Rhea . ... Rhea is an icy body with a density of 1.33 gm/cm 3 . The low density indicates that it is composed of a rocky core taking up less than one-third of the moon's mass, with the rest composed of water-ice. ... Rhea is heavily cratered with bright whispy markings. ... The second area, in parts of the polar and equatorial regions, has craters under 40 kilometers (25 miles) in diameter. ... Orbital period (days) . ... Credit: Calvin J. Hamilton) . ... Copyright ї 1997 by Calvin J. Hamilton . ...

... Dione's icy surface includes heavily cratered terrain, moderately cratered plains, lightly cratered plains, and whispy material. The heavily cratered terrain has numerous craters greater than 100 kilometers in diameter. ... Much of the heavily cratered terrain is located on the trailing hemisphere , with the less cratered plains area existing on the leading hemisphere . ... Because Dione is relatively small, an impact causing a 35 kilometer (21 mile) crater could have spun the satellite. ...

Astronomy Picture of the Day . Water Discovered on the Moon . ... 28.09.2009 . ... Credit: ISRO / NASA / JPL-Caltech / USGS / Brown U. Explanation: Water has been discovered on the surface of the Moon. No lakes have been found, but rather NASA's Moon Mineralogy Mapper aboard India's new Chandrayaan-1 lunar orbiter radios back that parts of the Moon's surface absorb a very specific color of light identified previously only with water. ... Publications with keywords: Moon - water . ...

... These other worlds are the moons of our Solar System , of which there are approximately 170 in orbit around our planets.Some of these moons are very interesting, and have diverse and unique features, very different to our barren, heavily cratered Moon .Jupiter, the largest planet in our solar system has the most moons of any planet with known 64 moons in orbit.The four ... Ganymede, the largest moon in the Solar System thought to have oceans located underneath its icy surface.( ...

... Luminous blue variable (LBV) stars are the most massive stars with 40-120 solar masses, which are passing the short stage of evolution losing their hydrogen envelopes before exploding as Supernovae. These are extremely rare objects, only about a dozen of the most massive LBVs are known in the Galaxy. ... In the spectral observations of stars with infrared circular nebulae, found in the Spitzer survey (24 microns), a new LBV star in the Galaxy was discovered. It was named MN112. ...

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . This image shows the relative size of the three newly discovered . planets around Kepler 37. Image Courtesy of NASA). ... Dr Tom Barclay who studied at Armagh Observatory for three years as a post-graduate student funded by the UK Science and Technology Facilities Council, has led a team of astronomers who have detected the smallest extra-solar planet, or exoplanet, yet found around a star like our Sun. ...

... When the Voyager 2 spacecraft flew by the planet Uranus in January 1986, astronomers were treated to their first close-up glimpse of the satellites that orbit the seventh planet. ... But by far the most intriguing of those 15 satellites was a jigsaw-puzzle world called Miranda . ... How dark was it at Miranda? One of the Voyager scientists put it this way: Taking pictures in the Uranus system is like trying to do photography in a ballpark at night when the only light comes from a single candle. ...

... We computed the permanently shadowed areas and temperatures inside the craters for the variation of the position of the lunar pole of rotation with respect to the ecliptic pole with a period of 18.6 years. ... According to our results, the total permanently shadowed area in the polar craters of the Moon is equal to 50428.7 km2, or 0.13% of the total area of the lunar surface [3]. ... The area of permanently shaded part of a crater makes 59 % from all area of a crater [3]. ...

... ATNF Home . About ATNF . ... About ATNF overview . ... Australia Telescope Steering Committee . ... The Optical Counterparts to Galaxies in the Cen A Group Discovered by HIPASS . ... This group of galaxies was recently the subject of a separate and thorough optical survey (CУДtУ? et al. 1997), and thus presented an ideal comparison for us to test the survey performance. ... Six of the new members are previously uncatalogued galaxies, while four were catalogued but assumed not to be group members. ...

... The name Discovery Date mag Size(m) Publication MASTER -Observatory --------------------------------------------------------------------------------------------------------------------------- HAZARDOUS ASTEROIDS : 7 MASTER HAZARD Asteroid 2015 UM67 2015 Oct 28.88218 16.9 940m MPEC 2015-V01 MASTER -SAAO automatically MASTER software 6 MASTER rediscovered HAZARD Asteroid 2011 QG21 2015 Aug 17.94764 17.2 300m MPEC 2015-Q28 ...

... Tonight's Sky . ... Observing . ... Hot lava flows discovered on Venus . ... Evidence for active volcanoes on Venus . ... Seeing the planet s surface is extremely difficult due to its thick atmosphere, but radar observations by previous missions to Venus have revealed it as a world covered in volcanoes and ancient lava flows. ... But whether Venus is active today has remained a hot topic in planetary science. ... Only registered members of Astronomy.com are allowed to comment on this article. ...

.

... It can · · obtain ice sample from 20 cm or deeper surface layer, then melt it and extract biomass from the ice surface water by filtration; Laser TOF MS for the measurements of element composition of the biomass; Gas TOF MS for the detection of: 1) volatile components, generated at the heating of biomass sample (closed window mode); 2) secondary ions , emitted from ice matrix by the influence of energetic magnetosphere ... Spectrum of yeast sample. ... Laser TOF MS 6. ...

... Bad Astronomy . ... Bitesize Astronomy . ... Have you ever looked at pictures of Saturn's rings and noticed what look like gaps in the rings? ... Gian Domenico Cassini discovered a large gap in Saturn's rings in 1675. Later, an astronomer named Encke discovered a smaller gap near the edge of the rings. ... It was found long ago that an orbit in the Cassini Division, as the large gap is named, has a period almost exactly one-half that of one of Saturn's moons named Mimas. ... 2008 Phil Plait. ...

Next: The Plan Up: No Title Previous: No Title . On the afternoon of 19 October 1999, it was discovered by John Briggs that the secondary mirror in the 2.5m SDSS telescope had developed a series of circular cracks around its axis of symmetry. As the telescope had not been in use since the early morning of 16 October 1999, there was a great deal of concern and consternation as to what caused these fractures in the glass. ... 11/24/1999 ...

... More than 300 surface reconstructions are already known for pure Si surface and Si surface with adsorbate. Study of their properties by the methods of surface physics reveal numerous interesting phenomena including various phase transitions accompanied by changes of Fermi-surface topology, development of the charge-density wave, etc . ... The charge-density wave (CDW) develops in materials with a chain-like crystal structure at temperatures below the Peierls transition temperature. ...

... Structure of Data . ... Catalog . ... In SAI OCL Catalog, we introduce our work on investigation of the Milky Way system of open star clusters. The main goal of our study is a search for new clusters using huge surveys. 168 new clusters have been already discovered by us using J,H,Ks data from 2MASS point source catalog. ... For 141 new clusters, we found their physical parameters using J,H,Ks data from 2MASS catalog and, for a number of clusters, our UBVRI CCD observational magnitudes. ...

... We have compared visualized fields of GSC and USNO A1.0 catalog with unpublished photographic finding charts that were sent by L. Plaut to the compilers of the GCVS. ... 7-15 A9 --- GCVS GCVS or NSV name 17-25 F9.4 --- GSC GSC number 26 A1 --- NoteFlag *Nonstar (GSC) flag 28-29 I2 h RA2000GSC.h Hours RA (GSC), equinox 2000.0 31-32 I2 min RA2000GSC.m Minutes RA (GSC), equinox 2000.0 34-38 F5.2 s RA2000GSC.s Seconds RA (GSC), equinox 2000.0 40 A1 --- DE2000GSC.- ... Plaut, L., 1966, Bull. ...

... The highest redshift X-ray jet discovered . by Chandra in GB 1428+4217 at z = 4.72 . X-ray jet discovered by Chandra . ... Science Papers on ADS . ... Chandra Press Release . The paper describing the details nas been published in ApJ and it is available also on astro-ph Feb. ... The jet paper published in ApJ Letters is available on astro-ph Oct. ... ApJ Letters paper available on astro-ph: Paper 2003 Feb. ... ApJ papers available on astro-ph: Paper 1, 2002 and Paper 2, 2007 . ...

Milky Way X-ray background emission « »: , . ... RXTE , . ... Using near-infrared Galaxy intensity measured with COBE/DIRBE experiment and X-ray data from RXTE and INTEGRAL it was shown that X-ray brightness of the Galactic background emission closely follows its stellar density and can be explained by a cumulative emission of a large number of weak Galactic X-ray sources. ... Map of Galactic background emission in hard X-ray energy band obtained with INTEGRAL observatory. ... 2006, &, 452, 169 ., ...