Two Earth-sized planets orbiting Kepler-20

Two Exoplanets Discovered at Keck Observatory

Two Extrasolar Asteroids with Low Volatile-Element Mass Fractions

Two new variable stars observed in the field of the extrasolar planet host star WASP-3

Two phase, inward-then-outward migration of Jupiter and Saturn in the gaseous Solar Nebula

Two Upper Limits on the Rossiter-McLaughlin Effect, with Differing Implications: WASP-1 has a High Obliquity and WASP-2 is Indeterminate

Two-Dimensional Study of the Propagation of Planetary Wake and the Indication to Gap Opening in an Inviscid Protoplanetary Disk

Two-fluid Instability of Dust and Gas in the Dust Layer of a Protoplanetary Disk

Type II migration of planets on eccentric orbits

Type III migration in a low viscosity disc

U and Th content in the Central Apennines continental crust: a contribution to the determination of the geo-neutrinos flux at LNGS

Ultra-Low Delta-v Objects and the Human Exploration of Asteroids

Ultraviolet and visible photometry of asteroid (21) Lutetia using the Hubble Space Telescope

Ultraviolet Spectroscopy of Asteroid (4) Vesta

Unbiased Inclination Distributions for Objects in the Kuiper Belt

Unbound or Distant Planetary Mass Population Detected by Gravitational Microlensing

Undisturbed Mesosphere Optical Properties from Wide-Angle Frequent Twilight Sky Polarimetry

Unprecedented accurate abundances: signatures of other Earths?

Unstable Planetary Systems Emerging Out Of Gas Disks

Upper limits for undetected trace species in the stratosphere of Titan