Free Astronomy Magazine November-December 2026

NOVEMBER-DECEMBER 2026 ASTRO PUBLISHING interest (such as Enceladus), while more generally the resolution was limited to a few kilometers per pix- el (km/px). The average resolution for the surfaces of the satellites of Uranus and Neptune was also very low, typically 3-10 km/px. Finally, Charon, imaged by the New Hori- zons probe with a maximum resolu- tion of 800 m/px. In light of this situation, astrono- mer T. Joseph W. “Joe” Lazio (NASA’s Jet Propulsion Laboratory), in his ar- ticle entitled “Technosignatures in the Solar System,” published last June on arXiv , formulated a provoc- F rom top to bottom, the Pioneer, Voyager, and New Horizons probes are depicted as they embark on their long, aimless wanderings through the Milky Way. [NASA] ative hypothesis: “One or more ex- traterrestrial physical technosigna- tures may be present in the Solar System.” A technosignature (or technomark- er) is any measurable property or effect that provides scientific evi- dence of past or present technol- ogy. In other words, and in this specific context, a technosignature is any evidence demonstrating the use of non-terrestrial technology anywhere in the Solar System. Lazio asks himself (and asks us) if, given the current state of affairs, it is possible to disprove his hypothe- sis. To answer this question, the as- tronomer starts from an indisputa- ble fact: five terrestrial probes, Pio- neer 10 and 11, Voyager 1 and 2, and New Horizons, have left or are about to leave the Solar System, beginning a very long wandering through our galaxy. Over timescales of tens or hundreds of thousands of years, those probes will whiz by (at fractions of a parsec) other plane- tary systems; over millions of years, they might even graze a planet. There’s no certainty about this, but the very existence of those five probes demonstrates that a techno- logical civilization can send artifacts to other stars, more or less voluntar- ily. Considering that our civilization is in its infancy in this practice and that more technologically advanced civilizations may exist in the galaxy, we cannot a priori rule out that a number of probes have traversed or are traversing interstellar space. If so, the presence of alien technology in our Solar System may not be pure fantasy. Depending on whether they are in flight or landed, silent or communi-