mercurydancer
I have been on the wrong end of a laser many times.
Yes, a momentary exposure will be very noticeable, even an oblique angle is enough to be distracting. At the wrong time, distracting enough to be dangerous.
However, I do not think that one used for astronomy, and presumably shone straight up at the heavens would cause any more than a fleeting "what was that"?
If you use your laser for astronomy regularly, why not get a NOTAM issued?
The aircraft must be intentionally targeted for the (UK) law to have been broken.
Note that by "intentionally" I mean intending to shine it at the aircraft, not necessarily intending harm to its occupants.
Fatty.