Recently, several possible solar transit observations have been reported here. Five unsuccessful attempts for such observations, undertaken in the last few days by a couple of friends and myself lead me to the following conclusions: 1. A satellite or rocket body in the 6m to 10m size class at typical distances between 1000 and 2000 km has an angular size in the order of 1 arcsecond, give or take 25%. 2. A rule of the thumb for the resolving power of a telescope objective lens is "13.8 arcseconds/objective diameter in cm". To resolve objects 1 arcsec apart, the minimum size of the objective lens is thus around 5 inches. This assumes perfectly collimated optics and does not account for the effects of bad seeing which in the case of solar transits is inevitable due to air turbulence. 3. Even if the object can be resolved by the telecsope optics, the human eye possibly cannot. Another common rule of the thumb says the eye's resolving power in arcseconds is "720/eye pupil's diameter in mm". The eye pupils' diameter is usually assumed to be 6 mm (depending on age), and this leads to the figure of 120 arcseconds often found in the literature. However, 6 mm corresponds to a dark-adapted eye. Under bright illumination, which can certainly be assumed for the observation of the sun (through a filter or by projection), the eye's pupil is closer to 2 mm in diameter. The eye can then only resolve objects of at least 360 arcseconds size. 4. The typical satellite/rocket body at a typical distance, observed through a telescope of suitable opening, must therefore be magnified at least 360 times. At this magnification it is exceedingly difficult to aim the telescope at a certain point on the solar disk, assuming it can be calculated at all which region of it will be crossed by the object. Magnifications which still show the entire solar disk in the field of view (i.e. in the order of 50 to 80 times) are clearly not sufficient no matter the size of the telescope aperture. 5. When staring for a minute or more at a bright surface like the sun or the moon in a telescope, strange objects tend to appear, all of which are inside the eye. Medical doctors call them "mouches volantes". Most of them cannot possibly be confused with satellites because of their thread-like appearance, but sometimes a more round or square object crosses the field of view. 6. In view of all the arguments above I have reluctantly conluded that the observation of solar transits of anything below the size of Mir is not feasible with amateur equipment. As regards the moon, the basic constraints are the same, except that the seeing will be much better and the eye's pupil probably somewhat larger. Can anybody prove me wrong? Bruno Tilgner 100533.2016@compuserve.com