the Sun’s moved 2 million miles in its orbit around the center of the galaxy.

That’s it! And congrats to whichever team won!

Football picture from Elvert Barnes’ Flick photostream.

[Note: Every week I hold a live video chat on Google+ where I answer questions from readers. I call it Q&BA, and when I get a question that stands alone, I'll make it its own video. ]

Every now and again, I hear this urban legend that pound for pound, the human body is actually hotter (or has more energy) than the Sun. I got this question in a recent Q&BA video chat session, so I tackled it. The answer is pretty interesting, and depends on how you ask the question!

I actually wrote about this legend on the blog a while back, and I show all the math. I really like this question, since it has a straightforward answer that makes it seem wrong, but then if you look at it more carefully the answer is a little trickier. And even in the video and that other post, it’s not really a complete answer; if you read the comments on the post you’ll see people arguing over it.

That’s really the best kind of question: the ones that keep on going! There’s always more stuff to figure out.

Visit the Q&BA Archive to see more videos like this one!