On Feb 27, 1:33 pm, j...@specsol.spam.sux.com wrote: > In sci.physics Robert Clark <rgregorycl...@yahoo.com> wrote: > > > That video I linked to previously and ones like it may also be able > > to address this question: > > > An Asteroid's Parting Shot. > > By Phil Plait > > Posted Tuesday, Feb. 19, 2013, at 8:00 AM > >http://www.slate.com/blogs/bad_astronomy/2013/02/19/near_earth_astero... > > > The video shows 2012 DA14 slowing moving through the frame, and > > meteors and artificial satellites streaking rapidly through the frame. > > Assuming we are able to distinguish the satellites, perhaps by > > knowing already their positions, perhaps we can determine if the > > number of meteors shown here are higher than normal. > > Better would be longer exposures that include at least the time > > period of the Russian meteor impact. > > > Bob Clark > > While people here have been speculating all sorts of nonsense, astronomers > from the University of Antioquia in Medellin, Colombia have figured out > where the Russian meteor came from and that it has no relationship to > the other close passing asteroid. > > http://www.space.com/19974-russian-meteor-explosion-origin-size.html
The Fireballs of February. Feb. 22, 2012 ... "They all hail from the asteroid belt?but not from a single location in the asteroid belt," he says. "There is no common source for these fireballs, which is puzzling." "This isn't the first time sky watchers have noticed odd fireballs in February. In fact, the "Fireballs of February" are a bit of a legend in meteor circles. "Brown explains: "Back in the 1960s and 70s, amateur astronomers noticed an increase in the number of bright, sound-producing deep- penetrating fireballs during the month of February. The numbers seemed significant, especially when you consider that there are few people outside at night in winter. Follow-up studies in the late 1980s suggested no big increase in the rate of February fireballs. Nevertheless, we've always wondered if something was going on." "Indeed, a 1990 study by astronomer Ian Holliday suggests that the 'February Fireballs' are real. He analyzed photographic records of about a thousand fireballs from the 1970s and 80s and found evidence for a fireball stream intersecting Earth's orbit in February. He also found signs of fireball streams in late summer and fall. The results are controversial, however. Even Halliday recognized some big statistical uncertainties in his results." ... http://science.nasa.gov/science-news/science-at-nasa/2012/22feb_februaryfireballs/
Note this was from last year, not this year in regard to this February's unusual meteor and asteroid encounters. But what's key is the article notes this has been noticed in other February's. The article suggests greater number of fireballs in February. It also mentions they are typically slow, long-lasting, and penetrate deep in the atmosphere. I don't know about the slow part, but the long-lasting and deep penetration aspects could be due to larger meteors during February's. If there is an association with the 2012 DA14 asteroid, then since it has approximately a year long orbit, this could explain why the fireballs are seen frequently in February. Note it was discovered last year in February also during a close approach. Also notable as Steve Willner mentioned the two orbital crossings could result in rather close approaches on the second crossing as well:
On Feb 26, 1:56 pm, will...@cfa.harvard.edu (Steve Willner) wrote: > ... > > > Does this mean there are two close approaches per orbit? It doesn't > > necessarily have to be since where the two orbits "cross" does not > > mean the two bodies have to be there at the same time. > > Yes, exactly. Typically one body will be far away when the other is > near a crossing point. > > > if they are close at one "crossing" point, they should be > > relatively close at the other. > > About half a day away at the next crossing point, given the period of > 366.24 days. That's about 400 Earth radii if I've done the > arithmetic right. The distance is cumulative, so a simple estimate > is that it will take another 366 years (365 orbits for the asteroid) > before there's another close approach. However, the recent Earth > encounter must have changed the orbit, so the simple estimate is > probably wrong. There are also likely to be non-gravitational > effects. This object is probably not one to worry about in the near > term, but this sort of rough estimate is no substitute for a proper > orbit calculation. >
This could explain the observation of Halliday that there seems to be a statistical increase also in late Summer and Fall.
In any case, the Air Force needs to release its satellite detections of these fireballs. For one thing they might be able to detect the meteors before they have any appreciable interaction with the atmosphere. For large meteors, of oblong shape, the atmospheric interaction could alter their direction, thus giving a misleading interpretation of their original orbits.
For many people the Air Force not sharing all the technical means at its disposal led to the loss of the shuttle Columbia crew. It must not be said that its keeping its meteor detections capability secret led to the loss of an entire city.