Leftover tea pic

I may be English, but I’m not a huge fan of tea. Sure, I’ll drink it if I’m thirsty and the only other option is battery acid, but it has to be said that thankfully, this is not a situation I’ve ever found myself in. Yet.

Michael Davis, a Canadian resident, had some leftover tea and, rather than pouring it into the sink like any sensible person would have done, he flung it dramatically into the freezing air with this rather spectacular result:

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Yes. That’s impressive.

Other images on Michael’s Flickr which didn’t quite manage the same level of sheer wonder (this one and this one) suggest that he had been drinking a lot of tea that morning, which, given that he apparently ended up chucking away the last fifty (or more) percent of each brew, seems both foolish and wasteful. Silly boy.

So why does tea do this? Wired knows.

A pot of boiling water can be thrown into the air on a cold winter day, and it freezes in mid air creating a shower of ice crystals. Whereas a pot of cold water thrown into the air comes down as large blobs of water. This happens because the hot water is so close to being steam, that the act of throwing it into the air causes it to break up into tiny droplets (hot water is less viscous than cold water, listen to the sound it makes when you pour it in the sink). The small water droplets have a large surface area which allows for a great deal of evaporation, this removes heat quickly. And finally, the cooled droplets are so small, that they can be easily frozen by the winter air.

Michael tells us that it was -40 degrees when he took the photo. He doesn’t say if that’s Fahrenheit or Celsius, but THAT DOESN’T MATTER! because -40 is the magic number at which these two temperature scales magically cross, in a magical manner.

40 degrees (Celsius) like it’s likely to be in the Western Cape today is equal to 104 degrees Fahrenheit. I wouldn’t advise throwing boiling water into the air above your head (or to be honest, throwing boiling water anywhere) in those sort of temperatures (or to be honest, in any sort of temperatures).

The results are unlikely to be as pretty as Michael’s.

Just where do perytons come from?

You’ve asked, I’ve asked. Everyone has asked: Just where do perytons come from?

Well, now Petroff et al. are able to tell you. But first – some background:

“Perytons” are millisecond-duration transients of terrestrial origin, whose frequency-swept emission mimics the dispersion of an astrophysical pulse that has propagated through tenuous cold plasma.

Damn that tenuous cold plasma. But, there you go. A peryton is essentially a very short signal detected by a radio telescope, like the Parkes Radio Observatory in New South Wales, Australia. And while we (we radio astronomers, that is) were pretty sure that they were generated on earth, we weren’t sure how. The problem with perytons though, is that they are very similar to Fast Radio Bursts or FRBs. FRBs aren’t generated on earth – so they are of great interest to radio astronomers. It doesn’t help that they may be being masked by perytons.

In their submission to the journal Instrumentation and Methods for Astrophysics, Petroff et al. claim to have found the source of these pesky perytons at their radio telescope:

Subsequent tests revealed that a peryton can be generated at 1.4 GHz when a microwave oven door is opened prematurely and the telescope is at an appropriate relative angle. Radio emission escaping from microwave ovens during the magnetron shut-down phase neatly explain all of the observed properties of the peryton signals.

u wot m8?

Yep. It was a someone opening the door of a microwave oven on site before the bing that was causing that blip on a screen.

Awkward.

I’ve never really understood the need to open a microwave door prematurely. What are you going to do with the extra 9 seconds you just “saved”? And do you realise that you could have set radio astronomy back by several years as they struggle to work out what just made all their alien invasion alarms go off? No. No, you don’t, because you only think of yourself, don’t you?

Anyway. Whatever, because they’ve sorted it. I wonder who came up with the premature opening of microwave doors hypothesis? Can you imagine being in that meeting?

E.Petroff (for it is she): So, what could be causing these perytons, then?
Scientist 1: Aliens.
Scientist 2: Aliens.
Scientist 3: (eating recently warmed up braai leftovers): No idea, mate.

Anyway – there is a serious side to all of this. Now that they have had a good look at the microwave oven-generated perytons, they have worked out that one of their FRBs – FRB010724, to be exact – wasn’t caused by anyone in their kitchen and did actually come from way out there in outer space. And that’s quite exciting.

UPDATE: And here’s how they discovered this:

Brilliant. (And am I the only one who sees the middle finger in that graph?)

Science Gun

I like the idea of a Science Gun.

image

We scientists like things to behave as they are expected to, because… well… that’s how they’re expected to behave. It’s simply unfair that we observe and document these organisms for hundreds of years and then one of them suddenly decides to break the mould, just trying to be clever. That’s what evolution is for, and that doesn’t happen overnight, Mr Emu.
Capisce?

Moon

I was alerted to an animation by this tweet:

If the Moon were only a few hundred km away, it would look AMAZING… but you’d be way too dead to notice.

An animation artist has arted an animation of what it would look like if the moon were about 420km above the earth’s surface. That’s about the same altitude as the International Space Station. And yes, it does look amazing:

Here’s the cool stuff:

If the Moon were that close — 420 km (260 miles) over the surface of the Earth — it would be over 100º in size, literally more than half the sky! Right now it’s a mere 0.5º in size, for comparison.
It’s dark in the middle because with the Moon blocking the Sun for so much of the Earth, there’s no light to reflect and illuminate the Moon there!
The motion in the video is sped up; at that distance the Moon would orbit the Earth in about 90 minutes or so. It would cross the sky in very roughly five minutes.

And here’s the kinda weird bit:

The Earth has about 80 times the mass of the Moon, so if you could situate yourself exactly halfway between them, the Earth would pull on you 80x harder than the Moon. But it’s worse than that; gravity drops as the square of the distance, and the Moon is pretty far away. Right now, the center of the Earth is roughly 6400 km below you, and the Moon’s center is about 380,000 km above you. Take the ratio and square it, and you see that the Earth pulls on you 3500 times harder just because it’s closer. Add in the fact that the Earth is more massive, and you’ll find it pulls on you about 300,000 times harder than the Moon!
That’s why you don’t notice the gravity of the Moon. It’s only 0.0003% as strong as what you feel from the Earth.

But if the moon were 420km away,and you redo the gravity calculation, you’d find the force of gravity from the Moon on you is 1/10th that of Earth!
When the Moon passed overhead, you’d weigh 10% less.

Weight Watchers paradise.

But sadly, that’s where the good news ends. Because tides.

If we bring the Moon in really close, suddenly one side of the Earth is a lot closer to the Moon than the other: The Earth’s near side is 2158 km from the Moon’s center, and the far side is nearly 15,000 km away. That’s a huge difference, and the tides felt by the Earth would be amplified enormously — nearly 100,000 times what we experience now! There would be global floods as a tidal wave kilometers high sweeps around the world every 90 minutes (due to the Moon’s closer, faster orbit), scouring clean everything in its path.

That, and the fact that the earth would be so pulled and stretched that the crust would start to fall apart and the sea would probably boil away as the magma beneath the earth’s surface was exposed.

Oh, and the high likelihood that the moon would be pulled apart by the earth’s gravitational forces.

Look, it’s not going to end well.

In fact, the reason we are still here – and that the moon is still there – is exactly that: that we are here and it is there. Anything else would result in certain disaster. So there’s something to brighten your journey home today.

More facts and information here.