Asteroid 2009 BD is cruising by us today at a distance of only about 400,000 miles, according to NASA's Near Earth Object Program. This strange asteroid is estimated to be 5. 7 meters to 13 meters in diameter.
Astronomers will be studying 2009 BD with great interest, because it may be a very rare coorbital asteroid. In 2006, NASA's Dr. Tony Phillips explained how these type of asteroids corkscrew as they move in tandem with Earth:
These asteroids are called Earth Coorbital Asteroids or "coorbitals" for short. Essentially, they share Earth's orbit, going around the Sun in almost exactly one year. Occasionally a coorbital catches up to Earth from behind, or vice versa, and the dance begins: The asteroid, while still orbiting the sun, slowly corkscrews around our planet.Sometimes, coorbitals hang around for awhile:
2004 GU9 is perhaps the most interesting. It measures about 200 meters across, relatively large. And according to calculations just published in the Monthly Notices of the Royal Astronomical Society (S. Mikkola et al., 2006) it has been looping around Earth for 500 years--and may continue looping for another 500. It's in a remarkably stable "orbit:.2009 BD will be in Earth's neighborhood for awhile, giving scientists a change to evaluate it, and its path. The Jet Propulsion Laboratory (JPL) has an applet that shows the asteroid's orbit.
What else is going on in our neck of the woods? Earth's Busy Neighborhood offers a traffic report.
Yesterday I discovered that another two neighbours had seen the "Black Headed Meteor". I have no doubt that it has been seen by hundreds in this locality over the years but no-one seems to want to know, especially the NEO experts, Defence Radar and sundry meteor societies.. The ideology is that Black Headed Meteors do not exist so it must be a bird, or a plane or a superhero trying out his new flight suit.
So why am I involved and what is this all about? I suppose it is a question of responsibility. I first saw this meteor in November 1985 around midnight as I walked from Canterbury towards Whitstable along the main road. I was surprised by a bright orange light behind and above me and turned to see a huge object in the sky above flying from South to North. It was about two thirds black and one third ruddy orange flame on the foreward end with a short flame tail. It rotated slowly and I could see surface ridges and hollows, reminiscent of those of a rocky asteroid, as the flame pattern evolved. A little less than a palms width when held at arms-length this absolute monster travelled silently to the North Kent coast where it vanished beyond the horizon about twleve seconds later. I waited a couple of minutes for the blinding white flash that would spell the end for the world I knew and myself. The flash never came. It remains the most awesome and magnificent experience of my life to this date. Of course I reported it to Space Sciences at UKC where I was doing a first degree in physics/astrophysics at the time. The opinion was it might be a satellite coming down. It wasn't, I knew that. But a near miss is a near miss and the meteor would disappear off into space never to be seen again. I had been lucky, we all had. At least that's how it seemed at the time.
Roll on 2007 and the late spring at dusk. Looking out towards the West I caught a movement in the sky to my left. This object was in view for maybe six seconds before it flew just below the ridgeline of a neighbours roof. This time a black head, slightly ovoid (like the earlier sighting) and a diameter about that of the width of my thumb when held at arms length. A small rotation was perhaps discernible. Its elevation was about twenty five degrees and its apparent track was South to North as before. There were small flames at the front and a double headed structure made up of the main head and a region of turbulent "particulate" cloud just behind and almost as big as the head. This region quickly necked down into a long black tail which I followed back across the sky to a point about 30 degrees of Azimuth behind the head. The tail at this point became an incandescent white streak as the air slowed faster than the rocks/particulates forming the tail and ignited them into a continuos stream of conventional meteors
In July 2010 my daughter and several friends saw a similar object aroud dusk. It had a "pony tail" of ruddy orange flame as she described it but the head was mainly dark with some flame to the front. It was about the size of her thumb's width but became smaller (the width of her finger) as it flew towards the northern horizon from its southern origin whereupon its flames went out (as it left the atmosphere). She says it "changed shape" or rotated.
In the summer of 2004, early hours, it was observed by two terrified fishermen in Sandwich Bay. Several seconds of flickering orange light preceeded the entire sea and land being illuminated and ten seonds of rumbling sonic booms which shook the windows across town as a bright orange monster flew "Out of France and over Thanet" (North to South) in just 4-5 seconds. I experienced it from the comfort of my bed with the curtains closed.
Most physicists should have difficulty in accepting the last description as being representative of a very near miss froma low flying meteor. I do so myself. I also have serious difficulties with the idea that this monster seems to have a particular affinity for a small strip of Western Europe longitude and as it happens and apparent maximum period in excess of three years. I am reporting what has been seen by about a dozen people over the last quarter of a century. I do have potential explanations and currently believe (i.e. have a working hypothesis) that:
1) There is a rocky asteroid or cometary core in a three body orbit around the Earth with a period of around 3 years or perhaps 1.5 years or less (if seen elsewhere). In effect the orbit is a co-orbital one but it is making one plus solar orbits between Earth approaches.
2) It has a diameter of 2.5 +/- 1 mile.
3) As its orbit passes through the Earth's atmosphere the orbital period will decline until it eventually impacts the earth in a few decades time or earlier if it suffers even a small pertubation due to perhaps the moon.
4) Its orbit is highly elliptical wrt the Earth. When close to the Earth it is far too fast for NEO telescopes. When in hover "near" the Langrange 1 point it lies between the Earth and the Sun so cannot be detected easily.
5) Its apogee lies 35-40 degree south of the plane of the solar system.
The above "belief" is not a full and authoratative description of the laws of physics. I am mainly concerned with the description of the sighting and requesting any readers who have seen this "black meteor" to report on their sighting.