On 6/25/2013 6:33 AM, Greg (Strider) Moore wrote:
"Brian Gaff" wrote in message ...


It is a matter of perspective. The sun really covers a very small part
of the sky. (Can't recall the number and having trouble finding it.)

But figure the station has to cover 360 degrees in 90 minutes (give or
take). It's covering 4 degrees in a minute.

Or 1 degree in 15 seconds.

Hmm, and I was betting the sun was about 1 degree of arc, so that all
jives.


Well obviously cannot see it, but it sounds an awfully short time to
cross the face of the sun, I'd have given it about twice that time,
but I suppose its all down to perspective.
Brian



Yeah I was under that same impression Greg & Brian. In fact it looks to
me closer to 15 times the time stated in the article.

According to this table from Wikipedia:

https://en.wikipedia.org/wiki/Angular_diameter

As seen from the Earth's surface, the Sun is approx. .53 degrees of arc.
That puts a transit at 7.5 seconds if the 360 deg / 90 minutes figure is
correct, which is about 15x the figure stated in the article.

So it somewhat depends upon one's definition of "transit time". For the
entire surface of the Sun, for a "naked eye view", not recommended btw,
see above. However, if we're talking about the "transit time" within a
particular field-of-view, well that can be made arbitrarily small
depending upon the magnification being used.

It may have been he had only a 1/2 second window to catch an image with
enough magnification to show the details of the Chinese Space Station in
that first photo.

But the way it is worded in that article leaves it confused to say the
least!

Dave