I've read that in advanced trajectory calculations, sunlight is even taken into account. Does this also apply to transient events like solar flares?
1$\begingroup$ Great question! Mostly unrelated; solar flares heat the atmosphere's of planets and increase atmospheric drag on things passing nearby. This is a big concern for artificial satellites in Earth orbit but that's not what you're asking about. This effect is going to be really really really small and someone might add an unsourced "No." answer based on that alone, but I suppose once could estimate both the radial force and frictional drag of the increased interplanetary medium and show just how small it is. $\endgroup$– uhohSep 3, 2022 at 20:14
$\begingroup$ related: Directionality of solar flares and Strength of the relationship between very large solar flares, coronal mass ejections, and solar proton events? and What are the main differences between solar flares and coronal mass ejections? and Possible Safe Areas In a Solar Flare $\endgroup$– uhohSep 3, 2022 at 20:21
Short answer: No.
Long Answer: Ha, no.
The solar sunspot cycle (~11 yr) affects a significant fraction of the photosphere, to greater and lesser amounts, and it’s a peak-to-valley difference of significantly less than one percent in Watt/m2. You think a flare, which is stochastic in time and radial vector, will be relevant? The overwhelming number of flares will be heading in the wrong way, even assuming a 2D Solar System …and the Solar System is 3D.
The Yarkovsky Effect is barely out of the noise for our finest instruments, integrating over years. YEARS, and only on the favorable asteroid targets. And that’s an effect of sunlight, CONTINUOUS sunlight. At all times, in all vectors. In all 3 dimensions.
And as for the notion of the interplanetary medium somehow increasing, ha, no. That’s a fundamental ignorance of space. Space above, say, 2000 km is a harder vacuum than the hardest vacuum ever drawn by our civilization. Heck, the coma of comet Churyumov-Gerasimenko was still cleaner than a standard cleanroom. Humans simply do not have a comprehension of just how empty ‘the void’ is, since we live out our lives in the terrestrial existence. It is the burden of a scientist to un-burden their mind with such default, Earthly, human assumptions and preconceptions. SPACE IS NOT EARTH, and it’s inhuman, and humans think highly of their own minds.