The probe is first used to take pictures of the planet Earth. Later, the second picture of the alien planet is actually one of the shots of Earth used during the opening credits.
Contrary to what Commander Sraker (Ed Bishop) explains at the IAC (International Astrophysical Commision) about a so-called 'electron TELE-scope' - being able to not only take pictures of Earth from '5-hundred miles above, with extreme clarity, and therefore, being able to take 'high definition' images of the alien planet, by the very nature of electrons, it would be impossible.
Electrons can be up to 100,000 times shorter than that of visible light (photons), which makes them terrific in MICRO-scopes, where they have a higher resolving power than (standard, visible) light microscopes, and can reveal the structure of very small objects.
But, the very thing which makes them terrific at small distances, would make them utterly impractical at long distances (such as s a telescope), in general, and utterly useless at being able to resolve objects at distances measured in light-years.
Electrons can be up to 100,000 times shorter than that of visible light (photons), which makes them terrific in MICRO-scopes, where they have a higher resolving power than (standard, visible) light microscopes, and can reveal the structure of very small objects.
But, the very thing which makes them terrific at small distances, would make them utterly impractical at long distances (such as s a telescope), in general, and utterly useless at being able to resolve objects at distances measured in light-years.
If the probe had following the UFO to the home planet, this place, as noted previously, would have to be at least 24 trillion miles from earth, as that is the distance to the closest star to our Solar System than the Sun. But light and radio signals would have to take at least four years to get to earth, not four months. After all, signals from Voyager 1, which is fifteen billion miles out, take twenty two hours to reach earth, and for a signal to reach from say fifteen trillion miles, which is a thousand times that first distance, this would take over two and a half years - and that is still only five eighths the distance to Proxima Centauri - and the aliens may be much further away than that.
The International Astrophysical Commission is repeatedly referred to erroneously as the Astro Space Commission.