A bittersweet update: On June 10, 2021 while preparing this post, I learned that Calvin University is eliminating its undergraduate astronomy minor program. I’m not sure what this will mean for astronomy research and the observatory programs at Calvin, but I’m sad for the loss of the academic program that drew me to Calvin in the first place, the one that made it possible for me to discover this asteroid and dozens more even as an undergraduate student.
I really love asteroids. As a kid, I loved anything astronomy-related in general, but I really fell hard for asteroids in my first year at Calvin University in Grand Rapids, Michigan. (Thankfully none have fallen for me… yet.) What started as a quick lab project turned into a summer research job and then a PhD over the course of a decade, and now I’m an Asteroid Girl.
I joined Calvin’s astronomy program right about when asteroid research was taking off, both at our school and in the field of planetary science in general. Professor Larry Molnar was championing the asteroid discovery program in the department, using the college’s remote telescope located in Rehoboth, New Mexico, underneath the dark skies of the desert Southwest. I found my first asteroid as a college freshman participating in a unique physics lab class, and soon after that I was hooked on asteroids — both discovering them and learning everything there was to know about them.
This post describes my journey of discovering and naming an asteroid, from start to finish. Not just any asteroid — a Hungaria-type asteroid, a nearby space rock with a special orbit that makes it unique and interesting. Not just any name — a tribute to the woman amateur astronomer who helped spark my growing interest in astronomy from the dusty fields underneath the dark skies of The Gambia, West Africa.
Step 0: Take pictures of the sky
To discover an asteroid, you first need really good pictures of the night sky. To get these pictures, you need a telescope. The one that I used belongs to the Calvin-Rehoboth Robotic Observatory, operated remotely from the control room in the Physics department at Calvin University in Michigan. It’s got a 16-inch diameter telescope with a CCD camera attached, and it’s parked under the really dark skies of the remote Southwest. In a lovely desert, one that I had the chance to visit more than once on field trips.
Where do you point the telescope? Just about anywhere in the night sky will do, but there are a few direction and time considerations that will get you the best pictures most likely to contain new asteroids. Specifically, you’ll want to point the telescope away from the Sun. This should seem obvious, but once the Sun sets and there’s a lot of night sky up there, you still want to find the parts of the sky that are farthest away from the Sun. The point in the sky that is directly opposite the Sun is the darkest, and objects passing through that area are said to be in opposition. Objects in opposition are also typically at their closest point to Earth’s orbit, so it’s a great idea to go looking for them there at the spot where the asteroids are brightest and the Sun is not.
How many pictures do you take? Once you’ve got your telescope pointed at a promising patch of night sky, you keep it locked in position relative to the unmoving stars in the background and take a series of about five pictures, with exposures of about five minutes each. This lets you catch a whole lot of light in the telescope’s camera, hopefully enough to notice faint things (and the asteroids will be faint!).
Step 1: Align the images and make a movie
The GIF below is the set of images from the actual discovery of the Hungaria asteroid that I found over a decade ago on March 26, 2007. The movie shows four frames of a particular spot in the night sky, blinking through each sequentially in time. The stars are aligned (that sounds epic, I know), and the asteroid can be seen as a tiny dot jumping along in a line in the movie. Do you see it?
But before I found this particular asteroid, I found a lot of other things too, most of them unexciting. Astronomical photos can have all sorts of “artifacts” in them that confuse would-be asteroid hunters, things like “hot pixels” that are always bright, and flashes of “cosmic rays” (epic, right?) that sear a bright spot in an image here and there on their way from somewhere in outer space to somewhere else in outer space. Then there are airplanes and satellites, more and more of them as our planet’s inhabitants keep traveling and communicating. Sometimes, although it’s rare, you can get a bug moseying its way down the telescope tube and into your images, or a flash of headlights from a passing truck on I-40 a few miles away from the observatory. All of these things have to be either removed from the images (and we’ve got cool techniques to do just that) or ignored in the final product.
After you’ve done all that removing and ignoring, you’ll see the asteroids as little jumping dots that move against the background of the stars. Most of the “normal” Main Belt asteroids move horizontally from left to right across the frame, because your telescope on Earth is essentially passing by them in the fast lane of its own orbit and taking pictures out the passenger window. The left-to-right motion is known as “retrograde motion.” Asteroids in opposition will also necessarily be moving in retrograde, with their fastest motion occurring at the moment of opposition itself. This extra speed boost, coupled with the brightness boost, makes it easier to find asteroids when they’re at opposition.
But some asteroids don’t follow the rules, and they’ll go jumping out of the recess line to play in whatever part of the playground they want. These are the interesting ones, and the Hungaria asteroid that you can see skipping straight toward the top of the frame in the video is one of them. Asteroids that move vertically in the images have to have at least some significant inclination, or tilt, to their orbit. Objects with a significant inclination to their orbit are the ones that can zip in out of nowhere and hit Earth — hence our heightened interest in them. The Hungaria asteroid that I discovered isn’t a Near Earth Object, so it’s not going to hit the Earth. But its unique orbit can tell us something about the structure of the asteroid belt and also of the motions of the planets through the early solar system, so it’s still a fascinating object.
Step 2: Measure the new asteroid’s orbit and check the database
Here comes the bad news: Most of the asteroids you find nowadays are going to be old news, discovered already by one or more of the big all-sky surveys designed to suck all the fun out of amateur astronomy. (Well, okay, not really. They’re designed to find things that might hit us someday. So we should really be thanking them for their success.) Asteroid discovery requires a necessary amount of patience to sift through and tag all of the objects in each set of images, knowing that most of them will not be new discoveries.
Once you’ve tagged all of the asteroids in your images, you send their precise position information to the Minor Planet Center, a database that keeps track of the brightnesses and orbital information of hundreds of thousands of asteroids. This helpful database will compare your position and brightness info to all the known objects ever, and tell you which are new and which are not.
If your discovery is new, go ahead and get excited! But don’t congratulate yourself just yet… Your journey has just begun.
Step 3: Track your new asteroid
If you could park your telescope in space and keep taking pictures 24 hours a day or night, you could easily follow your new asteroid across the night sky without losing track of it. But you don’t get that luxury down here on Earth where the sun rises, so you have to wait until the next sunset to try catching another glimpse. Not only that, but you’ll have to measure the asteroid’s speed and direction and carefully plan where you need to try to find it next. (It feels a bit like running to the bathroom to get some toilet paper to squash the spider that is making its way across the basement carpet while hoping it doesn’t reach the safety of the crack behind the bookshelf before you return.)
If your asteroid is unique and moving fast like the Hungaria was, it’s wise to take a grid of image sets surrounding the predicted position, just in case the new asteroid is moving faster or slower or in a different direction than you expect.
Science Snippet I — Uncertainty
In any scientific measurement, you’re always going to need to estimate the uncertainty of your measurement. Most of this uncertainty comes from your instrumentation — you have to catch light in little buckets in your CCD camera and turn those buckets into pixels, rather than zipping off in your spaceship to measure the asteroid directly. (Even if you zipped off in your spaceship, you would still have to know the uncertainty of your direct measurements.) If you know how far off your measurement could be, you’ll be able to estimate how far off you might need to take your next pictures in order to be sure you catch your new asteroid again.
Hopefully the weather cooperates and you can get more pictures of your new asteroid’s expected position the next night. (If the weather doesn’t cooperate, your grid of possibilities will widen for every night that you can’t image your asteroid, and you might end up losing it.) When you wake up the next morning, you get to do it all over again with the new sets of images, hoping you find your friend. You might end up finding more new friends in these images, and then you can choose to track them down, and then you’ll find others, and then… the process can go on forever. At least for as long as you have willing college students to comb the data.
If you find your new asteroid over again, hooray! You can put the new data into the Minor Planet Center and get more predictions for more follow-up observations. Once you have two nights of measurements to your name, you have officially discovered a new asteroid. Congratulations!
Science Snippet II — Uncertainty and The Spider
Why do you have to have two nights of observations in order to officially claim a discovery? The answer to that question gets back to the concept of scientific measurement and uncertainty. And the spider on the carpet. Let’s pretend that the spider is required to travel in a straight line at the same speed. If you just catch a half second’s glimpse of the spider before running to the bathroom, you will probably know its position and maybe be able to guess at its velocity (speed and direction of motion). But if you’re able to find it again after you come out of the bathroom, you can now draw a line between where it was and where it is now, and extend that line out forward or backward to predict where it was and where it will be later. If you measure the time between your glimpses, you’ll know its speed. All this information you can get from just a quick glance and a second discovery. But if you want to predict where the spider will be in a day or a week, you might want to come back an hour later and find it again, to get a longer baseline for your measurements. This will reduce the uncertainty and help you predict the future. Tada!
Step 4: So you want to name your asteroid…
After you claim your discovery, your new asteroid will get a provisional designation, a string of letters and numbers that is unique to the asteroid and contains information about the discovery. For example, the Hungaria that I discovered on March 26, 2007 was given the designation “2007 FM42”. The provisional designation is actually a neat little code, and here’s how to understand it:
2007 — the year of the discovery
F — the half-month of discovery, where January 1-15 is ‘A’, January 16-31 is ‘B’, etc.
M42 — the discovery’s position in the alphabet, and the number of times the alphabet has cycled through already
For example, the first discovery in the second half of March 2007 was called 2007 FA, then the second was 2007 FB, and so on until 2007 FZ, at which point they cycled the provisional designations back around and gave the next object the designation 2007 FA1, 2007 FB1, etc. If I did my math right and understand the code correctly, my Hungaria was the 1063rd object found in the second half of March 2007. This tally is mostly made up of main belt asteroid discoveries; comets get their own unique designations too.
But the provisional designation isn’t a name yet. In order to get its full name, the Hungaria asteroid had a lot of waiting and telescope observations to go through still. The next step toward a name was the permanent designation, a simple number that indicates the asteroid’s placement in the lineup of discoveries that have good enough measurements to establish their orbits. The Hungaria’s permanent number is 375005, which goes to show that there are a lot of objects out there that have been discovered.
Once we’ve established the orbit (to within a certain tiny bit of uncertainty, as always) and the asteroid has its number, we can start to think about a name.
But first there are some naming rules. I’m sorry to say it, but you can’t name an asteroid just anything. Here are the official guidelines from the Minor Planet Center:
- 16 characters or fewer, including spaces
- Preferably one word
- Pronounceable (in some language) (I wonder if they count Huttese…?)
- Non-offensive (I wonder if they have a list of Huttese cuss words…?)
- Not too similar to an existing name in the database
- Not named after any living or recent politicians or military
- Oh and naming after pets is discouraged
That’s it! Go ahead and pick your name, and your asteroid can start printing business cards.
What’s this asteroid’s name?
I’m so glad you asked. Allow me to introduce you to asteroid (375005) Newsome, named for Deb Newsome (b. 1957), an early mentor and friend of mine who first introduced me to amateur astronomy under the dark skies of the rural town of Ndungu Kebbeh in The Gambia, West Africa. “Aunt Deb” was a missionary who worked at the local literacy center in the village for over 27 years, but in the evenings she was known to take out her backyard telescope and enjoy the night sky. She helped me identify one strange and bright “star” in the constellation Taurus one night, explaining that my mystery star was actually the planet Jupiter and introducing me to the concept that the night sky can change from one night to the next. Years later I watched this little asteroid skip across the changing sky and decided that naming an asteroid after Deb would be a worthy tribute.