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Yarkovsky Effect On Asteroid Detected
Henry writes "New Scientist is reporting that a JPL team has measured the recoil effect of an asteroid caused by the Sun in the process of re-emission of absorbed sunlight as heat. Astronomers believe this phenomenon, known as the Yarkovsky Effect, has brought asteroids - which are otherwise mainly located in and near the belt - towards Earth. This effect on asteroids was previously predicted, but this is the first proof."
From the yarkovsky link in the article... ==== The effect of this tiny thrust on the object's orbit depends on how it spins. If the spin goes one way, Yarkovsky thrust adds to the orbital speed and the asteroid moves outward, away from the sun. If the asteroid rotates the other way, Yarkovsky thrust slows the asteroid's orbital velocity, and it draws closer to the sun.
It'll mean the death of all of us.
Though the second law will probably get us far sooner.
More conclusive proof that the universe abhors life. It's just so negentropic.
... I thought they were talking about the Yakov Effect.
"Yeah, well, Dracula called and he's coming over tonight for you and I said okay."
These guys collected 12 years worth of data, to finally determine that an asteroid 16 million kilometers from the earth was 15 kilometers further away than calculated by the influence of gravity alone.
No wonder noone else was able to measure this till now..
But it just makes all those long term asteroid orbit simulations a little harder now, since not only do you have to know the position and velocity accurately, you now have to know it's spin and it's thermal properties. It's a great example of how orbital mechanics can be considered chaotic on reasonable timescales.
Oh since I'm here - Oblibatory link to my map of the solar system showing all the near earth asteroids.....
http://szyzyg.arm.ac.uk/~spm/
The White House's immediate reaction was to try to control the spin, thereby eliminating any deviation from the status quo.
My guess would be no, because the Earth's atmosphere would absorb the thrust. The particles would push directly on the mass of the asteroids, however, since very few have any atmosphere to speak of.
Second, the impact of charged particles wouldn't inherently alter a rock's orbit in a different way from uncharged particles. They'd both push in the direction of flow. The thing that makes the Yarkovsky effect work is that it depends on re-emission of particles (photons, as heat), and the direction of re-emission depends on the axis and rate of rotation.
Time is Nature's way of keeping everything from happening at once... the bitch.
However, the Yarkovsky effect on Earth is going to be much smaller (probably unmeasurably small) than on a sub-kilometer asteroid for these reasons:
- Earth's atmosphere and oceans buffer the temperature changes, leading to less variation in IR emissions per rotation and thus less net thrust.
- While the net IR emission is proportional to the intercepted sunlight and thus the area of Earth's disc (proportional to radius squared), the acceleration is inversely proportional to the mass (which is proportional to radius cubed). On top of this, Earth is denser than typical asteroidal rocks, due to its iron core and compression of lower layers to denser mineral forms.
It would be interesting to calculate the likely influence of the Yarkovsky effect on Earth, as a high-school physics exercise (like calculating the De Broglie wavelength of a moving car). I suggest this exercise to you, for fun; if nothing else, it will give you an idea of how hard it is likely to be to measure it.Time is Nature's way of keeping everything from happening at once... the bitch.