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 . ...

In this gallery are many images of Low Surface Brightness Galaxies which have recently been discovered and analyzed. ... The central surface brightness of this galaxy is 24.28 . Malin 2 This galaxy is another huge disk galaxy with a scale length of 15 kpc and a redshift of 15000 km/a. The high surface brightness knot in one of its spiral arms actually has the same color, luminosity and H-alpha equivalent width as the entire Large Magellanic Cloud . ... Truly it is a Low Surface Brightness Galaxy. ...

... 2013 July 31 . 130 Years of Earth Surface Temperatures . Image Credit: GISS , NASA . Explanation: How has the surface temperature of Earth been changing? ... On average, the display demonstrates that the temperature on Earth has increased by nearly one degree Celsius over the past 130 years, and many of the warmest years on record have occurred only recently. ... About APOD | ... NASA Official: Phillip Newman Specific rights apply . NASA Web Privacy Policy and Important Notices . ...

... 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.( ...

Supernova 2009js in NGC 918 . This page is devoted to information on Supernova 2009js in NGC 918 . Basic information on this SN, including the last reported brightness, on this Supernova can be found on the main page . Information on the original web pages for many of these images can be found on the updates and links web pages. Discovered independently by Lick Observatory Supernova Search (USA) and Koichi Itagaki (Japan). ... 2009/10/11.44 . 17.2 . ... Joseph Brimacombe . ...

... 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. ...

... Scientists from G. I. Budker Institute of Nuclear Physics- Syberian Branch of the Russian Academy of Science, Novosibirsk State University, Novosibirsk State Technical University, Samara State Aerospace University (SSAU) and Image Processing Systems Institute (IPSI) of the Russian Academy of Science, became the first people in the world obtained terahertz non-diffractive twisted Bessel beams and used them for the first time the formation of surface electromagnetic waves on the metal surface. ...

... 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. ...

... 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]. ...

... several mechanisms of sound generation by electromagnetic waves, all specific for low temperatures, were disclosed and studied (V.F.Gantmakher and V.T.Dolgopolov; see Sov.Phys.-JETP 30, 78 (1970); . ... it was demonstrated that quantum oscillations of conductivity in bismuth had smaller period near the crystal surface that in the bulk (S.S.Murzin and V.T.Dolgopolov, JETP Lett. 37, 696 (1983); . ... JETP 74, 905 (1992); 76, 714 (1993); 77, 513 (1993); 78, 226 (1994); 82, 951 (1996); JETP Lett. ...

Image credit: Michael Nolan, Arecibo Observatory. These radar images of near-Earth asteroid 2001 SN263 were obtained on 2008 Feb 12 and 13. ... Image from Feb 12 . ... First near-Earth triple asteroid discovered by Arecibo Observatory . ... was discovered this week by astronomers at the sensitive radar telescope at Cornell University?s Arecibo Observatory in Puerto Rico. ... For example, Arecibo has discovered more than half of the near-Earth binary asteroid systems discovered since 1999. ...

... 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. ...

... Be Stars . ... Stellar Winds . ... He had found the first emission line star. ... More emission line stars were found soon, and one had to make subclasses to keep some overview. Cas is a main sequence B-type star, and together with other such stars showing hydrogen emission it forms the class of "Be stars", where the "e" stands for emission. ... Struve further speculated that those stars would be surrounded by a disk, basically thrown off the stellar surface by the rapid rotation. ...

... 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 . ... solar system . ... Scientists discover factors to predicting changes in comet rotation . ... Scientists studied comets including 103P/Hartley, shown here, to develop a way to predict rotational changes in comets. ... PSI Senior Scientists Nalin H. Samarasinha and Beatrice E.A. Mueller have determined such changes are a function of a comet s size, period, and the solar energy it receives, but surprisingly not a function of the fraction of a comet s surface that is active. ...

... Brown dwarfs are small, cool objects - they become very faint, very quickly. ... Next . ... look in young star clusters Next . ... One of the primordial elements present in every star and brown dwarf at formation is lithium. ... It was a different search technique, however, which turned up the first unequivocal example of a brown dwarf: searching for companions to stars known to be relatively close to the Sun. ... The primary star is an M dwarf only 17 light years from the Sun, L ~ 0.02 L(sun) . ...

Giant Jupiter. Jupiter . ... Jupiter has no solid surface that is why speaking about its dimensious point the radius of the upper border line of the clouds, where the presseru is about 10 KPa; radius of Jupiter on the equator is 71400 km. ... The Jupiter satellites. ... Nowadays 16 satellites of the Jupiter are known: Adrastea, Mitis, Amaltea , Phina,then 4 Galilei satellites: Io , Europe , Hanimed , Callisto , Leda, Aimalia, Zicitea, Elara, Ananke, Carme, Pasipe and Sinope. ... Jupiter's ring. ...