What are the things we want to know about giant planet meteorology? What are some of its broader implications? What does Dr. Statia Cook love about this research? And what project is she particularly excited about right now?
In her lecture at Columbia University’s Pupin Hall on Friday, March 9, the Columbia Science Fellow and researcher outlined her answers to these questions, in her fascinating presentation entitled Alien Weather.
Dr. Cook started by summarizing the weather conditions and patterns on Earth: a relatively thin atmosphere, clouds composed of water vapor, weather and climate influenced both by land and by oceans, and weather powered by energy from the Sun. But when we look, for example, at Jupiter, we see an entirely different picture: a “bottomless” thick atmosphere, clouds composed of trace gases rather than water vapor, no seasonality, and weather powered by the giant planet’s internal heat rather than the Sun’s energy.
Our solar system has four giant planets: two gas giants (Jupiter & Saturn), composed primarily of hydrogen; and two ice giants (Uranus & Neptune) composed mostly of water. As these giants are at different distances from the Sun, have different internal heating and varying axis tilts, their planetary weather differs dramatically.
Dr. Cook then proceeded to walk us through the similarities and differences among the four planets: how clouds and hazes are formed, what is their composition and what processes control their structure, as well as storms on each of the four giants, and seasonality and the effects of axis tilt and the sun’s distance. Far from being boring blue-green balls of gas, Uranus and Neptune have record-breaking storms, despite their receiving little energy from the Sun.
In terms of broader implications, the observable weather on these planets tells us about their composition, which in turn encodes their original formation—so we can learn about their formation through observing weather effects. In addition, it is increasingly apparent that our four giant planets and even the solar system in general are atypical. Generally speaking, our planets and especially giant planets orbit much farther out from their star than we observe in exoplanet systems, which of course dramatically affects our local neighbors’ weather.
So what does Dr. Cook love about her research? First, giant planet weather is visually beautiful. Importantly, atmospheres are dynamic systems, which change and evolve over time. And finally, this research is challenging. If, after it is deployed, we wish to point the James Webb Space Telescope at Jupiter, for example, we will have to contend with a number of practical issues: Jupiter’s size and proximity mean the JWST will have to mosaic many small images to capture the whole planet; and we would have to do this quickly due to Jupiter’s rapid rotation; and we have to avoid saturating the images due to the planet’s high brightness, etc. It is clear that planetary meteorology is nothing if not challenging!
Finally Dr. Cook spoke to us about Neptune’s New Dark Spot, only the fifth of such storms ever found in the solar system. Incidentally, this storm was discovered in 2015 and monitored by amateur astronomers using relatively small, 20” or less telescopes, and followed up by Hubble observations. We still need to understand how Dark Spots are born, how they move, how they die, and why they are dark. This is the focus of Dr. Cook’s current research.