Crossing Saturn’s Rings

The Cassini imaging team (CICLOPS, the Cassini Imaging Central Laboratory for Operations) just released some new images of Saturn today. Among them is this incredible time-lapse video from photographs Cassini took as it crossed Saturn’s ring plane. You can see how thin the rings are as the orbiter crosses them.

The spacecraft crosses the ring plane twice each orbit. This video represents approximately twelve hours and so runs around a thousand times faster than real time. Cassini starts on the sunlit side of the rings, then crosses to the darker side. We see six moons during the video, though the smaller ones aren’t really visible at the low-resolution version of the video I’ve shown here. A high-resolution version is available at the CICLOPS web site and is definitely worth the download. The first large moon is Enceladus; the second one is Mimas.

The Cassini spacecraft was launched from Earth on 15 October 1997 as part of the Cassini-Huygens mission, a joint project between NASA, the ESA (European Space Agency), and the Italian Space Agency. It entered into Saturn orbit on 1 July 2004. It is the first spacecraft to orbit Saturn and the fourth one to visit it (after Pioneer 11, Voyager 1, and Voyager 2).

(Thanks to the Bad Astronomer for the link!)


The Moon and Saturn

On 2 February, the moon drifted right past Saturn’s position in the sky (from the point of view of Earth, of course). It made for quite a lovely sight, though as the moon approached its closest, it would not have been possible to make out the dot of Saturn right next to the extremely bright full moon—with the naked eye, that is.

P-M Hedén maintains a great web site with his collection of astrophotography; he captured this beautiful portrait of both worlds:

View of full moon and Saturn

Copyright P-M Hedén. Used with the author’s permission.

The full-sized version is quite striking. Both worlds are essentially on the opposite side of Earth from the sun, so they are fully lit from our view. The contrast of the incredibly sharp detail of the moon’s geologic features with the blurriness of Saturn, as well as the remarkable size difference, just underscores the unbelievably vast distance between Saturn and Earth.

It’s a wonder we’ve been able to guide spacecraft to Saturn and beyond.

Planet and Star Size Comparison

Via THS Earth/Space Science (a weblog for a 9th-grade science class), I came across this neat animation comparing the relative sizes of planets in our solar system and various stars. It really does a good job!

Humans evolved on Earth, and our brains do a poor job grasping sizes much larger (or much smaller) than that which we’d find in our typical environment. True, we can describe it mathematically, but it’s so difficult to really see the comparison.

Unfortunately, I do not know who the creator of this video is. No credits are given, and a web search was unsucessful. It is perhaps European, based on the spelling of the star names. If anyone has any information, please let me know.

Update: It appears the original video used copyrighted music without permission of the copyright holder, and has been removed. I changed the post to a different version of the video without music.

Update #2: The old link no longer worked (thanks, Sara!) so I updated it.

What Does the Atmosphere Say About Earth?

To date, astronomers have discovered about 209 extrasolar planets; that is, planets outside our solar system. From Earth, it is quite difficult to even detect them, much less learn anything about them. We haven’t been able to determine much about these planets—usually only the mass—though we’ve been able to get glimpses of atmosphere in a couple cases.

Of course, we have no idea if there is life on other planets, or how we might detect it. One way to think about it is to imagine what other life forms might think of Earth if they were to stumble across it.

Continue reading “What Does the Atmosphere Say About Earth?”

Space News Update (11 Jan 2007)

In recent years, NASA, the United States’ space agency, has been dominating exploration of the solar system. At Mars, NASA has two craft in orbit (2001 Mars Odyssey and Mars Reconnaissance Orbiter—plus the recently lost Mars Global Surveyor, and the two rovers Spirit and Opportunity on the surface), while Europe has the Mars Express. But as Stephen Battersby reports in New Scientist, Euprope is contemplating additional moon and Mars missions, including speculating on the possibility of human spaceflight.

Also, Bill Christensen at writes about a proposed partnership between Google and NASA. Google will help process the data and make it available to the public. Google doesn’t seem to derive any significant direct benefits, but it certainly isn’t making enemies by its continued support of science and nerdy topics in general.

NASA Finally Switches to Metric

Map showing that only the United States, Liberia, Myanmar, and Thailand have not switched to the metric system.
Countries primarily using non-metric systems of measurement (Liberia, Myanmar, Thailand, and the United States). Source: Wikipedia.

As reported in,

When NASA returns astronauts to the Moon, the mission will be measured kilometers, not miles.

The agency has decided to use metric units for all operations on the lunar surface, according to a statement released today.

(continue reading at

Continue reading “NASA Finally Switches to Metric”

Dark Matter, in Three Dimensions

Image comparing distribution of normal and dark matter
Comparison of the large-scale structure of normal matter and dark matter. Credit: NASA, ESA, and R. Massey (California Institute of Technology)

The American Astronomical Society is meeting in Seattle, and researchers just announced the results from an intense, international, multi-telescope survey looking deep into the universe. Using data from the survey, called COSMOS, astronomers were able to map out the distribution of dark matter and compare it to the distribution of normal matter. The data confirmed several theories we have, though we’re still quite far from understanding even the fundamentals of dark matter.

It has been theorized that dark matter became arranged in enormous filaments as the universe cooled after the big bang. And since normal matter would be gravitationally attracted to the dark matter, we would expect that galaxies would be distributed along the dark matter filaments as well. As you can see in the accompanying image, they match up remarkably well. There are some discrepancies, though they may be related simply to the limits of our ability to detect all the matter. Continue reading “Dark Matter, in Three Dimensions”

New Year 2007

As we approach the arbitrary point many cultures have decided to designate as the boundary between years, I would like to wish everyone a Happy New Year. It is customary for media to publish reviews (often themed) of the past year, so I thought I would share with you some of my favorite science-related articles from The Onion, a satirical newspaper.

Mars Rover Beginning to Hate Mars

NASA Jet Propulsion Laboratory scientists overseeing the ongoing Mars Exploration Rover Mission said Monday that the Spirit’s latest transmissions could indicate a growing resentment of the Red Planet.

Spirit has been displaying some anomalous behavior,” said Project Manager John Callas, who noted the rover’s unsuccessful attempts to flip itself over and otherwise damage its scientific instruments.” And the thousand or so daily messages of ‘STILL NO WATER’ really point to a crisis of purpose.”


Kansas Outlaws Practice of Evolution

In response to a Nov. 7 referendum, Kansas lawmakers passed emergency legislation outlawing evolution, the highly controversial process responsible for the development and diversity of species and the continued survival of all life.

“From now on, the streets, forests, plains, and rivers of Kansas will be safe from the godless practice of evolution, and species will be able to procreate without deviating from God’s intended design,” said Bob Bethell, a member of the state House of Representatives. “This is about protecting the integrity of all creation.”


Continue reading “New Year 2007”