This week, I conclude my three-part series on filters by discussing specialty filters. Everyone's welcome to their opinion, but, to me, any filter that's not a color filter is a specialty filter. Most specialty filters fall into the category of "light-pollution-reduction" (LPR) filter. Two exceptions are neutral density and polarizing filters. A neutral density (ND) filter reduces the amount of light (by absorbing it) but doesn't...

Saturn's rings glint brightly thanks to the "opposition effect" in this June 12 image, taken by the Cassini spacecraft. NASA/JPL/SSI While I was out walking Wednesday evening, brilliant Jupiter stood slightly above the gibbous Moon. With the Moon waxing toward its full phase this weekend, I couldn't help but think about how quickly our satellite brightens as Full Moon approaches. As if to drive the point home, NASA has just released...

Q: What's the difference between trash and important archaeological artifacts? A: About 100 years. Where people tossed their garbage a century ago, archaeologists can often find revealing remnants of culture. On the Moon, the transformation from trash to treasure took less than 4 decades. U.S. astronauts left a lot more behind on the Moon than their footprints as they took small steps for man and giant leaps for mankind. The detritus at Tranquillity...

This week, I continue my three-part series on filters by giving specific recommendations about planetary observing through color filters. Mars lies at opposition as 2007 ends, and it's already on most observers' minds, so let's start with the Red Planet. As I mentioned last week, choose the filter density that's correct for your telescope. For example, if I suggest a red filter for a certain feature, choose 1) a #21 (orange) filter...

I just read, with a mixture of fascination and embarrassment, writer Nancy Atkins' compelling article — posted on the Universe Today web site — about the realities of landing humans on Mars. The article asks the simple question of how we would land a crewed spacecraft on Mars. She does a beautiful job with it, and you should stop right here and read the article for yourself. My embarrassment is in regard to the fact that the whole...

The first photo ever taken from the surface of Mars showed lots of rocks and sand — and the footpad of the Viking 1 lander. NASA/JPL Virtually everyone who reads this blog knows what happened on this date in history. But I'm not going to spend much time talking about Neil Armstrong's and Buzz Aldrin's small steps. Instead, I want to recall a lesser leap in human history, one that launched our search for life elsewhere in the universe...

Dava Newman models her BioSuit on the MIT campus. Donna Coveney Ever since NASA has launched people into space, astronauts have worn bulky, gas-pressurized outfits. Over time, these suits have increased in weight to 300 lbs. — limiting mobility. Thanks to MIT, astronauts could don a sleeker outfit on future missions. Dava Newman, Jeff Hoffman, her students, and design firm Trotti and Associates have designed a Spandex and nylon BioSuit. According...

Do you want a little help appreciating the utter inherent coolness of the Mars Exploration Rover missions? Check out the video created by up-and-coming digital artist Daniel Maas . The 9-minute video, accurate to the smallest detail, depicts the launch, landing, and surface meanderings of a rover. Two of the robotic buggies, Spirit and Opportunity, remain alive and well on Mars. My favorite sequence is the rover's bouncy air-bag landing, after...

With Mars beginning to brighten to its best appearance of the year (which will happen Christmas Eve), I thought I'd blog about filters. Lots of articles will explain the best way to observe Mars — you can catch mine in December's Astronomy — and they'll all have something to say about color filters. It's a big subject, so I'm breaking it down into three parts. First, a small point about filters. No filter makes any...

Several dark spots mar Jupiter’s atmosphere after Comet Shoemaker-Levy 9 smashed into it between July 16 and 22, 1994. NASA/Hubble Space Telescope Science Team Where were you 13 years ago? If you're like me, you were eagerly anticipating a once-in-a-lifetime event — with no clue as to how it would play out. Astronomers and backyard observers around the globe had their sights set on Jupiter. More than 20 fragments of a rogue comet known...