Appropriately for such a sunny day, this is a good news blog 😛
Good news i)
We retook the film from our experiment the other day, and now have excellent results! Here is a picture of our second-best film (my partner has the other one!):
The top wide grey stripes contain the lines from Lithium and necessarily a bit of Carbon as that was what the electrodes are made out of. The smaller lines in the middle of these are from Mercury, which we will use as a reference to help identify the important Lithium spectra, and finally, the bottom row of greyish blurs are the pure Carbon emission spectra.
You might think they seem a little blurry for emission lines (which are the discrete wavelengths of photons given off when an electron jumps down into a lower energy state) and you would be partially correct, because most of what you can see in the Carbon spectra are continuum regions. This is where the Carbon in the source has been ionised (lost one or more electrons) and is then getting repopulated by another electron joining its state and giving off energy as a photon to do so.
This didn’t make any sense to me until I thought about it as literally the reverse of ionisation—when an element is ionised it must absorb photons with energies above a certain minimum value which is needed to escape. Here we see the electrons re-joining the atom and giving back off a photon with that same amount of energy. The Carbon continuums have been recorded so that we can differentiate them from the Lithium lines.
Yey results! Also yey for the fact that we didn’t drop or lose our films in the dark room, which is actually pitch-black.
Good news ii)
I have got into the final of the Science Challenge! If you are an attentive follower of my blogs you will remember that I wrote an essay for Imperial’s essay competition, the Science Challenge about the hunt for exoplanets.
Today I got an email saying that I am in the top three for my question so on Monday I am going to the cabinet war rooms (the underground world war two bunkers) for the awards ceremony where they announce the winner! Excite!
Good news iii)
In my astrophysics lecture today we did something interesting called orbital resonances, and now I know why the Moon and Earth are tidally locked (why we only ever see one side of the moon). In case you didn’t know, I will tell you too.
The gravitational force between the Earth and Moon causes both bodies to bulge out towards each other. The bulge on the Moon gets moved around as it rotates, but since it is closer to the Earth it is more strongly attracted, so the Earth tries to pull it back and keep our bulges in line. Over time this slows down the Moon’s orbit until we are always facing the bulge e.g. only one side of the Moon is visible to us.
Since forces are equal and opposite, the Moon is having the same effect on the Earth—just a lot more slowly. That means our days are slowly lengthening—though this small change in time is only noticeable from fossils.
That this can be measured is also crazy—you can apparently tell how many days there were in a year 350 million years ago from looking at the bands of growth in corals like tree rings. It turns out there were about 385 days in a year back then, meaning that days were less than 23 hours long! (I found this out from this article: http://www.scientificamerican.com/article/earth-rotation-summer-solstice/)
Complete tidal locking has taken place between Pluto and its moon Charon, which orbit always facing one part of each other like there is a giant rod between them.
Good news iv)
It was Alex’s birthday yesterday so I got to spend the morning sneakily turning his room into a desert island (long story) and making burger cakes and chips. Mmm.
Which leads me smoothly into this hilarious joke:
Why does hamburger have a lower energy than steak?
Because it’s in its ground state.