gravitational interactions with planets (as many as 1013 such objects in the case of the Solar System). Objects ejected from planetary systems of other stars might plausibly be throughout the Milky Way and some may pass through the Solar System. Pan-STARRS may detect collisions involving small asteroids. These are quite rare and none have yet been observed, but with a dramatic increase in the number of asteroids discovered it is expected from statistical considerations that some collision events may be observed. In November 2019, a review of images from Pan-STARRS revealed that the telescope had captured the disintegration of asteroid P/2016 G1. The asteroid was struck by a smaller object, and gradually fell apart. Astronomers speculate that the object that struck the asteroid may have massed only , traveling at . Beyond the Solar System It is expected that Pan-STARRS will discover an extremely large number of variable stars, including such stars in other nearby galaxies; this may lead to the discovery of previously unknown dwarf galaxies. In discovering numerous Cepheid variables and eclipsing binary stars, it will help determine distances to nearby galaxies with greater precision. It is expected to discover many Type Ia supernovae in other galaxies, which are important in studying the effects of dark energy, and also optical afterglows of gamma ray bursts. Because very young stars (such as T Tauri stars) are usually variable, Pan-STARRS should discover many of these and improve our understanding of them. It is also expected that Pan-STARRS may discover many extrasolar planets by observing their transits across their parent stars, as well as gravitational microlensing events. Pan-STARRS will also measure proper motion and parallax and should thereby discover many brown dwarfs, white dwarfs, and other nearby faint objects, and it should be able to conduct a complete census of all stars within 100 parsecs of the Sun. Prior proper motion and parallax surveys often did not detect faint objects such as the recently discovered Teegarden's star, which are too faint for projects such as Hipparcos. Also, by identifying stars with large parallax but very small proper motion for follow-up radial velocity measurements, Pan-STARRS may even be able to permit the detection of hypothetical Nemesis-type objects if these actually exist. Selected discoveries See also C/2014 G3 Vera C. Rubin Observatory List of near-Earth object observation projects Zwicky Transient Facility Notes References External links PS1 Science Consortium web site The Pan-STARRS1 data