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The Winchcombe meteorite

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nickjames's picture
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The Winchcombe meteorite

Following predictions that the bright fireball of February 28 might have led to a meteorite fall east of Cheltenham (here), UKFALL and the Natural History Museum last night announced that a large carbonaceous chondrite and other fragments have been found in the Cotswolds town of Winchcombe. The attached press release was sent out last night.

This is an amazing achievement for UKFALL and the other organisations involved. Particular congratulations to Jim Rowe and Dr. Ashley King who gave a BAA webinar  on the methods involved only two months before their first success. This is a real demonstration of the power of video meteor astronomy.

Derek Robson, of the NEMETODE group, has a spectrum of this fireball so we have the very unusual situation of being able to compare this with analysis of the fallen meteorite.

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winchcombe Meteorite

Brilliant  news !!!   Congratulations to  every one who contributed to the  tracking and  recovery. . Fantastic that the meteorite was recovered  uncontaminated. Better than  the cost of a sample return mission  , a rare  items delivered free!!!  Now the  science  can begin to  see what this  rare  meteorite  cam tell us regarding the  beginnings of the Solar System.

Richard Miles's picture
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Collect the samples before it rains!

Primitive CCs are chemically modified by contact with liquid water. The samples collected so far have escaped this fate. Covid or no Covid a special effort should be made today to find more!

Denis Buczynski's picture
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WINCHCOMBE METEORITE; PAST AND PRESENT QUESTIONS.

1) Where did this object originally form and where has it resided in the Solar System since its formation 4.6 Billion years ago?
2) Has its original orbit(within the asteroid belt?) around the Sun been constantly altered by planetary perturbations etc?
3) What was its present orbit and period around the Sun prior to impact with the Earth?
4)How has its orbit evolved to put it on an Earth crossing orbit.
5) Have there been previous near misses in the past?
Signed INTERESTED and CURIOUS of TARBATNESS

Richard Miles's picture
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Questions questions

Denis - From the composition it will be possible then to come up with some answers. Such small meteoroids have a high chance of being fragments from a collision in the not so distant past. Knowing its orbit is really helpful - so it had an aphelion at the outer edge of the Main Belt and so would have been ejected from that region to become an Earth-crosser.

Derek Robson's picture
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The Winchcombe meteorite

Thanks Nick, appreciated.  Here's a composite image of the meteor viewed from my Loughborough SW-facing Watec camera. The star at image centre is Betelguese. The meteor appears in Orion.  The video should contain more images which can also be used for spectral generation at selected points along the trail. I ran a LASER calibration last night for wavelength calibration of the dispersion given by the diffraction grating (~500 lines/mm).

Dominic Ford's picture
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Good questions...

Denis,

These are good questions, but as Richard suggests, they will probably remain unanswered for some time - and perhaps forever!

The orbits obtained by meteor cameras are only very approximate, and in particular it's quite difficult to measure the velocity of meteors accurately. This is unfortunate, since even a small error in a meteor's velocity can make a big change to the inferred orbit.

The result is that we don't really know where this object was a few years ago, let alone any further back in time. Its composition will probably give us some clues about where it was 5 billion years ago, when the solar system formed. Where it's been hanging out for the past 5 billion years, we can only guess.

But there are clues. Its aphelion is rather close to Jupiter, so in all likelihood it was thrown onto an Earth-crossing orbit by an encounter with Jupiter's gravitational field. Was this recent? Probably yes. Earth-crossing orbits are quite unstable, so that encounter almost certainly happened in recent decades / centuries.

Has it had previous close encounters with the Earth? Probably not very close. If it had done, its orbit would have been perturbed. Specifically, its aphelion would no longer be close to Jupiter. The encounter would either have thrown it out the solar system (most likely), or closer in to the inner solar system (unlikely). But it probably has crossed the Earth's orbit before. It would be relatively unlikely to hit a bullseye on the first attempt.

Best wishes,

Dominic