ASTRONOMY MAGAZINE The March, 2013, issue of Astronomy Magazine was an interesting one. I have bought this magazine off and on ever since it began. David J. Eicher is the editor, and Kalmbach Publishing out of Waukesha, Wisconsin, is the publisher. Several articles caught my eye. LIZ KRUESI wrote one called How Astronomers Know the Universes Age. They know the universe is 13.7 billion years old, but how did they arrive at that age? Kruesi begins by saying the universe is older than the objects in it and that the original stars are gone. The sun is a third generation star and contains more heavy elements than previous generations. Astronomers determine the age of stars by measuring the amounts of uranium-238 and thorium-232. The oldest star known is HE 1523-0901 at 13.2 billion years. Kruesi tackles the Hubble constant. This is the rate at which the universe expands. Edwin Hubble overestimated his constant. It took Wendy Freedmans team to come up with a constant of 74.3 kilometers per second per megaparsec. Knowing this value helps to determine the universes age. The cosmic background radiation gives the best estimate of the universes age. The Wilkinson Microwave Anisotropy Probe (WMAP) not only determined that the universe is flat but analyzed fluctuations to set its age at 13.7 billion years. MICHAEL BAKICH devoted 6 pages to exploring springs best deep sky objects. Several were new to me: 1 The Broken Engagement Ring is an asterism near the Big Dipper. 2 The Silver Needle Galaxy in Canes Venatici sure looks like a needle. 3 Stargate is a cluster in Corvus. 6 stars form 2 triangles, one inside the other. 4 The Leo Triplet is a set of 3 spiral galaxies. They are M65, M66 and NGC 3628. 5 The Theoreticians Planetary (IC 3568) is a planetary nebula near the north celestial pole. It is a dying star, not a nebula. It is more appropriately called the Lemon Slice Nebula. The Index Catalogue is an update of the New General Catalogue. 6 The Whale Galaxy in Canes Venatici is an edge-on spiral. It sure looks like a whale. 7 The Hockey Stick Galaxy (NGC 4656-7) is an irregular galaxy near Cor Caroli. Astronomers see a stick and a blade. 8 The Antennae (NGC 4038 & NGC 4039) are two galaxies colliding. They got their name from tails caused by tidal interaction. 9 The Eyes (NGC 4435 & NGC 4438) are two interacting galaxies in Virgo. They sure look like eyes. BOB BERMAN does a column for Astronomy Magazine. In the March issue, he names various categories of astronomers. I am no beginner. Nor am I a backyard amateur in that I no longer have a telescope. Traveling the world for star parties puts me in the advanced group. Jen Winter and Fred Bruenjes went to Australia for the November, 2012, solar eclipse. They are the ones from Astronomical Tours I went to Bolivia with. Michael Bakich wrote a piece about this eclipse. Naturally, the group paid a visit to the Sydney Opera House and crossed the Harbor Bridge. They flew to Cairns for the main event, which occurred shortly after sunrise. They witnessed first contact as the moon bit into the sun. They saw Bailys beads. They saw prominences, the corona and diamond rings. There were 2 minutes and 6 seconds of totality. YVETTE CENDES did an article about cosmic rays. I am amazed at how many women are into astronomy. CENDES worked at the Pierre Auger cosmic ray observatory in Argentina. It consists of water tanks rather than mirrors or radio dishes. Cosmic rays are subatomic particles coming from outer space. Nobody says outer space anymore! I like it because it conjures up the romance of the 1950s. CENDES says ultra-high-energy cosmic rays (UHECRs) are the most energetic particles ever observed. They remain a mystery. As for me, I do not know the difference between cosmic rays and gamma rays. A sidebar discusses Zodiacal Light. This is sunlight reflected by meteoroids in the plane of the solar system. It is visible in the west after sunset. ________________________________________________________________________________________________________________________________________________ The August, 2013, Astronomy Magazine celebrated the magazines 40 years in existence. I think I bought the first one. This issue boasted several 40 articles: 1) 40 greatest astronomical discoveries 2) 40 greatest mysteries of the universe 3) 40 years of amateur astronomy 4)40 deep-sky targets in Sagittarius. RICHARD TALCOTT listed the 40 greatest astronomical discoveries: #2 Copernicus heliocentric model placed the sun at the center of the solar system. #6 Hans Bethe showed that stars generate energy by nuclear fusion, turning hydrogen into helium. #12 William Hershel discovered Uranus in 1781. #16 Alvan Clark discovered Sirius B, the first known white dwarf. White-dwarfs are the final stages in the evolution of sun-like stars. #22 In 1995, Swiss astronomers confirmed the first exoplanet orbiting a sun-like star: 51 Pegasi. 1797 exoplanets have been confirmed as of June, 2014. #23 NASA satellites identified Cygnus X-1, the first known black hole. #25 Harlow Shapley figured out that the center of the Milky Way is in the direction of Sagittarius. #28 Edwin Hubble proved that the Andromeda Galaxy M31 lies outside of the Milky Way. #29 A supermassive black hole was found at the center of the elliptical galaxy M84. It became apparent that black holes are at the center of many large galaxies, including our Milky Way. #33 Edwin Hubble showed the universe to be expanding and that the farther galaxies travel, the faster they go. #34 Albert Einsteins General Theory of Relativity explained gravity as a warping of space/time. It explained black holes and gravitational lensing, the bending of light around massive objects. #40 Dark energy was found to be responsible for the universe expanding at an ever increasing rate. SARAH SCOLES explored the 40 greatest mysteries of the universe. Q How big is the universe? A The diameter of the observable universe is 96 billion light-years. Q Do we live in a multiverse? A Inflation theory suggests we may. Q Do gravitational waves exist? A If so, they are ripples in space/time caused by the merging of black holes. Q How many galaxies are in our Local Group? A 63 are known. Many are dwarf galaxies. The Local Group is part of the Virgo Supercluster. Q What is space/time like outside black holes? A The Event Horizon Telescope will image the event horizon around Sagittarius A*, the Milky Ways black hole. Q How many stars have rocky planets? The Kepler Space Telescope suggested that 17% of sun-like stars have Earth-size planets. Q What were the primordial sources of organic matter? A Stars manufacture organic molecules, then eject them into space. Organic matter was produced in our presolar nebula. Q What percentage of stars have planets? A There are at least as many planets in the Milky Way as there are stars. All stars may have planets. Q How would we recognize the presence of extraterrestrial life? A We might detect methane made by metabolizing cells or synthetic chemicals produced by intelligent life. MICHAEL BAKICH presented the highlights of 40 years of amateur astronomy. Professional astronomers draw a sharp distinction between themselves and amateurs. 1973 - The first issue of Astronomy Magazine on the stands in August. 1979 - Deborah Byrd of EarthSky helped to organize the Texas Star Party. 1987 - Supernova 1987A appeared in the Large Magellanic Cloud. 1991 - The first Grand Canyon Star Party. 1994 - Fragments of Comet Shoemaker-Levy 9 hit Jupiter. 1996 - Comet Hyakutake was discovered by a Japanese amateur. 1997 - Comet Hale-Bopp reached perihelion on April 1. 2001 - The Leonids produced a meteor storm with an estimated 1000 meteors per hour. 2012 - Transit of Venus on June 5. MICHAEL BAKICH compiled 40 deep sky targets in Sagittarius. Sagittarius has many interesting deep sky objects from the Messier, NGC, IC and Barnard catalogs. The Little Gem (NGC 6818) - Planetary nebula M25 (IC 4725) - Open cluster Small Sagittarius Star Cloud (M24) - Star cloud Barnard 92 - Dark nebula NGC 6590 - Reflection nebula Trifid Nebula (M20) - Emission nebula Lagoon Nebula (M8) - Emission nebula Starfish Cluster (NGC 6544) - Globular cluster Castaway Cluster (NGC 6520) - Open cluster Chandelier Cluster (NGC 6723) - Globular cluster Barnards Galaxy (NGC 6822) - Irregular galaxy .
Posted on: Mon, 24 Nov 2014 17:25:59 +0000
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