Has Mars ever mirrored Earth? I would like to begin this discussion by defining the term “specular” as similar to or characteristic of a mirror image. So for the proposals in this discussion I will use this definition, meaning that it is a similarity and not a direct copy of each other. Now, once all the formalities are done, let's move on. After spending a small portion of my life reading articles about the geology of Mars, I have come to the conclusion that Mars does indeed have evidence to support the fact that it was once a mirror planet to Earth. Or better said, Earth is currently a mirror image of Mars in the past. In the following paragraphs I will support this statement with evidence from research findings, documents and photographs. It will also be structured like this: interior, magnetic field, atmosphere, plate tectonics, volcanoes and water. Mars has an interior that is very similar to Earth's interior. Mars has a core, mantle and crust just like Earth. Both are made primarily of iron and behave quite similarly. Mars has a much smaller interior than Earth, but that makes sense when you take into account that Mars is almost half the size of Earth. The Earth's core is made up of two parts: a solid inner core and a liquid outer core. Radioactive decay in the core generates heat. This heat is lost from the core to the upper layers. Convective currents in the liquid outer core together with the rotation of the Earth produce the Earth's magnetic field. This is where Earth and Mars begin to differentiate from each other. The outer part of Mars' core could be molten, but that's unlikely, because Mars has only a weak magnetic field (less than 0.01% of Earth's magnetic field). Even though Mars does not have a strong magnetic field now, it may have had a p...... middle of paper ...... ideal for supporting liquid water and with the abundance of evidence I think it's just It It is logical that the Earth reflects the past shape of the Martian planet. Based on the fact that both Mars and Earth had very similar geology, I believe that these two planets actually mirrored each other as defined above. They both share having had a magnetic field, a thick, life-rich atmosphere, volcanoes, plate tectonics, liquid water, and share similar interiors. The planet's orbits are within the habitable zone, and conditions following the formation of Mars would also have allowed it to be an early Earth. I hope this discussion has been informative and an interesting read. Please comment below if you have any questions, comments or concerns. My thanks also go to NASA and others for the webinars, slides, and information on these topics that allowed me to write in the first place.