Now that your May 2009 issue of Astronomy is in hand, we’ve updated Astronomy.com with our newest web extras to give subscribers exclusive complementary information on this special collector’s edition that celebrates the 400th anniversary of Galileo turning his telescope to the sky.

Take a sneak peek inside the May 2009 Astronomy magazine.

If you subscribe to Astronomy, make sure you’re registered with Astronomy.com so you can access these great extras.

Here are the highlights:

• Associate Editor Liz Kruesi compares the optics of the first three telescope designs — Gregorian, Newtonian, and Cassegrain — in “The early reflectors.”
• Associate Editor Daniel Pendick asks “Experience Galileo’s Italy” author William Sheehan about his appreciation for the great astronomer's life and work.
• Senior Editor Michael E. Bakich details a night of galaxy hunting from Animas, New Mexico, in “Observing Ursa Major galaxies through a large scope.”
• Associate Editor Daniel Pendick answers the “Ask Astro” question: “What is the difference between an open cluster and a globular cluster?”
• Columnist and Contributing Editor Phil Harrington recommends some targets in Hydra and Corvus and offers a tip on holding your binoculars in “More southern-sky treasures.”
• And we’ve included a few more Q&As with Geoff Marcy, Jay Gallagher, and Sara Seager in “Astro Confidential: Extending the conversations.”

Of course, we’ve also posted “Bob Berman’s Strange Universe,” “Glenn Chaple’s Observing Basics,” “Phil Harrington’s Binocular Universe,” and “Stephen James O’Meara’s Secret Sky” columns for the May issue, in addition to “The Sky this Month” and “Ask Astro.”

Related:

• Blog: "On the road: Galileo's Italy," — Editor David J. Eicher's daily accounts of his experiences on the Galileo's Tuscan Sky tour, March 27–April 3, 2009
• Image gallery: "Italy: Galileo's Tuscan Sky tour" — Images from Editor David J. Eicher's trip.
• Video: "The day Galileo changed the universe" — Editor David J. Eicher talks about how Galileo turned a telescope toward the Moon
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