Well, I'm partial to... The Green Hills of Earth Let the sweet fresh breezes heal me As they rove around the girth Of our lovely mother planet Of the cool, green hills of Earth. We rot in the moulds of Venus, We retch at her tainted breath. Foul are her flooded jungles, Crawling with unclean death. We've tried each spinning space mote And reckoned its true worth: Take us back again to the homes of men On the cool, green hills of Earth. The arching sky is calling Spacemen back to their trade. ALL HANDS! STAND BY! FREE FALLING! And the lights below us fade. Out ride the sons of Terra, Far drives the thundering jet, Up leaps a race of Earthmen, Out, far, and onward yet --- We pray for one last landing On the globe that gave us birth; Let us rest our eyes on the fleecy skies And the cool, green hills of Earth. --Robert A Heinlein
Well if that is ever proven it's kind of awesome... You made me think of an old movie from the 60s "Journey to the far side of the Sun" where they find another Earth orbiting the Sun but on the exact opposite side of the Sun so we never see it. It's a silly movie but lots of fun.
Yeah, that's known to be a dynamically unstable configuration. http://www.universetoday.com/119065/could-there-be-another-planet-behind-the-sun/
If Earth had a twin at the opposite side of its orbit, would Earth—by definition—no longer be a planet? Pluto got demoted because it does not sweep out its orbit of all other bodies.
If we suddenly discovered that Earth had a twin, I think you'd see the IAU modify or clarify the definition of planet real quick!
Of course if it did, the laws of physics would have to be different and we wouldn't be here. OTOH, the term "double planet" and or "binary planet", while not officially recognized, already do exist, and could be adapted in the event of the discovery of two planets sharing an orbit (although it would be far more likely for a double planet system to consist of two planets orbiting each other.) Since such a system would still gravitationally dominate its orbit (what "clearing its orbit" really means), they would still count as planets.
Yes, by definition it would not be. However, Earth did clear its orbit and there is no twin on the opposite side. If there was in the past I is very unlikely that it would be a stable situation, and this is possibly why no such planet exists now. It is also a great example of how the definition has real meaning.
Ugh. That's disturbing. O/T It is interesting--what unsettles adults vs. youngsters. We laugh when we see an adult dressed up for kids--like this sad little incident A child only knows Eeyore as a small, clean little animated figure on the screen--smaller than the child. But if that animated little figure popped out of the screen--the kid would probably be cool with it--and it would be the adults who would run...