David Grinspoon Quote
This comet was much smaller, less than half a mile across, and would miss Mars by about eighty thousand miles. This was still close enough to splatter the atmosphere with hydrogen and dust, producing atmospheric effects that were observable with telescopes and spacecraft. When the close approach occurred, it provided a great opportunity to learn more about the infrequent (on human timescales) but inevitable interactions of planets with comets. For me there was also an unsettling aspect. We hear more about the impact threat from stray near-Earth asteroids, but a comet like this one, plunging at a frightening pace from the dark periphery of the solar system, would be a more formidable threat. In contrast to the many years or even decades of warning we’d likely have for a menacing asteroid, a comet can appear with little notice. This Martian near miss occurred less than two years after McNaught’s discovery. If the wrong comet appeared, we might have only a similar warning interval between detection and Earth impact. The chances of this happening in any year are minuscule, but recent solar system history teaches us that, if we watch long enough, seemingly unlikely objects and events will eventually materialize.
This comet was much smaller, less than half a mile across, and would miss Mars by about eighty thousand miles. This was still close enough to splatter the atmosphere with hydrogen and dust, producing atmospheric effects that were observable with telescopes and spacecraft. When the close approach occurred, it provided a great opportunity to learn more about the infrequent (on human timescales) but inevitable interactions of planets with comets. For me there was also an unsettling aspect. We hear more about the impact threat from stray near-Earth asteroids, but a comet like this one, plunging at a frightening pace from the dark periphery of the solar system, would be a more formidable threat. In contrast to the many years or even decades of warning we’d likely have for a menacing asteroid, a comet can appear with little notice. This Martian near miss occurred less than two years after McNaught’s discovery. If the wrong comet appeared, we might have only a similar warning interval between detection and Earth impact. The chances of this happening in any year are minuscule, but recent solar system history teaches us that, if we watch long enough, seemingly unlikely objects and events will eventually materialize.
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About David Grinspoon
His research focuses on comparative planetology, with a focus on climate evolution on Earth-like planets and implications for habitability. He has also studied, written and lectured on the human influence on Earth, as seen in cosmic perspective.
He has published four books, Venus Revealed, which was a finalist for the Los Angeles Times book prize, Lonely Planets: The Natural Philosophy of Alien Life, which won the 2004 PEN literary award for nonfiction, Earth in Human Hands, which was named one of NPR's Science Friday "Best Science Books of 2016" and Chasing New Horizons: Inside the Epic First Mission to Pluto, co-authored with Alan Stern. He is adjunct professor of Astrophysical and Planetary Science at the University of Colorado, a former Fellow of the Institute for Cross-Disciplinary Engagement at Dartmouth College and a former Distinguished Visiting Scholar in the College of the Environment at Wesleyan University.