In the Scottish Highlands we’re blessed with many dark locations from which to view the Milky Way, the band of diffuse light revealing our place within a giant spiral galaxy.
Even if you live in a busy city like Inverness, a short drive is all that’s needed to escape to relatively dark skies. Regrettably, in many parts of the UK and central Europe this important connection with our home galaxy has been rubbed out due to light pollution.
Looking up at the Milky Way lets us connect with something vast and far bigger than ourselves – an important check on our own sense of self importance.
More needs to be done to curtail unnecessary outdoor lighting and to educate people on the basics of dark sky preservation. Retaining access to our night skies needn’t be an economically crippling ideal. There are simple practical steps people can take that make dramatic differences. Please see this excellent guide on the International Dark Sky Association website for tips on how you can help.
I’ve made a short video celebrating our views of the Milky Way and how overwhelmed our position is amidst an estimated two trillion other galaxies in the observable universe.
NGC 1032. A perfectly edge on view of a giant spiral galaxy in the constellation Cetus, around 100 million light years away.
A lovely edge on view of galaxy NGC 1032.
This beautiful image, ablaze with the light from over 100 billions suns, perfectly captures the thin aspect of large galactic discs. Most spiral galaxies are incredibly slender relative to their diameter. The thickness of our own Milky Way is only 1% of its total 100 thousand light year diameter. So next time you see the band of the Milky Way overhead you can roughly approximate its width to be 1000 light years.
The dynamics of gravity and centrifugal force can explain much about the formation of spiral galaxies but the fine detail and the rotational speed of the various bands of stellar material are still shrouded in some mystery. Without concepts like ‘dark matter’, for instance, the outer portions of many galaxies are rotating so fast they would simply rip themselves apart.
Many people are uncomfortable with terms like ‘dark matter’ and ‘dark energy’ because they’re ‘inferred’ phenomena rather than being directly detected. This might be so but science is riddle with such pre-emptive constructions.
Take air for example. For untold millennia people knew about the existence of this invisible substance which would fill people’s lungs and impede the flow of water ‘an air lock’. However, it would have to wait until the discovery of modern chemistry for air to be properly defined as a mixture of several atomic elements (mainly oxygen and nitrogen).
Why this galaxy on this particular night? Simply because it was a relatively bright object that was high in the sky within Leo and facing south, the direction of least obstruction from my local observing position. One of the best tips I learned about observing deep sky objects, in particular galaxies, is to never underestimate the benefits of superior elevation.
Setting up my video telescope at its maximum integration time of 10 seconds, I wasn’t holding too much hope of anything spectacular appearing from these semi light polluted skies. I was thankfully mistaken.
Despite its staggering distance of nearly 30 million light years, the video screen began resolving a beautifully presented barred spiral galaxy with easily discernible spiral pathways, surrounding a very bright core. I’m always in awe when viewing distant galaxies like this in real time. The main idea that captures my imagination is the understanding of what makes up those dim dust lanes – billions of suns!
NGC 2903 is only slightly smaller than our own Milky Way at over 80,000 light years across and is very similar in structure to our own island universe. Its central bar is a common feature in spiral galaxies found in around two thirds of them. The formation of these bar structures is still poorly understood. The most popular hypothesis is due to a density wave propagating from the galactic core, reshaping surrounding dust into a long column. In general these structures indicate relative maturity for a galaxy – younger galactic siblings don’t have them.
They say good things come to those who wait. Never was this more exemplified than this evening after several hours in bitterly cold conditions on Culloden moor with my video telescope. The cold made setup and targeting much more fraught than usual, and the small gas stove I’d balanced pecariously beside the monitor did little to help.
However, near the end of my session I hit the jackpot when this stunning image of the Whirlpool galaxy, over 23 million light years away, materialised from the video screen.
This image is a true testament to the power of video astronomy and the huge increase in aperture it lends to amature telescopes. Dust lanes and connective spiral arms are clearly in evidence here. The best naked eye views of the Whirlpool I’ve seen have only really resolved the two central cores of the interacting galaxies. You generally need a scope of 16 inches or more to reveal dust tendrils in this much detail.
This is how the Earl of Rosse sketched the galaxy back in 1845 with his monstrous 72 inch dobsonian from the grounds of Birr Castle in Ireland.
Of course back then these structures were given the loose classification of ‘nebulae’ and were assumed part of our local galaxy. It wasn’t until the 1920s when Edwin Hubble observed cepheid variable stars within each bright core of the Whirlpool that this image was understood to be two distinct but interacting galaxies, the larger of which has been estimated to be 35% the size of our own Milky Way galaxy.
M51 is still a hot target for professional astronomers, not least because of the black hole that exists within the heart of the larger galaxy. This central region is undergoing rapid stellar changes and star formation.