Astronomy Magazine

Text-only Version: Click HERE to see this thread with all of the graphics, features, and links.



Jim Colyer
I picked up the March, 2013, issue of Astronomy Magazine. It seemed like an interesting one. I have bought this magazine off and on ever since it began in August, 1973. David J. Eicher is the editor, and it is published by Kalmbach Publishing out of Waukesha, Wisconsin.


Several articles in this issue came to my attention. Liz Kruesi wrote one called "How Astronomer's Know the Universe's Age." They know the universe began 13.7 billion years ago, but how did they arrive at that age?

Liz begins by saying that 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 their amounts of thorium-232 and uranium-238. The oldest star known is HE 1523-0901 at 13.2 billion years.

Liz tackles the Hubble constant. This is the rate at which the universe expands. Edwin Hubble overestimated the constant. It took Wendy Freedman's team to come up with a constant of 74.3 kilometers per second per megaparsec. Knowing this value helps determine the universe's age.

The cosmic microwave background gives the best estimate of the universe's age. The Wilkinson Microwave Anisotropy Probe (WMAP) not only determined that the universe is flat but analyzed CMB fluctuations to set its age at 13.7 billion years.


Michael Bakich devoted 6 pages to exploring spring's best deep sky objects. Several are colorful and new to me.

1 The Broken Engagement Ring is an asterism of 7 stars near the Big Dipper.

2 The Silver Needle Galaxy (NGC 4244) is in Canes Venatici at magnitude 10.4. It sure looks like a needle.

3 Stargate is a cluster in Corvus the crow. 6 stars form 2 triangles, one inside the other.

4 The Leo Triplet is a set of 3 spiral galaxies in the constellation Leo. They are M65, M66 and NGC 3628.

5 The Theoreticians Planetary (IC 3568) is a "planetary nebula" near the north celestial pole. Of course, it is a dying star, not a nebula. It is more appropriately termed The Lemon Slice Nebula. It sure looks like a lemon slice. The Index Catalogue was an update of the New General Catalogue.

6 The Whale Galaxy (NGC 4631) is in Canes Venatici. It 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 get 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. But traveling the world for star parties and experiences in astronomy puts me in somewhat of an advanced group.


I knew Jen Winter and Fred Bruenjes were going to Australia for the November, 2012, solar eclipse. They are the pair from Astronomical Tours with whom I went to Bolivia. Michael Bakich wrote a piece about the eclipse for Astronomy. Naturally, they visited 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 shadow bands and Baily's beads. They saw prominences, the corona and 2 diamond rings. There were 2 minutes and 6 seconds of totality. After the eclipse, they flew to Ayers Rock. I went to Australia in 2002. My idea was to wait for the March 9, 2016, solar eclipse and to see it from Indonesia.


Yvette Cendes did an article about cosmic rays. I am always amazed at how many women are into astronomy. Yvette was working at the Pierre Auger cosmic ray observatory in Argentina. It is different, consisting of water tanks rather than mirrors or radio dishes. Cosmic rays are subatomic particles from outer space. Nobody says "outer space" anymore. I like it because it conjures up the romance of the 1950s. Yvette calls ultra-high-energy cosmic rays (UHECRs) the most energetic particles ever observed. They are rare and remain a mystery. As for me, I do not know the difference between cosmic rays and gamma rays. I do know that the Higgs bosun was named for Peter Higgs.


A sidebar discusses Zodiacal Light. This is sunlight being reflected by meteoroids in the plane of the solar system. It is visible in the west after sunset.


There has been a lot of talk about China recently, and Eric Peng contributed an article called "China's Race to Study the Cosmos." The Chinese have built the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST)in the Xinglong Observatory near Beijing. There will be a five-year spectroscopic survey of Milky Way stars.


Michael Bakich admonished us to get ready for Comet PANSTARRS. The comet will be closest to Earth on March 5. We will see it in the west after sunset, setting 15 minutes after the sun. On March 9, PANSTARRS will be at its brightest. It will be at perihelion, as close as it gets to the sun. It is estimated to be at magnitude -1.0. PANSTARRS will act as a prelude to Comet ISON in November.

Text-only Version: Click HERE to see this thread with all of the graphics, features, and links.