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We measured the Moon's temperature cycles with the Lunar Reconnaissance Orbiter's Diviner instrument to make the first global maps of important physical properties of the dusty surface layer. These maps reveal a rich new view of the last billion years of impact processes and volcanism on the Moon. Impacts by meteorites cause the breakdown of rocks and accumulation of regolith—the granular surface materials. Our results show that regolith formation is a rapid process, which homogenizes and redistributes fine particles over large distances. These new observations provide a wealth of data for future study and also suggest a new technique for determining the ages of craters on the Moon and other planetary surfaces, using temperatures to infer the depth of accumulated regolith.

Titan, the largest moon of Saturn, is unique in our solar system. It is the only moon with a dense atmosphere and the only other thick nitrogen atmosphere besides that of Earth. In the atmosphere very complicated chemistry, started by sunlight, forms molecules made of carbon, hydrogen, nitrogen, and oxygen (sometimes called “organic” molecules); these molecules end up on the surface where they are moved by wind and rain to form dunes, lakes, and seas. It is the only world besides Earth that has lakes and seas presently on its surface, although they are made of liquid methane and ethane instead of water. The conditions in Titan's atmosphere are ideal for creation of smog-like particles called haze, which may have molecules that are important for the origin of life. The combination of liquid and organics means that Titan may be the best place in the solar system to test ideas about how life begins and how common it is in the universe. The Cassini-Huygens mission to the Saturn system has provided a wealth of new information allowing us to study Titan as a system. Here I review our current understanding of Titan's atmosphere and climate forged from the powerful combination of Earth-based observations, measurements from spacecraft, laboratory experiments, and computer models. I conclude with some of our remaining unanswered questions as the incredible era of exploration with Cassini-Huygens comes to an end.

This work presents a new database of lunar impact craters. Over 2 million craters were identified and measured, and 1.3 million of them are larger than 1 km in diameter. The database is estimated to be a complete census of all craters larger than approximately 1 to 2 km across. Where there are overlaps, this database compares well with past databases with respect to crater diameters and locations, but the database contains more craters smaller than about 20 km across than any other crater database. This increase is attributed primarily to the fully manual effort involved in searching multiple instruments' data sets, using both imagery and topography, and multiple searches of the lunar surface. A spatial density analysis of the craters in different diameter ranges shows many trends that have been seen before, but it also reveals details of nonuniformity, which have not been previously described, including an enhanced small crater population at the Moon's north pole and many effects of secondary craters—craters that form from the ejecta of a larger, primary impact. Additionally, the database contains ellipse properties of the craters, and it shows that large craters' orientations are indistinguishable from randomness.

“Hot Jupiters” are gas giant planets, thought to be akin to Jupiter and Saturn, that orbit their parent stars with typical orbital periods of only a few days. These perplexing planets under strong stellar irradiation, found around 1% of Sun-like stars, have been extensively studied. Here, we review many aspects of the physics of hot Jupiters. First, we discuss the leading scenarios for the formation and orbital evolution of the planets, including the dominant ideas that these planets originally form much further from their parent stars. Next, we describe models to assess their interior structure and thermal evolution and how strong stellar irradiation leads to radii that are significantly larger than that of Jupiter itself. Finally, we discuss many aspects of their atmospheres, including the opacity sources that control the temperature structure, the mass-loss processes that drive a planetary wind, and the dynamical processes that control atmospheric circulation and day-to-night temperature contrasts.

The Vredefort impact structure, which formed over 2 billion years ago in South Africa, is the largest preserved remnant impact crater on Earth (originally 250–280 km in diameter). It is widely accepted that the crater formed by an impactor 15 km in diameter with velocity 15 km/s, which is based on a numerical simulation that produced a crater size of 172 km. A new model is needed because this model does not reproduce the common estimate of the crater diameter as well as newly identified geologic constraints. Here, we conduct simulations to match these updated constraints. We find that either an impactor with a diameter of 25 km and impact velocity of 15 km/s or a diameter of 20 km and impact velocity of 25 km/s are able to reproduce the crater. We are able to use our results to predict the amount of material ejected by impact at some distance from the crater center. Using this model and an ejecta layer found in Karelia, Russia, we predict that these two locations were 2,000–2,500 km apart 2 billion years ago. Such a large impact would have global consequences, especially due to the release of climatically important gases which change the global climate.