Popular Astronomy

Share to Facebook Share to Twitter Stumble It More...

Notable Meteors and Fireballs : 2017 July-August

Here, in reverse chronological order, is a summary of notable meteors and fireballs reported to the section during July and August

 

2017 August 5th  22:50 GMT (23:50 BST)

Bill Ward has posted a very interesting video showing the persistent train left behind by a very bright Perseid meteor.

The video can be viewed via this this link

Bill refers to the emission being due to a "forbidden" spectral line. This means that the transition between the atom's energy levels is one that can only be produced in the low density of the upper layer's of the Earth's atmosphere. Such transitions are not produced in oxygen atoms at lower altitudes because the higher atmospheric density results in the oxygen colliding with another atom before the "forbidden" transition has the chance to take place.

 

2017 July 30th  23:36 GMT (00:36 BST on July 31st)

This fireball was imaged by Alex Pratt (Leeds) via his north west facing camera.

Alex notes it to have been of magnitude -4 and possibly a Perseid.

During July, Alex reports that his automated video cameras recorded many meteors, including 62 Perseids, 28 Alpha Capricornids and 35 southern Delta Aquarids.

The Perseids included a mag -2 event at 03:04 UT on July 28 and another mag -2 event at 00:16 UT on July 29.

Early August brought a mag -2.5 Alpha Capricornid at 00:03 UT on Aug 1.

 

 

 

 

2017 July 28th  00:17 GMT (01:17 BST)

The start of this fireball was imaged by Richard Fleet (Wilcot, Hants) low in his northern sky.

Alex Pratt reports that the fireball was also imaged low in the north north west by Nick James (Chelmsford, Essex).

Their analysis of the two images suggests that the fireball had an atmospheric trajectory near the England-Scotland border and was heading in a south westerly direction, as can be seen in the accompanying diagram.

Obviously there is some uncertainty in the trajectory due to the fireball being very distant from the two cameras.

The fireball was probably about magnitude -5.

 

Unfortunately, it seems that all cameras closer to the ground track were clouded our at the time.

 

2017 July 17th  00:43 GMT (01:43 BST)

This fireball was imaged by three cameras of the NEMETODE video camera network.

William Stewart analysed the sky paths and speeds recorded by the individual cameras and determined that its atmospheric trajectory was over the southern Pennines/northern Peak District, as can be seen in the accompanying map.

William added "The meteoroid had a relatively low geocentric velocity (14.1km/s) and hence must have been of a reasonable size to produce a meteor this bright. Calculations suggest an object of circa 300g with a diameter of around 50mm penetrating to an altitude of just under 30km."

The fireball was probably around magnitude -4.

 

2017 July 9th  22:52 GMT (23:52 BST)

This fireball was reported by Neil Fraser (Faringdon, south Oxfordshire). It was in his north eastern sky, had a duration of 1-2 seconds, left a train approx 30 degrees in length that persisted for 0.5 seconds and ended with a terminal flare.

The fireball was also witnessed by three other observers who submitted reports to the IMO. Two were elsewhere in Oxfordshire and one witness was in Kent. Taking into account the sky directions reported from each location would suggest that the fireball's atmospheric trajectory was over the east midlands and it was heading a roughly northerly direction.

Added by:  Tracie Heywood