Category Astronomy/Space

Comet 252P/LINEAR is shown as it passed by Earth. Credit: NASA, ESA, and J.-Y. Li (Planetary Science Institute)

This sequence of images by Hubble shows Comet 252P/LINEAR as it passed by Earth. The visit was one of the closest encounters between a comet and our planet. The images were taken on April 4, 2016, ~2 weeks after the icy visitor made its closest approach to Earth on March 21. The comet traveled within 3.3 million miles of Earth, or about 14X the distance between our planet and the moon. These observations also represent the closest celestial object Hubble has observed, other than the moon.

The images reveal a narrow, well-defined jet of dust ejected by the comet’s icy, fragile nucleus. The nucleus is too small for Hubble to resolve. Astronomers estimate that it is <1 mile across...

This artist’s rendition shows the four identical MMS spacecraft flying near the sun-facing boundary of Earth’s magnetic field (blue wavy lines). The MMS mission has revealed the clearest picture yet of the process of magnetic reconnection between the magnetic fields of Earth and the sun — a driving force behind space weather, solar flares and other energetic phenomena. Credit: NASA

A new study provides the first major results of NASA’s Magnetospheric Multiscale (MMS) mission. The paper describes the first direct and detailed observation of magnetic reconnection, which occurs when 2 opposing magnetic field lines break and reconnect with each other, releasing massive amounts of energy. The discovery is a major milestone in understanding magnetism and space weather.

Evidence suggests reconnec...

An image of the galaxy AGC 198691 (nicknamed Leoncino, or “little lion”) taken by the Hubble Space Telescope. Credit: Photo by NASA; A. Hirschauer & J. Salzer, Indiana University; J. Cannon, Macalester College; and K. McQuinn, University of Texas

‘Little lion’ ie Leoncino galaxy contains lowest level of heavy elements ever detected in gravitationally bound system of stars. A faint blue galaxy about 30 million light-years from Earth and located in the constellation Leo Minor could shed new light on conditions at the birth of the universe. “Finding the most metal-poor galaxy ever is exciting since it could help contribute to a quantitative test of the Big Bang,” Salzer said...

The University of Chicago’s Sean Mills (left) and Daniel Fabrycky describe the complex orbital structure of the Kepler-223 expolanetary system in the May 11, 2016 Advance Online edition of Nature. Credit: Nancy Wong

The 4 planets of Kepler-223 star system seem to have little in common with planets of Earth’s own solar system. And yet a new study shows Kepler-223 system is trapped in an orbital configuration that Jupiter, Saturn, Uranus, and Neptune may have broken from in the early history of the solar system. “Exactly how and where planets form is an outstanding question in planetary science,” said Sean Mills. “Our work essentially tests a model for planet formation for a type of planet we don’t have in our solar system...