FIREBALLS LATEST

FIREBALLS LATEST

By Alastair McBeath, SPA Meteor Section Director

French meteor analyst Karl Antier has reported to us that a magnitude

-8 or so fireball was seen from places across western and northern

France on January 24-25 at 20:51 UT. It was also caught on video, as

can be seen via the link at:http://snipurl.com/ucps2  . The fireball was

observed in the southern sky from Le Havre, so it is possible the

meteor might have been spotted, probably low to very low in the sky,

from southern England. As yet, no comparable UK reports have been

received, however.

More recently, somewhat confused reports have come through,

suggesting possibly up to three separate fireballs were seen from Ireland

and/or Northern Ireland before 20h UT on February 3-4.

Much of this news came from media reports, suggesting there were
"hundreds" of sightings, though so far, very few usable observations
have been submitted to the Section. Of those sufficiently detailed to
tell, one report each from around 17:55-18:00 UT has arrived from
Co Armagh in Northern Ireland, and a little south of Dublin's city centre
in the Irish Republic. 

The Co Armagh observer saw the object in the northwest to

north-northwest sky, while the near-Dublin observer saw the fireball

pass behind buildings to the north-northeast, at a similar elevation above

the horizon to what the Armagh witness reported for the meteor's start.

If correct, these positions show the sightings must have been of different

meteors. That might suggest there were two fireballs, one off northwest

Ireland/Northern Ireland, the other off northeast Northern Ireland/

Ireland, the neighbouring Irish Sea, or adjacent parts of western Britain,

around ~18h. 

A further fireball, seen from parts of Ireland around 19:30-19:40, was
reported as apparently fainter than the earlier meteor(s), but almost no
information other than this has reached the Section about it as yet.

For the media weblinks and further discussion, see topics on the SPA's
Observing Forum topic at:

http://snipurl.com/ucsif ,and the UK Weather World's Space Weather

Forum at: http://snipurl.com/ucsim 

Claims of a video recording of the ~18h fireball have proven false, as 

this was imaged in 2008 apparently, and in some places online, it 

seems to have been shown in reverse anyway.

FIREBALL OVER NORTHERN BRITAIN

from the 

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The SOCIETY for POPULAR ASTRONOMY

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Electronic News Bulletin No. 281   2010 January 31

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JANUARY 16 FIREBALL OVER NORTHERN BRITAIN

By Alastair McBeath, SPA Meteor Section Director

Three observations of a bright fireball seen around 22:45 UT on January16-17 have been received, two from the Wirral peninsula (where themeteor passed almost overhead) and one from Shropshire. 

 

Informationprovided by the lucky witnesses has suggested the object probably flew above parts of north Wales and northern England, on a roughly WSWto ENE track, and that the meteor was almost grazing the atmosphere,producing a long visible trajectory. 

 

The start has not been well-established so far, but assuming a height of between ~120-100 km altitude suggests the fireball may have first become visible overCaernarfon Bay, about 35 km off the northern Lleyn Peninsula coastof Gwynedd, likely near 52.9°N, 5.1°W for a ~120 km altitude start,or 53°N, 4.8°W for a ~100 km start. 

 

From there, it passed over the extreme north of mainland Wales, from roughly Caernarfon to Point ofAyr, then across the mouth of the Dee to the northern tip of the Wirral in northwest England (plausibly between West Kirby to Birkenhead),above the Mersey, Liverpool (likely a little south of the city centre) and the Pennines of the Lancs-Yorks border northeast of Manchester-Oldham, and somewhat south of Leeds, to end around 75 km altitudenear Mickletown on the River Aire, midway between Castleford andRothwell southeast of Leeds (above approximately 53.7°N, 1.4°W). 

 

Assuming this trajectory was correct would imply the entry angle was very shallow, between ~6° to ~11° from the horizontal, giving an atmospheric path length from ~246 to ~269 km. The observers estimated the meteor was visible from 5 to 8 seconds, whose average

(~6.5 seconds) would indicate an atmospheric velocity, not allowing for deceleration, of ~38-41 km/sec, so about medium-speed on the 11 to 72 km/sec atmospheric velocity scale for meteors. The outlying range for this rough velocity would be ~31-54 km/sec. Some fragmentation along the path was seen, with the colours noted as mainly yellow or white. 

 

The very high end height and the significant fragmentation would both count against any meteorites surviving and being recovered, while the shallow approach-angle makes it almost impossible to define where any such falls could have happened; perhaps into the eastern North Sea, the Baltic, or nearby parts of southern Scandinavia, as a best-guess. No reports of any such falls have been received as yet.

Any fresh sightings of this fireball, or others seen from the UK and nearby, would be welcomed by the Meteor Section. See the "Making and Reporting Fireball Observations" page of the SPA website, at: http://snipurl.com/u8aer, for details of what information to send, and to where.

Saturn's New Ring - It's Massive!

Lots of news this week about the discovery of a new ring around Saturn.

The Spitzer observatory, which views infra-red light, has discovered a massive ring around Saturn.




More details can be found on the NASA site(http://www.nasa.gov/mission_pages/spitzer/news/spitzer-20091006.html) and also here: http://www.astronomy.com/asy/default.aspx?c=a&id=8698

What's more, the Cassini flypast has shown some fascinating effects of the moon Daphnis as it skates through the ring - http://www.nasa.gov/mission_pages/cassini/multimedia/pia07809.html

and how about this - ripples in the rings as tall as the Rockies! : http://www.foxnews.com/story/0,2933,553624,00.html

All very exciting!

--LyndaH

Saturn's Rings As Never Seen From Earth

Cassini has taken photos of Saturn's rings that can never be seen from the Earth.

Read more here in Astronomy Magazine.

Near-miss asteroid

Near-miss asteroid

Here's a snippet I picked up:

ANOTHER ASTEROID PASSES BY

Spaceweather.com

Newly-discovered asteroid 2009 FH passed by the Earth on March 17 at

a distance of only 85,000 km (0.00057 AU), only a little more than

twice the height of a geosynchronous communications satellite. This

is the second time in March that an asteroid has flown so close to

the Earth. As described in the last Bulletin, on March 2 one passed

only 72,000 km away. Measuring some tens of metres in diameter, the

two are approximately Tunguska-class objects, so they do not pose a

global threat but would cause local damage if they actually hit the

Earth. In the past, asteroids of that size often passed unnoticed,

but recent improvements in asteroid surveys have resulted in growing

numbers of space rocks caught in the act of near-Earth fly-bys.

------- ends --------

Yes, I'd say that was a bit close!

But only last November another asteroid missed us by only 45,000km - which is an 8th of the distance to the moon. What's more, it was only detected a few hours before, so if it had been inbound there wouldn't have been anything we could have done. Just the month before that, and with a whole day's warning, one did reach us; exploding in the skies over Sudan. All spooky stuff.

If an asteroid only 250 metres across were to hit our planet it would cause an explosion over 30,000 times the power of the Hiroshima bomb. The Krakatoa eruption of 1831 was half that power and killed over 36,000 people.

But the overall chance of 'death by asteroid' has been calculated as 1 in 10 million per year.

But it seems the powers that be in the world are finally taking note and doing something about the possibility of an asteroid actually being on collision course with Earth.

There are all kinds of scenarios for dealing with a potential 'hitter', one of them does not include blasting it with a nuclear bomb! Why not? Because of the risk of turning it into thousands of pieces which would scatter in every direction - including ours; so we'll leave that idea to the movies.

Early warning systems are the key, and in that respect there are plans to track every potential threat using automated surveys, such as that of the Catalina Sky Survey. This is a group of three telescopes - two in Arizona and one in Australia which will closely examine the sky. Software then takes the images and looks for movement. Anything found is then passed to real astronomers for further examination.

NASA is also involved. They are bringing on the huge 8 metre Large Synoptic Survey Telescope (LSST) in Chile for 2015. It is so big that they anticipate finding virtually all the remaining asteroids.

Once found the asteroids are assessed for risk using the Torino Scale. This works like the Richter scale for earthquakes and is simply a scale from 1 to 10 to classify the threat risk of an asteroid actually hitting our planet.

It is likely that for anything large enough to cause significant damage, that there will be plenty of warning so that plans can be put in place to deflect it. This deflection will need to take place far enough out so that not much is required. The closer to us, the more difficult the task - hence the early warning systems.

The most sensible options seem to be using gravity tractors, kinetic impact (different from nuclear bomb), rocket motors, space mirrors or even painting it!

As long as plans are in motion in time, then there's a chance of success. But it does need all the nations of the world to co-operate and agree - and here's where there may be stumbling blocks. But we live in hope.

(Issue 201 of the BBCs Focus magazine is my main source of information for this blogpost.)

-- Lynda

Asteroid's Passes By Earth - Just

Just a quick post today.

From the BBC

Space rock makes close approach An asteroid which may be as big as a ten-storey building has passed close by the Earth, astronomers say.

If you like this sort of thing, sign up for the BBC's daily e-mail.

All the best

-- Lynda
(I said it was a quickie!)

Green comet approaches Earth

Green comet approaches Earth

Comet Lulin is a green beauty that could become visible to the naked eye any day now. The comet makes its closest approach to Earth (0.41 AU) February 24, 2009. Current estimates peg the maximum brightness at 4th or 5th magnitude, which means dark country skies would be required to see it. No one can say for sure, however, because this appears to be Lulin's first visit to the inner solar system and its first exposure to intense sunlight.

Visit the Astronomy.com website HERE to find out more.


For info on comets - WIKIPEDIA