June 29, 2012 at 20:34 pm | Leave a Comment
Could Well Be!
The more we explore the outer solar system with probes like the Cassini spacecraft, the cooler things we discover. This week planetary scientists working with data from that spacecraft announced that there’s a good chance Saturn’s moon Titan has a layer of liquid water hidden beneath that desolate icy surface.
The discovery came from the study of tides on Titan. This moon is squeezed and stretched as it orbits Saturn, and that is bound to cause some heating in the core. It’s also a shape-changing process.
The scientists figured out that Titan is not a big rocky ball that would show a slight bulge on its surface as Saturn’s strong gravitational pull tugged on it. The way they did this is quite ingenious. They looked at Titan during its 16-day orbit of Saturn. As it whirls around the huge planet, Titan’s shape changes and scientists could chart those changes. Titan is not a perfectly round sphere. Instead, it’s slightly elongated like a football. As it orbits Saturn, its long axis grows when it’s closer to Saturn. Eight days later, when Titan is farther from Saturn, it’s much less elongated and more nearly round. Cassini measured the gravitational effect of that squeeze and pull. These measurements and the assessment of Saturn’s gravitational pull on Titan provide the best data yet of Titan’s internal structure and what they show is that for the shape to change as much as it does, Titan likely has a an ocean layer. It’s not necessarily a huge or deep one, but the fact that it’s there at all is one more step in learning more about Titan’s structure.
Now, I read a few stories here and there about how this supposed ocean is darn near proof that life could exist on Titan.
Not so fast. The presence of a subsurface layer of liquid water at Titan is not necessarily an indicator for life. There are still a lot of studies to be done before scientists understand what Titan looks like in its interior, and whether or not the conditions are right for life to exist in that ocean, or perhaps at a rock-water interface deep inside.
The implications of an ocean in Titan is an exciting finding, no matter what else is discovered there. This mysterious, cloudy world is slowly yielding up its secrets, and in the process, is opening our minds about what other surprises we’re going to find in, on, or near the worlds of the outer solar system.
June 4, 2012 at 10:00 am | Leave a Comment
A Hell of a Planet
In honor of the transit of Venus, NASA-JPL offered up a look at our “sister” neighbor planet. It’s a gorgeous evening/morning star as seen from Earth, but if you were to travel there, you’d find it be less than gorgeous. Or, you might say it has a terrifying beauty of its own.
“Venus is a fascinating yet horrendously extreme place all at once,” explains Sue Smrekar, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Although the surface is hot enough to melt lead due to its runaway greenhouse atmosphere, in many respects it is Earth’s twin [in size, gravity and bulk composition].”
Decades of exploration of Venus using spacecraft in orbit and flying by our “twin” has shown us a volcanic world smothered in clouds, and a world with an oppressive atmosphere that is so heavy it could crush a human standing on its surface. What’s not to like about that? Particularly if you’re a planetary scientist, Venus offers a fascinating place to study. I’ve often heard that it perfectly fits the old vision of what Hell would be like (if it existed): hot, oppressive, inescapable, and torturous. Great place to visit if you can breathe carbon dioxide, stand up to sulfuric acid rain, and you revel in dodging electrical storms and volcanoes.
Well, nothing says every world in the solar system has to be like Earth. In fact, it’s great that we have this array of worlds to study, including Venus. What we learn there and at other places in our solar system will help us understand the worlds we are finding around other stars. Which, poetically enough, will help us understand our own origins as a star and planetary system even more. Think about that as you watch the transit of Venus tomorrow!
June 3, 2012 at 14:01 pm | Leave a Comment
Eclipses and Transits and More Eclipses, Oh My
It’s been a banner couple of weeks for interesting celestial events. First, like many folks, I got to see the annular eclipse of the Sun on May 20th. We went to southern Utah to get a clear view of the Moon slipping between Earth and the Sun and almost (but not quite) blocking out all the sunlight. What we saw was a pretty amazing “ring” of light. I took a few pictures, like the one here, but mostly I just sat and watched it.
We’ve chased a few eclipses now (we’re four for six), so instead of running around and trying to get the best pictures and video, we like to sit and watch. Oh, we did do some automated photography — just let the camera and timer do all the work. But, mostly we watched. And were rewarded with a cool view that doesn’t come along very often.
In the national park where we viewed (Kolob Canyon, part of Zion National Park), we talked with various people who had driven over from California or Las Vegas or Colorado, and everyone seemed excited about the eclipse. There were a few telescopes and cameras with solar filters set up, and a fair number of people using the pinhole projection method of viewing the eclipse. So, I was gratified to see that the campaign of “NEVER LOOK DIRECTLY AT THE SUN WITHOUT PROTECTION” was paying off. It’s common sense, but still, in the heat of an eclipse sometimes even seasoned veterans forget the rule and take a peek, risking their eyesight forever.
The next big event is the Transit of Venus, which occurs June 5/6 (date depends on where you live), when Venus’s orbit will take it across the face of the Sun for several hours. These don’t occur very often; they happen in pairs every hundred or so years, so the next one after this one will be in the year 2117. If you’re inclined to take a look, the same rules apply: don’t look directly at the Sun, use proper filters (NOT SUNGLASSES), and enjoy! There’s a ton of information out there about the transit, so if you want to know more about it, go here, or here. I even talk about it in my monthly edition of “Our Night Sky” for Astrocast.TV, which you can watch below.
Finally, there’s a little bit of a lunar eclipse occurring tomorrow June 4th. The best places for viewing this eclipse will be in and near the Pacific Ocean, according to the folks at eclipse.nasa.gov. However, people in the Americas will see part of it, as will people in eastern Asia. If you want to watch as part of the Moon slips through Earth’s shadow, get more information at the link above.
It’s kinda cool that three events that are the result of sunlight being blocked by celestial objects are occurring so close together. There’s nothing magical about it, but there is something fascinating to watch, so check out the transit and the eclipse (if they’re visible where you live). Participate in observing! That’s what astronomy’s all about!
This blog a wholly pwnd subsidiary of Carolyn Collins Petersen, a.k.a. TheSpacewriter.
Copyright 2013, Carolyn Collins Petersen
Image of Horsehead Nebula: T.A.Rector (NOAO/AURA/NSF) and Hubble Heritage Team (STScI/AURA/NASA)
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