Dean W. Armstrong

I have never seen a noctilucent cloud. I've been far enough north before, roughly the arctic circle, but I was up there in September a...

The live radiation readings from the Reg is back up and running. I took it down to use it for the Scavenger Hunt this year. The item was...

My apologies--I've been visiting an ailing family member, but am back in Chicago.

A fragmenting comet passed the Ring Nebula yesterday: Animation from Horace Smith Color image from Stefan Seip / Steffen Brückner . Spacewe...

I spent today trying to do all of the maintenance work at the Ryerson Observatory that has been long-delayed by lack of time. We generally...

Wonderously descriptive imagery of the earliest moments of the gas giants by Greg Laughlin at systemic : The atmosphere bulks up fast. Libe...

Epimetheus glides in front of Saturn's rings with Titan far in the background. Phil Plait's Bad Astronomy has pointed out another ...

Check out this awesome movie of the aurora as seen from the ISS: Movie Also see Astronaut Don Pettit's longer science movie with real-...

This weekend I traveled to Yerkes Observatory in Williams Bay, Wisconsin, on a trip organized by the Ryerson Astronomical Society . It was...

The Messenger spacecraft on its way to Mercury flew back past Earth on August 2nd, 2005, and produced this wonderful movie while departing ...

Steven previously mentioned his favorite absorption line in the sun's spectrum as sodium. And what's not to like: Strong, conspicu...

A recent flight to Los Angeles had great results. Halfway through the flight the pilot announced he was dropping from the 38,000ft cruising...

Mike Brown, Emily Schaller, Henry Roe, David Rabinowitz, and Chad Trujillo released their Hubble measurements of the disk of 2003 UB313 and...

I had the good fortune of being quite busy over the weekend: I was a guest of Hugh M. Hefner at the occasion of his 80th birthday , and it ...

While on the couch in my apartment in the late-evening last night the light of the just-past First Quarter Moon fell upon my eyes. It told...