Globular clusters are some of the best deep space objects to view with a video telescope setup. These tightly bound swarms of stars orbit our Milky Way at a distance of 100,000 lights years or more and contain many more older stars than open clusters. The density near the core of these stellar globules is very pronounced indeed, such that any inhabitants of a planet deep inside one would see a night sky peppered with incredibly bright stellar neighbours. This artist impression from William Harris and Jeremy Webb illustrates the point beautifully.
What the sky might look like inside globular cluster ’47 Tucana’ where nearly 600 thousand stars jostle within a volume of space only 120 light years across.
I planned to video the famous M3 globular tonight after seeing its relative high altitude and fortuitous position in SkySafari, and noting with some relief how clear and enticing the moonless sky looked.
After very little effort, and with a short 3 second integration time, I was able to watch this spectacular sight slowly materialise in the video monitor
M3 contains over 500 thousand suns at a distance of 34 thousand light years from earth.
This image is incredibly bright and vibrant compared to naked eye views of M3 and is only slightly marred by a few visual artefacts due to the sensor technology. The bloated white dots at the widest periphery of the image are not stars but hot spots due to the video chip heating up during long exposures. Despite this I’m sure you’ll agree the view is a triumph of video observing, readily revealing the awesome density and structure of the cluster.
There are over 150 of these satellite clusters orbiting our Milky Way galaxy and their formation is the topic of excited debate. The fact they harbour such a high proportion of older stars suggests they were some of the first stars to evolve within the overall galactic neighbourhood.
As far as the question of technological life existing within these systems, the chaos from closely interacting stars (on average only 1 light year apart) might prove an unfavourable environment. Stars and planets in such a system would be under constant perturbation from nearby neighbours imparting gravitation ‘tugs’, resulting in unstable planetary orbits.
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.
Venus has been a constant jewel in the evening sky recently, popping into view during twilight in the south west and burning with an astonishing intensity in the western skies after darkness.
I’ve been taking my telescope out a few evenings in a row to view the planet from kerb side and marvelled at how well resolved it is at high power. It’s a half crescent right now, revealing a lovely hazy terminator where Venusian day meets night. Eager to record its majesty, I trained my video setup on it this evening, using leg stabilisers and a barrow to maximise the surface area per pixel captured on my Samsung’s CCD chip. Here’s what I captured.
The visual scale of Venus is impressive here compared to general viewing with eyepiece observation. This is one of the advantages of having a smaller CCD sensor. Whilst more limited for large deep sky objects (without focal reduction) it permits big and bold presentations of the planets with just a modest x2 barlow lens.
Notice the pronounced atmospheric haze and refraction of light at the terminator between day and night. Venus has a thick cloud covered atmosphere which is highly reflective – giving the planet its bright white appearance. There’s also the slightest hint of mottling or streaking on the surface. These fine streaks are large cloud structures that ebb and flow slowly within the Venusian atmosphere.
Not so long ago Venus was the target for many pulpy science fiction stories. These authors imagined the planet full of swamps with dinosaurs and primitive tribes battling across vast continents. These fantasies were shot down after robotic probe and satellite recognisance of the planet was undertaken, first by the Soviets and later NASA.
Our current understanding of Venus is that it’s a planetary embodiment of hell. An atmosphere of nearly 96% carbon dioxide traps heat from the sun, raising the pressure to 92 times that of earth, with surface temperatures approaching those inside the finest Italian pizza ovens. This pizza analogy would apply to any human making it all the way down to the surface of Venus!