Sky & Telescope's March 2012 issue is now available to digital subscribers. Some print subscribers have already received it, and it's officially on-sale at newsstands starting January 31st.
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The March issue features a special report on a long-standing stellar mystery in astronomy: the nature of the star Epsilon Aurigae. Epsilon Aur has befuddled observers since they first noticed variations in its brightness nearly 200 years ago. Every 27 years the star dims for at least 18 months — but there’s no companion star to be seen that could explain the dip by blocking the light in an eclipse. Now, an international campaign by amateur and professional astronomers may finally have built up enough evidence to clear up the enigma.
The solution? A thick, elongated disk surrounds a hidden hot, massive star, and as this disk passes in front of the bright, white-yellow star that we normally see, the light dims.
The details of this picture look pretty solid, and indeed when the issue went to press the staff here were pretty much convinced. But not everyone’s onboard yet. While at the American Astronomical Society meeting in Austin, I ran into Edward Guinan (Villanova University) and his student, Cole Johnston. They were presenting work done with an American, Czech, and Croatian team that suggests the primary star is roughly five times more massive than reported by Robert Stencel (University of Denver) and his collaborators in S&T. Stencel says he isn’t convinced by the other team’s high-mass results, and the debate continues. As Stencel puts it, “That’s what makes Epsilon Aurigae such fun — honest people can disagree!” You can listen to an interview with Stencel in our Beyond the Printed Page content.
Epsilon Aurigae isn’t the only mystery in the March issue. A strange glow from Venus’s nightside, called the ashen light, has puzzled astronomers even longer than Stencel's eclipsing binary. Thomas Dobbins explores what this light might be, admitting that he, too, once thought it was merely a trick of the eye until he saw it for himself.
Tracking down where the Sun might have shone its first light, spotting all five classical planets, and picking telescopes for peeking at the Sun — all these adventures and more can be had in the March issue. To find out more, read our online Table of Contents.