T he Sun is an ordinary G2 star, one of more than 100 billion stars in our galaxy. diameter : 1,390,000 km . mass : 1.989e30 kg temperature : 5800 K (surface) 15,600,000 K (core) T he Sun is by far the largest object in the solar system. ... C onditions at the Sun's core are extreme. ... I n addition to heat and light, the Sun also emits a low density stream of charged particles (mostly electrons and protons) known as the solar wind which propagates throughout the solar system at about 450 km/sec. ...

... The Trifid nebula (M20) is a bright star forming region in Sagittarius, 5000 light years from Earth. In visible light, the interstellar gas cloud is crossed by dark, obscuring dust lanes which roughly divide the glowing emission nebula into three major parts. ... Sometimes the sky itself seems to glow. ... If the glow appears as a faint band of light running across the whole sky, you are probably seeing the combined light from the billions of stars that compose our Milky Way Galaxy. ...

Astronotes Armagh Planetarium's Stellar Blog! ... Solar System . Sun . ... March . ... The extent of the solar eclipse of 3 November€а 2013 at 13:22 UTC as seen from Accra, Ghana. We will see a similar sight.€а (Image credit: Kwabena under Creative Commons Licence) . ... Your viewing location is not important as long as it offers an unobstructed view of the south eastern sky.. ... You can use ?eclipse glasses? to view the Sun, these are made from aluminized Mylar filter material. ...

... We present a computer program for modelling energy flux distribution and light curves of eclipsing binaries from far ultraviolet to infrared regions. The Roche model is assumed. Proximity effects of components (reflection of radiation and surface gravity darkening) are taken into account. ... Figure 1: The surface temperature distribution for Algol A-B system before (upper plot) and after (lower plot) correction for temperature due to the irradiation effect. ...

Jupiter is the largest of the nine planets, more than 10 times the diameter of Earth and more than 300 times its mass. ... The mean density of Earth is 5.245 times that of water. The pull of gravity on Jupiter at the top of the clouds at the equator is 2.4 times as great as gravity's pull at the surface of Earth at the equator. ... It is tipped about 11њ to Jupiter's axis of rotation, similar to Earth's, but it is also offset from the center of Jupiter by about 10,000 kilometers (6,200 miles). ...

... Tonight's Sky . ... The Magazine . ... Observing . ... The double star 54 Leonis, spiral galaxy NGC 3198, and emission nebula NGC 3199 . ... Astronomy for Kids . ... Observing springtime deep-sky objects with a large telescope . ... Bright planets meet at dusk . ... Astronomy magazine subscribers can read the full article for free. ... Get instant access to subscriber content on Astronomy.com! ... Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter....

... NASA SPACECRAFT FINDS NEW EVIDENCE FOR WATER ICE ON MERCURY . ... The new data indicate the water ice in Mercury's polar regions, if spread over an area the size of Washington, D.C., would be more than 2 miles thick," said David Lawrence, a MESSENGER participating scientist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., and lead author of one of three papers describing the findings. ... Water ice concentrations are derived from the hydrogen measurements. ...

Venus in visible light (violet filter) 17k jpg . Venus in visible light 73k gif . image from Pioneer Venus 15k jpg ; 28k jpg ( caption ) . ... UV image from HST WFPC2 (false color) 23k jpg ; 99k gif . ... New Magellan mosaics (5 hemispheres) 13500k tiff ; ( caption ) . ... 7 pancake volcanoes, alpha region 227k gif ; . Lada Regio, 47 deg S, 25 Long, showing mountains and craters 121k gif ; . ... False color IR image of Venus' lower clouds as seen by Galileo 37k jpg 112k gif ( caption ) . ...

The Earth's magnetosphere global structure is conditioned by the interaction of the Solar wind and Earth's magnetic field. ... Many various magnetospheric models are available in the NSSDC . ... Fairfield D. H., Average and unusual location of the Earth's magnetopause and bow shock, J. Geophys. ... Stasiewicz K., Polar Cusp Topology and Position as a Function of Interplanetary Magnetic Field and Magnetic Activity: Comparison of a Model with Viking and other Observations, J. Geophys. ...

... Science highlights . Exoplanets Disks 2016 . ... My post on the STScI science blog: "Disk, gaps, and exoplanets - a journey on the wings of a dragonfly" . ... Read here the scientific publication of this work, on the Astrophysical Journal: Banzatti Pontoppidan 2015, ApJ, 809, 167 . Read here a more poetic description on the STScI science blog: "Disk, gaps, and exoplanets - a journey on the wings of a dragonfly" . ... Do exoplanet compositions retain the imprint of large-scale disk processes? ...

... Australia Telescope Compact Array Radio Imaging of the Proplyd-like Objects in the Giant HII Region NGC 3603'' . M?cke, A., Koribalski, B.S. , Moffat, A.F.J., Corcoran, M.F., Stevens, I.R. 2002, ApJ 571, 366 . ... Brenneman, L., Corcoran, M.F., Moffat, A.F.J., Marchenko, S.V., Ptak, A., Skalkowski, G., Mushotzky, R., Stevens, I.R., Mueke, A., Koribalski, B.S. , et al. ... Physical Properties of visual counterparts to X-ray sources in the giant HII region NGC 3603'' . ...

PixelVision Inc. ... Soft X-ray Imaging Systems . ... Figure 1: Schematic of a Back-Illuminated CCD . ... To complete CCD thinning, the back surface must be specially "treated" or very low and very unstable responsivity will be exhibited. ... Figure 2: Back-illuminated CCD electron hole pair generation rate as a function of depth from back surface . X-ray detection occurs in a CCD when a high-energy primary x-ray dissipates its energy in the silicon of the back-illuminated CCD. ...

... The March 20 total solar eclipse was visible over the North Atlantic and Arctic Oceans. ... Solar eclipses are of interest for radio astronomy, as they make it possible to observe individual details on the solar disc (spots, filaments, flocculi, etc.) ... On March 20, 2015 the integrated observations of the solar eclipse were carried out at the RATAN-600 radio telescope at 70 wavelengths simultaneously in the range of 1.65cm to 10cm with the 1% frequency resolution. ...

... Science User Portal . ... ESO, the European Southern Observatory . ... Travel and Contacts . Travel to ESO Headquarters . ... Travel to Guesthouse . ... Survey Telescopes . ... This video fades back and forth between views of the stellar nursery Monoceros R2 in visible and infrared light. The visible-light view was created from digitised photographs through red and blue filters forming part of the Digitized Sky Survey 2 (DSS) and the new infrared view comes from the VISTA telescope at Paranal. ...

... Australia?s 2002 Total Eclipse of the Sun . ... A total eclipse of the Sun is arguably the most awesome sight in all of nature. Day is suddenly replaced with an eerie twilight and the Sun?s brilliant disk is blocked by the dark Moon. ... This incredible spectacle is visible once every year or two when the Moon?s small dark umbral shadow races across our planet?s surface. The ensuing path of totality is typically about 150 kilometers wide but can stretch halfway around the globe. ...

The SOHO spacecraft currently supplies daily images of the solar corona at 1.1-3, 2-6 and 4-30 solar radii. Are ground-based solar corona observations during total solar eclipses have becoming obsolete nowadays? A quick view of SOHO data shows that it is not perfect in some respects. ... On March 9, 1997 an expedition has been organized by the Russian Academy of Sciences to the Baikal region in Siberia for observation of the total solar eclipse. ... Fig. ... Lens: F = 1m, D = 170 mm . ...

... Conjunction Over Armagh . ... Comet and Pleiades . ... Pleiades . ... Antares Region . Helix and Cat's Eye Nebulae . Orion Nebula . Lagoon and Eagle Nebulae . Crab Nebula . ... Our Galaxy Core . Andromeda Galaxy . Wide-field and Zoomed-in Galaxies . Interacting Typhoons and Galaxies . Spiral Galaxy M106 . Sombrero Galaxy . Whirlpool Galaxy . Colliding Galaxies . ... й Miruna Popescu, Armagh Observatory ...

... Series 4000 filters thread into the barrels of virtually all 1.25" eyepiece brands. Meade Series 4000 filters are a large 26mm in clear aperture and are manufactured from the purest crown optical glass, dyed-in-the-mass ( not "color coated"); there are no finer filters available for telescopic applications. ... For visual applications Series 4000 filters thread into the barrels of all Meade 1.25" eyepieces, and into the barrels of virtually all other 1.25" eyepiece brands as well. ... Meade 4M | ...

... 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]. ...

Class 1 Introduction, Background History of Modern Astronomy The Night Sky, Eclipses and the Seasons Kepler's Laws Newtonian Gravity General Relativity Matter and Light Telescopes Class 2 Solar System Characteristics Formation Exosolar Planets Class 3 Stars The Sun Stellar Evolution of Low and High Mass Stars Deaths of Stars Exotic Stars Class 4 Galaxies Galaxy Classification Formation of Galaxies Galactic Evolution ... So far, one planet has been studied by this method. ...