To know if there are aliens, we need to ask the right questions

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Are We Alone in the Universe?

Panel from “Are we alone?”, a comic written by me with art by Maki Naro. [Credit: Maki Naro (art)/moi (words)]

How can we know if life exists elsewhere in the cosmos? To answer that question, we have to place Earth — and Earth life — in the context of other worlds in the Solar System and beyond. In my latest comic for The Nib with Maki Naro, we look at the science of planetary chemistry and the conditions of habitability as we know them, with the help of Johns Hopkins astrochemist Sarah Hörst and American Astronomical Society Public Policy Fellow Ashlee Wilkins.

Imagine a planet 7 times the mass of Jupiter, hot enough to glow slightly, and containing dusty clouds of carbon monoxide and water. That planet is HR 8799c, one of the few worlds outside our Solar System which astronomers have been able to image directly. Part of the reason for its weirdness is its youth: the planet is only about 30 million years old, compared to the Solar System’s 4.5 billion-year age. In fact, up until an observation published this week, astronomers couldn’t be sure HR 8799c was even a planet: many of its properties make it look more like a brown dwarf, the star-like objects not quite massive enough to shine via nuclear fusion. Despite its strange aspects, the planet could help astronomers understand how the HR 8799 system formed—and reveal information about the origins of our own Solar System.

Quinn Konopacky, Travis Barman, Bruce Macintosh, and Christian Marois performed a detailed spectral analysis of the atmosphere of the possible exoplanet. They compared their findings to the known properties of a brown dwarf and concluded that they don’t match—it is indeed a young planet. Chemical differences between HR 8799c and its host star led the researchers to conclude the system likely formed in the same way the Solar System did. [Read more…]

Analysis of atmosphere reveals: weird exoplanet is weird