Imke de Pater
UC Berkeley
“A View of our Solar System at Radio Wavelengths“
General Astronomy lectures about our own Solar System typically feature incredible images at visible and infrared wavelengths taken by spacecraft, the Hubble Space Telescope, and ground-based telescopes equipped with adaptive optics to overcome the blurring in our own atmosphere. At radio wavelengths we are sensitive to different types of emissions, broadly divided into thermal and non-thermal emissions. The former pertains to, e.g., blackbody radiation from below a planet’s surface or cloud layers, and emission/absorption lines arising in atmospheres or cometary comae. Non-thermal radiation is usually caused by emissions in a planet’s magnetic field, such as synchrotron radiation or low-frequency auroral emissions. Thanks to an order of magnitude improvement in the VLA’s sensitivity and the advent of ALMA, thermal emission has now been measured from objects in the far outer reaches of our Solar System, enabling us to derive the size and reflectivity of Kuiper Belt Objects, and produce spatially resolved maps of the Galilean moons, Titan, and comets.
After a broad introduction to radio observations of our Solar System, I will focus on Jupiter, and contrast VLA maps with Juno’s microwave data. VLA observations of Jupiter have revealed structures very similar to those seen in Hubble Space Telescope images. At radio wavelengths, however, we are not sensitive to Jupiter’s clouds; rather we peer below the clouds and essentially construct a 3-dimensional image of the ammonia distribution. This in turn provides information on the dynamics in the atmosphere.