Posted on 11/20/2007 7:40:12 PM PST by NormsRevenge
The moon formed after a nasty planetary collision with young Earth, yet it looks odd next to its watery orbital neighbor. Turns out it really is odd: Only about one in every 10 to 20 solar systems may harbor a similar moon.
New observations made by NASA's Spitzer Space Telescope of stellar dust clouds suggest that moons like Earth's are—at most—in only 5 to 10 percent of planetary systems.
"When a moon forms from a violent collision, dust should be blasted everywhere," said Nadya Gorlova, an astronomer at the University of Florida in Gainesville who analyzed the telescope data in a new study. "If there were lots of moons forming, we would have seen dust around lots of stars. But we didn't."
Gorlova and her team detail their findings in today's issue of the Astrophysical Journal.
Violent birth
Shortly after the sun formed about 4.5 billion years ago, scientists think a vagrant planet as big as Mars smacked into infant Earth and ripped off a chunk of our home's smoldering mantle. The rocky, dusty leftovers fell into orbit around our wounded planet, eventually coalescing into the moon we see today.
The scenario is unique among other moons in the solar system, which formed side-by-side with their planet or were captured by its gravity. Gorlova and her colleagues looked for the dusty signs of similar smash-ups around 400 stars, all about 30 million years old—roughly the age of our sun when Earth's moon formed.
Only one of all the stars they studied, however, displayed the telltale dust. Considering the frequency of planetary solar systems, the amount of time the dust should stick around and the window for moon-forming collisions to occur, the scientists were able to peg the frequency of extrasolar bodies that formed like our moon.
The estimate, however, is possibly a generous one.
"We don't know that the collision we witnessed around the one star is definitely going to produce a moon," said study co-author George Rieke, an astronomer at the University of Arizona in Tucson, "so moon-forming events could be much less frequent than our calculation suggests."
Odd moon out?
Planetary scientists like Gorlova and Rieke think infant solar systems can form moons between 10 and 50 million years after a star forms. That only a single star with collision-generated dust could be found in their latest research, the astronomers said, indicates that the 30 million-year-old stars in the study have finished making their planets.
"Astronomers have observed young stars with dust swirling around them for more than 20 years now," said Gorlova, noting that the dust could be collision-derived or primitive planet-forming material. "The star we have found is older, at the same age our sun was when it had finished making planets and the Earth-moon system had just formed in a collision."
While most the our type of moon may be rare, astronomers think there are billions of rocky planets out there with plenty of moons orbiting around them. The upshot for lunar lovers? There could be millions—or billions—of Earth-like moons drifting through the cosmos.
Four billion is still plenty of time.
Mostly I regard the Oort cloud as a hypothetical construct made necessary by theory rather than detected through observation (iow, a kludge), but a spherical concentric cloud doesn't seem too likely -- although it might have got there (if it is found to exist) when an earlier version of the Sun blew up.
Re: the 490K MPH
That velocity is of course relative. It would probably be more accurate to state that it is relatve to some fixed coordinate in the universe around us than the center. It is however the shared velocity of everything in this particular orbital distance from the center.
A hypothetical body wandering in from interstellar space would most likely be moving far slower especially to be slow enough to either be captured in solar orbit or to not impart a solar escape velocity to an impacted early Earth. (This raises the question of why such a high velocity collision did not impart a highly elliptical orbit after combining their inertia.) The length of time necessary to reach Earth over stellar distances is further increased... by a lot. This decreases the candidates for its source even more. This wandering rock would have to come from somewhere close to be at the required velocity to meet the criteria for our Moon maker.
re:
http://www.freerepublic.com/focus/f-chat/1929042/posts?page=34#34
Moving the convo over here.
That Astronomy article appears to be online, as a PDF:
Why is the solar system cosmically aligned?
Dragan Huterer
http://huterer.physics.lsa.umich.edu/~huterer/PLOTS/CMB_Huterer.pdf
Maybe the Oort cloud is the source of the background microwave radiation.
Okay. If the background microwave radiation is a local phenomenon then the Big Bang is in question.
The Galactic Environment of the Sun
http://www.americanscientist.org/template/AssetDetail/assetid/21173/page/2
“Our sun is also in motion. Relative to the average motion of the most commonly measured nearby stars, the sun moves with a speed of about 16.5 kilometers per second, or nearly 50 light-years per million years... The sun oscillates through the plane of the galaxy with an amplitude of about 230 light-years, crossing the plane every 33 million years. However, the sun’s motion relative to the local stellar neighborhood should not be confused with its movement around the center of the galaxy, since the whole solar neighborhood (including the sun) orbits the galactic center once every 250 million years. Just as we do not include the earth’s velocity around the sun when calculating the speed of an airplane (we are only interested in the ground-speed), astronomers do not include the sun’s galactic orbital velocity when describing its local motion.”
That's true, but that colloquilism causes large numbers of astronomers and physicists to incorrectly estimate the Speed of Gravity as being equal to the Speed of Light...whereas the correct answer when one factors the speed of the Sun's movement and overall galactic orbital velocity shows that the only way that our planets can revolve in a flat plane around our Sun with such coincidental momentum is for the Speed of Gravity to be vastly faster than C.
If Gravity was slower, as the Sun head North, the planets' orbits would look like a wedding cake with each rotation being further South as you went outward from the Sun from one planet to another...because there would be a gravitational lag by the time the Sun in its old position affected a planet.
TVP appears to have discovered the “pushing gravity” model.
The extension of the pushing gravity model into the quantum world
http://metaresearch.org/cosmology/Quantum_Physics/StructureOfMatter.asp
Pushing Gravity
http://metaresearch.org/cosmology/gravity/meta_cycle.asp
Here’s the older stuff he’s been writing about for a long while:
Speed of gravity — What the experiments say
http://www.metaresearch.org/cosmology/speed_of_gravity.asp
Speed of gravity — repeal of speed limit
http://www.metaresearch.org/cosmology/gravity/speed_limit.asp
Meaning of the “speed of gravity”
http://www.metaresearch.org/home/Viewpoint/Kopeikin.asp
Does gravity have inertia?
http://www.metaresearch.org/cosmology/gravity/Does%20Gravity%20Have%20Inertia.asp
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What about when the moon is out during the day?
;)
The Top 30 Problems with the Big Bang (Van Flandern)
http://metaresearch.org/cosmology/BB-top-30.asp
“(2) The microwave ‘background’ makes more sense as the limiting temperature of space heated by starlight than as the remnant of a fireball.”
Quantum Entanglement And Free WillDistance between Mirror Universes. A Chiral "Oscillating Quantum Vacuum Lattice" guided by "Big Bang-entanglement" could lead to the explanation how the Quantum Mechanical World is able to mimic Relativity... Gravity is the IMBALANCE between two opposing PUSHING forces: the Vacuum oscillatory impulse force, averaged over time (=Dark Energy), against less powerful Graviton Vacuum oscillatory impulse force, induced on the vacuum by mass. Not only gravity but all 4 forces are supposed to have the same dual imbalance system as origin. Thus the attraction forces are the reduction of the repelling vacuum force and repulsion is the increase of the repelling vacuum force. This means that there is not a maximum on all 4 fundamental forces of nature based on the maximum (ZPE) vacuum force, because repulsion is based on the increase of this force. Only attracting forces can have a maximum based on this system. All Fermionic energy / mass has its origin in the vacuum oscillations... Recently the scientists J.P. Luminet, J. Weeks, A. Riazuelo, R.Lehoucq and J.P. Uzan proposed, that according to the structure found in the WMAP, the universe resembles a finite 12 lobed Dodecahedron shaped soccer ball. However, according to this new Fractal Big Bang model, the universe is more like a 12 lobed raspberry. In this new Fractal Big Bang model, the hotter areas in the MAP picture are supposed to be the Vortices of the Fractal Big Bang splitting process, during the expansion of the Big Bang leaving groups of Black Holes behind. These groups of Black Holes are able to produce gas by the chiral vacuum system and create massive gaseous envelopes, which show up as "Hotter" areas in the MAP Probe picture. The Hotspots are supposed to be the connection to the Progenitor Gaseous Halos which are found in the Deep Field High-Z Subaru survey called Massive Halos. The Massive Halos harbour so called Lyman Alpha Emitters (LAEs) and Lyman Alpha Break Galaxies (LBGs) see before (K. Shimasaku).
by Leo Vuyk
I've not heard too much about that, if anything. What happened?
Ooh WOW! Another one-liner.
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