Astrophotography – Revealing the Universe

In the last blog post available here we covered how astronomers gradually used new discoveries in photographic techniques to not just record what could be seen at the telescope’s eyepiece but to capture even fainter details than humans could perceive.

Like new technologies tend to do, once photography became commonly available advances in materials and techniques quickly arrived.  Major telescopes at professional observatories that were built in most of the 19th century were designed purely for visual observing. It was only late in the 1890s that telescopes were constructed with astrophotography in mind. Notable were the 40” Yerkes refractor – still the largest of its type –  and the 60” reflector on Mt Wilson which was the largest telescope in the from 1908 to 1917.


The 60″ Telescope at Mt Wilson, California.

It was from the analysis of photographs taken through the 60 inch telescope that astronomer Harlow Shapely measured the brightness and distribution of variable stars in the Milky Way and globular clusters surrounding it. He suggested the Milky Way was vastly larger than then current estimates. He also showed the Sun and the Solar System were not as thought, in the centre of the Milky Way but  much further away, about two thirds of the way towards the edge of the galaxy.

One of  Harlow Shapely’s images from Mount Wilson Observatory

Astrophotos had changed the where we thought the Earth was located much like Copernicus had moved the Earth from the centre of our Solar System. And there was more to come!

We won’t go into details here about George Ellery Hale, the astronomer behind the Yerkes 40″ and Mt Wilson 60″ telescopes. He was a towering , complex figure. If you’re not familiar with this life, he’s well worth discovering or talk to us at BINTEL – we’ll chew your eye off about this period.  Having been the driving force behind these two observatories, he then went on to establish another two large telescopes, the 100″ Hooker Telescope at Mt Wilson and the 200″ Hale telescope at Mt. Palomar.

Some of the most important astro photos of all time were taken with the 100″ Hooker Telescope

Three years after the “The Great Debate”, a series of lectures in 1920 which intensely discussed the topic of are the “spiral nebula” seen in the night sky part of the Milky Way or galaxies in their right, astronomer Edwin Hubble used the 100″ Hooker telescope to measure the brightness to variable stars to show M31, the Great Andromeda Spiral Nebula was in fact outside the Milky Way and another galaxy. The Milky Way was not the entire Universe. We live on the edge of one of countless galaxies in our Universe.

Negative of Edwin Hubble’s image of M31

Over the space of just a few short years, Earth had been removed from being at the centre of the Milky Way and the Milky Way itself was no longer unique.

But wait, there’s more…

Building on previous work, Hubble and his assistant Milton Humason noticed something curious once they started to measure the distance to galaxies using variable stars. The further away a galaxy is, the faster it’s receding away from us and this in all directions too.

Hubble and Humason at Mt Wilson

Speed away from the Milky Way was measured using “red shift”. The lines on a spectra showing the make up of the galaxy was moved towards the red or longer wavelength of the spectrum caused by the Dopler Effect This is same thing you hear from a car that goes past you. The sound it makes changes tone.

This “Expansion of the Universe” shown on photographic images was confronting on numerous levels. The issue of a seemingly endless Universe that had existed for all time become difficult to accept. What if you ran time backwards? Was there a “Big Bang” when this expansion of the Universe began?

Will gravity overcome the force that pushed galaxies out into space and will it collapse back on itself? Currently not only is the Universe expanding,  but the rate of this expansion is accelerating due the presence of Dark Energy. It’s force that’s yet to be fully explained and discovered using images taken from the Keck and MMT Observatories of exploding stars called Type 1A Supernova.

Whether Dark Energy will always continue to drive the rate of expansion in unknown. Some researches have even suggested it will possibly fade away over time and the Universe will collapse back itself – or matter will continue to fly apart.

Part of the JWST’s mission is to help us learn more about the early formation of the galaxies so we can come closer to discovering the Universe’s ultimate fate. In much the same way those fragile glass plates from Mt Wilson changed who we see ourselves, who knows where the JWST will lead us!


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