The "alien mothership" hypothesis for interstellar comet 3I/ATLAS is about to have a key test, as it hits solar conjunction and perihelion. What does that mean, and why is a Harvard professor of astronomy telling people to book their vacation ahead of October 29? Let's find out. The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.

On July 1, astronomers from the Asteroid Terrestrial-impact Last Alert System (ATLAS) spotted an object hurtling through our Solar System on a course that will take it right back out again and into interstellar space. We had our third confirmed visitor after 1I/'Oumuamua and 2I/Borisov.

The object was soon confirmed to be a comet, and a pretty interesting one at that. The object has unusual chemistry and polar

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