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The giant planets of the Solar System formed on initially compact orbits, which transitioned to the current wider configuration by means of an orbital instability. The timing of that instability is poorly constrained. In this work, we use dynamical simulations to demonstrate that the instability implanted planetesimal fragments from the terrestrial planet region into the asteroid main belt. We use meteorite data to show that the implantation occurred >60 million years (Myr) after the Solar System began to form. Combining this constraint with a previous upper limit derived from JupiterÕs trojan asteroids, we conclude that the orbital instability occurred 60 to 100 Myr after the beginning of Solar System formation. The giant impact that formed the Moon occurred within this range, so it might be related to the giant planet instability. [ABSTRACT FROM AUTHOR]

Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk. [ABSTRACT FROM AUTHOR]

Direct imaging of gas giant exoplanets provides information on their atmospheres and the architectures of planetary systems. However, few planets have been detected in blind surveys with direct imaging. Using astrometry from the Gaia and Hipparcos spacecraft, we identified dynamical evidence for a gas giant planet around the nearby star HIP 99770. We confirmed the detection of this planet with direct imaging using the Subaru Coronagraphic Extreme Adaptive Optics instrument. The planet, HIP 99770 b, orbits 17 astronomical units from its host star, receiving an amount of light similar to that reaching Jupiter. Its dynamical mass is 13.9 to 16.1 Jupiter masses. The planet-to-star mass ratio [(7 to 8) × 10−3] is similar to that of other directly imaged planets. The planetÕs atmospheric spectrum indicates an older, less cloudy analog of the previously imaged exoplanets around HR 8799. [ABSTRACT FROM AUTHOR]

The article highlights that soon after the Solar System's formation, gravitational disturbances among giant planets caused significant upheaval, impacting their orbits and scattering icy bodies. Topics include the chaotic period around 60 million years post-formation, marked by meteorite evidence, impacting planetary size, composition, and potential Moon formation scenarios.

The article focuses on potential issues with the Europa Clipper spacecraft's metal-oxide-semiconductor field-effect transistors (MOSFETs), which may not meet the required radiation-hardness standards for the mission. It highlights the challenge posed by Jupiter's intense radiation environment and the recent discovery of performance problems in these transistors, which could impact the spacecraft's ability to function properly.

Hot gas giant exoplanets can lose part of their atmosphere due to strong stellar irradiation, and these losses can affect their physical and chemical evolution. Studies of atmospheric escape from exoplanets have mostly relied on space-based observations of the hydrogen Lyman-a line in the far ultraviolet region, which is strongly affected by interstellar absorption. Using ground-based high-resolution spectroscopy, we detected excess absorption in the helium triplet at 1083 nanometers during the transit of the Saturn-mass exoplanet WASP-69b, at a signal-to-noise ratio of 18. We measured line blueshifts of several kilometers per second and posttransit absorption, which we interpret as the escape of part of the atmosphere trailing behind the planet in comet-like form. [ABSTRACT FROM AUTHOR]

The article reports that National Aeronautics and Space Administration's James Webb Space Telescope orbiting observatory has made its first discovery of a previously unknown planet around another star and is searching for its atmosphere can parse the atmospheres of gas giants and exoplanets.

Direct imaging allows for the detection and characterization of exoplanets via their thermal emission. We report the discovery via imaging of a young Jovian planet in a triple-star system and characterize its atmospheric properties through near-infrared spectroscopy. The semimajor axis of the planet is closer relative to that of its hierarchical triple-star system than for any known exoplanet within a stellar binary or triple, making HD 131399 dynamically unlike any other known system. The location of HD 131399Ab on a wide orbit in a triple system demonstrates that massive planets may be found on long and possibly unstable orbits in multistar systems. HD 131399Ab is one of the lowest mass (4 ± 1 Jupiter masses) and coldest (850 ± 50 kelvin) exoplanets to have been directly imaged. [ABSTRACT FROM AUTHOR]

The article examines how the discovery of exoplanets has informed developments in planet formation theory. It details the history of research on the formation of planets and stars dating back to the 18th century. The article goes on to provide information on research regarding inner parts of planetary systems and the subsequent expansion into observing distant giants.

The article focuses on the claim of scientists Mike Brown and Konstantin Batygin of the California Institute of Technology (Caltech) on evidence of a Planet X which orbits the sun and settles in a distant elliptical orbit. It says that Brown and Batygin have inferred the presence of the giant planet from the clustering of known objects which orbit beyond planet Neptune. Planetary dynamicist Alessandro Morbidelli mentions that he was convinced by the scientists' claims.

Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 x 10-6 and an effective temperature of 600 to 750 kelvin. For this age and luminosity, "hot-start" formation models indicate a mass twice that of Jupiter. This planet also has a sufficiently low luminosity to be consistent with the "cold-start" core-accretion process that may have formed Jupiter. [ABSTRACT FROM AUTHOR]

The article discusses the authors' observation of the insulator-to-metal transition in dense liquid deuterium. Particular focus is given to its implications for planetary sciences, especially regarding theories about the transition of solid hydrogen to metal. Other topics include boundary layer pressure in gas-giant planets and hydrogen-helium immiscibility.

A retraction of the article "Direct imaging discovery of a Jovian exoplanet within a triple-star system" is presented, which discusses a gas giant exoplanet in the star system HD 131399.

Close-in giant planets (e.g., ‘hot Jupiters’) are thought to form far from their host stars and migrate inward, through the terrestrial planet zone, via torques with a massive gaseous disk. Here we simulate terrestrial planet growth during and after giant planet migration. Several-Earth-mass planets also form interior to the migrating jovian planet, analogous to recently discovered ‘hot Earths.’ Very-water-rich, Earth-mass planets form from surviving material outside the giant planet's orbit, often in the habitable zone and with low orbital eccentricities. More than a third of the known systems of giant planets may harbor Earth-like planets. [ABSTRACT FROM AUTHOR]

Stratospheric temperatures on Saturn imply a strong decay of theequatorial winds with altitude. If the decrease in winds reported fromrecent Hubble Space Telescope images is not a temporal change, then thefeatures tracked must have been at least 130 kilometers higher than inearlier studies. Saturn's south polar stratosphere is warmer thanpredicted from simple radiative models. The C/H ratio on Saturn is seventimes solar, twice Jupiter's. Saturn's ring temperatures have radialvariations down to the smallest scale resolved (100 kilometers). Diurnalsurface temperature variations on Phoebe suggest a more porous regoliththan on the Jovian satellites. [ABSTRACT FROM AUTHOR]

The Cassini Imaging Science Subsystem (ISS) began observing Saturnin early February 2004. From analysis of cloud motions through earlyOctober 2004, we report vertical wind shear in Saturn's equatorial jetand a maximum wind speed of ∼375 meters per second, a value thatdiffers from both Hubble Space Telescope and Voyager values. We alsoreport a particularly active narrow southern mid-latitude region inwhich dark ovals are observed both to merge with each other and to arisefrom the eruptions of large, bright storms. Bright storm eruptions arecorrelated with Saturn's electrostatic discharges, which are thought tooriginate from lightning. [ABSTRACT FROM AUTHOR]

The article offers information related to a gas-giant planet, like giant Jupiter, is orbiting a small star spurs found to be rethinking of planet formation. Topics discussed include unexpected discovery of a giant Jupiter-like planet; planetary systems that resemble scaled-up versions of the satellites circling giant planets in Solar System; and information on high-precision spectrographs of unlikely location of gas-giant planet.

A review is presented of the article "Direct imaging discovery of a Jovian exoplanet within a triple-star system" by Kevin Wagner, Dániel Apai, Kaitlin Kratter, and others which is published in the same issue concerning the discovery of a substellar object orbiting in a triple-star system.

The article discuses a study of 32 meteorites by German geochemists that concluded any meteorite originated from either a grist near the asteroid belt or near the orbit of Saturn. It details how the chemical difference in meteorites confirms meteoriticist Paul Warren's concept of the Warren gap that also provides insight onto the movement of giant planets.

The article discusses research on the formation of the gas giants, the solar planets Jupiter and Saturn, noting models on the formation of planetesimals in relation to a solar system model discussed in the August 19, 2015 issue of the journal "Nature."

Reports the observations and solar system research of the Jovian planets, or outer planets, by the European Space Agency. Observations using the Infrared Space Observatory; Details of observations gained by two spectrometers; Range of wavelength of spectra obtained; Theory of formation of the Jovian planets; Determination of deuterium/hydrogen that has been provided by the observations.

The article reports on unusual discoveries in the search for extrasolar planets in 2011, including several massive planets orbiting the Kepler 11 star, a gas giant with an orbit opposite to its star, and 10 planets that appear to have no host star.

The article describes the dynamics of the south polar vortex (SPV) of planet Saturn. The authors show that the planet's SPV has unique properties, some of which resembles other vortices but not any other vortex, in all respects. Images taken by the Cassini imaging science subsystem reveals that Saturn's SPV is anomalously warm in both the tropopause and stratosphere. Saturn's vortex resembles Venus's polar vortices which are cyclonic and have warm features at the poles, and it differs from Jupiter's Great Red Sport and white ovals, which are anticyclones with high clouds at their centers.

The article reports that the Cassini spacecraft has been touring Saturn's neighborhood since it entered orbit there on July 1, 2004. As well as interrogating the giant planet and its filigree rings, understanding the formation of Saturn's moons is one of the key goals of the mission. Saturn has 35 named moons in its family, as well as a plethora of smaller objects hidden in the rings. Some consist of exposed rock; others are enveloped in thick ice. Some are pock-marked with billion-year-old craters; others varnished with fresh snow. Cassini's busy schedule included more than 20 encounters with Saturn's moons in the past year, offering but a sampling of these different worlds. One of the most curious of all Saturn's moons is Enceladus. The sixth largest saturnian satellite--although at a mere 504 km across, its width is smaller than that of Arizona or Spain--Enceladus rides in the middle of Saturn's E ring, a wide and diffuse blue ring of fine particles. Because this ring lacks the bigger shards characteristic of ancient satellite smash-ups, astronomers have long suspected that the E-ring particles emanate from Enceladus itself.