First things first, the image:
Markarian’s Chain
The Objects
Markarian’s Chain is a string of galaxies in the Virgo Galaxy cluster. It’s named after an astrophysicist, Benjamin Markarian, who discovered that 7 of the galaxies in this cluster move in synchrony together through space. The center of the chain is about 50 million light years away. The biggest galaxy in the chain, M84, is 110,000 light years in diameter, just a little bit bigger than our galaxy, the Milky Way.
Click and zoom in on the high-res image above to see some of the different galaxy shapes and structures. This pair, known as Markarian’s Eyes, is my favorite:
This isn’t my favorite astrophotography image I’ve taken from an aesthetic perspective, but it probably is the one that blows my mind the most. There are over 30 galaxies visible in this image - just about anything that isn’t a perfectly circular point of light is a galaxy.
Every one of those galaxies has upwards of a 100 billion stars in them, and each star likely has planets in orbit around it. With those odds, I find it very hard to believe that there isn’t some form of intelligent life in at least one of them (shoutout to Drake & Fermi). The alternative, that there are mind blowingly vast stretches of space that are completely devoid of life, is almost harder to wrap my head around.
The photo that originally sparked my interest in astrophotography is the Hubble Deep Field image:
According to NASA’s website:
The first Deep Field, the Hubble Deep Field North (HDF-N), was observed over 10 consecutive days during Christmas 1995. The resulting image consisted of 342 separate exposures, with a total exposure time of more than 100 hours, compared with typical Hubble exposures of a few hours. The observed region of sky in Ursa Major was carefully selected to be as empty as possible so that Hubble would look far beyond the stars of our own Milky Way and out past nearby galaxies.
The results were astonishing! Almost 3000 galaxies were seen in the image. Scientists analysed the image statistically and found that the HDF had seen back to the very young Universe where the bulk of the galaxies had not, as yet, had time to form stars.
The fact that this seemingly empty patch of space is actually bursting with thousands of galaxies fills me with wonder.
To me this is exactly what makes astrophotography so unbelievably cool: it’s a mix of exploration, discovery, time travel, and a very humbling reminder of our relative scale in the universe.
The Image
Shooting galaxies, I have learned, is not easy in surburban New Jersey light pollution. Galaxies are broadband targets, meaning their light spans the full visible spectrum, so using the light pollution filters that are super effective on nebulae cuts out a lot of signal in galaxy images and therefore isn’t an option.
The data for this image was captured over two nights (the first two clear nights in almost a month!) where there was luckily close to no moonlight.
I had to keep exposures very short to prevent the brighter galaxies from totally blowing out the shots and to keep light pollution from taking over, so the final image is composed of ~540 individual relatively short ≤ 60 second shots totalling roughly 7.5 hours of total exposure time.
Here’s one 60 second exposure from the first night:
Even with the short exposure and the light pollution you can still see the brighter galaxies come through.
What’s Up Next
Originally I planned to revisit some of my first targets with some new techniques I’ve learned, but I forgot about the fact that the Earth moves throughout the year, so most of them are no longer visible. Whoops! Spring is “galaxy season” in astronomy, so I may take a crack at a few more galaxy shots if the conditions are right, or maybe go after some entirely new stuff. Just need these clouds to go away!
I hope you enjoyed the pic and happy Spring.
-Kristian
Sensei- beautiful shot and write up as always!
Was looking at the deep Hubble field image that inspired you and notice that the galaxies appear in a variety of different colors. Is Hubble using a spectrometer, and different galaxies have different prevailing gasses which give them color? Curious why there would be such a diversity of colors, presumably indicating different gaseous components of the galaxies?