Bob Donahue

Ever since I was a little kid, I wanted to be an astronomer. It was my first love. With my first 2" Tasco telescope I “discovered” the rings of Saturn and moons of Jupiter, double stars, and the brightest star clusters, nebulae, and a few galaxies.
Soon after I got to college (Villanova, U.) I was then bitten by the research “bug”, and again it was “love at first sight”, this time with variable stars, actually collecting data used to “figure it all out”. Then I joined the HK Project at the Smithsonian Astrophysical Observatory, with more data collection but now with the 60-inch at Mount Wilson Observatory (and then the 100-inch) - the real telescopes!
Over that career, I studied stars similar to the Sun, monitoring stellar activity on timescales of days (rotation) to months (active region evolution) to years (sunspot cycles). I finished my PhD dissertation using that data: “Surface Differential Rotation in a Sample of Cool Dwarf Stars” (looking for latitudinal drift, just like Carrington’s “butterfly” diagrams for the Sun.
Then exoplanets were discovered: and somewhat coincidentally, many of the first stars were in our program, so the research extended into exoplanet system environments. We soon discovered that some exoplanets weren’t exoplanets at all, but large sunspots: the motion of “cool” spots traversing the stellar surface along the line of sight also causes fluctuations in the shape of the star’s spectral lines - completely mimicing the radial velocity variations from an exoplanet. And so - oops! - two reported exoplanets were “disproved”.
But the funding climate - always precarious - meant having to abandon astronomy - at least for a while. Since I moved to the Berkshires a few years ago, I rekindled my original passion of just looking at the sky “for fun”. Armed with a “fleet” of smart scopes (I have four as of 2026), I’m combing through the skies “re-discovering” objects, and learning about all the scientific knowledge we’ve gleaned since first reading about them in high school. We’ve learned a lot!
Articles by Bob Donahue
Smart Scope Challenge: Haumea and Makemake
Two dwarf planets near opposition

May Challenge: Galaxies in the Virgo Cluster
10 Galaxies to find in Virgo
Venus and Jupiter Inch Closer Together
The two brightest planets in the early-evening sky
Coordinates Systems in the Sky
The different coordinate systems and what they're used for
SN 2026kid in NGC 5907 (Draco)
A new SN in a bright, large, edge-on galaxy in Draco
Identifying Clusters in the Andromeda Galaxy
Finding DSOs in DSOs

T Coronae Borealis: The Blaze Star Prepares to Erupt
The Blaze Star prepares to erupt!
