My first photograph of Pluto

The year was 1987. I had been a backyard astronomer since 1980. During those 7 years, I felt like I had made good progress in the hobby. I was on my 4th telescope, a Meade 8-inch Schmidt-Cassegrain. I had tracked down nearly half of the Messier objects. I had seen the moons of Jupiter and the rings of Saturn. I was practiced at the art of astrophotography with color negative film, having shot a lunar eclipse in 1982, Halley's Comet in 1985 and 1986, and numerous deep-sky objects at the prime focus of my 8-inch f/5 Newtonian reflector. So, when I received the May issue of Astronomy magazine in 1987, and saw the article on page 100, titled "Where to Find Pluto[:] Spring and Summer 1987," I felt ready to accept the challenge to take a photo of the most distant planet in the solar system. 

To be honest, before reading that article, I had never given any serious thought to hunting down Pluto. I didn't know much about it. Nobody did. I knew that it wouldn't look like much in my telescope. But the main reason for not bothering with Pluto is that I didn't know where it was or how to find it. And even if I could take a picture of it, how would I know which "star" was Pluto?

In those days, the way to track down Pluto was to get your hands on an ephemeris, a list of coordinates for the planet during some period of time, like 15 or 30 days. You would then plot the position of the planet in your star atlas, for each of the dates in the ephemeris. If you were lucky and lived in a town with a university that offered a degree in astronomy, you could go to the university library and find an astronomical almanac for the current year, which would likely contain an ephemeris for each of the planets. But I lived in a small town in the middle of nowhere. How could I find such information? 

Backyard telescope enthusiasts like me relied on magazines like Sky & Telescope and Astronomy to help us locate the distant planets, asteroids, and comets. Both magazines were pretty good about occasionally highlighting the positions of these objects whenever they happened to be passing near bright and familiar stars. And the spring of 1987 was just such a time when locating Pluto would be pretty easy. 

The May issue of Astronomy arrived at the end of March or early April, which gave me plenty of advance notice on Pluto's position. All I needed to know was that Pluto would be passing near the star 109 Virginis in the last days of April and beginning of May. I had my trusty Sky Atlas 2000.0 to show me where 109 Virginis is. All I'd have to do is aim the scope at 109 Virginis and take some 5- or 10-minute exposures. Pluto would be in the field somewhere. If Mother Nature would cooperate, then maybe there was a chance of success.

In my hometown in Pennsylvania, Mother Nature was never very cooperative! And getting a shot of Pluto was asking a lot because I would need not just one, but two clear nights, hopefully two clear nights in a row. By taking two pictures a day or two apart, I'd be able to look at my pictures and figure out which "star" moved. And that would be Pluto. Well, Mother Nature didn't give me two in a row, but she did oblige by giving me two clear nights that were close enough together such that Pluto didn't leave the area before I could capture him. Fortunately, Pluto is a slow mover! 

My back yard wasn't the darkest of back yards at nighttime, but the overall light pollution in our small town wasn't bad enough to prevent deep-sky astrophotography using film. My neighbors to the northeast had a floodlight mounted on the back wall of their house that was aimed right at my back yard. Why do people need to install terrible lighting like that? What's the purpose? All it does is shine right in my eyes! They should aim their lights downward, onto their own property, so that their light doesn't trespass onto their neighbors' properties. And, of course, they never ask their neighbors if they mind having a blinding floodlight hit them in the eye when they walk outside at night to enjoy the stars. They just put their awful lights up without warning and without a thought for their neighbors. Some nights, my neighbors didn't turn on their floodlight, so it wasn't always as bad as the picture above makes it look. One good thing about the nasty neighbor light, though, was that it allows you to see my setup here. If you look closely, you'll see that I used an off-axis guider. I had to remove the camera to take the picture. I had a Lumicon Easy Guider. It included an f/6.3 focal reducer, which was much more tolerable than shooting at the native f/10 of my SCT. You'll note a couple of cords attached to the telescope. One was for power to the telescope. Another was to power the declination motor, seen on the left fork arm. A third cord powered the illuminated-reticle eyepiece on the Easy Guider. While the camera was exposing, I used that eyepiece to make sure the telescope was tracking on the stars. If you zoom in, you can see the hand controller with red and blue buttons for guiding corrections. I would find a guide star and keep it centered in the crosshairs using those guiding buttons throughout the entire exposure, which could be anywhere from 5 minutes to an hour, depending on how faint my targets were. I don't recall the exposure times I used for Pluto, but I'm guessing either 5 or 10 minutes. I only needed to get an image of a star-like object, so a short exposure like 10 minutes on Kodak VR 1000-speed film would be ample. Longer exposures were required for extended, diffuse objects, like nebulae and galaxies. 

As you can see from the above orbital diagram from JPL's Small-Body Database website, April of 1987 was a very good time to get a picture of Pluto! At that time, Pluto was still inside the orbit of Neptune. Yeah, at the time, Pluto was not actually the most distant planet in the solar system! In fact, it was about as close to earth as Pluto ever gets! The red arc represents the 38 years since I took the pictures at the top of this page. Pluto will only get dimmer now as it rolls on toward its farthest distance from the sun.

Another reason why April of 1987 was a good time to target Pluto is that it was passing through the constellation Virgo. That's about as far away from the Milky Way as you can get! That means the backdrop for Pluto had relatively few stars, compared to recent years when Pluto plowed through Sagittarius, as seen below in my photo from 2015. The time filter helped to make it stand out.

Pluto on the nights of April 28 and 29, 2015. 11-inch
SCT and HyperStar @ f/2. Starlight Xpress H-9C
CCD camera. Animation of two 7-minute exposures

A lot has changed since I took my first photograph of Pluto in 1987. For starters, Pluto is no longer regarded as a major planet. In 2006, the IAU (International Astronomical Union) officially ruled that Pluto is just one of many other minor planets lying in the distant Kuiper Belt. I can't say that I'm terribly saddened by that determination from the IAU. I've held onto the memory aid our teachers taught us long ago to recall the major planets in order of their distance from the sun, "My Very Earnest Mother Just Sewed Uncle Ned's Pants." And honestly, other than the fact that I was taught way back in grade school (in the mid- to late-1960's) that there were 9 major planets, there isn't any compelling reason to mourn Pluto's declassification. 

Asteroid (1) Ceres went through the same demotion process more than a century before Pluto was discovered. At first, it was thought to be a major planet lying between Mars and Jupiter. But then when other asteroids were found to be orbiting in the same region of the solar system, everyone accepted the fact that instead of a major planet, there were an unknown number of asteroids orbiting there. We grew accustomed to calling that region, "The Asteroid Belt." 

So, now, instead of major planet Pluto, we have to just get used to calling that region of the solar system, "The Kuiper Belt" (your preference: "KOY-per Belt" or "KIPE-er Belt," after the Dutch-American astronomer, Gerard Kuiper).  As for the charming memory aid regarding our mothers' sewing skills, technically, it's no longer correct (politically, or otherwise), but it's still useful. We can just stop at "Ned's." 

Another big change since 1987, is how we amateur astronomers can now find and photograph Pluto in our back yards. Rather than wait for a magazine with an ephemeris to arrive in the mail, we can use our "smart" Go-To telescopes and select Pluto from the list of planets, and the telescope will point itself at Pluto for us. Alternatively, we can use planetarium programs (like the free Cartes du Ciel) on our computers to show us where Pluto is on any night of the year. Additionally, those planetarium programs can control our smart telescopes and aim them at Pluto for us, if we want them to. So, we don't have to plot positions in our printed sky charts and hunt for Pluto the old-fashioned way. And as if that isn't enough, we can now remotely control our telescopes and cameras in our back yards, so the neighbors annoying lights don't have to bother us! We can sit in front of our computers in the comfort of our living rooms or dens while we're taking pictures of Pluto. 

A personal change that I am very happy I made later on in 1987 is that I left the cloudy skies of Pennsylvania and moved to the clear skies of Arizona. From here, two or three nights in a row of clear sky is nothing! I've been able to image for 100 nights in a row in my back yard. Mother Nature is much kinder to Arizonans than she is to Pennsylvanians. Hmmm. I wonder why that is!

The biggest change since 1987, though, is that the New Horizons flyby in 2014 finally gave us a closeup view of Pluto and its moons so that we now know what the system looks like. The distant world seen as a little dot in my photos needs no longer to be imagined. 

New Horizons image of Pluto (from Wikipedia)

The red arc in the JPL orbital view (several paragraphs up), representing 38 years since my first photograph of Pluto, means a whole lot more to me than it probably does to you. In the words of Paul Simon, it's the "arc of a love affair." Yeah. Hearts and bones kind of stuff. For Pluto, 38 years is nothing. It takes 248 earth years for Pluto to make one circuit around the sun. Since its discovery in 1930, Pluto hasn't even made it halfway through its year. Meanwhile, we've witnessed the passage of 95 years here on earth. The young farm boy, Clyde Tombaugh, discoverer of Pluto, grew old and passed away in 1997 at the age of 90. My parents, born after 1930, have lived out their lives and succumbed to Father Time. I was a young man, in my mid-20's, in 1987. In that short arc of Pluto's orbit, I went back to school and started a career. My wife and I had children and bought a house. We lived in that house for more than 20 years. Then I retired and we sold the house. Our kids are grown. This year my wife and I will celebrate our 42nd year of a happy marriage. Now I'm in my 60's. While the love affairs with my wife and the stars are still going strong, my body is not! In years past, I knew and accepted that I probably wouldn't live to see another apparition of Halley's Comet or the next Mercury transit. But now it's the shorter stuff that I'm coming to realize that I won't be around for. The next close approach to Mars, for instance. And this probably will be the last time I witness the disappearance of Saturn's rings. I may succumb to Father Time before NASA's Europa Clipper arrives at Jupiter. These are some sobering thoughts, indeed.

 

Update (May 23, 2025):

In 2015, I was looking at future opportunities to shoot Pluto passing familiar deep-sky objects using Cartes du Ciel, and I saw that in October of 2023, Pluto would pass close enough to globular cluster M 75 that I would be able to capture both Pluto and M 75 in the same field of view. Of course, little did I know then that within a few years, my camera would fail, and I would need to buy a new one. The new one had a larger field of view, and I wouldn't have to wait quite as long. I captured Pluto with M 75 in April of 2022. Or so I thought!

I don't recall if I ever tried to find Pluto by blinking those images from April 5, 2022. A few days ago, I remembered that Pluto was going to pass by M 75 in 2023, and I couldn't even recall if I took any images of the appulse. So, I searched my computer files and found that I had shot Pluto on the night of April 5, 2022. But in hindsight, I made a huge mistake that night. Pluto is much farther away from earth than the main asteroid belt, so you can't just take two pictures an hour apart and see any parallax for Pluto. You need several hours or possibly a whole day between images to see any shift in Pluto's position. On that night in April of 2022, I didn't even give it an hour! And that's because I was up against the break of dawn. M 75 is pretty low in the sky on April mornings. I took my first shot around 5 AM, and then the second one around 5:40 AM, because the sky was getting bright. I don't know what I was thinking! For whatever reason, I didn't even try again the next morning. Those were the last images I shot of Pluto near M 75.

But when I discovered the other day that I had two sequences of shots of Pluto near M 75 in 2022, I decided to stack and blink them. I searched and searched those images while blinking them and I could not find a single wiggling star! No matter how much I zoomed in, no matter how much I adjusted the contrast and brightness, all the stars in those images were rock solid. Nothing moved or even wiggled. 

Of course nothing moved! What a dope I was to take images of Pluto less than an hour apart and expect to see any movement!

Well, it needn't end there. I can always check my images against the DSS image and see if I can find Pluto. I can't blink them, but I can use Cartes du Ciel to go back in time and see exactly where Pluto was on that night in April of 2022, and see if there's a star in my images that doesn't appear on the DSS photo of that patch of sky. That took some time! And in the end, it was inconclusive, because although I found a candidate, there was a star at the same location in the DSS image. It's just that the star was a lot brighter in my image than it looked on the DSS image. I was pretty sure it had to be Pluto. But if I really wanted to make certain I was looking at Pluto, I should shoot that field again and try a blink comparison with my images from April of 2022. And fortunately, I didn't have to wait! The moon is not a factor and May mornings offer an opportunity to shoot M 75 before dawn.

A blink comparison of April 2022 and May 2025

So early this morning, I grabbed some images of M 75, which I haven't shot since 2022! They were the last images of the night and then I put my gear away and went to bed. After a good night's sleep of about 5 hours, I got up and poured myself a cup of coffee and sat down at my computer to see if I had any success. The image above is the proof in the pudding! The star I suspected was indeed Pluto, being seen in the image from April 5, 2022, but not in the image of May 23, 2025. 

As I mentioned earlier in this post, Pluto is a slow mover. I was curious to see how far Pluto had moved since I shot it in 2022. All I had to do was zoom out a little bit in Cartes du Ciel this morning while I was shooting the M 75 field, and Pluto was not very far away. Technically, it had crossed the border into Capricornus, but it was still only 4.5 degrees away from M 75! 

Above is a screen capture from my telescope-control program, Cartes du Ciel. The three concentric circles in the Cartes chart represent the Telrad (a popular finder scope) coverage of the sky. The large rectangle represents the field of view of my DSLR camera, while the smaller rectangle represents the field of view of the camera that I used for the pictures of Pluto and M 75. At the center of the concentric circles is the telescope's target location on the sky. Pluto is seen to the left (east) of where I was shooting this morning. It's hard to believe that it took Pluto nearly 3 years to move only that far (roughly three camera fields-of-view) across the chart!