[meteorite-list] OT: Live Video of Iceland Eruption
I know this is not meteorite related. Live video of an erupting volcano can just as fun. Iceland Eruption Live Stream | Geldingadalur Daily Iceland, March 22, 2021 https://www.youtube.com/watch?v=ApcVizUV0Xk Helstu tíðindi: Gas mælist yfir hættumörkum https://www.ruv.is/frett/2021/03/18/helstu-tidindi-gas-maelist-yfir-haettumorkum Sjáðu hraunrennslið í Geldingadölum síðasta sólarhring 22.03.2021 - 16:29 Innlent · Geldingadalagos · Jarðhræringar á Reykjanesskaga https://www.ruv.is/frett/2021/03/22/sjadu-hraunrennslid-i-geldingadolum-sidasta-solarhring Scientists Grill Hot Dogs Using Lava From Iceland Volcano CBS Miami, Mar 22, 2021 https://www.youtube.com/watch?v=y6VHewvyH5o Yours, Paul H. __ Visit our Facebook page https://www.facebook.com/meteoritecentral and the Archives at http://www.meteorite-list-archives.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com https://pairlist3.pair.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] [EXTERNAL] Meteorite-list Digest, Vol 222, Issue 24
AMS reports four significant fireballs over the weekend: https://amsmeteors.org/2021/03/four-fireballs-spotted-during-the-week-end/ I checked the three stateside events on NEXRAD radar and couldn't find anything convincing. The Pennsylvania one does show up in GLM imagery, in the GOES-16 satellite image at 04:20 UTC. Radar tells the same story I've been left with many times, though - there's a few pixels here and there that might be something, but its not enough to tell a consistent story. I'll insert my usual caveat - a small meteorite fall may slip past the radars undetected. There are a few examples, such as the New Orleans fall which was evidently a single stone. Cheers, Marc Fries -Original Message- From: Meteorite-list On Behalf Of meteorite-list-requ...@meteoritecentral.com Sent: Monday, March 22, 2021 12:31 AM To: meteorite-list@meteoritecentral.com Subject: [EXTERNAL] Meteorite-list Digest, Vol 222, Issue 24 Send Meteorite-list mailing list submissions to meteorite-list@meteoritecentral.com To subscribe or unsubscribe via the World Wide Web, visit https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpairlist3.pair.net%2Fmailman%2Flistinfo%2Fmeteorite-list&data=04%7C01%7Cmarc.d.fries%40nasa.gov%7C22ce962df16242c8993b08d8ecf3cf77%7C7005d45845be48ae8140d43da96dd17b%7C0%7C0%7C637519879197351727%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=4knC6tqHY%2Bk5skzpoYpHW8WDscYsgwVOjXJ0Tw1ZRmw%3D&reserved=0 or, via email, send a message with subject or body 'help' to meteorite-list-requ...@meteoritecentral.com You can reach the person managing the list at meteorite-list-ow...@meteoritecentral.com When replying, please edit your Subject line so it is more specific than "Re: Contents of Meteorite-list digest..." Today's Topics: 1. Meteorite Picture of the Day (valpar...@aol.com) 2. Fireball on Eastern Cuba (yasmani.ceba...@nauta.cu) 3. Fwd: For your entertainment - Bringing you Mars rocks (Kevin Kichinka) -- Message: 1 Date: Sun, 21 Mar 2021 00:35:55 -0700 From: To: Subject: [meteorite-list] Meteorite Picture of the Day Message-ID: <3AB1C5A8B76A456787046FA0A8F388ED@s10718094116> Content-Type: text/plain Today''s Meteorite Picture of the Day: NWA 8310 Contributed by: Paladino Vincenzino https://gcc02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.tucsonmeteorites.com%2Fmpodmain.asp%3FDD%3D03%2F21%2F2021&data=04%7C01%7Cmarc.d.fries%40nasa.gov%7C22ce962df16242c8993b08d8ecf3cf77%7C7005d45845be48ae8140d43da96dd17b%7C0%7C0%7C637519879197351727%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=ygqneI7J4PV0dU7%2F4XKQ%2FQL8tk8Yx2B1zGxa2MwG58A%3D&reserved=0 -- Message: 2 Date: Sun, 21 Mar 2021 12:03:50 -0400 From: yasmani.ceba...@nauta.cu To: meteorite-list@meteoritecentral.com Subject: [meteorite-list] Fireball on Eastern Cuba Message-ID: <20210321120350.horde.zc2xhaqzgr9n5tp2vsfq...@webmail.nauta.cu> Content-Type: text/plain; charset=utf-8; format=flowed; DelSp=Yes Hello friends, I imagine many of you must have seen the increase on facebook, twitter, etc. of several post including fake photos about a "meteorite on eastern Cuba". No meteorite has been recovered, it was just a fireball. I have the data, but I need a fireball expert to help me better interpret the data to prepare an explanatory note. Please direct inbox, thanks! -- Message: 3 Date: Sat, 20 Mar 2021 16:28:41 -0600 From: Kevin Kichinka To: meteorite-list@meteoritecentral.com Subject: [meteorite-list] Fwd: For your entertainment - Bringing you Mars rocks Message-ID: Content-Type: text/plain; charset="utf-8" TeamMeteorite: Perseverance on site. Super Hi-Def. Explanatory. I'll bet that you can't watch it just once (Good music, too.) ? https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DwxSOx2DoFN8&data=04%7C01%7Cmarc.d.fries%40nasa.gov%7C22ce962df16242c8993b08d8ecf3cf77%7C7005d45845be48ae8140d43da96dd17b%7C0%7C0%7C637519879197351727%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=cUzvOvdCDlQhrRzGwYJvCSDe4MAU%2BikoYtUfOmav7CQ%3D&reserved=0 The Red Planet remains N x NW of the Pleiades. MARSROX -- next part -- An HTML attachment was scrubbed... URL:
Re: [meteorite-list] hot vs. cold meteorite falls
A meteoroid in space is nominally at or just above freezing (i.e. 0° C), but there is a fair range around that, especially toward the higher end, depending on its emissivity. It almost certainly will not be very cold. Space is not "cold". It is, of course, dominated by radiative heating and cooling. While it is radiating into something just barely above absolute zero, it is also absorbing the same amount of solar energy as a rock on the ground. In most cases, I would expect a meteorite to be on the cold side when it impacts. The heating that occurs during its brief ablative phase will have almost no effect on its internal temperature. But it will spend several minutes falling through air at one or two hundred meters per second, and for almost all of that time the air will be on the order of -40° C. That will result in significant cooling of typical meteorites of a few hundred grams to a few kilograms. I think that what can easily happen is that people who touch a freshly fallen meteorite actually experience cold as hot, due to their expectations. Whether we perceive something as hot or cold can be unrelated to the actual temperature. Remember that kids' game where you dare somebody to keep their back to you while you touch the back of their neck with a hot iron, and then actually touch them with an ice cube? Most people startle and believe you've burned them. Chris *** Chris L Peterson Cloudbait Observatory https://www.cloudbait.com On 3/22/2021 1:37 PM, Eric Christensen via Meteorite-list wrote: There was a recent discussion on a social media forum about a stone from the recent Punggur fall being warm enough on impact to melt a synthetic bedsheet. I followed the discussion with interest but don't have an account on that platform - so wanted to post here. The original poster also referenced the other recent Indonesian fall (Kolang), where a finder reported the stone felt as if it had been "cooked with sunlight". There are many other references to freshly fallen meteorites being warm or hot to the touch, or sometimes cold to the touch. The oft-repeated rebuttal is that meteoroids come from the icy void of space where they must be extremely cold, and that any brief heating experienced during the luminous ablative phase will dissipate during the few minutes of dark flight through the atmosphere. Also, that the human brain will trick surprised finders into misinterpreting "very cold" for "very hot". It seems to me that there's an obvious error in this argument - the initial condition of a meteoroid being very cold is not (necessarily) true. In fact the opposite can be true - meteoroids (or asteroids) can actually be very hot prior to Earth impact. "Cooked with sunlight" is an extremely good description. Consider figure 1 from Delbo and Harris "Physical properties of near-Earth asteroids from thermal infrared observations and thermal modeling", published in 2002 in MAPS: https://onlinelibrary.wiley.com/doi/pdf/10./j.1945-5100.2002.tb01174.x The sunlight side of a model asteroid at 1 AU has a temperature of about 400 Kelvin = 127 C = 260 F. The side facing away from the sun will be cooler; how much cooler will depend on the thermal inertia of the body, pole orientation, rotation speed, etc. There may be steep temperature gradients across an asteroid at impact time, or it may be relatively equilibrated. Most meteorite droppers should fall into the latter category, being small (sub-meter), fast rotators, and regolith free. How much heat is gained during ablation, and retained during dark flight, ought to depend on the thermal inertia of the meteorite. Metal-rich meteorites or those with low porosity ought to retain more heat, and be less efficiently cooled during dark flight. So - are fresh meteorites hot or cold on impact? I think the answer is, "it depends!". One could even contrive a set of circumstances where an asteroid with a large thermal gradient drops two meteorites of equal sizes right next to each other, coming from different parts of the asteroid, where one lands hot and the other lands cold. Tarp-melting hot? I don't see why not. Cold enough to form frost? Sure. Hot enough to ignite a grass fire? No. Regards, Eric Christensen __ Visit our Facebook page https://www.facebook.com/meteoritecentral and the Archives at http://www.meteorite-list-archives.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com https://pairlist3.pair.net/mailman/listinfo/meteorite-list __ Visit our Facebook page https://www.facebook.com/meteoritecentral and the Archives at http://www.meteorite-list-archives.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com https://pairlist3.pair.net/mailman/listinfo/mete
[meteorite-list] hot vs. cold meteorite falls
There was a recent discussion on a social media forum about a stone from the recent Punggur fall being warm enough on impact to melt a synthetic bedsheet. I followed the discussion with interest but don't have an account on that platform - so wanted to post here. The original poster also referenced the other recent Indonesian fall (Kolang), where a finder reported the stone felt as if it had been "cooked with sunlight". There are many other references to freshly fallen meteorites being warm or hot to the touch, or sometimes cold to the touch. The oft-repeated rebuttal is that meteoroids come from the icy void of space where they must be extremely cold, and that any brief heating experienced during the luminous ablative phase will dissipate during the few minutes of dark flight through the atmosphere. Also, that the human brain will trick surprised finders into misinterpreting "very cold" for "very hot". It seems to me that there's an obvious error in this argument - the initial condition of a meteoroid being very cold is not (necessarily) true. In fact the opposite can be true - meteoroids (or asteroids) can actually be very hot prior to Earth impact. "Cooked with sunlight" is an extremely good description. Consider figure 1 from Delbo and Harris "Physical properties of near-Earth asteroids from thermal infrared observations and thermal modeling", published in 2002 in MAPS: https://onlinelibrary.wiley.com/doi/pdf/10./j.1945-5100.2002.tb01174.x The sunlight side of a model asteroid at 1 AU has a temperature of about 400 Kelvin = 127 C = 260 F. The side facing away from the sun will be cooler; how much cooler will depend on the thermal inertia of the body, pole orientation, rotation speed, etc. There may be steep temperature gradients across an asteroid at impact time, or it may be relatively equilibrated. Most meteorite droppers should fall into the latter category, being small (sub-meter), fast rotators, and regolith free. How much heat is gained during ablation, and retained during dark flight, ought to depend on the thermal inertia of the meteorite. Metal-rich meteorites or those with low porosity ought to retain more heat, and be less efficiently cooled during dark flight. So - are fresh meteorites hot or cold on impact? I think the answer is, "it depends!". One could even contrive a set of circumstances where an asteroid with a large thermal gradient drops two meteorites of equal sizes right next to each other, coming from different parts of the asteroid, where one lands hot and the other lands cold. Tarp-melting hot? I don't see why not. Cold enough to form frost? Sure. Hot enough to ignite a grass fire? No. Regards, Eric Christensen __ Visit our Facebook page https://www.facebook.com/meteoritecentral and the Archives at http://www.meteorite-list-archives.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com https://pairlist3.pair.net/mailman/listinfo/meteorite-list
[meteorite-list] Meteorite Picture of the Day
Today''s Meteorite Picture of the Day: Australite Contributed by: Sang-Hyeok, Lee http://www.tucsonmeteorites.com/mpodmain.asp?DD=03/22/2021 __ Visit our Facebook page https://www.facebook.com/meteoritecentral and the Archives at http://www.meteorite-list-archives.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com https://pairlist3.pair.net/mailman/listinfo/meteorite-list
