Leslie A. Young

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Observations of the 1.4- to 2.4-micrometer spectrum of Pluto reveal absorptions of carbon monoxide and nitrogen ices and confirm the presence of solid methane. Frozen nitrogen is more abundant than the other two ices by a factor of about 50; gaseous nitrogen must therefore be the major atmospheric constituent. The absence of carbon dioxide absorptions is(More)
Pluto's first known satellite, Charon, was discovered in 1978. It has a diameter (approximately 1,200 km) about half that of Pluto, which makes it larger, relative to its primary, than any other moon in the Solar System. Previous searches for other satellites around Pluto have been unsuccessful, but they were not sensitive to objects less, similar150 km in(More)
The temperatures in Jupiter’s stratosphere, as measured by the Galileo Atmosphere Structure Instrument (ASI), show fluctuations that have been interpreted as gravity waves. We present a detailed description of these fluctuations, showing that they are not likely to be due to either measurement error or isotropic turbulence. These fluctuations share features(More)
Stellar occultation data for Charon obtained by Walker (1980, Mon. Not. R. Aston. Soc. 192, 47p-50p) have been fit by a model that includes possible differential refraction by an atmosphere, followed by an abrupt occultation by Charon's limb. We find a lower limit (3 or, where ¢r = 0.8 km) on Charon's radius of 601.5 km, which can be used as a constraint(More)
The Pluto system was recently explored by NASA's New Horizons spacecraft, making closest approach on 14 July 2015. Pluto's surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and(More)
The Voyager mission to the outer solar system discovered that the thermospheres of all the giant planets are remarkably hot. To date, no convincing explanation for this phenomenon has been offered; however, there are a number of recent observational results which provide new information on the thermal structure of Jupiter's upper atmosphere that bear on(More)
We observed Triton using HST/STIS on 1999 Aug 28, Sep 11, and Sep 13 UT. On all three occasions, we obtained images at both 271 nm and 374 nm, and spectra from 215 to 318 nm. We find that Triton's geometric albedo is high through the near and mid-UV, decreasing from 0.64±0.02 at 374 nm to 0.53±0.05 at 223 nm. We compare these data to a previous UV dataset(More)
The New Horizons spacecraft mapped colors and infrared spectra across the encounter hemispheres of Pluto and Charon. The volatile methane, carbon monoxide, and nitrogen ices that dominate Pluto's surface have complicated spatial distributions resulting from sublimation, condensation, and glacial flow acting over seasonal and geological time scales. Pluto's(More)
Observations made during the New Horizons flyby provide a detailed snapshot of the current state of Pluto's atmosphere. Whereas the lower atmosphere (at altitudes of less than 200 kilometers) is consistent with ground-based stellar occultations, the upper atmosphere is much colder and more compact than indicated by pre-encounter models. Molecular nitrogen(More)
We present new imaging of the surface of Pluto and Charon obtained during 2002–2003 with the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) instrument. Using these data, we construct two-color albedo maps for the surfaces of both Pluto and Charon. Similar mapping techniques are used to re-process HST/Faint Object Camera (FOC) images taken in(More)