Image:  NASA/JPL/Space Science Institute  –  Cassini

Cassini has weathered its Nov 2, 2009 flyby of the Saturn’s moon, Enceladus, in good shape.  The flyby placed the spacecraft at about 100 km (60 miles) above the surface of Enceladus at its closest point, and directly through the plume you see imaged here in the south polar region.  Water vapor, sodium, complex hydrocarbons such as propane and ethane, and other organic molecules have been detected in the plume in previous flybys.  This closer look at the material in the plume might help answer some of the questions science has for Enceladus.

Currently thought to have an ocean of liquid water under a mantle of ice, and known to be geologically active, Enceladus looks like a good place to search for extraterrestrial life.  Material released from Enceladus is also thought to be the source of Saturn’s E ring.  Modest in size (its diameter is only about 500 km), this moon certainly is an interesting study.  As it’s surface is covered in water ice, Enceladus reflects almost 100% of light reaching it.  In addition, it has a source of internal heat, and it even has a thin atmosphere composed of water vapour, nitrogen, carbon dioxide, and methane.

Here is a beautiful image of Enceladus with Saturn behind it, and the rings below it:

NASA/JPL ESA SSI Cassini Imaging Team

This natural color image was taken early in 2006.  The marks on Saturn in the upper left of the image are ring shadows.

NASA scientists will be working to interpret the information Cassini collected as it passed through the icy plume Monday.  I’m hoping we’ll gain more of an idea of what lies beneath the ice crust of Enceladus.

You can read more about Cassini by going to the Mission homepage.

Hubble's image of a portion of M83. Click for larger. Image credit: NASA, ESA, R. O'Connell (University of Virginia), the WFC3 Science Oversight Committee, and ESO.

Hubble was trained on the spiral galaxy M83 and the new camera took this image. WOW!  This is just a portion of the galaxy, click the Hubblesite link below to see the image in it’s full context.

M83 is the designation in the famous Messier catalog for the galaxy is also known as the Southern Spiral.  Here’s the SEDS page.

I really enjoyed the description of the image from Hubblesite (click the link for more images) be sure to give it a read:

The spectacular new camera installed on NASA’s Hubble Space Telescope during Servicing Mission 4 in May has delivered the most detailed view of star birth in the graceful, curving arms of the nearby spiral galaxy M83.

Nicknamed the Southern Pinwheel, M83 is undergoing more rapid star formation than our own Milky Way galaxy, especially in its nucleus. The sharp “eye” of the Wide Field Camera 3 (WFC3) has captured hundreds of young star clusters, ancient swarms of globular star clusters, and hundreds of thousands of individual stars, mostly blue supergiants and red supergiants.

The image, taken in August 2009, provides a close-up view of the myriad stars near the galaxy’s core, the bright whitish region at far right.

WFC3’s broad wavelength range, from ultraviolet to near-infrared, reveals stars at different stages of evolution, allowing astronomers to dissect the galaxy’s star-formation history.

The image reveals in unprecedented detail the current rapid rate of star birth in this famous “grand design” spiral galaxy. The newest generations of stars are forming largely in clusters on the edges of the dark dust lanes, the backbone of the spiral arms. These fledgling stars, only a few million years old, are bursting out of their dusty cocoons and producing bubbles of reddish glowing hydrogen gas.

The excavated regions give a colorful “Swiss cheese” appearance to the spiral arm. Gradually, the young stars’ fierce winds (streams of charged particles) blow away the gas, revealing bright blue star clusters. These stars are about 1 million to 10 million years old. The older populations of stars are not as blue.

A bar of stars, gas, and dust slicing across the core of the galaxy may be instigating most of the star birth in the galaxy’s core. The bar funnels material to the galaxy’s center, where the most active star formation is taking place. The brightest star clusters reside along an arc near the core.

The remains of about 60 supernova blasts, the deaths of massive stars, can be seen in the image, five times more than known previously in this region. WFC3 identified the remnants of exploded stars. By studying these remnants, astronomers can better understand the nature of the progenitor stars, which are responsible for the creation and dispersal of most of the galaxy’s heavy elements.

M83, located in the Southern Hemisphere, is often compared to M51, dubbed the Whirlpool galaxy, in the Northern Hemisphere. Located 15 million light-years away in the constellation Hydra, M83 is two times closer to Earth than M51.

Messengers look at Mercury. Click for larger. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

As the Messenger spacecraft approached Mercury for its third and final flyby, it took this image of the planet.  Taken through red, green and blue filters we can see Mercury in full color.  I am a little surprised at how much color there is actually, I had expected a rather bland grey tone with the occasional bright crater.

Mercury is a pretty remarkable planet.  It’s a pretty bright place too.  Apparent brightness is inversely proportional to the square of the distance, so if Mercury is 3 times closer to the Sun, the Sun appears 3² or 9 times brighter than it does to us on Earth.

You would think that being so close to the Sun the orbit of Mercury would have a pretty circular orbit, it doesn’t, it has the most elliptical orbit of ANY of the planets!

Of course you know it’s hot, as hot or hotter than the oven in your kitchen, but you knew that. A long hot day on Mercury is really long too, 176 days long actually.   As hot as it is, the nights are bone chilling to say the least, how about -279 ^oF!  At one time there was speculation there may be ice in some of the craters in the perma-shade at the poles – sound familiar?  I”m not sure what the current thinking is on that.

Mercury is very dense, 5.43 grams/cc, almost as dense as Earth at 5.52 grams/cc.  How come?  Mercury has a HUGE iron core, the iron core is about 75 percent of the radius of Mercury. Messenger has found that iron is also prevalent in the mantle.  This was kind of an unexpected finding, the conventional thinking was the mantle was mostly basalts like the moon.

How the iron core came to be is for another time.

Head over to the Messenger site for much more on Mercury.

Region of Taurus Littrow valley around the Apollo 17 landing site. Click for larger. Credit: NASA/GSFC/Arizona State University

The Lunar Reconnaissance Orbiter captured this look at the landing site for Apollo 17. If you click the image above you will get a larger version of the image. You can see an enlargement of the Challenger Descent Stage and the immediate area by clicking here.

Want to know what the more cryptic annotations mean? Here’s the LRO press release:

Apollo 17 Lunar Module Challenger descent stage comes into focus from the new lower 50 km mapping orbit, image width 102 meters. Credit: NASA/GSFC/Arizona State University.

LRO maneuvered into its 50-km mapping orbit on September 15. The next pass over the Apollo 17 landing site resulted in images with more than two times better resolution than previously acquired. At the time of this recent overflight the Sun was high in the sky (28° incidence angle) helping to bring out subtle differences in surface brightness. The descent stage of the lunar module Challenger is now clearly visible, at 50 cm per pixel (angular resolution) the descent stage deck is 8 pixels across (4 meters), also note that the legs are also now distinguishable. The descent stage served as the launch pad for the ascent stage as it blasted off for a rendezvous with the command module America on 14 December 1972.

Tracks are clearly visible and can be followed to the east, where astronauts Jack Schmitt and Gene Cernan set up the Surface Electrical Properties experiment (SEP). Cernan drove the Lunar Roving Vehicle (LRV) in an intersecting north-south and east-west course to mark positions for laying out the SEP 35-meter antennas (circle labeled “SEP” marks the area of the SEP transmitter). The dark area just below the SEP experiment is where the astronauts left the rover, in a prime spot for monitoring the liftoff.

Confessions of an Alien Hunter, by Dr. Seth Shostak of the SETI Institute, is a look at SETI from the inside.  In addition, Dr. Shostak talks about who, and what, our first alien contacts may be (aside from microbes or pond scum).  You know me; I would be excited out of my tiny little mind with a microbe.

The hope, the belief, that we are not alone in the universe has been with us since we could envision ourselves as “self”.  We have always looked to the sky and wondered.  Science now tells us that there must be other life; the universe is simply too big for there not to be.  Life is ubiquitous on Earth, it’s found from the bottom of the Mariannas Trench to the summit of Mount Everest.

The SETI Institute was officially funded and created by NASA in 1971, although the first SETI experiment took place eleven years earlier at Green Bank, West Virginia.  Now privately funded, SETI uses scientific methods for the systematic search for evidence of intelligent extraterrestrial life.  They aren’t looking for pond scum.

Confessions of an Alien Hunter is published by the National Geographic Society, one of the world’s largest non-profit organizations.  National Geographic is involved in natural science, education, geology, archaeology, exploration, and conservation… just to name a few.

Dr. Shostak gives televised lectures and interviews, in addition to writing books.  Here is a link to just one of them.  I’d recommend you take time to watch as Dr. Shostak is an incredibly interesting speaker.

This is the link to SETI@home, if you’re interested in linking your computer to assist SETI during the times you aren’t busy.  It functions much like a screen saver.  I’ve had my computer linked to SETI for over a year, and haven’t had any trouble, although some people say it makes their computer over-heat.

Dr. Shostak has already promised us an interview in the future, so if you have any questions for him, let me know and I’ll ask him.

Click here to view the embedded video.

I had a meeting out of town and missed the launch, so I thought I’d put it up in case you did too.  I like the imagery from the rocket.

Some were trying to do their best to make the launch a failure because of a partial parachute failure for the booster section as it returned.  Partial = one of three parachutes and the one that failed actually deployed first.

The parachutes are being checked out this weekend and it could be a failure of he suspension system and not of the chute material.

It may be a moot point.  The Obama administration may be heading towards ending human spaceflight anyways.  Some will cheer this news I suppose, I don’t exactly cheer the “dumbing down” of America any more than we have.  Even from an economic standpoint it’s not a great move either, unless  putting thousands more out of work is good.

Course, the argument is well we can leave these things to someone else and just get what we need from them.  Them being somebody else, anybody else.  Yep that is true, and look how good that’s working for us in general.  In the whole country we don’t even have a single manufacturer for the flu vaccine for crying out loud.  We have allowed ourselves to be at the mercy of everybody else because we have lost the ability to do for us.

It’s a disgraceful situation.  Oh and for the record, the handling of he H1N1 thing is an embarrassment, good thing it’s not a more serious flu we’d really be up the creek.

Here’s the video source.

The Witch Head Nebula. Click for larger. Image Credit and copyright: APOD and Star Shadows Remote Observatory (Steve Mazlin, Jack Harvey, Rick Gilbert, Teri Smoot, Daniel Verschatse).

This is an Astronomy Picture of the Day selection from last year featuring the Witch Head Nebula.

The Witch Head Nebula is about 1,000 light-years away in the constellation of Orion.  The nebula is known as a reflection nebula because it is illuminated by a nearby star or group of stars, in this case the star is the blue supergiant Rigel.

I was going to use a different version of this nebula for today, but this one is just too good not to use, the bright star Rigel just makes the image all the better.

You can see this image in it’s original context AND links to other scary sights (be very sure to look at the link for the veiled spectre) at APOD.

The original image: A “Witch by Starlight”  Credit & Copyright: Star Shadows Remote Observatory (Steve Mazlin, Jack Harvey, Rick Gilbert, Teri Smoot, Daniel Verschatse).  I tried to image the Witch Head a couple years ago and had very little success so in my book this image isn’t just good, it’s extraordinary.

If you are out and about tonight HAVE FUN AND BE SAFE!

Oh and when you go to the APOD site you can get a larger version so you can put it on your desktop.

The Jewel Box, NGC 4755 from the ESO. Wallpaper links below. Credit the ESO.

The Jewel Box is another name for the open cluster NGC 4755. From the looks of this ESO image, it’s little wonder how English astronomer John Hershel came up with the name when he coined it in the 1830’s.

NGC 4755 is an open cluster, a collection of stars bound loosely by gravity evolved from the same “nursery”, or cloud of dust and gas, so they tend to be similar in age and composition.  Because they are all of the same approximate age, but do vary in mass so they can be at differing life stages.

Higher mass stars will age faster than lower mass stars and sometimes you can see stars in the red giant phase (more mature and nearing the end of their lives) right along with other stars that might only be half way through their lives or even less.

Located about 6400 light-years away, in the constellation of Crux, near the Southern Cross, I know many readers can see it just fine, sadly it’s too far south for me.  No matter, The Jewel Box is stunning and I decided it would make a very nice desktop.  While I was at it I made up a few different sizes, most required some clipping of the image.  Many thanks to the ESO for  sharing this.

Here’s the wallpapers: