Mars and Jupiter are always visible from Earth, assuming you have clear skies and are in a location where they are above the horizon at the time you are looking.

However, the brightness of Mars and Jupiter varies depending on their positions relative to Earth and the Sun.

To answer your question more directly, we need to clarify what you mean by "last saw". Do you mean:

* When were Mars and Jupiter last in a particular configuration, such as a conjunction? This is when the planets appear close together in the sky. This happens periodically. For example, Mars and Jupiter were in conjunction in late April 2023.

* When were Mars and Jupiter last at their brightest? This happens when the planets are at their closest point to Earth in their respective orbits. These events are also periodic but occur less frequently than conjunctions.

To find out specific dates for these events, I recommend checking out:

* Astronomy websites: Sites like NASA's website, EarthSky, or the Astronomical Society of the Pacific can provide you with up-to-date information on planetary positions and visibility.

* Planetarium software: Programs like Stellarium or SkySafari can show you the positions of celestial objects, including planets, at any given time.

Please let me know if you have any further questions.