Duncan I. Steel (born 1955) is a British space scientist.^[1] He has discovered several minor planets and has written four popular science books. He is a member of the International Astronomical Union,^[2] and has worked at the Xerra Earth Observation Institute in Nelson, in the South Island of New Zealand.^[3][4] He was formerly on the staff of the University of Salford in the United Kingdom.^{[citation needed]} Steel completed a PhD at the University of Canterbury in 1984 with a thesis on the orbital characteristics of meteoroids.^[5]

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Between 1990 and 1994 he discovered twelve numbered minor planets.^[6] The asteroid 4713 Steel, discovered by Robert McNaught in 1989, is named after him.^[7][8]

In August 2022 Steel pleaded guilty to burglary and breaching the New Zealand Harmful Digital Communications Act. He was sentenced to 12 months' house arrest and ordered to pay $3000 in reparation for emotional harm.^[9][10]

• Rogue Asteroids and Doomsday Comets: The Search for the Million Megaton Menace That Threatens Life on Earth. New York: Wiley. 1995. ISBN 0-471-30824-2. (with a foreword by Arthur C. Clarke).
• Target earth. Pleasantville, N.Y.: Reader's Digest Association. 2000. ISBN 0-7621-0298-5. (with an afterword by Arthur C. Clarke).^[11]
• Marking Time: The Epic Quest to Invent the Perfect Calendar. New York: Wiley. 2000. ISBN 0-4712-9827-1.^[12]
• Eclipse: The Celestial Phenomenon That Changed the Course of History. Washington D.C.: Joseph Henry Press. 2001. ISBN 0-309-07438-X. (with a foreword by Paul Davies).