Astronomy / Astrophysics

The Asteroid Day website's home page

Today marks the first Asteroid Day, a day dedicated to raising public awareness about the potential danger posed by asteroids and any space object whose trajectory passes through the Earth’s orbit. The date was chosen because it’s the anniversary of the Tunguska event, the destruction of a large area of ​​Siberia that took place on June 30, 1908 due to the impact of a meteorite or a piece of comet.

Six of the icy areas on the surface of the comet 67P/Churyumov-Gerasimenko found by the Rosetta space probe (Image ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)

The OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) camera on ESA’s space probe Rosetta allowed to identify 120 icy areas on the surface of the comet 67P/Churyumov-Gerasimenko. A study of the presence of ice has just been published in the journal “Astronomy & Astrophysics”. That presence was well known but Rosetta’s observations allowed to understand the phases of transformation into gas, how much of it forms the comet’s coma and tail and what falls back to the surface.

Artistic illustration of the planet GJ 436b surrounded by its huge tail and its parent star GJ 436 (Image NASA, ESA, and G. Bacon (STScI))

An article in the journal “Nature” describes a research about the planet GJ 436b, whose mass is similar to that of Neptune. Using the Hubble Space Telescope, a team of astronomers led by David Ehrenreich of the Observatory of the University of Geneva in Switzerland discovered that it leaves behind a huge tail of the estimated size of about 50 times that of the star it orbits. Those are hydrogen emissions ripped from the planet which make it looke like a huge comet.

Artistic impression of the galaxy CR7 (Image ESO/M. Kornmesser)

An article accepted for publication in “The Astrophysical Journal” describes the discovery of a galaxy called CR7 seen as it was at the time of the early universe in which first-generation stars were found. This research was carried out mainly using ESO’s Very Large Telescope but data collected by the W. M. Keck Observatory, the Subaru Telescope and the Hubble Space Telescope were also used.

Galaxies containing quasars observed using the Hubble Space Telescope: in the top row the quasars are visible, in the bottom row the quasars' light is subtracted (Image NASA/ESA)

An article in the journal “Astrophysical Journal” describes a research conducted on quasars using the Hubble Space Telescope. These objects that are incredibly bright were observed in their formation phase, when they were in a sense teen-agers. The observations confirm the hypothesis that quasars are generated by galactic collisions that feed the supermassive black hole at their center.