CKA Forums
Login 
canadian forums
bottom
 
 
Canadian Forums

Author Topic Options
Offline
CKA Uber
CKA Uber
 Vancouver Canucks


GROUP_AVATAR

GROUP_AVATAR
User avatar
Profile
Posts: 23555
PostPosted: Thu Nov 24, 2011 6:49 pm
 


Although I won't stop submitting space stories, I think a thread on its own for photos, video, and whatever else tickles the fancies of the astonomers out there would be fun.

I'll start of with Enceladus:

Image

wiki wrote:
Enceladus is the sixth-largest of the moons of Saturn.[14] It was discovered in 1789 by William Herschel.[15] Until the two Voyager spacecraft passed near it in the early 1980s very little was known about this small moon besides the identification of water ice on its surface. The Voyagers showed that the diameter of Enceladus is only 500 kilometers (310 mi), about a tenth of that of Saturn's largest moon, Titan, and that it reflects almost all of the sunlight that strikes it. Voyager 1 found that Enceladus orbited in the densest part of Saturn's diffuse E ring, indicating a possible association between the two, while Voyager 2 revealed that despite the moon's small size, it had a wide range of terrains ranging from old, heavily cratered surfaces to young, tectonically deformed terrain, with some regions with surface ages as young as 100 million years old.

In 2005 the Cassini spacecraft performed several close flybys of Enceladus, revealing the moon's surface and environment in greater detail. In particular, the probe discovered a water-rich plume venting from the moon's south polar region. This discovery, along with the presence of escaping internal heat and very few (if any) impact craters in the south polar region, shows that Enceladus is geologically active today. Moons in the extensive satellite systems of gas giants often become trapped in orbital resonances that lead to forced libration or orbital eccentricity; proximity to the planet can then lead to tidal heating of the satellite's interior, offering a possible explanation for the activity.

Enceladus is one of only three outer solar system bodies (along with Jupiter's moon Io and Neptune's moon Triton) where active eruptions have been observed. Analysis of the outgassing suggests that it originates from a body of sub-surface liquid water, which along with the unique chemistry found in the plume, has fueled speculations that Enceladus may be important in the study of astrobiology.[16] The discovery of the plume has added further weight to the argument that material released from Enceladus is the source of the E ring.

In May 2011 NASA scientists at an Enceladus Focus Group Conference reported that Enceladus "is emerging as the most habitable spot beyond Earth in the Solar System for life as we know it".


Image

Image

Cassini has produced thousands of amazing images and Enceladus has produced some of the most amazing. Although Titan got most of the initial attention, Enceladus with its outgassing and likely liquid oceans had been a very pleasant surprise. The images themselves are haunting and the exciting potential for astro-biological discoveries keeps me watching the news items on this moon with growing interest every day.

To think that outside of Earth, the only stellar bodies we've found to contain surface liquids (Titan) and subsurface liquids (Enceladus) would orbit a planet as far our as Saturn.


Offline
CKA Uber
CKA Uber
 Vancouver Canucks
User avatar
Profile
Posts: 23765
PostPosted: Thu Nov 24, 2011 7:34 pm
 


Great idea Gunnair! I'm constantly blown away by the Hubble photos. If I wasn't on shaky Internet I'd post them.


Offline
CKA Super Elite
CKA Super Elite
 Vancouver Canucks


GROUP_AVATAR

GROUP_AVATAR
Profile
Posts: 6629
PostPosted: Thu Nov 24, 2011 8:08 pm
 


Ok, so when can we occupy this moon?

The views would be amazing.


Offline
CKA Uber
CKA Uber
 Vancouver Canucks


GROUP_AVATAR

GROUP_AVATAR
User avatar
Profile
Posts: 23555
PostPosted: Thu Nov 24, 2011 8:10 pm
 


Image

Image

Image

A few more of Enceladus.


Offline
CKA Uber
CKA Uber
 Vancouver Canucks


GROUP_AVATAR

GROUP_AVATAR
User avatar
Profile
Posts: 23555
PostPosted: Thu Nov 24, 2011 8:11 pm
 


Tricks wrote:
Great idea Gunnair! I'm constantly blown away by the Hubble photos. If I wasn't on shaky Internet I'd post them.


Thanks.

Check out this site.

http://apod.nasa.gov/apod/archivepix.html]

An image per day and the archives are amazing.


Offline
CKA Uber
CKA Uber
 Vancouver Canucks


GROUP_AVATAR

GROUP_AVATAR
User avatar
Profile
Posts: 23555
PostPosted: Thu Nov 24, 2011 8:15 pm
 




Offline
CKA Uber
CKA Uber
 Vancouver Canucks
User avatar
Profile
Posts: 23765
PostPosted: Thu Nov 24, 2011 8:59 pm
 


Gunnair wrote:
Tricks wrote:
Great idea Gunnair! I'm constantly blown away by the Hubble photos. If I wasn't on shaky Internet I'd post them.


Thanks.

Check out this site.

http://apod.nasa.gov/apod/archivepix.html]

An image per day and the archives are amazing.

Thanks for the link!


Offline
CKA Super Elite
CKA Super Elite
 Toronto Maple Leafs
User avatar
Profile
Posts: 9178
PostPosted: Thu Nov 24, 2011 11:02 pm
 


Gunnair, Interesting read. I had thought Europa was another potential for habitability due to the potential for liquid oceans from the tidal forces from Jupiter.


Offline
CKA Uber
CKA Uber
 Vancouver Canucks


GROUP_AVATAR

GROUP_AVATAR
User avatar
Profile
Posts: 23555
PostPosted: Fri Nov 25, 2011 6:51 am
 


llama66 wrote:
Gunnair, Interesting read. I had thought Europa was another potential for habitability due to the potential for liquid oceans from the tidal forces from Jupiter.


It is, but at this point the presence of sub- surface oceans is highly likely but still theoretical. There was a recent article I read that had more evidence of liquid beneath the surface.

There's even some theories that Pluto might even have liquid under the surface which will be confirmed or denied in 2015.


Offline
CKA Uber
CKA Uber
 Vancouver Canucks


GROUP_AVATAR

GROUP_AVATAR
User avatar
Profile
Posts: 23555
PostPosted: Sun Nov 27, 2011 8:34 am
 


A look at Rhea.

wiki wrote:
Rhea is an icy body with a density of about 1.236 g/cm3. This low density indicates that it is made of ~25% rock (density ~3.25 g/cm3) and ~75% water ice (density ~0.93 g/cm3). While Rhea is the ninth-largest moon, it is only the tenth-most-massive moon.[note 2]

Earlier it was assumed that Rhea had a rocky core in the center.[7] However measurements taken during a close flyby by the Cassini orbiter in 2005 (see below) cast this into doubt, though this remains controversial. In a paper published in 2007 it was claimed that the axial dimensionless moment of inertia coefficient was 0.4.[note 3][8] Such a value indicated that Rhea had an almost homogeneous interior (with some compression of ice in the center) while the existence of a rocky core would imply a moment of inertia of about 0.34.[7] In the same year another paper claimed the momentum of inertia was about 0.37[note 4] implying that Rhea was partially differentiated.[9] A year later yet another paper claimed that the moon may not be in hydrostatic equilibrium meaning that the moment of inertia can not be determined from the gravity data alone.[10] In 2008 an author of the first paper tried to reconcile these three disparate results. He concluded that there is a systematic error in the Cassini radio Doppler data used in the analysis, but after restricting the analysis to a subset of data obtained closest to the moon, he arrived at his old result that Rhea was in hydrostatic equilibrium and had the moment inertia of about 0.4, again implying a homogeneous interior. Further measurements are necessary to resolve this problem.[11]

The triaxial shape of Rhea is consistent with a homogeneous body in hydrostatic equilibrium.[12]

Models suggest that Rhea could be capable of sustaining an internal liquid water ocean through heating by radioactive decay.[13]


Image

Image

Quote:
Rhea's features resemble those of Dione, with dissimilar leading and trailing hemispheres, suggesting similar composition and histories. The temperature on Rhea is 99 K (−174 °C) in direct sunlight and between 73 K (−200 °C) and 53 K (−220 °C) in the shade.

Rhea has a rather typical heavily cratered surface,[14] with the exceptions of a few large Dione-type chasmata or fractures (wispy terrain) on the trailing hemisphere (the side facing away from the direction of motion along Rhea's orbit)[15] and a very faint "line" of material at Rhea's equator that may have been deposited by material deorbiting from its rings.[16] Rhea has two very large impact basins on its anti-Cronian hemisphere, which are about 400 and 500 km across.[15] The more northerly and less degraded of the two, called Tirawa, is roughly comparable to the basin Odysseus on Tethys.[14] There is a 48 km-diameter impact crater at 112°W that is prominent because of an extended system of bright rays.[15] This crater, called Inktomi, is nicknamed "The Splat", and may be one of the youngest craters on the inner moons of Saturn.[15] No evidence of any endogenic activity has been discovered.[15]

Its surface can be divided into two geologically different areas based on crater density; the first area contains craters which are larger than 40 km in diameter, whereas the second area, in parts of the polar and equatorial regions, has only craters under that size. This suggests that a major resurfacing event occurred some time during its formation. The leading hemisphere is heavily cratered and uniformly bright. As on Callisto, the craters lack the high relief features seen on the Moon and Mercury. On the trailing hemisphere there is a network of bright swaths on a dark background and few visible craters. It had been thought that these bright areas might be material ejected from ice volcanoes early in Rhea's history when its interior was still liquid. However, observations of Dione, which has an even darker trailing hemisphere and similar but more prominent bright streaks, show that the streaks are actually ice cliffs resulting from extensive fracturing of the moon's surface.

The January 17, 2006 distant flyby by the Cassini spacecraft yielded images of the wispy hemisphere at better resolution and a lower sun angle than previous observations. Images from this and subsequent flybys showed that Rhea's streaks in fact are tectonically formed ice cliffs (chasmata) similar to those of Dione.

Atmosphere

On November 27, 2010, NASA announced the discovery of a tenuous atmosphere—exosphere. It consists of oxygen and carbon dioxide in proportion of roughly 5 to 2. The surface density of the exosphere is from 105 to 106 molecules in a cubic centimeter depending on local temperature. The main source of oxygen is radiolysis of water ice at the surface by ions supplied by the magnetosphere of Saturn. The source of the carbon dioxide is less clear, but it may be related to oxidation of the organics present in ice or to outgassing of the moon's interior.[17][18]


Aother moon with possible sub-surface liquid oceans or lakes and a very tenuous atmosphere.


Offline
Active Member
Active Member
Profile
Posts: 413
PostPosted: Sun Nov 27, 2011 10:40 am
 


I've always wanted to go on a spaceship like the Enterprise or Red Dwarf and go and explore strange planets and moons.

It'd be great to land on Titan and then - with a protective spacesuit on, of course - walk about its surface and stand on the edge on one of its lakes of liquid methane. What better thing to do than explore a strange, alien world?


Offline
CKA Moderator
CKA Moderator
User avatar
Profile
Posts: 33963
PostPosted: Mon Nov 28, 2011 11:21 am
 


Where to begin?? I've been debating that since Gunnair started this thread.

Let's start on Saturn. Cassini-Huegens. These are real colour photos, not retouched:

Image

Image

One of Saturns' moons, Hyperion:

Image

The surface of Titan. Ignoring that it's -200, the similarity to many places on Earth is uncanny.

Image

Image


Offline
CKA Moderator
CKA Moderator
User avatar
Profile
Posts: 33963
PostPosted: Mon Nov 28, 2011 12:01 pm
 


How about Hubble? Wayyyy too many to post, but here are some good ones:

Close-Up of Light Echo Around V838 Monocerotis (September 2006)
Image

Image

Visible View of Pillar and Jets HH 901/902
Image

The Carina Nebula, one of my favourite images. If you go to the original site, there are high def versions that are very zoomable. Incredible detail in them, but *HUGE* files.

http://hubblesite.org/gallery/album/neb ... 016a/warn/

Image

Some of the detail in that image:

Image


Offline
CKA Uber
CKA Uber
 Vancouver Canucks


GROUP_AVATAR

GROUP_AVATAR
User avatar
Profile
Posts: 23555
PostPosted: Mon Nov 28, 2011 1:29 pm
 


I love that photo of Hyperion!


Offline
CKA Moderator
CKA Moderator
 Vancouver Canucks


GROUP_AVATAR
User avatar
Profile
Posts: 63921
PostPosted: Mon Nov 28, 2011 2:05 pm
 


llama66 wrote:
Gunnair, Interesting read. I had thought Europa was another potential for habitability due to the potential for liquid oceans from the tidal forces from Jupiter.


No, the Monolith told us that we have to stay away from Europa.


Post new topic  Reply to topic  [ 2416 posts ]  1  2  3  4  5 ... 162  Next



Who is online

Users browsing this forum: No registered users and 1 guest




 
     
All logos and trademarks in this site are property of their respective owner.
The comments are property of their posters, all the rest © Canadaka.net. Powered by © phpBB.