HIDDEN GEMS: The “jewels” in this polarized light micrograph of a slice from a chondrite are chondrules, tiny beads of silicate minerals. Despite this chondrite's beauty, it belongs to the class known as ordinary.
Image: J. M. DEROCHETTE
In Brief
- Chondritic meteorites are made of the stuff that formed the planets, moons, asteroids and comets. Each chondrite group has its own distinctive textural and compositional characteristics.
- From these properties, the author and other scientists have inferred roughly the locations where the chondrite groups formed and the relative amount of dust present in those regions.
- The dust distribution resembles that seen in protoplanetary disks of dust and gas swirling around several stars known as T Tauri stars—in particular, young, one- to two-million-year-old versions about as massive as our sun. This resemblance suggests that T Tauri systems are good analogues of the sun and its own disk during the early stages of solar system history.
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I pity Astronomers. They can see the objects of their affection—stars, galaxies, quasars—only remotely: as images on computer screens or as light waves projected from unsympathetic spectrographs. Yet many of us who study planets and asteroids can caress pieces of our beloved celestial bodies and induce them to reveal their innermost secrets. When I was an undergraduate astronomy major, I spent many a cold night looking through telescopes at star clusters and nebulae, and I can testify that holding a fragment of an asteroid is more emotionally rewarding; it offers a tangible connection with what might otherwise seem distant and abstract.
The asteroidal fragments that fascinate me most are the chondrites. These meteorites, which constitute more than 80 percent of those observed to fall from space, derive their name from the chondrules virtually all of them contain—tiny beads of melted material, often smaller than a rice grain, that formed before asteroids took shape early in the solar system's history. When we examine thin slices from chondrites under a microscope, they become beautiful to behold, not unlike some of the paintings by Wassily Kandinsky and other abstract artists.
This article was originally published with the title Secrets of Primitive Meteorites.
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6 Comments
Add CommentCollisions between dust particles and asteroids seems like a possible mechanism for chondrule formation. The collisions would be widespread and multiple. They would vary in intensity and be more common in dustier areas, as seems to be the case for the chondrites listed in the article. Is there a reason this possibility wasn't mentioned?
Reply | Report Abuse | Link to thisYou pity astronomers? Gee, I'm sorry to hear that, since I'm not sure many of us need or want pity. Please let me explain.
Reply | Report Abuse | Link to thisYou think we're missing so much by being so far from the objects of our research? In fact, those galaxies, active stars, nebulae, planetary moons, and multiple stars -- all the contents of the universe that our brains can imagine -- are all very real and vivid inside our minds. We can spin those images through all four dimensions in an instant, change the emission line filters from oxygen to hydrogen and shocked carbon or forbidden sulfur faster than any laptop, visualize the results of our models then change one parameter and see what happens. Who needs a photo?
You think astronomers chose their pursuit because they expected direct sensory gratification? I was nearly 30 before seeing the Milky Way in a dark, western sky. I was well past 30 before I looked through my first telescope at a tiny, ringed Saturn.
Simply knowing that a physical process is occurring, even if your evidence for it is indirect and invisible, is incredibly satisfying. In fact, understanding anything is unimagineably beautiful, as beautiful as an orchestral score. The deeper the understanding, the more detailed and colorful the picture made in your mind, the richer the music. I suspect most scientists find our fields by realizing what delights and intrigues us most. And that may have very little to do with we can see or touch.
My mind's eye sees far more than my actual eye, always has. Don't pity me.
What I've tried to say here is far more important than what my words have communicated; age has something to do with that, but I apologize nonetheless.
This one astronomer neither needs nor wants pity because she has chosen to work in a virtual laboratory. No budget cut in the world, no misfigured Hubble mirror, no cataracts, nothing can compromise what I see in my head.
The origin of the meteorites:
Reply | Report Abuse | Link to thisWhen astronomers study, they convince themselves with the present theories and explanations given by the teachers and professors, or else they will not pass the examination.
But really many of the explanations and theories now available are not logical and in fact are non-sense.
Therefore anyone giving them any explanation which is not in their lectures and in their textbooks .. such exlplanation will be rejected absolutely, why? Because it is not like the lectures and the conviction of the lecturer.
The best example is what is said here about the origin of the planets and the solar system.
In fact it is not like what they say, but actually these meteorites are parts of some destroyed planets in the past.
The previous planets of the previous solar system that was in the place of the present solar system: destroyed on the previous Doomsday.
What remained are these rocks, some of which fall on Earth and the planets and theie moons.
These meteorites carried the germ of life to our Earth and the rest of the planets of our solar system.
http://quran-ayat.com/huda/showthread.php?3626-The-origin-of-meteorites
I agree that the current model is so flawed as to be laughable. I agree that a "previous Doomsday" occurred (Type 1b supernova 4.5 Gya) and blasted pieces of Venus and Earth into the surrounding area - to fall back during the Late Heavy Bombardment. I would love to read your theory - but its on a Arabic website and the translation isn't working.
Reply | Report Abuse | Link to thisThis is why I came up with a theory that explains EVERYTHING we see in our current Solar System. I invite everyone to look and tell me why I don't deserve a Nobel Prize ...
Thanks.
Sorry, here are the links:
Reply | Report Abuse | Link to this(Picture story) http://rampsontheory.blogspot.com
(Background research) http://FBG2BM.blogspot.com
Of course pity is not required, but I interpreted the first sentence simply as some light humour. This works for me.
Reply | Report Abuse | Link to thisMany things can only be seen remotely or indirectly, such as atoms, biological pathways, the thinking inside a brain, and so on.