Explanation: It's been raining on Titan. In fact, it's likely been raining methane on Titan and that's not an April Fools' joke. The almost familiar scene depicted in this artist's vision of the surface of Saturn's largest moon looks across an eroding landscape into a stormy sky. That scenario is consistent with seasonal rain storms temporarily darkening Titan's surface along the moon's equatorial regions, as seen by instruments onboard the Cassini spacecraft. Of course on frigid Titan, with surface temperatures of about -290 degrees F (-180 degrees C), the cycle of evaporation, cloud formation, and rain involves liquid methane instead of water. Lightning could also be possible in Titan's thick, nitrogen-rich atmosphere.
OMG -- thought Astronomy Picture Of The Day was supposed to be about the science called Astronomy, rather than unscientific figments of the imagination.
alright, as someone not too well-versed in chemistry : if it's raining methane etc, how come the lightning wouldn't ignite it and cause a big explosion? :-/
Wolfie, look at the first post and think about it. Ann if you lived on Titan you might well have infrared detecting eyes; or think of it as yet another mapping of the spectrum. Pgp this is a fairly scientific figment of the imagination. I presume it uses a good dollop of the latest info on Titan. Let's face it, a lot of us are interested in astronomy because of what we've imagined as being out there at one time or another.
And it broadens our choices. Not just another pretty galaxy. I support the occasional APOD of this sort.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk. — Garrison Keillor
I was kind of hoping to see one here, actually. Thus, this (otherwise excellent and enjoyable artists rendering) was rather a disappointment. A small consolation was the "Water on Mars" APOD, which I had all but forgotten.
Upon reading today's APOD, my immediate reaction was the same as wolfie138's above - wouldn't the lightning, if it existed, ignite the methane even when it is in liquid form?
If lightning did exist there, it seems that there would be an entirely different atmosphere resulting.
A previously-speculated but little-known NASA mission has been successfully completed. Two probes were sent to the moon to do further experiments on the lunar surface, some of which necessitated lighting up the fields of experimentation. Miniature rovers were released from the probes to gather information; tracking was done both through radio signals and visually, requiring that the fields be lit. Alert amateur and professional astronomers were stunned to see and capture this and similar images of the moon during the 20-minute period that portions of the moon were flooded with artificial light. Though initially the experiments were to run while the moon was new, the launching of the probes was delayed due to bad weather and the experiments were performed instead during the crescent phase.
biddie67 wrote:
Upon reading today's APOD, my immediate reaction was the same as wolfie138's above - wouldn't the lightning, if it existed, ignite the methane even when it is in liquid form?
It's interesting that many people don't realize that free oxygen isn't a given, but a (happy) consequence of billions of years of life and photosynthesis on this planet in the Goldilocks zone by the very entities (bacteria, plants) we seem to have been working SO hard to wipe out.
I cannot look at this picture of Titan without imagining a horrible, gagging death in just a few short moments.
Ann wrote:You couldn't see Saturn from Titan, unless you had infrared detecting eyes.
Ann
Why someone would need infrared detecting eyes to watch Saturn from Titan? Would the visible spectrum of Saturn's light(reflection) eliminated by Titans atmosphre?
You may actually be able to see saturn in normal light. Dim, to be sure.
Titan is NOT in the equatorial ring plane except twice a month (one titan revolution). So you could often see the rings at a low angle.
But there is another problem with the painting. From the equatorial region, the ring plane would be almost vertical. If you saw the primary near the horizon (as in the painting), the rings would point up and down. Or else the location is not in the equatorial region.
Another painting from about 20 years ago of the Huygens probe chuting down in the titanic atmosphere showed saturn in the background SILHOUETTED against the sky. Somebody did not do his/her homework!
A lovely image, even if it is an artist’s imagination. We can always pick away at the technical details, but it still conjures up images of an alien environment. It is our imaginations that got a probe out there in the first place.
That said, I have a question about the technical details.... The rivulet of methane running down the slope seems to show ripples at the surface. I’m not a chemist, so I ask, given the properties of methane, the atmospheric pressure and composition, and the gravity on Titan, would ripples form in flowing liquid methane, as shown here?
Is oxygen the only element that supports combustion??
I love all the free oxygen that comes my way and comfortably live in the forest that is self-directed. I'm even comfortable with all the hordes of eco-friendly bacteria in this ol' world. I refuse to use hand-sanitizers and, so far, have had the good fortune to avoid hospitals with their growing colonies of monster GM bacterias and viruses .....
booky1@earthlink.net wrote:
You may actually be able to see Saturn in normal light. Dim, to be sure.
If the Huygens probe couldn't even see the Sun...
http://en.wikipedia.org/wiki/Titan_%28moon%29 wrote:
<<The Huygens probe was unable to detect the direction of the Sun during its descent, and although it was able to take images from the surface, the Huygens team likened the process to "taking pictures of an asphalt parking lot at dusk".>>
booky1@earthlink.net wrote:
But there is another problem with the painting. From the equatorial region, the ring plane would be almost vertical. If you saw the primary near the horizon (as in the painting), the rings would point up and down. Or else the location is not in the equatorial region.
Correct... A tribute to Chesley Bonestell, no doubt:
booky1@earthlink.net wrote:Titan is NOT in the equatorial ring plane except twice a month (one titan revolution). So you could often see the rings at a low angle.
Pushing a few numbers around, I think that from the points where Titan has the greatest displacement out of the ring plane, the rings would have an angular thickness of a couple of minutes of arc. That's below the limit of unaided vision.
Chlorine has minimal solubility of 0.7g Cl2 per kg of water at ambient temperature (21ºC). Dissolved chlorine reacts to form hydrochloric acid (HCl) and hypochlorous acid, a solution that can be used as a disinfectant or bleach:
Cl2(g) + H2O(l) → HCl(aq) + HClO(aq)
Bromine has a solubility of 3.41 g per 100 g of water,[5] but it slowly reacts to form hydrogen bromide (HBr) and hypobromous acid (HBrO):
Br2(g) + H2O(l) → HBr(aq) + HBrO(aq)
Iodine, however, is minimally soluble in water (0.03 g/100 g water @ 20ºC) and does not react with it. However, iodine will form an aqueous solution in the presence of iodide ion, such as by addition of potassium iodide (KI), because the triiodide ion is formed.>>
booky1@earthlink.net wrote:
Titan is NOT in the equatorial ring plane except twice a month (one titan revolution). So you could often see the rings at a low angle.
Pushing a few numbers around, I think that from the points where Titan has the greatest displacement out of the ring plane, the rings would have an angular thickness of a couple of minutes of arc. That's below the limit of unaided vision.
One should distinguish seeing from resolving.
One has no trouble 'seeing' Saturn from Earth with unaided vision
though it is never more than a third of a minute of arc in diameter.
Astronaut William Pogue thought he had seen the Great Wall of China [5 to 9 m wide] from Skylab [440 km] but discovered he was actually looking at the Grand Canal of China near Beijing. He spotted the Great Wall with binoculars, but said that "it wasn't visible to the unaided eye.">>
It s Raining on Titan
