Category Archives: Astronomy

Back to the night sky

I started observing the night sky in late 2012 and kept up a pretty steady pace until about 12 months ago when my observing time shrank drastically. Partly due to weather, also due to a lack of effort on my part. I’m hoping to turn that around. I doubt I’ll be logging the 6 hour observing sessions I was doing in the first couple of years but I’d at least like to get in a couple hours when the skies are clear. Like many things in life, I find that when I make the effort my passion and interest deepen. When I fail to make the effort, they fade. My interest in observational astronomy is interwoven with my interest in cosmology, chemistry, physics and other related areas. These are not interests I am willing to give up due to laziness.

So, I logged a few sessions this past week. Right now our night sky faces in towards the Milky Way so lots of globular clusters and nebulae are visible. Oh, also, Saturn. Had a good, long look at Saturn. Then I spent a couple hours each night looking at globular clusters in Sagittarius, Pegasus (M15), and M2 in Aquarius.

 If you’ve never looked at a globular cluster and you get time with a telescope make sure you find one. They are fantastic to see in a medium to large amateur telescope, one of the best objects to view. They are equally amazing to learn about. For example M2, one of the oldest known clusters at 13 billion years, is also one of the larger globular clusters and is 175 light years in diameter. Within that space there are 150,000 stars. In other words, it is very densely packed with very old stars. Viewing it with my 12″ dobsonian scope with an 11mm eyepiece resolves many of the stars and the result is stunning.

These stars are nearly as old as the Universe and, as I understand it, still remain a bit of a mystery in terms of how they came to be in clusters orbiting galaxies. Our galaxy has about 150 such clusters. They typically reside outside the disk of the galaxy and orbit the galactic core as satellites with an orbit radius of 130,000 light years. The Andromeda Galaxy is thought to have as many as 500 such globular clusters.

Speaking of our neighbor, I also had a nice long look at Andromeda. As always, a beautiful galaxy to look at through even a small scope.

Eclipse

Like many, I spent my Monday afternoon observing the moon cross between the Earth and the sun. My cabin is located in the path of the totality. I had 1:40 of totality and was lucky enough to share it with a handful of friends under clear skies.

To put it simply, it was absolutely glorious.

Understanding the eclipse by creating a to-scale demonstration of orbits and moon phases

I was recently asked to do a presentation about the upcoming solar eclipse at our library as I am one of a small local group of amateur astronomers. I happily accepted. I always enjoy putting together Keynote presentations for such events. I spent several days last week assembling the 38 slide presentation and did the presentation last night. It seemed to go well. For one part of the presentation I used three volunteers to serve as the sun, moon, and Earth. The idea was to illustrate the phases of the moon as well as the angle of the moon’s orbit with these three people and in truth, after a bit of initial confusion, I think it went pretty well. But it wasn’t to scale as we were crowded into a fairly small room at the library. After the event I got to thinking about how that sort of presentation, in particular the bit involving the volunteers, could be expanded into something really fun but in an outside location so that a sense of scale could be created. It would involve a bit of math so I thought it might be fun to recruit Siri as my helper in preparing this activity.

The idea would be to create a scale model of the Earth in relation to the sun and moon based on a circle of 365 feet in circumference. Each foot represented one day in the Earth’s orbit around the sun. Now, at this scale, I wanted to properly represent the position the sun at the center of our orbit. I needed the radius of my circle. Okay. I asked Siri to calculate the radius of a circle with a circumference of 365 feet. I was given a WolframAlpha calculation screen as a result: 58.1 feet. But I wondered if I could copy/paste the content. It had never occurred to me to tap the WolframAlpha icon, just a bit of text in a square in the corner of that display of results. I’ve done this kind of thing many times but never thought to see what would happen if I tapped. I expected it would do nothing. Instead, it took me to the AppStore for the WolframAlpha app. It never occurred to me that there was such an app but of course there is! I downloaded it and it opened my results into the app. It’s a very nice app that allows further input and new calculations among many other things. But no option to copy/paste the content.

Now, back to working out the activity. I’ll need to get some string but before that, I now know that if my orbit is scaled to 365, feet my radius is 58.1 feet. So, I’ll position my sun with a pole with string tied to it. From there I’ll walk out 58.1 feet and place another pole. I’ll have two strings. One which I’ll keep tied to the center pole (my sun) and which will guide my “orbit”. The second string will be tied to the second pole. Now it’s just a matter of walking the circle around the sun and dropping my string to represent the 365 feet of orbit. The next step is to convert a few other distances. For this I hopped over to this solar system scale model calculator.

Next, I used Siri to do a bit of math. First I asked her for the average circumference of the Earth’s orbit. Then I asked her to convert this from miles into feet. Then I divided that by 365 come up with my model scale of 8,447,618,973. With that number input into the solar system scale calculator I confirmed my Earth orbit radius of 58.1 in the results. Next, I wanted to get the moon’s orbit as well as the size of my three solar system objects at this scale. I made sure to select the Moons option and on the form and I got an orbit radius for the moon of 1.79 inches. TINY!! With that radius the average circumference of the lunar orbit is just 11.25 inches. Whats’ the size of the sun, Earth and moon at this scale? According to this same calculator, at this scale the sun is just 6.49 inches in diameter. Of course, the Earth and moon are very tiny! The Earth is just .06 inches in diameter and the moon is .016. Just a spec.

So, I’ve got the scale though in truth it might be best done at a slightly larger scale given how tiny the Earth and moon are in this model. Regardless of the ultimate scale of the model it is fun to play with and I expect it will be a fun model to explore in the yard. The idea would be to set the scale and then discuss the movement of the moon in it’s orbit of the Earth and the Earth’s orbit around the sun. By positioning volunteers it becomes a bit more obvious why a new moon is invisible to us. By adjusting the position of the volunteer “moon” in orbit around the volunteer “Earth” it become easier to understand how the moon gradually becomes more visible as a crescent then a quarter then a full moon and so on. Further discussion of the 5° elevation of the moon off of the ecliptic helps participants further understand why we do not have solar eclipses with every new moon.

Jupiter in an amazing fly-by video


Wired has a great post about the project.

Jupiter is immense. The fifth planet from the sun has a diameter of 89,000 miles, and could easily envelop every other planet (and Pluto). The gas giant also has 2.5 times the mass of all those planets combined. Even its enormous storms boggle the mind: the Great Red Spot is big enough to contain the Earth.

Photos provide glimpses of Jupiter’s grandeur, but you can’t appreciate its stunning scale without some perspective. Gerald Eichstaedt and Seán Doran provide some with a stunning flyby video made from dozens of still photographs taken by the Juno probe.

Painting the Horsehead Nebula

This is one I have attempted to view through the telescope but which is fairly difficult to view. Through the telescope and in any image taken in the visual spectrum the Horsehead nebula is a dark patch of dust and gas against the glowing background nebula. This painting is based on an image taken by Hubble in the infrared, a wavelength in which the gas of the nebula can be observed. It's just a very tiny part of the much larger Orion Molecular Cloud Complex.

As all of my iPad paintings have been, this was done with Procreate using an iPad Air 2 with a generic stylus.

Denny

February 18, 2017

Had an opportunity to share a view of the Orion Nebula through the telescope last night. Sharing astronomy is always great fun.

Painting the Lagoon Neblua

My first effort at using the iPad and Procreate to paint was the Eagle Nebula. To be honest I started that first project assuming I would not get very far. I'd never painted and expected it would be a huge mess. But it wasn't half bad and I enjoyed the process far more than I expected I would. In fact I enjoyed it so much that when I finished I decided to try another, the Orion Nebula. When I finished that I thought I'd give the Lagoon Nebula a try. I chose the Lagoon Nebula because I'd recently viewed it as it is a great summer object and one I always view at least a few times each season.

Finishing the Herschel I program

In the fall of 2012 I bought my first telescope since having one as a kid. I wasn't sure how much use I'd get out of it but I wanted to give it a go. I suspected I'd not regret the purchase. Within the first couple of weeks I'd become obsessed. I went out each clear night and sometimes stayed up till I started dozing at the scope which was often in the wee hours of the morning. Within a couple weeks I'd started keeping track of the objects I was viewing. I started just with the date, object name/ID, date and time. Soon after I started noting the eyepiece I was using as well as a description. It occurred to me that it would be fun to do the full Messier list and get the certificate from the Astronomical League. Not that I cared all that much about the recognition but having a list helps give a bit of order to the process. Had I not taken it on I might have gotten stuck looking at the same objects. Another side effect of having a list and doing the "official" program is the requirement that the observer find the objects on their own. No go-to telescopes allowed. Which was not as much of an issue as I didn't have a go-to telescope. But reading about the program drew my attention to the idea of systematic searching and recording.

A month into the Messier list I realized there were some nights that when I would have no objects to search for as I would have already found all the available objects on the list that were up in the sky. So it occurred to me to look for another list that I could start at which point I became aware of all the various programs that the Astronomical League administers. I settled on the Herschel I and got started. It's a list of 400 objects from the NGC catalog of 7,840 objects, largely based on the observations of William Herschel, his son John and his sister Caroline. It's a mix of galaxies, star clusters and various kinds of nebulae. It's a great list to do after the Messier list because it is slightly more difficult with fainter objects.

I finished up, or thought I did, about a year later. Upon checking my list though I discovered that I'd bungled a few by not recording proper descriptions and I was also missing a few. So, I started filling in my gaps until, about a year later, I thought I was finished. And, again, I discovered a few I had missed! So, back to it. With each successive check my list of missed objects was getting smaller. Essentially my transition from the initial list to spreadsheet to database introduced a few errors. Over the past couple of months I've been taking care of the few remaining objects and in the wee hours of a late September morning I finally got the last object in my eyepiece. NGC 2372, a planetary nebula in Gemini. I entered it in to my report and spent the rest of the morning double checking my final list. All in all the list took about four years and during that time I recorded well over 500 observations for that particular list (many duplicates due to the first 100 or so having been recorded without the detailed descriptions).

What did I learn during the experience? I learned much more about seeing the objects. Early on I was moving too quickly from one object to the next. It was not uncommon for me to log 15 objects in a 4 or 5 hour session. That's three to four an hour. When you consider the time it takes to find an object in the scope and record the observation it turns out I was only looking at some objects for 5 minutes or so. That's a minimal amount of time. These days I tend to look at about half that number of objects and I spend more time on each one.

The process of really seeing a faint object requires dark adapted eyes (no bright lights after you start viewing. Only low levels of red light!) and it requires at least 10-15 minutes, often times more, for each object. I also find it helpful and more educational if I take some time reading about the object. I don't necessarily see the object better but reading about it helps me appreciate what I'm seeing. It's easy to do using Sky Safari which is my preferred astronomy app. Each object has a description associated with it, many of them are quite detailed. There are also images in the app which can be very helpful in finding some of the details that might otherwise be missed.

I also was also reminded that there is an important connection between observation, vocabulary and description. As with any skilled observation it is important to develop an understanding of the components of what is being viewed. For example, if I'm viewing birds I pay attention to not just the colors but also the shape of the beak and tail, the physical habits, the body shape, the song, etc. There are many details that will help me identify the species of bird I'm looking at as well as understand something about the bird for example it's diet or food gathering habits. The same might be said of plants, trees, butterflies or any other observation of the natural world including astronomical objects. There is a certain literacy that goes with observation and increased literacy means a more detailed interpretation of the sensory data.

When I first began looking at galaxies I mostly just saw smudges of light. But right off it was evident that the shapes varied. For example, the Andromeda Galaxy (M31) and it's two neighbor galaxies (M32, M110) vary quite a bit in size, shape, brightness and features. They're a good starting point and learning tool. M31, a spiral galaxy, fills even the largest wide-field eyepiece with its large disc and offers a concentrated, bright nucleus as well as dust lanes. By comparison, M32, an elliptical galaxy, appears as a compact and bright nucleus with no disc. M110 is also an elliptical galaxy but is much larger than M32 and better described as an oblong nebulosity with a slightly bright central area but no bright core or nucleus. But while these three nearby galaxies are a good starting point and each offer different characteristics to be described they are just the beginning of many galaxies. Then there are the many kinds of nebulae and star clusters to learn about. No doubt astronomy offers many years of possible observation, a lifetime of possibilities in fact.

So, where to next? I've already started three other programs: double stars, nebulae, and the Herschel II list. I think I'm going to start the lunar program as well. As our closest neighbor the moon can cause a great deal of light pollution for much of each month making other observations difficult. But it's a fascinating subject itself, why not enjoy it?!

Looking at other galaxies

One of the best things about living under really dark skies and having a decent telescope is viewing other galaxies. While I equally enjoy the many beautiful objects in our own galaxy such as nebulae and globular clusters, the hunt for distant galaxies has a meditative quality for me. Sometimes the finding is a bit of a let down. For example, last night I went looking for NGC 7042, a spiral galaxy. It took some doing but I found it. It’s 250 million light years away. Yeah. It was the faintest little smudge of light barely detectable on a very clear night with a decently sized telescope (12.5 inches). When I find these really faint ones I always laugh at my disappointment. Yes, it is a galaxy filled with billions of stars and yes, I just sighed in disappointment. But, but, it’s 250 million light years away I remind myself. Not only that it is moving away from us at 5,083 kilometers per second or, 1.7% the speed of light. There will come a time in the distant future when that galaxy and others are no longer visible from Earth. The stretched out light will no longer reach us. The Universe is expanding and that expansion is accelerating. Eventually galaxies that are currently visible to us will blink out. Of course, by that time we’ll likely not be here to notice.

The thing about viewing other galaxies is that it helps frame the scale of the Universe. When I look at the star Vega I’m seeing a star that is only 25 light years away. Yes, still a vast distance from our perspective. But it’s in our local neighborhood so to speak. In fact, it’s like a neighbor on our own street. Funny thing, the stars we see when we look up without a telescope are all in our local neighborhood. We’re only seeing about 6,000 of the very closest stars in our galaxy of 200 billion stars. When I look at the Orion Nebula I’m looking at something that is only 1,400 light years away. Sure, that’s a good bit further than Vega but again, remember that our Milky Way galaxy is an average of 100,000 light years in diameter. So, Orion is still very much in our local neighborhood.

The Andromeda Galaxy is the largest galaxy of the Local Group which consists of about 45 other galaxies including our Milky Way.

The Andromeda Galaxy is the largest galaxy of the Local Group which consists of about 45 other galaxies including our Milky Way.

But back to the viewing of galaxies, the easiest to view from the Northern hemisphere of Earth is Andromeda which is “only” 2.5 million light years away. It fills the eyepiece of my telescope and can actually be seen with the naked eye if you’re under dark skies. I have no problem picking it out from the stars of the Milky Way. It’s oval of faint light is actually quite large and fills an area larger than the full moon in our night sky. It’s quite close and in fact, billions of years in the future we will in fact merge with Andromeda. I viewed Andromeda just two nights ago. I also viewed the Bode’s galaxy, M81 and the Cigar Galaxy, M82 which are a pair of galaxies 12 million light years away and are fairly bright and easy to find with a telescope. In 2014 a star went supernova in M82 and we were able to view it from Earth. Quite a show! So the pair is, in the larger scale of things, quite close. A bit further than Andromeda but not nearly as far as the 250 million light years that makes NGC 7042 so faint.

Faint and distant or bright and close, viewing other galaxies is a thrill because it means looking at the starlight of hundreds of billions stars. As those photons stream into my eyes I’ve got a direct connection with the ancient starlight created by billions of suns. It is light that has been stretching through the Cosmos for millions of years and ends its journey in my eye. The experience is one which enhances my perspective and gives life on Earth an added dimension. In seeing such distant worlds I begin to contemplate and understand the scale of the Universe in a way I had not before. It has changed who I am as a human as well as my understanding of what it means to be human.

Painting the Orion Nebula

In the fall of 2012 I had my first ever look at the Orion Nebula through a telescope. Like many people I'd seen Hubble images which are obviously stunning. Also, like many that know their constellations, I had seen it with my naked eyes as one of the stars in the sword of Orion. But with a telescope of any size or even with good binoculars, the middle star of the sword emerges as the center of this fantastic nebula. It's the sort of object many amateur astronomers will revisit many times. I know I have. It's a winter object, often referred to as the gem of the winter sky and with good reason. Of all the nebula visible from the northern hemisphere, winter or summer, The Orion Nebula is the most distinctive in terms of size and contrast. It provides amateur astronomers an opportunity to train their eyes in the discernment of greater details. Provided the same seeing conditions, a first viewing for 10 minutes is likely to be improved with a second viewing for 10 minutes the same night or another. Look again a third time for 15 minutes and you are very likely to see more detail. With each subsequent viewing more details emerge. It's also an object that benefits from larger, better instruments. So, while I can view it with binoculars or a 6" reflector if I get a chance to view it with a 10 or 12" reflector I will see a great deal more especially if I've had numerous previous sessions with it.

I've not yet tried to sketch or paint the nebula while at the scope though I hope to do just that this winter. In the mean time I decided to give it a go as my second painting using Procreate on the iPad. My intent is to do a series of these in part to improve my painting technique and knowledge of Procreate but also to better learn the details of the object. Just as more time looking through the telescope results in noticing more detail, more time looking at and painting an image, does the same. With each painting I'm also spending more time reading about the object. Usually using a combination of the Sky Safari description in combination with the Wikipedia entry. Here's the entry for the Orion Nebula.

In total I've spent about 27 hours broken up into 5 or so sessions. Here's a look after about 16 hours:

At this point it was easily recognizable but still missing many details. I should mention that I have no experience painting on any medium. It may well be that this sort of project should have taken half the time. Or double the time. It may also be that I'm going about it all wrong. The gist of it is that I'm layering. I've got a layer of stars on the very top, another for the base nebula which is largely created with the airbrush and sits at the bottom. Then I end up with at least two layers of wispy nebulosity and yet one more which consists of the darkest nebulosity and sits on top. These are often the thickest, clumpiest bits of dust and gas which more completely block the light coming from behind. The thickest of these are often referred to as bok globules.

The next image represents about 22 hours. Lots of refinements and new details.

Much closer but still not there. It's hard to know when it's "done". I could have stopped at this point but many details were missing and some bits that I did have were not right. That said, it's a painting and not meant to be exact. I suspect that going forward I'll play with this idea of what's finished because there is no way to know. Especially with something such as this, my intent is to get something that very closely resembles the photographic image but which is still obviously a painted version. It's not necessarily a creative project as much as it is a documentary.

The last image was finished this morning. I thought I was finished last night. But upon opening it up noticed more details. And that's the thing of it. I made some changes this morning but could have kept going. I could have spent all day on it and tomorrow as well. There's always another wisp of gas to be painted. Another knot of darker gas. A missing star. An area of gas in which my color is off. So is it finished? Yeah, for now. It's time to take a break and then move on. Here it is after about 27 hours.

Of course it should be said that the photographic images vary. Not only can the color very but also the emphasis on stars or nebulosity can change (among other things). It depends, in part, on the spectrum in which the photo was taken. The electromagnetic spectrum is a wonderful thing consisting of a variety of wavelengths each of which is photons traveling at different energy levels. The lower energy wavelengths such as radio or microwave are longer and pass through gas and dust more readily thus images taken in those wavelengths will tend to allow more background stars through. Images taken at higher wavelengths such as the visible will tend to show fewer stars as the foreground gas and dust will block some of them. Here's the image I used for this painting, taken from the Wikipedia: