The Day the Earth Smiled: Saturn Shines in this Amazing Image from the Cassini Team

This summer, for the first time ever, the world was informed that its picture was going to be taken from nearly a billion miles away as the Cassini spacecraft captured images of Saturn in eclipse on July 19. On that day we were asked to take a moment and smile and wave at Saturn, from wherever we were, because the faint light from our planet would be captured by Cassini’s camera, shielded by Saturn from the harsh glare of the Sun.

A few preliminary images were released just a few days later showing the “pale blue dot” of Earth nestled within the glowing bands of Saturn’s rings. It was an amazing perspective of our planet, and we were promised that the full mosaic of Cassini images was being worked on and would be revealed in the fall.

Well, it’s fall, and here it is:

The full mosaic from the Cassini imaging team of Saturn on July 19, 2013... the "Day the Earth Smiled"
The full mosaic from the Cassini imaging team of Saturn on July 19, 2013… the “Day the Earth Smiled”

Simply beautiful!

Cassini Imaging Team leader Carolyn Porco wrote on her Facebook page:

“After much work, the mosaic that marks that moment the inhabitants of Earth looked up and smiled at the sheer joy of being alive is finally here. In its combination of beauty and meaning, it is perhaps the most unusual image ever taken in the history of the space program.”

Download a full-size version here.

Earth and Moon seen by Cassini on July 19, 2013
Earth and Moon seen by Cassini on July 19, 2013

In this panorama of the Saturnian system, a view spanning 404,880 miles (651,591 km), we see the planet silhouetted against the light from the Sun. It’s a unique perspective that highlights the icy, reflective particles that make up its majestic rings and also allows our own planet to be seen, over 900 million miles distant. And it’s not just Earth that was captured, but the Moon, Venus, and Mars were caught in the shot too.

Read more: Could Cassini See You on the Day the Earth Smiled?

According to the description on the CICLOPS page, “Earth’s twin, Venus, appears as a bright white dot in the upper left quadrant of the mosaic… between the G and E rings. Mars also appears as a faint red dot embedded in the outer edge of the E ring, above and to the left of Venus.”

This was no simple point-and-click. Over 320 images were captured by Cassini on July 19 over a period of four hours, and this mosaic was assembled from 141 of those images. Because the spacecraft, Saturn, and its moons were all in constant motion during that time, affecting not only positions but also levels of illumination, imaging specialists had to adjust for that to create the single image you see above. So while all elements may not be precisely where they were at the same moment in time, the final result is no less stunning.

“This version was processed for balance and beauty,” it says in the description. (And I’ve no argument with that.)

See below for an annotated version showing the position of all visible objects, and read the full article on the CICLOPS page for an in-depth description of this gorgeous and historic image.

2013 Saturn mosaic, annotated version.
2013 Saturn mosaic, annotated version.

“I hope long into the future, when people look again at this image, they will recall the moment when, as crazy as it might have seemed, they were there, they were aware, and they smiled.”

–Carolyn Porco, Cassini Imaging Team Leader

Also, check out another version of this image from NASA made up of submitted photos from people waving at Saturn from all over the world. (Full NASA press release here.)

All images credit NASA/JPL-Caltech/Space Science Institute

UPDATE 11/13: CICLOPS Director Carolyn Porco describes how this image was acquired and assembled in this interview video from the World Science Festival:

Spitzer, the Wallpaper Factory, Does it Again

At the end of the proverbial day, space-based missions like Spitzer produce millions of observations of astronomical objects, phenomena, and events. And those terabytes of data are used to test hypotheses in astrophysics which lead to a deeper understanding of the universe and our home in it, and perhaps some breakthrough whose here-on-the-ground implementation leads to a major, historic improvement in human welfare and planetary ecosystem health.

But such missions also leave more immediate legacies, in terms of the pleasure they bring millions of people, via the beauty of their images (not to mention posters, computer wallpaper and screen savers, and even inspiration for avatars).

Some recent results from one of Spitzer’s programs – SAGE-SMC – are no exception.

The image shows the main body of the Small Magellanic Cloud (SMC), which is comprised of the “bar” on the left and a “wing” extending to the right. The bar contains both old stars (in blue) and young stars lighting up their natal dust (green/red). The wing mainly contains young stars. In addition, the image contains a galactic globular cluster in the lower left (blue cluster of stars) and emission from dust in our own galaxy (green in the upper right and lower right corners).

The data in this image are being used by astronomers to study the lifecycle of dust in the entire galaxy: from the formation in stellar atmospheres, to the reservoir containing the present day interstellar medium, and the dust consumed in forming new stars. The dust being formed in old, evolved stars (blue stars with a red tinge) is measured using mid-infrared wavelengths. The present day interstellar dust is weighed by measuring the intensity and color of emission at longer infrared wavelengths. The rate at which the raw material is being consumed is determined by studying ionized gas regions and the younger stars (yellow/red extended regions). The SMC is one of very few galaxies where this type of study is possible, and the research could not be done without Spitzer.

This image was captured by Spitzer’s infrared array camera and multiband imaging photometer (blue is 3.6-micron light; green is 8.0 microns; and red is combination of 24-, 70- and 160-micron light). The blue color mainly traces old stars. The green color traces emission from organic dust grains (mainly polycyclic aromatic hydrocarbons). The red traces emission from larger, cooler dust grains.

The image was taken as part of the Spitzer Legacy program known as SAGE-SMC: Surveying the Agents of Galaxy Evolution in the Tidally-Stripped, Low Metallicity Small Magellanic Cloud.

The Small Magellanic Cloud (SMC), and its larger sister galaxy, the Large Magellanic Cloud (LMC), are named after the seafaring explorer Ferdinand Magellan, who documented them while circling the globe nearly 500 years ago. From Earth’s southern hemisphere, they can appear as wispy clouds. The SMC is the further of the pair, at 200,000 light-years away.

Recent research has shown that the galaxies may not, as previously suspected, orbit around our galaxy, the Milky Way. Instead, they are thought to be merely sailing by, destined to go their own way. Astronomers say the two galaxies, which are both less evolved than a galaxy like ours, were triggered to create bursts of new stars by gravitational interactions with the Milky Way and with each other. In fact, the LMC may eventually consume its smaller companion.

Karl Gordon, the principal investigator of the latest Spitzer observations at the Space Telescope Science Institute in Baltimore, Maryland, and his team are interested in the SMC not only because it is so close and compact, but also because it is very similar to young galaxies thought to populate the universe billions of years ago. The SMC has only one-fifth the amount of heavier elements, such as carbon, contained in the Milky Way, which means that its stars haven’t been around long enough to pump large amounts of these elements back into their environment. Such elements were necessary for life to form in our solar system.

Studies of the SMC therefore offer a glimpse into the different types of environments in which stars form.

“It’s quite the treasure trove,” said Gordon, “because this galaxy is so close and relatively large, we can study all the various stages and facets of how stars form in one environment.” He continued: “With Spitzer, we are pinpointing how to best calculate the numbers of new stars that are forming right now. Observations in the infrared give us a view into the birthplace of stars, unveiling the dust-enshrouded locations where stars have just formed.”

Little Galaxy with a Tail (Small Magellanic Cloud imaged by Spitzer)

This image shows the main body of the SMC, which is comprised of the “bar” and “wing” on the left and the “tail” extending to the right. The tail contains only gas, dust and newly formed stars. Spitzer data has confirmed that the tail region was recently torn off the main body of the galaxy. Two of the tail clusters, which are still embedded in their birth clouds, can be seen as red dots.

Source: Spitzer

Nebula Wallpaper

Nebula Wallpaper

Want a nebula wallpaper to put as the background image of your computer desktop? Here’s a handful of nebula images. To make any of them your computer’s background image, just click on the image to see a larger version. Then right-click on the image and choose to set the image as your desktop background.

The nebula wallpaper is the Flame Nebula, captured by the European Southern Observatory. Also known as NGC 2024, it’s a famous nebula located about 1,500 light-years away in the constellation of Orion. The bright star at the top of the image is Alnitak, one of the belt stars of Orion.


Crab Nebula

This is a wallpaper image of the Crab Nebula taken by the Hubble Space Telescope. Also known as M1, the Crab Nebula is the results of a supernova explosion that occurred almost 1000 years ago. Astronomers in 1054 AD reported a star brighting in the sky, and lasting for a few weeks before it dimmed again. That was the supernova that went on to create the Crab Nebula.


Butterfly Nebula

This is a wallpaper of the Butterfly Nebula (or NGC 6302) captured by Hubble. This is a planetary nebula, the result of a dying star blasting out its outer layers into space. This is what our own Sun might do in about 7 billion years from now after it becomes a red giant star.


Ring Nebula

This is Hubble Space Telescope image of the Ring Nebula, also known as M57. It’s actually a planetary nebula, where the outer layers of a dying star are puffed out into space. The Ring Nebula is located about 4000 light-years away, and measures about 500 times larger than the Solar System.


Carina Nebula

This is the Carina Nebula, photographed by the Hubble Space Telescope. This is just one pillar of gas and dust in the nebula, measuring 2 light-years across. It’s located about 7,500 light years from Earth.

We’ve written many articles about nebulae for Universe Today. Here’s an article about dust in the Iris Nebula, and here’s an article about Hubble images of the Helix Nebula.

If you’d like more information on nebulae, check out NASA’s Photo Gallery of Nebulae, and here’s a link to the Hubblesite Homepage for recent stories and images.

We’ve recorded an episode of Astronomy Cast all about nebulae. Listen here, Episode 111: Nebulae.

Space Wallpapers

Earthrise

Here are some amazing space wallpapers. If you want to make one of these your computer desktop wallpaper, just click on the image. That will take you to a much larger version of the image. You can then right-click on the image and choose, “Set as Desktop Background”. That will make any of these space wallpapers your desktop background.

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This is one of the most famous space photographs every taken. It’s called “Earthrise”, and it was captured by the crew of Apollo 8 as they were orbiting around the Moon. They saw the Earth rising over the Moon’s horizon and captured this amazing photograph.


Earth from space
Earth from space

NASA created this amazing wallpaper as part of its celebration for Sun-Earth day in 2008. You can see the Sun shining just outside of the photograph above.


Supernova 1054 AD
Supernova 1054 AD

Almost 1000 years ago, a star detonated in the sky as a supernova, shining brilliantly for a few days. After it faded away, it was replaced by this amazing nebula.


Star formation in the Eagle Nebula
Star formation in the Eagle Nebula

This amazing space wallpaper shows active star formation in the Eagle Nebula. These newly forming stars are blasting out huge clouds of gas and dust into space.


Saturn wallpaper
Saturn wallpaper

Here’s a beautiful image of Saturn captured by NASA’s Cassini spacecraft during a time that it was positioned over the planet’s pole.

We have got lots of image galleries here in Universe Today. Here are some Earth wallpapers, and here are some Venus wallpapers.

You can also download some cool space wallpapers from NASA’s JPL, and here are some wallpapers from Hubble.

You might also want to try listening to an episode of Astronomy Cast. Here’s an episode just about the Hubble Space Telescope.