Research.

Transient bright flashes observed by Juno UVS
​
The Juno UVS instrument primarily studies Jupiter's auroral emission. However, on occasion, we observe transient bright flashes of light originating from outside the aurora. We find that there are two distinct categories of these bright flashes: Transient Luminous Events (TLEs) and meteors. The former are extremely short-lived bursts of H2 emission that are triggered by an underlying lightning strike. TLEs have previously only been observed on Earth, although theoretical papers have predicted that they should also be present on other planets known to have lightning, like Jupiter and Saturn. So far, we have observed 11 events that are consistent with TLEs. In addition, we have observed one event that is consistent with a meteor impact. This bright flash consisted of blackbody emission and was longer lived than the TLEs.

Papers: Giles et al. (2020b), Giles et al. (2021)
TLE Press: CNN, New Scientist, Sky & Telescope 
Meteor Press: Forbes, Nature Highlights, Universe Today

Bright ultraviolet flash observed in Jupiter's upper atmosphere

Time series of Jupiter's Quasi-Quadrennial Oscillation

Jupiter's Quasi-Quadrennial Oscillation

The Quasi-Quadrennial Oscillation (QQO) is an oscillation in Jupiter's equatorial stratospheric temperatures with a period of ~4 years. It is analogous to the Earth's Quasi-Biennial Oscillation (QBO). We used observations from the TEXES spectrograph at NASA's IRTF to track the evolution of the QQO over an eight-year period (2 cycles). Previous long-term studies of the QQO had made use of imaging data, which does not provide vertical resolution. By using high-resolution spectroscopy, we were able to retrieve the vertical temperature profile in the stratosphere during each observing run. Combining the results from many observing runs from 2012-2019 allowed us to build up the time series seen on the left, and showed a disruption to the oscillation in 2017.

​Papers: Giles et al. (2020), Cosentino et al. (2020)

Jupiter's tropospheric composition and clouds using 5-micron spectroscopy

The 5-μm atmospheric window is a unique region of Jupiter's infrared spectrum; at 4.5-5.2 μm, the planet's atmosphere becomes relatively transparent, allowing us to probe down to the 4-8 bar region in the troposphere. In the image on the right, we are observing the bright radiation from these deeper parts of the atmosphere, with Jupiter's main cloud decks seen in silhouette above. Spectra from this wavelength region can provide information about both abundances of molecular species deeper in the atmosphere, and the absorption/scattering properties of the cloud layer. I have worked with 5-micron data from both the VIMS instrument on the Cassini spacecraft (taken during the Jupiter flyby) and extremely high spectral resolution spectra from the CRIRES instrument at the Very Large Telescope in Chile.

Papers: Giles et al. (2015), Giles et al. (2017a), Giles et al. (2017b)

Jupiter at 5 microns. Credit: Gemini Observatory/AURA/NSF/UC Berkeley

Composite near-infrared image of Jupiter. Credit: Gemini Observatory/AURA/NSF/JPL-Caltech/NASA.

Tracking Jupiter's cloud morphology using high-resolution near-infrared images
​
The NIRI imager on the Gemini North telescope in Hawaii can be used to take incredibly high spatial resolution images of Jupiter - by using the Galilean moons as natural guide stars, spatial resolutions of ~0.1" can be achieved. This allows us to track the changing morphology of aerosols in Jupiter's upper troposphere. By using several different filters in the near infrared, each of which is sensitive to a slightly different altitude, we can obtain three-dimensional information about the aerosol distribution. We take the observations at regular intervals in order to support the Juno mission; these global maps of the planet provide valuable contextual information for the observations obtained by the Juno instruments. In addition to supporting Juno, the observations allow for the study of unusual features that vary with time. In my 2019 paper, I use these observations to track the evolution of a wave pattern in Jupiter's North Equatorial Belt. 

Papers: Giles et al. (2019)

Ground-based observations of solar system bodies and astrophysical targets using the TEXES spectrograph ​

The TEXES instrument is a mid-infrared spectrograph, covering the 5-25 μm wavelength range at resolving powers of up to 85,000. It is a visiting instrument at both NASA's Infrared Telescope Facility and the Gemini North telescope, and we typically have several observing runs each year. As a member of the instrument team, I run observations both for my own programs and on behalf of a wide range of collaborators. These observations cover solar system bodies (both planets and moons) and also non-solar system targets including protoplanetary disks and star-forming regions.

Papers: Fletcher et al. (2014), Sinclair et al. (2017), Melin et al. (2018)
​​

The TEXES instrument in the lab at NASA's Infrared Telescope Facility