Waspie_Dwarf Posted March 3, 2015 #1 Share Posted March 3, 2015 Lucky Earth survived cosmic pinball Rogue alien planets are forcing astronomers to rethink the birth of our Solar System. What's emerging is a tale of hellfire, chaos and planetary pinball - and it's a miracle our Earth survived.Hunting for alien planets is big business. Since the first exoplanet was discovered in 1995, astronomers around the world have been searching for those elusive Earth-like planets that could harbour life. The tally of planets found is staggering. So far, more than 1,800 confirmed planets have been discovered orbiting around other stars in our galaxy (the latest figure from Nasa is 1,816 planets around 1,117 stars). Read more... 1 Link to comment Share on other sites More sharing options...
+Hammerclaw Posted March 3, 2015 #2 Share Posted March 3, 2015 Not to mention the Sun came within less than a lightyear of colliding with a binary star system just seventy or so thousand years ago. Link to comment Share on other sites More sharing options...
Waspie_Dwarf Posted March 3, 2015 Author #3 Share Posted March 3, 2015 (edited) Not to mention the Sun came within less than a lightyear of colliding with a binary star system just seventy or so thousand years ago. Stars pass close to each other regularly. Many such events will have happened in the life of the solar system. Generally they do not pose a major threat to the Earth. Edited March 3, 2015 by Waspie_Dwarf Link to comment Share on other sites More sharing options...
+Hammerclaw Posted March 3, 2015 #4 Share Posted March 3, 2015 Stars pass close to each other regularly. Many such events will have happened in the life of the solar system. Generally they do not pose a major threat to the Earth. Well, this one passed through our Orc Cloud. For me, that's just a little too close for comfort. Just sayin'. Link to comment Share on other sites More sharing options...
+OverSword Posted March 3, 2015 #5 Share Posted March 3, 2015 Ort cloud. This is just one more indicator that life evolving is probably even more rare than is believed. Link to comment Share on other sites More sharing options...
Waspie_Dwarf Posted March 3, 2015 Author #6 Share Posted March 3, 2015 Well, this one passed through our Orc Cloud. So what? The outer edge of the Oort cloud is 1 light year away, that's a quarter of the way to Alpha Centauti. The star passed at a distance of 0.8 ly, which is more than 5 TRILLION miles. Such events are estimated to occur, on average, every 9 million years. Given that the Earth is 4.54 billion years old that means it has survived around 500 such encounters. Like I said, not generally a threat to the Earth, s few extra meteorite impacts a couple of million years later but nothing to drastic. For me, that's just a little too close for comfort. Just sayin'. I hope I don't get a cab driver with your idea of close, when I ask to be dropped off close to my front door I will be lucky to arrive on the right continent. Just saying. Link to comment Share on other sites More sharing options...
Waspie_Dwarf Posted March 3, 2015 Author #7 Share Posted March 3, 2015 Ort cloud. Close but no cigar. It's Oort cloud. Link to comment Share on other sites More sharing options...
+Hammerclaw Posted March 3, 2015 #8 Share Posted March 3, 2015 (edited) So what? The outer edge of the Oort cloud is 1 light year away, that's a quarter of the way to Alpha Centauti. The star passed at a distance of 0.8 ly, which is more than 5 TRILLION miles. Such events are estimated to occur, on average, every 9 million years. Given that the Earth is 4.54 billion years old that means it has survived around 500 such encounters. Like I said, not generally a threat to the Earth, s few extra meteorite impacts a couple of million years later but nothing to drastic. I hope I don't get a cab driver with your idea of close, when I ask to be dropped off close to my front door I will be lucky to arrive on the right continent. Just saying. I suppose it's all a matter of perspective. On a cosmic scale it practically brushed us. As far as the damage such a close encounter could potentially cause, all I have to do is look at the moon. Our sun and it's entourage of planets orbits galactic center at about 220km/s completing and orbit about every 240 million years. In the five billion years of the life of our star it has made, perhaps twenty orbits. In that time it has drifted in and out of spiral arms. On one it's early trips, as a new star settling into its orbit, such close encounters may have been more frequent. 4.1 to 3.8 billion years ago, spanning the Neohadean and Eoarchean eras, a disproportionately large number of asteroids apparently collided with the early terrestrial planets in the inner solar system, including Mercury, Venus, Earth, and Mars. This is pertinent to the substance of your post as far as the solar pinball match goes. Or, as I'm sure you will insist, such melodramatics are not required to explain the gravitational interactions and perturbations in play at that time. In any case, you and your cabbie aren't likely to ever experience such interesting times. More's the pity. Edited March 3, 2015 by Hammerclaw Link to comment Share on other sites More sharing options...
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