As of today, there are currently 1453 known potentially hazardous asteroids that could impact Earth and cause a real planetary catastrophe. Given the new diverse “snow globe” model of our solar system in relation to asteroids, how may more don’t we know about? It only takes one. Of more pragmatic interest, this new paper suggests a diverse asteroid population stirred up in the ‘snow globe’ model was essential to bringing water to Earth.
From the Harvard-Smithsonian Center for Astrophysics Cambridge, MA –
Our solar system seems like a neat and orderly place, with small, rocky worlds near the Sun and big, gaseous worlds farther out, all eight planets following orbital paths unchanged since they formed.
However, the true history of the solar system is more riotous. Giant planets migrated in and out, tossing interplanetary flotsam and jetsam far and wide. New clues to this tumultuous past come from the asteroid belt.
“We found that the giant planets shook up the asteroids like flakes in a snow globe,” says lead author Francesca DeMeo, a Hubble postdoctoral fellow at the Harvard-Smithsonian Center for Astrophysics.
Millions of asteroids circle the Sun between the orbits of Mars and Jupiter, in a region known as the main asteroid belt. Traditionally, they were viewed as the pieces of a failed planet that was prevented from forming by the influence of Jupiter’s powerful gravity. Their compositions seemed to vary methodically from drier to wetter, due to the drop in temperature as you move away from the Sun.
That traditional view changed as astronomers recognized that the current residents of the main asteroid belt weren’t all there from the start. In the early history of our solar system the giant planets ran amok, migrating inward and outward substantially. Jupiter may have moved as close to the Sun as Mars is now. In the process, it swept the asteroid belt nearly clean, leaving only a tenth of one percent of its original population.
As the planets migrated, they stirred the contents of the solar system. Objects from as close to the Sun as Mercury, and as far out as Neptune, all collected in the main asteroid belt.
“The asteroid belt is a melting pot of objects arriving from diverse locations and backgrounds,” explains DeMeo.
Using data from the Sloan Digital Sky Survey, DeMeo and co-author Benoit Carry (Paris Observatory) examined the compositions of thousands of asteroids within the main belt. They found that the asteroid belt is more diverse than previously realized, especially when you look at the smaller asteroids.
This finding has interesting implications for the history of Earth. Astronomers have theorized that long-ago asteroid impacts delivered much of the water now filling Earth’s oceans. If true, the stirring provided by migrating planets may have been essential to bringing those asteroids.
This raises the question of whether an Earth-like exoplanet would also require a rain of asteroids to bring water and make it habitable. If so, then Earth-like worlds might be rarer than we thought.
The paper describing these findings appears in the January 30, 2014 issue of Nature.
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.
“This raises the question of whether an Earth-like exoplanet would also require a rain of asteroids to bring water and make it habitable. If so, then Earth-like worlds might be rarer than we thought.”
This raises the question of whether asteroids are common to all star systems. If so, then they would bring water to Earth-like exoplanets and thus Earth-like worlds may be more common than we thought.
Since the Hubbell Deep Field images show nearly 3,000 galaxies in an area said to be only 1/24 millionth of the sky, then it’s a good bet that there are lots of habitable planets out there. I doubt if they’re that much smarter than us and it’s probably a real good idea that we’re so far apart.
This finding has interesting implications for the history of Earth. Astronomers have theorized that long-ago asteroid impacts delivered much of the water now filling Earth’s oceans. If true, the stirring provided by migrating planets may have been essential to bringing those asteroids.
Here is a different take on this [slow to load] http://arxiv.org/pdf/1401.7490.pdf :
“The asteroid (4) Vesta, parent body of the Howardite-Eucrite-Diogenite meteorites, is one of the first bodies that formed, mostly from volatile-depleted material, in the Solar System. The Dawn mission recently provided evidence that hydrated material was delivered to Vesta, possibly in a continuous way, over the last 4 Ga, while the study of the eucritic meteorites revealed a few samples that crystallized in presence of water and volatile elements. The formation of Jupiter and probably its migration occurred in the period when eucrites crystallized, and triggered a phase of bombardment that caused icy planetesimals to cross the asteroid belt. In this work, we study the flux of icy planetesimals on Vesta during the Jovian Early Bombardment and, using hydrodynamic simulations, the outcome of their collisions with the asteroid. We explore how the migration of the giant planet would affect the delivery of water and volatile materials to the asteroid and we discuss our results in the context of the geophysical and collisional evolution of Vesta. In particular, we argue that the observational data are best reproduced if the bulk of the impactors was represented by 1-2 km wide planetesimals and if Jupiter underwent a limited (a fraction of au) displacement.”
Alan Robertson says: @ur momisugly January 30, 2014 at 4:42 pm
….. it’s probably a real good idea that we’re so far apart.
>>>>>>>>>>>>>>>>
Predators are generally smarter than prey….
Jupiter may have been as close to the sun as Mars? Given Jupiter’s gravitational field/strength how did we end up with Mars, Earth, Venus and (possibly) Mercury – wouldn’t they have been either swallowed up by Jupiter or torn apart in the the gravitational tide wars between Jupiter and the Sun?
Need to underline real in the first sentence.
I think the evidence shows that we have not been hit by anything larger that up to 15 kms in the last 4 billion years. That means, we are one lucky planet.
The largest impact crater is Vredefort South Africa from 2.0 billion years ago and it was only a little larger than the Chicxulub asteroid which wiped out the dinosaurs.
From the modeling and the study of the effects of these asteroid impacts in the 10 km range (as these two were), we wouldn’t have life on the planet if a 20 km asteroid hit us or, especially if a 20 km comet coming in at faster speeds hit us or if one of the very largest comets at 100 kms across hit us.
Perhaps the early Earth, just after the Mars-size planet impact that created the moon and established the final size of Earth 4.4 billion years, was hit by larger asteroids/or comets in the first 200 hundred million years afterward. But after that, we have been one lucky planet. We know this because you are reading this.
Ben, I highly recommend the book “Rare Earth: Why Complex Life is Uncommon in the Universe” by Peter D. Ward and Donald Brownlee
These guys really did their homework, and it ties in nicely to your comment.
Nice ! Thanks for the path to it Anthony.
Leif, thanks for the pdf too. It was not slow to load from my seat. Albeit, I will spend a significant amount of time thinking about it tonight, so maybe you are correct in the end 🙈🙊🙉
“Given the new diverse “snow globe” model of our solar system in relation to asteroids”
So, how long will it take for all of the asteroids to settle at the bottom of the solar system if someone (God?) doesn’t come along and shake it again?
Another potential catastrophe caused by global warming. Apparently, as the Earth’s atmosphere heats up due to anthropogenic causes, the atmosphere expands. Thus, as this planet sails through the heavens, CAGW causes it to be a bigger target and therefore more likely to be hit by one of those asteroids. I promise, on my honor, that I am not making this up. I have read this.
This gets me to thinking. Who knows, maybe in the early, formative days of the Solar System the Earth’s atmosphere was so laden with CO2 that it was a really hot place with a really heat ballooned atmosphere that made it a very large target for all those asteroids near its path. And all those asteroids sucker punching the planet brought in lots and lotsa water. See, CO2 controls everything.
Man, this is a fanciful tale! I could take some speculative musing about earth’s water, etc but this kind of detail in a CWAG (crazy wild ass guess) makes it Hollywood material. I think CAGW (which is just a mixup of CWAG) must have encouraged scientists to lose all restraint and open the door to “cubist” or “postimpressionism” physics. I knew this Ravetz was going to be trouble. At least there should have been a sober explanation for these planets jumping all over the place and then settling down to smallest at the front, biggest at the back like my grade two class photo. Those asteroids, to not have been sucked in by all these giant vagabonds, are made of stern stuff and must have an attitude. Perhaps they are the skeptics of the order.
I have only one question – how much more CO2 must I output personally in order to increase the mass of the earth enough to alter the orbit of an asteroid so it strikes Washington DC on a day when all the climate lobbyists are there?
[And] then throw in the “binary planet” system that we reside in – http://chiefio.wordpress.com/2014/01/25/a-remarkable-lunar-paper-and-numbers-on-major-standstill/
And the ingredients for life on other worlds becomes much rarer. It seems we have to look outside our planet for answers on the climate. At least for parts of the answer.
There is another obvious theory about where most of the water of Earth came from. The Earth itself.
When magmas cool, they expel water. The top ~30-70km of the earths crust formed very early on after the planet formed when the earth cooled, and during this process vast volumes of water were expelled, forming the oceans. There is enough volume in the earth to more than account for the world’s oceans. Moreover, the earths crust continually mixes with the mantle’s through e.g. convection currents, providing a further source of oxygen and hydrogen. (It is also possible that during more active tectonics, more water reaches the outer surface, affecting sea levels).
Most astronomers have little to no understanding of magmatic processes, the processes of magma-generating water still goes on today. On other planets, in some cases there is no crust (if it is a gaseous planet), or the water was lost as gas as the planet was too hot (Venus and Mercury). Venus has evidence of plate tectonics, but which has apparently shut down. Mars, being a rocky planet, should have also expelled its’ water during cooling, which is why they are still looking for water there.
“Their compositions seemed to vary methodically from drier to wetter, due to the drop in temperature as you move away from the Sun.”
A very important point. There is a “snow line” in the solar system at 3 AU, inside which ice cannot last in the light of the sun.
Remember what Stephan-Boltzmann worshippers say about earth’s oceans? That without downwelling LWIR from the atmosphere they would freeze solid.
Now lukewarm ManBearPiglet believers can go all “flappy-hands” about ice sublimating in vacuum over -20C or diurnal SW cycling at the earth’s surface reducing available SW but it won’t work. Their figures are so far out it makes no difference. They applied SB instantaneous radiative flux equations to liquid heated at depth by SW.
If you remove all features of the atmosphere above the oceans except pressure they would get hot enough to boil the whales.
The NET effect of the atmosphere on the oceans is cooling. There is only one effective cooling mechanism for the atmosphere. Radiative gases.
Leave it to Leif, to upset ones world-view 🙂
thingadonta says:
January 30, 2014 at 6:00 pm
“There is another obvious theory about where most of the water of Earth came from. The Earth itself.”
Yeah, average granite magmas have about 5% water. This is the trouble with astronomers speculating on earth science. They linearly think the stuff has to rain down only from above. Also, why would the snowballs wait so patiently for the earth to be fully formed before they attacked. Hey, there must have been even more of them in the earlier chaotic period while the earth was agglomerating.
Why would Asteroids be more likely to be composed of, or with water than any other celestial body?
I don’t see an explanation or speculation thereto.
Gary Pearse says:
January 30, 2014 at 5:33 pm
CAGW = Crazy As Guesses Wild
Works for me.
“As of today, there are currently 1453 known potentially hazardous asteroids that could impact Earth and cause a real planetary catastrophe.”
See. I said we were doomed.
One’s world view.
Two worlds’ views.
Three worlds’ views.
Four worlds’ views …. 8<)
RACookPE1978 says:
January 30, 2014 at 6:31 pm
=======
Did you have to rub it in ?
I’ll never remember it.
Oil Vey!
T’was not ye who were commented, but the Leif who was to be (indirectly) complimented (via your words – however ingrammarnumerical they may be) for educating the world’s views!
Hmmm, wondered if the referenced Immanuel Velikovsky in his 1950’s book “Worlds in Collision”?