On 29 September 2022, the Juno spacecraft performed the first close flyby of Jupiter's icy moon Europa in generation. The low-light sensitive Juno SRU navigation camera was used to photograph a part of the surface that was lit only by sunlight scattered off Jupiter, from a spacecraft-to-surface distance of 412 km. This innovative use of a high-resolution star camera designed to detect dim stars produced Juno's highest resolution image of Europa, and provides the highest resolution coverage of the targeted region to date. The imaged area is revealed to be incredibly complex and rich with many different types of terrains and features. Dark stains that may be associated with plumes, and an area of ice shell disruption nicknamed “the Platypus,” are compelling targets for future missions to investigate possible present day surface activity.

The major moons of Uranus, Miranda, Ariel, Umbriel, Titania, and Oberon, are interesting targets for a future space mission because they might host liquid at present. Studying these bodies would help address the extent of habitable environments in the outer solar system. We model their thermal, physical, and chemical evolution. Because their heat budget is limited, with little or no tidal heating at present, we find that most of the moons can preserve only a few tens of kilometers of liquid until present. Furthermore, if the oceans are maintained by antifreeze, such as ammonia and chlorides, then their electrical conductivities may be close to zero. In this case, the detection of a magnetic field induced in these oceans would be challenging. We explore additional geophysical, as well as compositional, observations that would reveal the existence of a deep ocean in these moons. None of the scenarios studied produce residual liquid in Miranda at present. Our simulations are consistent with constraints on the dissipative properties of the moons inferred from dynamical evolution models.

Meteorite collisions should have formed throughout the 4.5 billion-year-long history of Earth, but we have only found impact craters that are less than half of the age of the Earth (2 billion years) and younger. In order to understand how to find very old impact craters, we studied the largest of the oldest preserved impact craters. The 2 Byr old Vredefort structure in South Africa has been deeply eroded, and thus provides a good view of its deep roots. We collected a series of samples of the exposed rocks known to have evidence of shock effects and measured their physical properties. We found that the physical properties do not show evidence of the meteorite impact event. We also established that the gravity profile of the crater preserves a weak signal. When the Vredefort structure erodes a bit more, the geophysical characteristics that make it identifiable will be gone. We expect that signatures of ancient impact structures even larger than Vredefort would be completely removed by erosion by now. Therefore, to find very old impact craters, we need to look in areas that have experienced unusually little erosion.

The Chang'E-4 rover is exploring the Moon with a two-channel ground penetrating radar (GPR). The GPR sends electromagnetic pulses into the lunar interior and receives echoes from subsurface layers. We use the high-frequency channel data to detect the structure of the upper 40 m along the rover's path, primarily consisting of rock debris and soil. This analysis reveals several layers and a buried crater. The low-frequency channel has the capability to penetrate deeper into the Moon, allowing us to search for large-scale layered structures such as lava flows. Through this investigation, we have discovered multiple layers in the upper 300 m, which likely indicate a series of basalt eruptions that occurred billions of years ago. The thickness variation of these lava flows suggests a decrease in eruption scale over time. By combining data from both channels, we are able to depict the overall structure of the Moon's upper several hundred meters.

“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.

Scientists learn about the formation and evolution of planets, such as Mars, by studying rock samples. Obtaining rock samples from Mars makes it possible to study them in state-of-the-art laboratories on Earth with high degrees of precision and accuracy. Currently, samples from Mars are obtained as meteorites that have been ejected from the planet. We can study these rocks to learn about volcanic processes and their chemistry and timing in the context of martian geology. This review paper summarizes the information we have learned about Mars's geology by analyzing martian meteorites. Most of the data collected provide evidence that the interior of Mars is compositionally varied with high diversity in chemical makeup throughout time. However, most meteorites are relatively young with few older rocks (older than 2.4 billion years old) analyzed to date. The Mars 2020 mission plans on collecting older samples directly from Mars's surface, in the Jezero crater, for eventual return to Earth, as early as 2031. The study of both meteorites and returned samples is essential to gain a full understanding of the interior composition, evolution, and geological characteristics of different locations on the Red Planet.

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.