Martin Brown wrote:
N:dlzc D:aol T:com (dlzc) wrote:

Dear Chris O'Riordan:

"Chris O'Riordan" wrote in message
oups.com...

The conventional explanantion for the superluminal motions observed
in
many quasar-type jets is that it is an optical illusion due to the
jets
being oriented at a fairly narrow angle to our line of sight.

And it is a very good explanation that fits the observations nicely.


There are key cases where it emphatically DOESN'T appear to fit, as I
mentioned in
http://www.geocities.com/chrisori2000/superjet.htm

To recap:-

(For the 7 known superluminals in 1983,) the structures did NOT in
general appear to be oriented close to the line-of-sight;

Mackay, Thompson et al suggested in 1993 that the (outer) jet of quasar
3C273 was nearly PERPENDICULAR, rather than nearly parallel, to the
line-of-sight. Superluminal motion of up to ~9.6c has been observed
along the (inner) jet;

The jet of the galaxy M87 needs to be at ~19 degrees to the
line-of-sight to explain by beaming superluminal motion of up to ~6c in
it -- but independent evidence on the jet's orientation suggests it is
at ~43 degrees to our line-of-sight.