I know you had a change of heart, but check it:
I think its possible that there was once life on further planets than the earth from the sun.
I think it could be possible as well, we just don't know. I'm hoping for anything on Mars or some of the icy moons, but who knows when or if.
I think as the sun gets weaker and burns off its fuel, its heat no longer reaches planets that are further out, killing all possible life forms on it.
See, sort've a reverse thing actually happens as a star ages... the type of star we have actually gets larger as it ages, at least in stages. One day the sun will be a red giant, its surface temp will be somewhat cooler, but the sun's core will be hotter. It won't matter though because the sun will be so large at that point, the earth will either be close to or inside the circumference of the sun. Huge, but not as dense.
Maybe there's only a certain range of heat that a planet can/cannot take for it to have life on it. Planets are either too far from the range, or too short.
That's called a "habitable zone." It's the distance from a star that would allow a planetary body to sustain liquid water.
Idk if this has been proven or tested, but perhaps mercury and venus's core's are full of lava (and have proportionally more than earth), because they are so close to the sun. Perhaps all planets were once a sun . What I mean by a sun is that they were on fire (maybe just like the sun) because of our (current) sun was so powerful it just torched that shit up. Which could explain why the core of our planet is of molten lava, or whatever the fuck it is, it's on fire and its moving around.
Nearly all of the planets were on fire at some point, as they were molten chunks being smashed and heated when the sun had an accretion disc (nearly all of the particles in the solar system traveling around the sun much like particles spin around Saturn). The inner planets were molten rocks that eventually developed iron cores of varying density. Mercury probably barely has any iron core (and it's probably dead), and Mars has one too small to sustain the mass of an atmosphere like ours. Venus is pretty close, and probably could fall into a habitable zone if it weren't for the fucked up chemistry, superheated greenhouse effect, and inhuman pressure and heat on the ground because of the amount of shit in its atmosphere.
Once a planet stops receiving sufficient heat from the sun, the core will freeze up.
Externally, but internally, different processes keep planetary cores hot. At least for us.
Topic: NASA confirms that meteor from Mars contains fossilized bacteria (Read 4033 times)