[imatfaal (OP)]

I am struggling to find consistent information about where to look in the sky this evening for a chance to see the Neo (I am in outer London on northeast).  Between Leo and the Plough seems the most regular advice from 8pm - but that's a big space and an uncertain time.  I have tried pasting the orbital elements into fourmilab yoursky without success

 

Any clues - preferable a sky map with a nice line drawn on it?  :-)

[David Cooper]

First find the cooking pot (plough / great bear). The asteroid will pass upwards through the middle of the first link of the handle of the cooking pot at 9:40 at nearly 90 degrees to the line of that part of the handle, but it'll be getting faint by that time and you'll probably need a birdwatching telescope to see it. Before that time, you'll need binoculars, and you'll be looking for a tiny dot moving at two moon diameters per minute. An hour before it crosses the pot handle, the asteroid will be a cooking pot length (including handle) below the cooking pot, slightly to the left of the line perpendicular to the line of the part of the handle at the pot end (ignore the huge kink in the line to the handle's outer end - it's the rest of the handle that you want to draw a line perpendicular to).

[imatfaal (OP)]

Thanks David.  I had found a lovely sky map (Heavensabove.com) which allowed me to put on a timed traced for DA14 - unfortunately not a single sight of stars beyond heavy clouds after about 1930z 

[David Cooper]

It was clouded out here too, but if you have to miss something, a tiny dot of light moving at imperceptible speed isn't such a great loss - if you haven't seen an asteroid, Ceres and Vesta are often visible as tiny dots of light with a birdwatching telescope and are about as easy/hard to see as Saturn's biggest moon Titan. Anyway, as it turned out, the only people who got a decent view of a small asteroid on the day in question were in Chelyabinsk.

Incidentally, I heard Dr. Karl (Radio 5, 3-4 in the morning) talking about that last night and he said something very interesting about the mechanism by which asteroids/meteors burn up or explode. I'd always thought it was down to friction and heating generated from that, but with a big lump of rock that's only going to do superficial damage. He explained that it's actually pressure that tears these rocks to pieces as the rock piles into gas which builds up in front of it, compressing the rock because it's easier to do that than to get out of the way. He also said that things which we are taught are incompressible like water are actually compressible - if you smack something into water hard enough it can be compressed to 3/4 of its normal volume (I don't know if that's a limit or just an example taken from some specific experiment), but it will apply to solid things too, thereby giving an insight into what can happen when a rock slams into the atmosphere at tens of thousands of miles an hour. He didn't explain the heating mechanism, but I would imagine it comes along for free as a direct result of the compression.

[imatfaal (OP)]

David - from my reading I think the same, and similarly it is just over the last few days that I have been learning about it.   The vast heat is as a result of hugely compressed gas at the leading edge of the meteor/object -> PV=nRT and all that jazz

[franklinw94]

Thanks Imatfaal for sharing with us such as nice post.

[distimpson]

Yes, the pv=nrt thing. When explaining the meteor/fireball glow, we do a demo at the museum to illustrate heating of air by adiabatic compression. I've got a little movie of this, do not know how to up load here??? Here are few still shots of the compression sequence. The kids love the fire piston demo.

[imatfaal (OP)]

I think I would love the fire-piston demo as well :-) 

You should just be able to paste a youtube link - or vimeo (which I prefer)

[distimpson]

plunger is rammed to rapidly compress the air, temperature increase is sufficient to ignite the cotton. http://vimeo.com/60880888

didn't know about vimeo, thank you!

[imatfaal (OP)]

Very neat - great idea to demonstrate the sort of principle we believe to be true, but would find hard to accept "out in the real world"