Sitchin was a delusional con man.
The idea that a planet between Mars and Jupiter blew up is fairly old. The discovery of Ceres, which is a nice spheroid and largest of the main belt asteroids, used to be regarded as a planet here and there, but the discover of the other three large main belt asteroids put the kibosh on the idea. Cere’s mass exceeds the combined mass of the rest of the main belt asteroids, which is slightly in favor of a failure of Ceres to finish gathering up the rest of the debris and clearing out its orbital path.
Ceres’ mass is only 27% that of the Earth’s Moon, which itself is only 1% the mass of the Earth.
Here’s the AI summary answer for the question I just asked in the Brave location box:
Some quotes and statements from the search results suggest alternative theories:
Johann Daniel Titius and Johann E. Bode proposed the Titius-Bode law, which predicted the existence of a hypothetical fifth planet between Mars and Jupiter. However, this did not imply that the asteroid belt was a former planet.
Giuseppe Piazzi discovered Ceres, the largest asteroid in the asteroid belt, and initially believed it might be a planet. However, subsequent discoveries of other asteroids and the realization that Ceres was much smaller than expected led to its reclassification as an asteroid.
Some scientists, such as Ivan I. Putilin and Tom Van Flandern, have proposed theories about the asteroid belt’s origin, including the idea that it might have been formed from the remains of a destroyed planet. However, these theories are not widely accepted, and most astronomers today believe that the asteroid belt formed through accretion of small bodies in the early solar system, rather than being the remnant of a former planet.
I agree. We’re not going to know until we start drilling out there, until then it’s fantasy. And Titius-Bode breaks down somewhere beyond Saturn. If only it were that easy!