Credit: Google/NASA Meteor Watch
California and Nevada residents may have been terrified by the loud sonic boom that shook their houses Sunday morning, but now that we know what caused it, they should feel privileged to have experienced such a rare event. We now know that the cause was a fairly large meteor that entered our atmosphere with the energy equivalent to a 5-kiloton explosion. I’ve read other estimates for the energy, but that is the official number from NASA’s Meteoroid Environments Office. That puts it entering our atmosphere at a blistering speed of over 33,000 mph. This meteor was about the size of a minivan, so it was easily visible during the daylight, and that fact that it caused a massive sonic boom means that it made it all the way down to the troposphere, the lowest level of atmosphere, or the level in which clouds and weather occur. Most meteors are much MUCH smaller, and even if they did cause a sonic boom, they burn up far too high in the atmosphere for us to hear it, not to mention that that the air up there is much thinner and doesn’t carry sound waves as well. Because of this meteor’s size and density there’s a decent chance that some fragments of it may have made it to the ground. Once they hit the ground they’re called meteorites, and there are people who make it their living to hunt for them. The rarity of this event is why I think the people who got to see it or hear it are very lucky. I’d give anything to witness something like that. Meteors of this size only occur about once a year, and the simple fact that earth is about 75% covered in water means that us land-dwellers only have a 25% chance of seeing one when they do hit. (Other sources: Universe Today and Discovery News)
California “missle launch” was likely only a jet contrail
November 10, 2010
Monday night must’ve been a slow news night in California, and everywhere really… but what most media has been calling a “mystery missle launch” was probably just a jet airliner contrail. It’s all a matter of perspective, really.
The footage came from a news helicopter that was flying off the coast of Orange County, CA, Monday night. The footage is shot looking westward and the object appears to be a rocket rising from the ocean. But if a jet airliner is flying directly toward you from over the horizon, and leaving a contrail behind it, it will look as though it is rising from the ground going straight up. If the atmospheric conditions are right, the contrail will quickly get widened by upper-level winds, and vortexes left by the plane’s wings can cause a spiral-like appearance. The bright light at the tip of the plume is only visible for a short time, which would indicate that it’s simply the glint of the setting sun reflecting off the plane’s underbelly. After some blog-reading I found that in fact, contrails have been mistaken for missles from this very same area before, and the culprits are planes traveling from Hawaii to Phoenix. There’s also a small possibility that it was a small target rocket from an island west of LA and used to test the military’s new airborne laser defense system, but the company that conducts those tests has said that it did not have any launches that day.
I think what we have here is a case of sensationalist media capitalizing on the mistake of a helicopter news team. Normal people probably see contrails from this same flight path almost every night and may think it’s interesting, but they forget about it and move on. Because it happened to be a news helicopter team who were fooled by the illusion this time, it instantly became a media blitz and got blown waaaay out of proportion. I’m saying I’m 100% sure it was a jet airliner contrail, but I’d be surprised if it wasn’t. More detailed info on this particular incident’s explanation can be found at NewScientist. Also, a detailed explanation and comparison of this incident to other contrail incidents can be found at the Contrail Science blog.
steve cross loves music and science 