Comments on early space controversies

David Cummings and Louis Lanzerotti’s article “Early debates in space science ” (Physics Today, February 2025, page 38) tells the stories of five early questions in astrophysics. One of those big questions was about the nature of gamma-ray bursts: whether they come from within the Milky Way or beyond it. As the authors discuss, a great debate on the subject was held in 1995. The debate papers were contained in a special issue ¹ of Publications of the Astronomical Society of the Pacific, for which I was managing editor.

The resolution of the issue came two years later, but not quite in the way that Cummings and Lanzerotti describe. A gamma-ray burst, named GRB 970508, occurred on 8 May 1997 and was detected by the BeppoSAX satellite, which provided a fairly accurate celestial position. I used a 0.9 m telescope at Kitt Peak National Observatory to image the location on two successive nights, resulting in the detection of a faint optically variable source within the error box.

Following my announcement, which gave accurate coordinates of the object, ² Charles Steidel of Caltech was able to obtain its spectrum at the W. M. Keck Observatory. ³ He reported that the afterglow has a redshift z of 0.835 and settled once and for all that GRBs indeed lie at cosmological distances.

As Cummings and Lanzerotti’s article recounts, Bohdan Paczyński had been the advocate for cosmological distance at the great debate. When I emailed him in the early morning to inform him of the results and to congratulate him on being right, he told me that he believed that he would allow himself a drink that evening.