An Ancient Universe: How Astronomers Know the Vast Scale of Cosmic Time . THE CHANGING UNIVERSE: EVOLUTION HAPPENS! . b) Changes in Stars . One of the great discoveries of modern science is that stars (like people) live only a measurable life-time and then die. Although the lives of the stars are enormously longer than the span of a human life, we can learn about the life story of the stars by studying them at many different stages in their life cycle, from birth to death. ...

... Stellar Evolution is driven entirely by the never ending battle between Pressure and Gravity . As imbalances are reached, the star is driven to find a new Energy source. ... Pressure and gravitational forces are equal, the star is stable and its core is sufficiently hot to fuse Hydrogen into Helium More about main sequence stars . ... The luminosity generated by the core fusion of Helium into Carbon is far greater than the shell luminosity associated with the fusion of Hydrogen into Helium. ...

For Cycle 9 the Science Program Selection Office (SPSO) has changed the selection process to ensure that HST will continue to perform the best possible science with the best return for the astronomical community. This report summarizes the changes to the selection process and offers suggestions on writing an effective proposal that accounts for these changes. ... Fewer panels: With more orbits to allocate, each panel will have more flexibility, especially to approve the somewhat larger proposals. ...

As in the last years, the Ephemerides of Minor Planets for 2015 are prepared by the IAA RAS only in the electronic form. ... Orbital elements of all numbered planets have been determined in IAA all over again on the ground of available observations in the catalog of the Minor Planet Center. ... More detailed information on orbital elements used in the present volume of EMP and their accuracy is given in section "Information on new orbital elements". ... a) information on new orbital elements; . ...

... Bad Astronomy . ... I think I will break from my usual format of Bad Astronomy/ Good Astronomy by saying that the way we define seasons currently is not strictly bad, but I feel (in my opinion!) that it could be better. The definition of when the seasons begin is at the moment of solstice or equinox; that is, winter (in the north) starts on December 22 nd and summer starts on June 22 nd . ... Now imagine breaking up the Sun's 46 degree up-and-down yearly swing into 1 day intervals. ...

Chiaki Kobayashi, Ralph Sutherland How galaxies did form and evolution? - to answer this unsolved problem, we are simulating the formation and evolutionary history of galaxies in the Universe, including star formation, supernovae feedback, and chemical enrichment. Comparing the spacial distribution of elements within galaxies with observations, we will examine fundamental physical processes that drive galaxy formation. ... COALA : Universe Galaxy AGN Star Planet ...

... Tonight's Sky . ... The Magazine . ... Star Atlas . ... An artificial comet holds secrets to Earths life . ... Astronomy for Kids . ... Observing springtime deep-sky objects with a large telescope . ... The planet has extreme temperature swings and perhaps active lava flows. ... A digital supplement to Astronomy magazine. ... Join TravelQuest International with Astronomy and Discover magazines on one of three great tour options surrounding this celestial spectacle . ... Astronomy Magazine . ...

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 S un Stellar Evolution of Low and High Mass Stars Deaths of Stars Exotic Stars Class 4 Galaxies Galaxy Classification Formation of Galaxies Galactic ... Low mass stars live and die differently than high mass stars. ...

... Stellar cinders . Born-again stars . ... Heavyweight Stars . ... What will happen inside the Sun and why? ... These are questions about "stellar evolution", the history of stars as they are transformed by nuclear processes deep inside. ... Most of what we know about stellar evolution comes from computer models of stars. ... We learn about the evolution of high-mass stars from HR diagrams of young galactic open clusters, and the evolution of low-mass metal-poor stars from old globular clusters. ...