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NEW YORK: The fiery demise of a fifth rocky planet in our Solar System might have led to a flurry of asteroid impacts that pockmarked the Moon and Earth billions of years ago. The Late Heavy Bombardment (LHB) is a relatively brief period, about 3.9 billion years ago, when wayward space projectiles heavily pelted the Moon and inner planets. Craters from that chaotic time are still visible on the Moon, but have been erased from Earth, where the crust is continually recycled. All shook up Try as they might, astronomers have not yet been able to pin down a cause for the bombardment. Some experts have postulated that a shuffling up of the arrangement of the planets in their youth may have been responsible. One popular theory is that the outward migration of a young Neptune perturbed rocky bodies in the distant Kuiper Belt, causing some to veer into the inner Solar System. But John Chambers, an astrophysicist at the Carnegie Institution in Washington DC, now says the size distribution of craters on the Moon better match asteroids from the Asteroid Belt, located beyond the orbit of Mars. And he thinks the misbehaviour of a long-lost, fifth rocky planet called 'Planet V' was the trigger that upset the gravitational balance of the belt and ejected some of its inhabitants. Our Solar System currently contains four rocky planets: Mercury, Venus, Earth and Mars. Using a new computer model detailed in a recent issue of the journal Icarus, Chambers provides the most compelling evidence yet that a hypothetical Planet V could have existed for hundreds of millions of years before minute gravitational tugs from Mars and Jupiter destabilised its orbit, causing it to fall into the Sun. "Before it was lost, its orbit would have moved across the Asteroid Belt for quite a long period of time, scattering asteroids as a result," Chambers said. "My model would predict that it's only asteroids, and not comets, that caused the impacts, and that the asteroids would tend to come from the inner asteroid belt." Unknown planet Planet V's orbit was between that of Mars and the Asteroid Belt, Chambers predicts, and it may have been smaller than Mars but larger than our Moon. "If it was bigger than Mars, then Mars should have been the one that was lost," he said. "If it's smaller than the Moon, that's not really big enough to disturb the Asteroid Belt much." David Kring, a planetary scientist at the U.S. Lunar and Planetary Institute in Houston, Texas, agrees that the Planet V hypothesis is interesting because it suggests an inner Solar System origin for the impacting debris. But he added that Chamber's "model relies on the invention of an unknown planet... so it is a hypothesis that will need to be rigorously tested with the geologic record." One such test could be done if scientists had more lunar rock samples, he said. It was using these samples, returned by NASA's Apollo missions, that scientists were able to date the Late Heavy Bombardment in the first place. Readers' commentsDetonation...noNo. Planets don't "detonate." What's going to explode? And even if they could, short of hitting another planet composed of antimatter, there's no way to get a planet that large (~3,000 miles diameter) to blow up with enough force to avoid reforming afterwards - it takes just oodles of energy to get most of the mass of a planet to reach that planet's escape velocity. I mean, look, Earth was hit by a planet the size of Mars, and the best it could do was "lose" (and not very far) the mass of the Moon. The rest, right back into Earth (Mark II). "Kryptons" only happen in comics. Submitted by David on 9 November 2007 - 9:49am.
Detonating planetsHi David Normally planets don't detonate - which has been a problem with Tom van Flandern's theory since he proposed it in the 1970s. It's not an original idea - even Oort thought the asteroid belt and the Oort Cloud of comets might be remnants of a planetary detonation. But planets certainly wander and they can collide, which well and truly packs enough punch to shatter worlds if they're similar in mass. Earth-Moon systems are one possible outcome. Look at the track record of the inner Solar System - Earth collided with Theia; Venus probably collided with two objects; Mercury lost its crust, and even Mars has a hemispherical asymmetry perhaps due to a mega-impactor. Here's my theory - Earth and Venus formed, and both formed with L4/5 planets accreting in the same orbits. But the Trojan planets got too big and started wandering around their orbits - Venus's Trojans collided with each other. One became Mercury, the other blew away Mercury's mantle, and big bits probably smacked into Venus, eventually. Earth's Trojans were Theia and Mars. But that's just one scenario - other extremes are possible. Most simulations assume a thousand Moon-sized bodies have formed out of the dust-disk and the simulation lets them orbitally evolve and collide until planets in stable orbits result. Surprisingly they do form, even eventually looking like our own inner planets. Submitted by Adam on 10 November 2007 - 10:39am.
Detonation of a planet?I was curious about the concept myself, and evidently a geophysicist with some good credentials has given it some thought - J. Marvin Herndon (nuclearplanet.com) proposes that under the high earth core temperatures and pressures, an actual ongoing uranium fission reaction is the driving force not only for geothermal forces but for the geomagnetic field. Some research tends to support this theory, however nobody has currently been able to devise an experiment to detect signature particles from a fission reaction that deep below ground. Herndon's theory also tends to support the possibility that planets can indeed "explode" - and both Uranus and Jupiter radiate far more energy than they absorb from the sun - whether this is indeed from a core fission reaction it is not known - however the math says it's possible. For a slightly more biased slant, check out Dr. Tom Chalko's article about the subject at http://nujournal.net/core.pdf - he backs his opinions up with math but the article gets a little emotional in places for a "scientific paper"... Have fun - oh, and check out http://www.thesurfaceofthesun.com - it's an interesting theory. No - I'm not trying to advertise for these folks, just thought the sites were interesting... Submitted by Kevin on 27 November 2007 - 6:52pm.
Of course we did!Yeah, we used to have another planet. We called it Pluto. Submitted by Forrest on 9 November 2007 - 10:23am.
It's also called as Planet XIt's also called as Planet X .. and the asteroid belt was a planet once which was hit by planet x. those pieces also made craters on moon surface. http://www.xfacts.com/MUFON_LA/ Submitted by Visitor on 9 November 2007 - 6:40pm.
A Rock Giant?I reckoned many years back, that before the sun consolidated/ expanded to its full scale in the period of accretion, that a `rock giant' may have existed between Jupiter & mars. & that the combo of increased gravitational force from the sun (transcending the sub rotational forces BEFORE it became large enough to exert a FULLY rotational orbit bringing to an end the period of accretion) would have caused an inbalance between its unstable internal pressures (unlike a gas giant nowhere else to go) & the INCREASED forces exerted on it by the FULLY rotational orbit. That what happened next was a process of REVERSE accretion (aided by massive collisions that could only take place ONCE the sun has expanded to the point that the SUB rotational phase of planetary development had ended. Trouble with THIS idea, is that you would expect a lot of metal debris. This notion of an exploding planet does however seem to match Mercury. which has a heavy metal core, which implies that after the explosive period (loss of matter) it had found equilibrium between internal & external pressures. Submitted by Adam Ghaznavi on 10 November 2007 - 6:52am.
Planet V was EarthI'm reading a story at www.fantazine.net/ that proposes the theory that the asteroids are the remains of our planet, which before existed between Mars and Jupiter until it collided with a non-elliptical object that gutted a hole in our world where the Pacific ocean is today. The other side of the planet became dryer from the water filling the Pacific crater and formed the continental tectonic plates of Earth. In the story dinosaur bones are found on an asteroid. Submitted by Davol on 10 November 2007 - 10:09am.
The Sumerians called it Nibiru......the Babylonians called it Marduk, and I wouldn't rule out the possibility that other ancient cultures also had a name for it. Some 20 years ago, a popular German tabloid newspaper published a story about an ancient Sumerian star chart listing a planet between Mars and Jupiter. And there is another source confirming the former existence of a planet where the Asteroid Belt is now -- one folks of your likes would hardly consider credible. The Great Gospel of John, supposed to be given by Jesus Christ Himself and written down by an Austrian called Jakob Lorber in the 19th century, depicts in detail that this planet was a rock planet about the size of Jupiter and that it ceased to exist as a planet a bit before 4000 BC due to being blown up by its own inhabitants -- intelligent human-like creatures with a free will who were constantly at war with each other, digging holes deep in the crust of the planet to deposit dynamite-like substances there in order to make their neighbours' lives even harder. At one point this 'dynamite' was so deep inside the planet that the hot mantle substances ignited it and basically blew the whole planet apart in a chain reaction. This event, in the Great Gospel of John, is the trigger for humankind on Earth to become what it is now because God, at that point, chose to put the spirit of Adam onto Earth creating the first human being on this planet with a completely unbound free will. You can download the Great Gospel of John and other writings of Jakob Lorber in HTML, PDF and/or SILO format in German from here; for English resources please feel free to research yourself, I haven't found a really good one yet. :) Submitted by Visitor on 22 February 2008 - 3:46am.
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Planet V wandered or detonated?
A wandering planet V could have caused the LHB, but what if several craters from the LHB on the Moon are investigated for remnants of the impactors - and they're all chemically identical? That would indicate that the LHB was caused by remains of a planet V. Could planet V have detonated?
Astronomer Tom van Flandern actually thinks several planets exploded in our solar system's history - could he be correct? Another possibility is that "twin" Trojan planets formed either side of Jupiter's orbit and were set into motion that perturbed them into a collision course with each other.
Many things are possible when it comes to wandering planets - even the survivors might be launched into wandering orbits. For example, Mercury has a small probability of becoming "unchained from the Sun" over the next billion years due to chaotic amplification of its orbital eccentricity.