Archive for the ‘Observing philosophy’ Category


Dr. Phonelove, or: How I Learned to Stop Worrying and Love Astronomy Apps

October 6, 2020

Warning: long, navel-gazey confession inbound. To wit: I used to be a bit of a snot when it came to planetarium apps. When I put together my “Astronomy Wish List for Beginning Stargazers” post back in 2014, I wrote:

Yes, you can get a free app for your phone that will show you thousands of celestial objects. If you get one with a good night-vision mode AND turn the brightness way down on your phone, it might not destroy your night vision, but it will still only show you a small slice of the sky at one time. At best, you’ll be outside under the stars and still looking at a dadgummed screen. Here’s a thought: put all the devices away, get out a lawn chair or just lie down on the grass, grab a planisphere, and spend a quiet half hour picking out the constellations. One of the chief advantages of a planisphere over an app is that you can see essentially the whole visible sky displayed at once, so you can figure out how the constellations relate to each other. 

Ugh! That was written out of ignorance and prejudice, and I cringe to read it now. Especially the bit about how an app would supposedly only show “a small slice of the sky at one time”. I didn’t own a smartphone at the time and I hadn’t actually used a planetarium app, I’d only seen other people use them, so I didn’t know about using two fingers to zoom in and out, which by now has become such second nature that it’s like looking back and realizing I didn’t know how to turn a doorknob.

My favorite constellation: Cassiopeia.

In any case, no, every planetarium app I know of will show as much or as little of the sky as you want. And most offer a red-based night vision mode for preserving your dark adaptation, which combined with the native screen brightness controls and night vision modes on most smartphones mean that you can use the apps under dark skies without sacrificing all your dark adaptation. (Another easy solution: close your observing eye when using the phone, and ask any companions to look away.)

So what pried me out of my self-dug hole of stupidity regarding astro apps? Direct experience. In 2015 I got my first smartphone, and in 2016 I got the job of writing the ‘Binocular Highlight’ column for Sky & Telescope magazine. I decided it was time to drag my ass into the 21st century, and since I was finally in a situation in which stargazing was bringing in money instead of consuming it, I could afford a decent astro app. I went with SkySafari 5 Pro, and it didn’t take long for it to eclipse almost all of my other astronomy tools put together in terms of how often I referenced it and how much I relied on it. Four years later, I’m on to SkySafari 6 Pro, and I’m sure that when 7 is released I’ll trade up.

For the Binocular Highlight column, we plan for and illustrate a 5-degree circle, and the ability to zoom the SkySafari screen to show a 5-degree field is extremely useful for planning my observing and my writing.

Also, I started noticing at public outreach events and star parties that basically everyone else was using planetarium apps. For people just starting out, they offer a ton of functionality that a planisphere doesn’t. Allow me a metaphor. I firmly believe that Wikipedia is how encyclopedias are supposed to work, and that the beloved World Books and Encylopedia Britannicas that I grew up with were about the best possible implementations of that idea in paper, but hobbled by not having hyperlinks, not being available via wifi, not being continually updated, etc. Similarly, even thought I love planispheres, I can admit that they are basically physical planetarium apps that restrict you to one latitude, one magnification, and a tiny subset of stars and deep sky objects. The digital apps are more intuitive, period, and not just for beginners. Experienced folks use them all the time, too, and for the same reasons: faster, easier, more information. Nowadays I find myself hauling out my phone almost every observing session–to check the positions of Saturn’s moons, or the classification of the components of a double star, or, most often, simply to find the distance to a celestial object.

I’ve enjoyed chasing the moons of Saturn this summer, and SkySafari has been clutch for making identifications — only after I’ve made my own sketches, to avoid spurious detections.

My app use in the field took another jump when I got the NexStar 8SE. Before I got that scope, I was pretty darned proud of my knowledge of the sky. I didn’t quite know all the Messiers by heart, but I could find probably 3/4 of them without even checking an atlas. But the NexStar taught me a hard truth: I may know most of the constellations backwards and forwards, but I know very few stars by name. Caph? Nunki? Alpheratz? Might as well be Farsi, Swahili, and Linear B to this monolingual doofus. So when it comes time to find alignment stars, out comes the phone, because with a handful of exceptions–Polaris, the Summer Triangle, the Winter Hexagon, and a few favorite doubles–I don’t know what these darned things are called.

Oh, hey, there’s Nunki!

(Aside: in a way, this reminds me of what it was like when I first started stargazing in the fall of 2007. Every month, new stars and constellations were up in the eastern sky. I still remember vividly the first time I got up before dawn to see the spring constellations. I’ll get a taste of that in the coming year, as I have to keep familiarizing myself with new alignment stars.)

So to sum up, actually using planetarium apps myself, and seeing how much they opened up the sky to other people, forced me to belatedly pull the stick out of my butt.

The bright, popular double star Eta Cassiopeiae consists of a Sun-like yellow main sequence star and an orange dwarf, which lie only about 19.5 light years from Earth. I didn’t know that until the star party at the park last Saturday, when someone asked if the Eta Cass companion was a red dwarf, and I was able to look up the answer in SkySafari.

There’s another, larger point, which is that I think it’s stupid to criticize how anyone else enjoys the night sky. I’m glad I missed the GoTo wars of the 90s and early 2000s, and I have no time for the limited conflicts that are going on right now over Electronically Assisted Astronomy–essentially, looking at the night sky with night-vision googles, with or without a telescope–and smart telescopes like the Stellina and eVscope. It was always pretty selfish and short-sighted to worry about how anyone else was engaging with the night sky. It’s not like people who have different preferences regarding their gear or observing habits are hurting anyone. Surely we should be able to focus on what matters–our shared love of the cosmos, and getting out to enjoy it–and not whether anyone else is doing stargazing the “right” way. And that’s especially true now, in a year that sees the world shambling among catastrophes like a shell-shocked orphan. With all the horribleness going on, I just don’t have it in me to be upset at other people when they’re not hurting anyone else, especially over something as innocuous and ultimately positive as stargazing.

To the (near) future: the moon will visit Jupiter and Saturn on the evening of October 22.

So I say, bring on the technology. Cameras, electronic eyepieces, smart scopes, light enhancement devices, and the things that no-one has yet thought of. There is plenty of room out there in the dark for those things to coexist with traditional stargazing, and if they bring a few more folks into this wonderful pursuit, so much the better. If the expense bothers you, go look at what people spend on boats and motorcycles, let alone gambling and drugs, and also, check out what serious astrophotographers spend on the rigs that get their photos into Sky & Tel and Astronomy, and also, seriously, just mind your own beeswax. If dealing with the computerized gizmos isn’t your cup of tea, or you feel like using night-vision goggles is cheating, fine, I’m pretty sure no-one will ever force you to use them. I’m also pretty sure that no matter how fancy the hardware and software gets, there will be times that I feel like heading out with nothing but a manually-driven scope or some trusty old binos for “unplugged” observing. But I’m going to try to not close myself off to any more observing experiences a priori, without even trying the new things to see what they have to offer. That was dumb.


3 Ways of Seeing the Cosmos:

April 13, 2017

An Unending – But Necessary – Observing Project

There are some things I don’t blog about because they are too small. Others go unmentioned because they are too large. What I am writing about now is something that started out as an uncomfortable feeling that I was missing out on something, then grew to become an interest and a motivation, and has finally come to be the framework in which I think. Only hints and reflections have made it into my writing so far, whether on this blog or in the pages of Sky & Telescope. The first time I explained it to anyone else was with my friend and fellow observer Steve Sittig about a month ago, and the second time was in the talk I gave at the Three Rivers Foundation star party last month. This is my first attempt to put it into written words – we’ll see how it goes. I’m illustrating this post with slides from my 3RF talk.

This is where we all start out. By necessity – there is nothing else to talk about if we can’t locate things in the sky. But crucially, at this stage to “locate things in the sky” means to figure out how to point at them in the sky as seen from our position on Earth. If we’re talking about a specific object, like M11, the Wild Duck Cluster, then it’s just an address on the surface of an imaginary sphere: RA 18 51, Dec -06 16. That’s important – it’s the basis for an entire science, that of spherical astronomy – but it’s only a start to understanding the structure of the universe and where we are in it.

This stage is what I’ve referred to as “shattering the bowl of the sky” – learning the distances to celestial objects so that we can see space as space, not just a dome with lights over our heads.

An important clue that this is something I should be thinking about came when I first observed M97 and M108. Here are two objects of roughly equal brightness, easily framed in the same field of view in binoculars and telescopes, that are in fact at vastly different scales and distances. We think of M97 as being “out there”, but it’s practically right next door to us in our own galaxy. If the Milky Way is 100,000 light years across – and it is at least that big – then M97 is only 2% of the way across the galaxy from us. It’s right next door. From the perspective of any observers in M108, looking across the intervening 46 million light years, the distance between our solar system and M97 would be unresolvably small.

Here’s an extended example: the major stars and Messier objects of the constellation Lyra. If you’ve been observing for long, you probably know your way around the triangle and parallelogram asterisms, and how to use them to find M57 and M56. It’s natural for us to think of these things as belonging together, because we use them as signposts to guide us when we navigate this part of the sky.

Adding the distances reveals some things. At only 25 light years distant, Vega is in fact closer to us than it is to any of the other stars or DSOs in the field. The other two stars in the triangle are about equally far away, roughly 160 light years, and the other three stars in the parallelogram are ranged between 600 and 1000 light years distant. M57 is a bit further, but M56 is way further out, almost a third of way across the galaxy. Even from M56, our own Sun and all the stars of Lyra would blend into the faint background of field stars that saturate the Orion Spur.

I was really proud of myself for starting to think about my observing targets on this level, and this view of the sky formed the basis for my article “Twelve Steps to Infinity” in the December 2016 S&T.

But it’s not enough. I’ve come to think of this as “army ant observing”. When they are foraging, army ants go out from their bivouacs in straight lines, eating everything they can catch along the way, and come back the same way, just like an observer looking at Lyra. If all we learn about objects in the night sky is how to find them and how far away they are, then we’re still trapped in an Earth-centric view of the universe. We don’t know how the objects relate to each other, any more than a colony of army ants knows that the lizard they devoured on Tuesday hatched out of the same clutch as they one they caught on Friday.

To return to the example of M11, it’s 6200 light years away. That’s pretty darned far for a bright open cluster – the average for Messier and Caldwell open clusters is 3000 light years. We might suspect that to be so bright and so rich at that great distance, the cluster must have many, many stars, and indeed it does, a whopping 2900 of them.

There’s at least one more level of understanding: to hold something of the true 3D structure of cosmos in our minds, and understand how celestial objects relate to each other, without reference to Earth. I illustrated this with a map of our galaxy laser-etched into a cube of crystal. To hold the structure of space in my mind and be able to turn it over and around, view it from all sides, like someone turning that crystal over in their hands – that’s what I aspire to.

I’ll never get there, really. It’s an impossible project. There’s just too much stuff out there. But that’s okay. As a paleontologist, I’m familiar with the problem of envisioning other worlds based on incomplete information. And everything I do learn, every step up the long road to the stars, deepens the experience of observing for me.

Back to M11. It’s a rich cluster, and it’s situated in the constellation Scutum (as seen from Earth…), not far from the center of the galaxy in Sagittarius. But in fact it has nothing to do with the central bulge of the Milky Way galaxy. The galactic center is 27,000 light years away from us, and M11 is only a little over 6000, a bit over one-fifth of the way. Instead of being part of the galactic center, M11 is one of the clusters that marks the Sagittarius arm of the Milky Way, which is the next arm inward, between us and the galactic center. M11 is still out in the burbs, with us, not downtown. In contrast, the globular clusters in Sagittarius, Scorpio, and Ophiuchus actually are related to the galactic center – they are swinging by it, like comets sweeping past the Sun, on incredibly long, elliptical orbits that carry them tens or hundreds of thousands of light years out into the galactic halo.

Next Steps

So here’s my ambition. We have loads and loads of observing guides, like NightWatch and Turn Left at Orion, based on Level 1. Again, that’s not a bad thing, and it’s of necessity. We all have to stand and walk before we can run, and finding things in the night sky is the first step. But as a community, we have people on this already, not only in the vast majority of existing observing guides, but also in the observing features – including most of my own! – published in astronomy magazines, blogs, and online fora.

There are also resources that address Level 2. Stephen James O’Meara’s books live there – they address not just where to find things in the sky, and what they look like, but also what they are, how far away they are (and how their appearance relates to their distance from us), and even, in some cases, how they relate to other nearby objects.

Things get better – a bit – when we get beyond our own galaxy and observe others. The Astronomical League has an observing program for the Local Group and galactic neighborhood, for example. And lots of observing guides and articles on the Virgo Cluster include some basic astrophysical data, including the fact that M87 is a monster elliptical and the central galaxy of the cluster.

A diagram I drew to help get my head around the shape of the galaxy and our place in it. Based on images and data from NASA.

What we don’t have many of, and what those of us who aspire to Level 3 desperately need, are observing guides that address the relationships of celestial objects within the Milky Way. I want an observing guide to the clusters and nebulae of the Sagittarius arm, for example, something that will tell me that M11 is not just 6200 light years away, but that it’s related to M16 and M17 because all three objects are in the same spiral arm of the galaxy. I want a guide to the Perseus arm, and another to the Orion Spur and Gould’s Belt. One of the reasons I’m so excited by Allan Dystrup’s “Classic Rich Field” thread on Cloudy Nights is that Allan has provided a wealth of information on easily-observable OB associations in the nearby reaches of the galaxy.

There is one book that does address the internal structure of the Milky Way, albeit more from an astrophysical than observing perspective. It’s The Guide to the Galaxy, published in 1994 by Nigel Henbest and Heather Couper. A couple of decades on, I assume that at least some of the information in the book has been superseded by new discoveries. But it’s still an interesting and useful resource, and with used copies going for just over two bucks on Amazon, a low risk for anyone who wants to investigate (I have a copy already).

UPDATE April 17: This is what I get for posting in the middle of the night. Several commenters reminded me of resources that do address Level 3 that I forgot to mention. Among them are Craig Crossen’s books Binocular Astronomy and Sky Vistas and Bill Tschumy’s resources at, including his program “Where is M13?” and his essays “Milky Way Rising” and “Escape From Plato’s Cave“. The oversight was particularly dumb since I have Crossen’s Binocular Astronomy on the bookshelf next to me, I’ve corresponded with Bill Tschumy before and he’s been very generous with his thoughts, and in “Escape From Plato’s Cave” he lays out basically the same manifesto as I have in this post. Chalk this up to tiredness – I certainly meant no slight to the other observers and authors who have trod this path before me.

Parting Shot: Bricks and Boards

It may seem like I’m being dismissive of observing guides – or observers! – that prefer to work at Level 1 or Level 2. That’s not my intention. As far as observing goes, I like Uncle Rod’s dictum that there’s no wrong way to do amateur astronomy. As long as you’re out soaking up photons, or letting your equipment soak them up for you, good on ya. May a thousand gardens grow. I started as a purely recreational observer, and stargazing for no more noble purpose than personal aesthetic enjoyment still occupies a lot of time out under the stars. It also, eventually, fired the curiosity and the hunger for a more informed and encompassing view of the universe. I see these approaches as complementary rather than conflicting. I would never have desired to learn the secrets of celestial objects – their relationships, the processes that shape them, their origins and fates – if I hadn’t fallen in love with them in the first place.

As far as observing guides go, here’s my thinking. The God’s Eye View of the cosmos is an edifice of the imagination. Each of us that wants to understand the structure of the cosmos on this level will have to build our own mental model to play with and learn from. And we need raw material. Those observing guides, books, and articles that never get beyond Level 1 or Level 2 are still good and useful things: they’re bricks and boards that we can build with. We may have to dig into online databases and astrophysical literature to find the connections we’ll need to join them, but we’ll get farther if we don’t have to invent everything from scratch. Everything is potential grist for the mill.

I have recommended the monthly Evening Sky Map to countless people as a way for them to learn the sky. I wonder how much progress I could make if I learned the distances to all of the targets on each month’s lists, and looked for connections among them?


Big fish with light tackle

October 20, 2013

From the first time I read it, I have had a strange fascination with Jay Reynolds Freeman’s “Refractor Red meets the Herschel 400” (available here), wherein he describes observing the legendary deep-sky list with a 55mm refractor. Freeman wrote, “Ask people who land big fish with light tackle, why I do what I do.”

Lately I’ve been working through a slew of the open clusters in the Herschel 400 myself. And I have found that some clusters are dead easy to recognize as distinct bright patches in my 9×50 finder, but at the eyepiece they just sort of dissipate into the background starfield. That plus some fairly transformative rich-field experiences with small refractors (like this one) are working some kind of alchemy on me.

In a feat of Freeman-like proportions, my friend and frequent 10MA contributor Terry Nakazono has logged and sketched over 500 DSOs in the past 3 or so years, including 368 galaxies, almost all with scopes under 5″ aperture, mostly from at least somewhat light-polluted skies. He is just religious about dark adaptation, averted vision, and patience.

Possibly as a result of all of the above, lately I have had this mad desire to go out to the desert with a 70mm or even a 50mm refractor and spend the whole night observing with only that instrument. It feels like my reverse aperture fever and my deep-sky interests are slowly colliding. That plus a sort of perverse desire to knowingly commit to a “suboptimal” (aperture-wise) observing program just because it sounds fun.

I shared this plan on CN and fellow user blb wrote:

No mater what size telescope you use, it seems that you are looking at objects that are on the limits of what can be seen with that size scope. Once I realized this and read, some years ago now, what Jay Reynolds Freeman had to say about his observations, I came to realize there were way more objects to be seen in a small telescope than I would probably see in my lifetime.

I think this is exactly right; I find that with whatever instrument I have to hand, I tend to throw myself up against its limits.

AstroMedia plumber's telescope: a 40mm achromat made with plastic plumbing fittings

AstroMedia plumber’s telescope: a 40mm achromat made with plastic plumbing fittings

In particular, I know that all of the Messier objects have been logged with a 50mm telescope. What about a 40mm scope? I see that AstroMedia has a 40mm f/11 achromat kit (also available from That is strangely fascinating to me. (It would be simpler to use a larger scope and simply stop it down to 40mm, but somehow it seems more “pure” to use a scope with a native aperture of 40mm.) However, I think I would first do a Messier tour with a Galileoscope; just because other people have found all the Messiers with a 50mm scope doesn’t mean that I will, and it makes sense to start with that easier goal before plunging right into uncharted territory. It would be mighty tempting to put the 40mm scope and the Galileoscope on the same mount, though…

So…I’ll keep you posted.


The Rule of Ones

October 19, 2013

C102 2013-10-18

Tonight: one scope, one target. Here’s the scope.

I have several distinct modes as a stargazer. Sometimes I’m in exploration mode and I want to see and log new objects. Sometimes I’m in gear mode and I want to see how a given piece of equipment performs. Sometimes I’m in aesthetic mode and I just want to look at beautiful things. Sometimes I do all three in one night, or even looking at one object.

The last post, about current and future observing projects, was written in exploration mode. “Exploration” might seem like an odd word to apply to the activity of tracking down lists of things compiled by other observers. But if I haven’t seen them myself, then there is still the thrill of the hunt and the rush of discovery. And looking at all of these things is how I personally transmute caelum incognitum into known space. That’s exploration in my book.

Saturday night at the Salton Sea, I was in a blend of aesthetic mode and gear mode, because my ongoing thought process was basically, “Oh, hey, that beautiful thing is up now. I wonder how it looks through these scopes?” I think the only new thing I logged was 8 Lacertae, and if I hadn’t been so close to fiinishing the Double Star program, I wouldn’t have logged any new objects at all, despite staying up almost all night.

I do like observing lists. Some people dismiss them as stamp collecting or say that they make a fun pursuit into work. Well, different strokes, I guess. For me, observing lists come with the implicit subtitle, “Hey, here are the next n-hundred things that are really out there to be seen, any of which might knock your socks off.” Every observing program I have completed has introduced me to new favorite objects, which I periodically revisit, and has broadened my knowledge and experience of the cosmos.

But with all of that said, I don’t do enough casual stargazing, with no plan or agenda. That’s all I used to do, in my first few months as an amateur astronomer, and it almost killed me. Observing programs gave me a way to simultaneously learn the sky and educate myself about what’s up there. But the pendulum may have swung too far now; I hardly ever haul out a scope just to take a quick peek at the moon or Saturn.

All of this is on my mind because of a thread on CN called “When astronomy becomes a chore….” Here’s are some excerpts that have been much on my mind:

RussL: If I feel lazy I can get by with just the 120ST and my trusty TV Widefield 32mm. That way I don’t even have to feel obligated to see each object at every power I can. Easy.

Me: Peace through deliberately limited options–I love it! You have inspired me, sir.

RussL: Well, thanks. I’m glad to know my laziness has helped someone. But, it’s true that sometimes we need to relax more. It’s kinda like when I was a kid with next to nothing to view with, but happy as a clam with whatever I had. I have much more now, although not all that much. I guess part of the difference nowadays is that I have so much more knowledge and feel like I need to use it more. But there’s also a lot to be said for just having a good time without feeling like I must do everything possible.

karstenkoch: I’ve been mentally kicking around an idea for awhile that is still taking shape in my head. For lack of anything better to call it, I’ll call it the “Rule of Ones”. I’ve seen some comments above like it, so I thought I would mention it. There’s really nothing to it other than in order to keep things simple, easy, pure, and enjoyable do or choose only one of everything. Take one scope outside. Take only one eyepiece too. Pick one target to observe. You can imagine all of the other variables involved … choose or do only only one of each. Then, with no more decisions to make, just have a rest under the stars and enjoy your time observing and reflecting.

I like that. One scope, one eyepiece, just go. That sorta dovetails with another idea that has been growing in my mind–more on that in the next post.

Full moon - Oct 18 2013

And here’s the target.


Letting the crazy out

April 24, 2011

From 2001 to 2006, we lived in Santa Cruz. This was before I became an amateur astronomer. Spring was storm season, which pretty much made it my favorite season. In the morning after a big storm, you could drive over kept strewn across West Cliff Blvd by the waves and wind. I used to go out the cliffs and just sit on the rocks. When a big wave came in and crashed against the cliffs, you could feel it, as if someone had gently kicked your chair. It was mesmerizing, watching the waves, thinking about the fact that the ocean had been there longer than life itself. Staring into that immensity always seemed to put me right with the world. My problems shrunk to manageable size. I often went down to the cliffs frustrated and bent out of shape and left with a little perspective and a little portion of calm.

I called it “letting the crazy seep out”. I don’t remember where I got that phrase, but it is one of my touchstones. It doesn’t just happen at the seaside (which is good, considering that I only lived next to the ocean for 1/7 of my life). Long drives through desolate country also do the trick, especially at night. Hikes of any length. The desert is a marvelous sponge for the accumulated mental grime of civilized life.

So is the night sky. I usually go out to observe with a purpose in mind–some new target to track down, or an old favorite I haven’t seen this season, or just to stare in awe again at the rings of Saturn or Jupiter with its little entourage of moons. But whatever purpose gets me out there looking up, one of the effects of stargazing for me has always been to let the crazy seep out. As if the telescope is a big syringe, drawing the poison out through my pupils. When I first realized this, back in Merced, I started to think of the night sky as another seashore. Carl Sagan’s description of the surface of the earth as “the shore of the cosmic ocean” resonates for me. If sitting on the cliffs in Santa Cruz brought me face-to-face with immensity, stargazing gives me a brush with eternity. I usually leave more tired but less crazy, and that’s a good trade.

Someone said of E.E. Barnard that he was a true observer because if he was prevented from making astronomical observations for any length of time, he got cranky. I can certainly relate. I am in a similar state right now. It’s been cloudy all week. It was cloudy the week before last. It cleared off last weekend, just in time for the camping trip to Owl Canyon, but the nearly-full moon and unsteady seeing made for one of the least satisfying nights of stargazing I’ve ever had, to the point that I gave up and went to bed at midnight (horror!). It’s not supposed to really clear off until Monday.

I did get out tonight, briefly. I was taking out some trash a little after 11:00 and noticed that the sky was mostly clear. By the time I got some warm clothes on, grabbed all my gear, and got set up out in the driveway, that was no longer true. Clouds from the west had already passed the zenith and were creeping down the eastern sky. Saturn and Virgo were already gone, and the Big Dipper was rapidly getting submerged in the soup. I tried without success to find a double star in Bootes, but it was eaten by the clouds too soon. The only stars I could make out lower in the sky were those of Hercules. I cruised down to M13, the Great Glob, mostly so I wouldn’t get completely skunked. It was barely there, but I swapped eyepieces around until I found the best magnification for this evening (75x; it might be higher or lower on other nights, under other conditions), cupped my hands around my face, and stared until the lights went out, which didn’t take long. Less than 10 minutes after I got the scope set up, the sky was completely socked in.

Needless to say, the experience was the opposite of therapeutic.

I know it’s probably galling for some to have a SoCal resident complaining about a measly week or two of clouds. William Herschel discovered 2500 or so deep sky objects, several hundred double stars, and the planet Uranus from England, where clouds are nearly omnipresent, sometimes even coming into people’s houses and carrying off their children. Herschel earned a post as Astronomer Royal, so stargazing was both his obsession and his occupation. If he could put up with a career of observing from England, I’m sure I can suck it up for a couple more days.

I hope so. The crazy is building up.


So close and yet so far

August 24, 2010

Some of the folks on Cloudy Nights have really cool quotes in their sig files. Last night I came across this one, which crystallizes the elusive feeling that I catch on some nights and pursue on all the rest:

There is a moment after you move your eye away
when you forget where you are
because you’ve been living, it seems,
somewhere else, in the silence of the night sky.

I figured this had to be part of a poem, so I Googled it, and found the original source here. It’s a poem entitled “Telescope” by Louise Gluck, and it originally ran in New Yorker on January 17, 2005. Since it’s already out there on the intarwebz, I don’t feel bad about reproducing it with attribution.


by Louise Gluck

There is a moment after you move your eye away
when you forget where you are
because you’ve been living, it seems,
somewhere else, in the silence of the night sky.

You’ve been stopped being here in the world
You’re in a different place
a place where human life has no meaning.

You’re not a creature in a body.
You exist as the stars exist,
participating in their stillness, their immensity.

Then you’re in the world again.
An night, on a cold hill,
taking the telescope apart.

You realize afterward
not that the image is false
but the relation is false.

You see again how far away
each thing is from every other thing.

I think it’s a smashing poem and I wholly agree with the sentiments expressed, right up until the last two stanzas. Then, as far as I’m concerned, it all goes straight to heck.

– – – – – – – – – –

M8 photographed by Rob Gendler

One of the things I like best about observing is that with very modest equipment, one can see most of the stages of the life cycles of stars. Turn to M8, the Lagoon Nebula, or M42, the Great Nebula in Orion, and you can see stellar nurseries. The nebulae are great clouds of gas and dust that are only visible because they are illuminated from within by the terrifying light and heat of newly formed stars.

This process cannot last forever. Even as the last few protostars of a nebula straggle into ignition, their older siblings are blowing away the nebular cocoon by the force of their stellar winds. Eventually the nebula will be entirely dissipated, and all that will remain is a cluster of young stars, all of similar ages and chemical compositions. These are open clusters–as opposed to the vast and ancient globular clusters that haunt the galaxy’s halo–and they include some of the sky’s most brilliant jewels, such as the Pleiades and Hyades, the Beehive, the Double Cluster, and thousands more, of many sizes, ages, and distances.

The Double Cluster photographed by Rob Gendler

Even the stars of open clusters are not destined to remain together forever. They may remain together for tens or hundreds of millions of years, but the lives of stars are measured in billions of years. As open clusters orbit the core of the galaxy, repeatedly passing through the galactic plane, being overtaken and left behind by successive spiral arms, their constituent stars are stripped away from their weak mutual gravitation embrace. Eventually the cluster is entirely dispersed, its constituents becoming the un-clustered field stars that make up most of the galactic disc. Almost all of the stars  that you can see with the naked eye are field stars, each pursuing its own course around the galactic core, forever sundered from their siblings. Lurking out there in the Milky Way are the long-lost sister stars of our own Sun, which we might identify now only by their chemical fingerprints.

Even stars do not last forever. Near the end of their lifespans, with most of the hydrogen fuel in their cores converted to helium, main sequence stars start fusing hydrogen in the shell around the helium core. The star’s interior heats up still further, and the outer layers expand into a vast tenuous envelope. The surface area of this envelope is much larger, in relation to the total energy passing through it, than the star’s old surface. Hence it is cooler, and the light emitted at the star’s surface is shifted toward the red. The star has become a red giant. Arcturus in the constellation Bootes and Aldebaran in Taurus are familiar examples, respectively the third and thirteenth brightest stars in the night sky.

Still larger stars start to fuse helium to carbon and eventually carbon into still heavier elements. These stars may become red hypergiants, so large that they could swallow the entire inner solar system. Betelgeuse in Orion and Antares, the glaring red eye of Scorpio, are red hypergiants, and respectively the eighth and sixteenth brightest stars as seen from Earth.

M27 photographed by Rob Gendler

Now we come to a fork in the road. In small and mid-sized stars, such as the sun, the process of helium fusion proceeds in fits and starts, alternatively heating and cooling the star’s outer envelope. As it expands and contracts, the gas in the outer envelope picks up enough kinetic energy to escape the star’s gravity and expand into space. This process repeats, and star comes to be surrounded by concentric shells of blown-off gas. The gas is still energized by the star’s radiation, and glows as a nebula. This type of nebula is called a planetary nebula, not because it has anything to do with planets (the planets of such a star will have been scorched to cinders or completely eroded by star’s late-stage pulsations), but because they are often round and looked something like planets in the small telescopes of early astronomers. M57, the Ring Nebula, and M27, the Dumbbell Nebula, are two of the best and brightest planetary nebulae. Even tiny NGC 7662, the tiny round glow Brian and I star-hopped to last week, could not be mistaken for anything else. After blowing off most of their mass, the cores of the former giants persist as white dwarfs, which glow not because they sustain fusion but because their matter is heated to fantastic temperatures by gravitational contraction. Even after their planetary nebulae dissipate, white dwarfs may shine feebly for tens of billions of years.

Stars over a certain size, just a few times larger than the sun, have a different destiny. Bigger, hotter, they sustain more rapid fusion, exhaust their hydrogen and other light elements in rapid succession, and then blow themselves apart as supernovae. The cores of the exploded stars persist as neutron stars and black holes. Although supernovae are frequently spotted in other galaxies, there hasn’t been a naked-eye supernova in the Milky Way in centuries. There are some fine supernova remnants, however, diffuse halos of material still expanding outward from the explosions that created them. M1, the Crab Nebula, is one, and the much older and larger Veil Nebula in Cygnus is another.

M1 photographed by Rob Gendler

The matter blown off by dying stars, slowly and gently in planetary nebulae or all at once and violently in supernovae, rejoins the vast, diffuse molecular clouds that clot the galactic disc. Eventually the clouds will be sufficiently compressed, by the pressure waves that form the spiral arms, or by the shockwaves of nearby supernovae, for knots of material to start to accumulate. As the gravitational force of these concentrations pulls in more and more material, they will pass a critical threshold: fusion reactions will start in their cores and they will become new stars, lighting the encircling nebula from which they were born. The circle is then complete.

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It is often noted that we are made of stardust. This is true, but it has become such a cliche that I fear it has lost its visceral impact. Consider: every breeze that has ever cooled you, every bite you’ve ever savored, every caress you’ve ever felt, the blood in your veins, the brain that you think with, the pillow under your head at night, the plastic and metal on which you’re reading this–every atom you’ve ever perceived with any of your senses, and all of others in the universe that you have not perceived, were born in the hearts of stars (except for the hydrogen and some of the helium atoms, which formed in the cooling fires of the Big Bang itself). So, yes, you are made of stardust. And so is everyone and every material thing you know.

And we will be stardust again. In five billion years the expanding sun will envelope the Earth. Our atoms, having been through the planetary cycles dozens  or hundreds of times, and incarnated in countless organisms of which we are but a snapshot, will be blown off with the rest of the crust and outer mantle. For a while we will shine as part of the sun’s planetary nebula, before being dispersed into the interstellar medium. But our constituents will know still greater fires when they are taken up into new stars, and new life when they are incorporated into other worlds.

Ashes to ashes, dust to dust, light to light.

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That is why I disagree with the estimable Louise Gluck, former Poet Laureate of the United States. When I am packing up the telescope, I don’t see how far each thing is from every other thing. I am still charged by what I have seen, and by the knowledge that I have been a nebula and an open cluster, a red giant and a supernova remnant. Any stage of stellar evolution that I can see in the sky, my atoms have gone through–and will go through again. There is no distance separating me from the stars. There is only time.


Lunchtime musings

February 24, 2010

In my first six months with my scope I spent most of my time observing the same double handful of objects. I realized that I was stuck in a rut, so one night I took Turn Left at Orion and a red flashlight out with my scope. I figured it couldn’t hurt to try. I decided to start with something I’d never seen before, but which was supposed to be easy–M41 in Canis Major. It was easy–and beautiful! I saw that M46 and M47 were a short distance away, so I tracked them down. And so it went, from one target to the next. I was too excited to linger on any one object. After a couple of hours I’d seen about two dozen DSOs that I’d never seen before. My final targets were M81 and M82. It was the first time I’d ever seen two galaxies in the same field, and it stopped me in my tracks.

In the two years since that night, I’ve been back to all of those objects and many more besides. Almost every time, I notice something that I haven’t seen before. The more times I observe, the more I learn to see, the more I realize how worthwhile it is to linger on each object for a few minutes and give myself a chance to tease out its details.

The objects that I found that night have become like friends. When I am in their neighborhood, I stop by to see what new impressions I will have. And then I go on to meet their neighbors down the street, and the folks on the next block over. Every observing run is an opportunity to improve my skills, to deepen my knowledge of the sky, to explore and to discover.

What kind of relationship do you have with the objects that you observe? Can you remember what they look like when you’re apart? Are they unique individuals or just a long line of warm bodies? Can you point out where they live? Could you get there with a map?

If someone abandoned you for a couple of hours in an empty field on a clear dark night with only binoculars or a spyglass, would that be too much time or too little?