http://i.imgur.com/SdzQiW8.jpg
So, first we need to get how far away Asgard is. It is said to be "in another dimension" but this is clearly misleading, as not only is physical travel to it possible and done on multiple occassions (even in modern comics, scan from Original Sin 5.4), but dimensions are also physically connected to the main universe.
So how far is it? At the least, "endless galaxies." While this isn't an exact measurement, I'd imagine 2 galaxies away would be a pretty massive low-end for this to say the least.
Galaxy Diameter - 100,000 lightyears
Distance Between Galaxies - 6,532,000 lightyears
Fraction of a Microsecond - 0.0000005 seconds
100,000*2 = 200,000
6,532,000*2 = 13,064,000
200,000+13,064,000 = 13,264,000 lightyears
13,264,000 lightyears/0.0000005 seconds = 2.51e29 m/s
Results
Odin Sends Thor to Earth - 8.37e20c, MFTL+