Dutch note: een Nederlandstalige versie van deze video is eerder hier gepost.
Added Note: the reality is slightly more complex than I present it in the video, as objects that graze just past the earth limb are slightly deflected by earth gravitation and can end up on (low) northern latitudes. Latitude 55 N is out of the question though, and as this added detail might make the story too complex I decided to leave it out.
Showing posts with label Russian fireball. Show all posts
Showing posts with label Russian fireball. Show all posts
Sunday, 17 February 2013
Filmpje: waarom de supermeteoor boven Rusland niets te maken heeft met planetoide 2012 DA14 - uitgelegd met behulp van een sinaasappel
Note to English readers: an English version of the Dutch language video below is posted in a separate post here.
Toegevoegde noot: Het is in werkelijkheid iéts complexer dan ik hier doe voorkomen, omdat een langs de rand van de aarde scherend object door de aardse zwaartekracht iets wordt afgebogen en er zo dus wel fragmenten op (lage) noordelijke breedtegraden terecht kunnen komen. Maar 55 Noord is echt buiten de mogelijkheid, en ik heb dit er daarom maar uit gelaten omdat het anders misschien te complex werd.
Toegevoegde noot: Het is in werkelijkheid iéts complexer dan ik hier doe voorkomen, omdat een langs de rand van de aarde scherend object door de aardse zwaartekracht iets wordt afgebogen en er zo dus wel fragmenten op (lage) noordelijke breedtegraden terecht kunnen komen. Maar 55 Noord is echt buiten de mogelijkheid, en ik heb dit er daarom maar uit gelaten omdat het anders misschien te complex werd.
Friday, 15 February 2013
[updated] HUGE fireball over Russia this morning! Not 2012 DA14 related.
A HUGE fireball has appeared over Chelyabinsk, Russia, this morning. And with HUGE I mean: HUGE. Apparent brightness rivalling the sun, and very strong sonic booms leading to glass damage and people being wounded by flying glass. This must have been a seizable object entering the atmosphere.
Phil Plait, the "Bad Astronomer" has very good coverage including some amazing videos here, so I will refer to him for imagery and the general story (apart from two I include below: one showing the meteor, the other one the arrival of the shock wave).
Below, I will briefly explain why this fireball cannot have been a fragment of 2012 DA14, the ~50 meter wide asteroid that will pass very close to earth coming evening (Feb 15, 2013).
First of all (and Phil Plait points this out as well), the fireball in Russia came from the wrong direction. Several of the videos show it appearing in the east near the rising sun, coming from a N-NE direction. That is the wrong direction: fragments of 2012 DA14 are on a south-north trajectory.
What is even more important: fragments of 2012 DA14 could never enter the atmosphere as far north as latitude 55 N (Chelyabinsk). Fragments in orbits similar to that of the asteroid, have a theoretical geocentric radiant at declination -81 degrees, i.e. almost at the southern celestial pole. They hence approach earth from due south. This means that the northern hemisphere is out of reach of these fragments: the northern hemisphere represents (as seen from these approaching fragments) the "far side" of the earth.
[video added 18/02/2013]
[added 18/02/2013] In the above video I explain this more visually, with the help of an orange. In reality, it is slightly more complicated than I present it in the video, as objects grazing the earth's limb are actually slightly attracted by earths gravity and can end up a little bit over the line between "front" and "far" side of the earth. Ending up at latitude 55 N is nevertheless out of the question.
The funny thing is that the latitude of Chelyabinsk and the approach direction of 2012 DA14 (and fragments in a swarm around it) are well established facts, even if the trajectory of the Russian fireball is less so at the moment. So it is quite nice that from the encounter geometry with the 2012 DA14 orbit and the latitude of the Russian meteor alone, we can actualy already exclude a connection between the two with a quite strong certainty.
Fragments in 2012 DA14-like orbits and the Russian fireball itself are also too fast to be temporarily captured in earth-orbit, so that is no explanation either.
This fireball was not man-made space junk either. Besides coming from an unlikely direction, it is too fast and much too bright for that.
These are amazing times: the reentry of a Russian rocket stage seen from NW Europe on the evening of the 13th, then this hughe meteoric fireball over Russia this morning, and a close pass of asteroid 2012 DA14 tonight. Wow!
Phil Plait, the "Bad Astronomer" has very good coverage including some amazing videos here, so I will refer to him for imagery and the general story (apart from two I include below: one showing the meteor, the other one the arrival of the shock wave).
Below, I will briefly explain why this fireball cannot have been a fragment of 2012 DA14, the ~50 meter wide asteroid that will pass very close to earth coming evening (Feb 15, 2013).
First of all (and Phil Plait points this out as well), the fireball in Russia came from the wrong direction. Several of the videos show it appearing in the east near the rising sun, coming from a N-NE direction. That is the wrong direction: fragments of 2012 DA14 are on a south-north trajectory.
What is even more important: fragments of 2012 DA14 could never enter the atmosphere as far north as latitude 55 N (Chelyabinsk). Fragments in orbits similar to that of the asteroid, have a theoretical geocentric radiant at declination -81 degrees, i.e. almost at the southern celestial pole. They hence approach earth from due south. This means that the northern hemisphere is out of reach of these fragments: the northern hemisphere represents (as seen from these approaching fragments) the "far side" of the earth.
[video added 18/02/2013]
[added 18/02/2013] In the above video I explain this more visually, with the help of an orange. In reality, it is slightly more complicated than I present it in the video, as objects grazing the earth's limb are actually slightly attracted by earths gravity and can end up a little bit over the line between "front" and "far" side of the earth. Ending up at latitude 55 N is nevertheless out of the question.
The funny thing is that the latitude of Chelyabinsk and the approach direction of 2012 DA14 (and fragments in a swarm around it) are well established facts, even if the trajectory of the Russian fireball is less so at the moment. So it is quite nice that from the encounter geometry with the 2012 DA14 orbit and the latitude of the Russian meteor alone, we can actualy already exclude a connection between the two with a quite strong certainty.
Fragments in 2012 DA14-like orbits and the Russian fireball itself are also too fast to be temporarily captured in earth-orbit, so that is no explanation either.
This fireball was not man-made space junk either. Besides coming from an unlikely direction, it is too fast and much too bright for that.
These are amazing times: the reentry of a Russian rocket stage seen from NW Europe on the evening of the 13th, then this hughe meteoric fireball over Russia this morning, and a close pass of asteroid 2012 DA14 tonight. Wow!
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