Galaxies Galore

The Spring sky is full of galaxies. We look towards the north galactic pole of our home galaxy the Milky Way, an ephemeral and rather anthropcentric point in the constellation of Coma Berenices.

We can be grateful that the Milky Way is a spiral galaxy with a flat disk enabling us to see into the depths of space; if it were not, we would still be wondering about the size of the universe and arguing that all the stars we see are the entire universe – the Milky way would be it.

Thankfully the 18th century philosophers Kant and Lambert  along with the visual astronomer William Herschel were correct in their surmise about the shape of our galaxy, eventually ending many years of debate. The Milky way is a flat disk. All we have to do is measure the distance to the furthest star across the disk and then anything outside that distance wuld be extra-galactic. Not an easy proposition to prove.

Nevertheless the follwing century saw the advent of parallax techniques under Friedrich Bessell and spectrographic use with Kirschoff and Bunsen. Together with astronomical photography pioneered by Henry Draper, the skills and techniques enabled Henrietta Leavitt, Harlow Shapley and Edwin Hubble to determine distance more accurately, eventually resulting in a very large universe full of extra-galactic objects like the Whirlpool galaxy above.

The distances to such objects was staggering – Messier 51 above is 27 milion LY away; the light entering the camera last Wednesday night had been travelling across space for 27 million years. A time far longer than human history, a time we now call the Oligocene when grasses began to populate the land and new mammals like deer, rhino’s and cats first appear. If you want time travel, this is it.

 This beautiful face on galaxy is undergoing gravitational inteaction with its smaller companion. New stars are forming along one of the spiral arms making it slightly bluer in colour than the body of the galaxy. Just at the bottom of the frame is galaxy NGC 5198 a galaxy at a distance of 100 million LY.

This beautiful shot was taken from the Algarve on the recent astronomy field school.



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