Here's another really sneaky trick you can do with this transit data, what's called the Rossiter Mclaughlin effect.
The idea is that you can actually use the transit to find out about the rotation of the star that you're orbiting.
So, here we have a star that's going and a transit is going to occur
and so this shows you where the object is as a function of how bright the star is as a function of time.
But, of course, the star is rotating. This part of the star is coming towards us, that part is going away from us.
Let's colour it now, so the blue is the bit that's coming towards us,
because the spectrum from that is going to be blueshifted, and the red bit is redshifted.
As the planet goes across, it'll block out some of the blue light, and then block out some of the red light.
So, as it's blocking out the blue light, the star will appear to be moving away from us a bit anomalously
and when you're blocking out some of the red light, the star will appear to be moving towards us,
so the velocity of the star will appear to go away and then come towards us.
Right, and so you can actually go through and measure, literally, how this stars rotation compares to the motion of the planet.
What you'd expect is that the planet would be going around the star,
in the same sense that the star is spinning by itself, like in this diagram here.
In our own solar system this is the case.
The direction the sun is spinning and the direction all the planets are going around are the same.
You'd expect this to be the case because both the sun and the planets form from the same protoplanetary disk.
This is what you'd expect. But I suppose, to complete this set we should consider the alternative possibility
which they are going in the opposite direction, in this case, stars been the same way but now the planet is going to come in from Brian's side.
So, it comes here, blocks the red side first and so it's going to appear like it's moving a bit bluer towards you,
it's going to be moving towards you when it comes on this side, relative to when it blocks out the blue light;
which is the part which normally indicates motion towards you.
This can be measured and has been measured multiple times, and here's one example of this.
The results were pretty surprising.
It turns out that between 45 and 85 percent of hot Jupiters are misaligned,
are more than 30 degrees out from the same plane as the stars going around.
So, these are completely different than our own solar system,
and it's really bazar because, clearly, these objects are being formed by the same gas as the sun.
I mean, they're not being drifted in from inner-planetary space or something, and yet we're looking at this and it's like
they almost don't even know about what made the angular momentum that made the star in the first place.
So, this is pretty baffling at the moment, we've got a couple of ideas of what might be going on here.
One idea is that maybe you actually had two protoplanetary disks.
Maybe you had one disk that formed the star and then it went away
and another disk got dumped down at some later stage with a different angle and formed the planets, I mean, why not?
Another possibility is that this whole Billiards stuff, the planets scattering off each other.
But if you have a play with the simulations, it's quite hard.
You tend to end up with things still going the same way around, but if you work on it a bit
and have enough time and allow them to very slowly work themselves up, maybe you can get them into these really weirdo orbits.
Alright, so still another mystery on our hands.