Robert Stephens
(Image Courtesy of Robert Stephens)


Rancho Cucamonga, California

What do you study?

I specialize in Trojans (asteroids sharing the orbit of a large planet). I study near-Earth asteroids, and I’ve dabbled in exoplanets a little.

Why do you do citizen science?

I guess I see myself as a bit of an explorer. If this were 200 years ago, I imagine myself sailing a ship for islands unknown. In today’s world, all the islands are known, of course. So now I sail the stars. The other thing I love to do as an amateur astronomer is chase solar eclipses. Take a globe, spin it, put your finger down: “Ok, I’m going here this year.” I’ve been all sorts of places nobody would dream of going to around the world. I’ve been to some dream places, too: the Great Barrier Reef, Zambia, Uganda, the Libyan border, a Kurdish village, Turkey, the Syrian border – places you couldn’t go today. They were great adventures back then.

What’s your day job?

I’ve been a CPA for the past 40 years.

Favorite contribution you’ve made

They blur together. A recent one – I found a new binary asteroid, 4435 Holt. (The main asteroid) was discovered by Carolyn Shoemaker in the 1980s. It’s a Mars crosser with a known rotation period of 2.7 hours. When they start rotating that fast, enough stuff lifts off the equator to coalesce in orbit; it creates a satellite. I was observing this guy and getting weird results – a signature that looked an awful lot like a satellite. I started hitting it really heavy every night. I eventually derived a second period (the orbiting object) that seemed reliable (later confirmed by astronomers in the Czech Republic). Interestingly enough, (I thought I observed) a third body. Unfortunately I never got enough data to actually prove that. I got discovery credit for a satellite with a suspicion of a third body.

It becomes interesting because there are only six known asteroids with two satellites in the solar system. If this eventually proves to be true, it’s the first one discovered by light curves. It’s a fun little discovery, not terribly eye-raising, not terribly important to the history of the solar system. It just goes to show that when amateur astronomers such as myself sit and stare at a target for four months, they find stuff professionals cannot get the telescope time to look at.

Citizen scientist Robert Stephens at the Cerro Tololo Inter-American Observatory in Chile in 2015.
Citizen scientist Robert Stephens at the Cerro Tololo Inter-American Observatory in Chile in 2015.(Image Courtesy of Robert Stephens)

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