From a long way off, both Earth and Jupiter crossed in front of the Sun on January 10, 2026.
This is how extraterrestrials could have detected both planets, just as the Transiting Exoplanet Survey Satellite has for other stars since 2018 and as the Kepler space telescope did from 2009 to 2018. Aliens in star systems from only a narrow strip near our ecliptic could have seen this.
Try spinning and tilting the orbits to make both Earth and Jupiter cross over the Sun. Zoom in for detail.