Expert: Tom Whiting - 7/29/2008

Question
Last Friday, 7/25/08, around 9:45 am, I saw a small, bright circle of light.  At first I thought it was a balloon floating in the air because it was about that size, but it was moving about as fast as a satellite and it was moving across the sky like a satellite.  Is it possible that this was what it was?  Are you able to see satellites during the day?  I observed it for about 45 seconds until I lost view of it.  It was moving too fast to be an airplane.

Answer
Hi Jessica,
 Unfortunately, you didn't state your location or the direction
of travel of the object, or how high it seemed to you, or how
fast.  But no matter, it was obviously a man-made object (Opps...sorry, human-made) and my initial guess WAS going to be a large weather balloon caught up in the jet stream which travels hundreds of miles per hour.
NO, no artificial satellite is visible in the daylight hours,
(except those Iridium Flare satellites, but then they are only visible for a few seconds at -9th magnitude like a quarter moon)....although once the ISS is completed, it may be just visible in the daylight at -4th magnitude (Venus' brightness, as Venus IS visible in daylight dark clear blue sky too, IF you know exactly where it is at in the sky.)
Most high altitude airplanes actually track faster across the
sky, their APPARENT motion, faster than most artificial satellites!
Or at least equal in apparent motion to a satellite.

With no other information available, my best guess would be a weather
balloon and my second guess would be a high altitude aircraft, in
both cases you are seeing the low sunlight (9:45 am Daylight time is only 8:45 am Standard time -the sun doesn't add one hour to 'its
watch' like us stupid humans do every summer) glinting off the surface of same.  Confirmation of this 'guess' would be that the
object just got dimmer as it faded from view as the sun angle
changed on it from your viewpoint, as opposed to instantly
disappearing while still very bright.
Hope this helps,
Clear Skies,
Tom Whiting
Erie, PA USA