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Sun, 03 May 2015 - Spectrum and Orbit for a bright meteor

Congratulations go to Bill Ward who recently achieved his aim of capturing a spectrum of a meteor that had also been imaged from elsewhere. 

The meteor involved appeared at 00:58 UT on the morning of 2015 April 10th.

The two images are shown here.

The first is Bill Ward's (emission line) spectrum, captured from Kilwinning.

The second is an image of the meteor captured by David Anderson from Lower Craighead in Ayrshire.

With the meteor having been imaged from two locations, it was possible, as always, to use triangulation to determine the meteor's atmospheric trajectory and then to work backwards to work out its former solar system orbit.

The additional capture of a spectrum meant that it was possible to link the composition of a meteor with a solar system orbit.

As far as Bill is aware, this is the first time that this has been achieved from the UK.

Triangulation

From both locations, the meteor appeared in the north eastern sky.

However, because the meteor was seen from a slightly different angle from each location, its path against the star background was different in each image.

Bill and David know how far their observing sites are apart. Hence it was possible to use triangulation to determine the atmospheric trajectory of the meteor. 

(This demonstrates why the trigonometry that you were taught at school is useful !)

Triangulation of the two images showed that the meteor had been over Fife and southern Tayside.

Orbit

 With the images having been captured using video cameras, it was also possible to see how fast the meteor was travelling across the field of view and hence to calculate its speed through the atmosphere.

From this, it is possible to work backwards and determine the speed at which it entered the atmosphere.

Combining this initial speed with its trajectory, it is then possible to work backwards and determine the former solar system of the meteoroid (before the earth got in its way!)

Fortunately nowadays, most of the hard work (i.e the calculations) is carried out by software. 

However, the existence of the software is of no use unless individuals like Bill and David carry out their excellent work to capture images and spectra.

The spectrum

The spectrum captured by Bill showed strong emission lines from magnesium and calcium, plus bands due to iron.

The meteor, a sporadic, was therefore most likely to have been a stony-iron meteor.

The orbit (see below) determined by the software indicates that the aphelion of the meteoroid had been in the asteroid belt.

(The four circular orbits are those of Mercury, Venus, Earth and Mars ; the elliptical orbit is the former orbit of the meteoroid).

For further information about meteor spectra, see this meteor spectra guide

 

Added by: Tracie Heywood