On July 19, 2013, NASA's Cassini spacecraft had been orbiting Saturn and weaving on and between its moons since 2004. On that day, the spacecraft aligned itself in such a way that Saturn eclipsed the sun as seen from its point of view. With sunlight blocked, space scientists captured the third image of Earth and Earth's moon, from the outer solar system, hundreds of millions of miles away.
When Cassini glided into Saturn's shadow that day, it was also able to capture images of the planets Venus and Mars, Saturn's backlit rings, and several of Saturn's moons, all at once. You can see Saturn's dark side, its bright member, the main rings, and the F ring, G and E rings. This view looks to the unlit side of the rings from about 20 degrees below the plane of the ring.
View larger. The | NASA's Cassini spacecraft took this natural-color portrait on July 19, 2013. It is the third image of Earth from the outer solar system, and the first image showing Saturn, its moons and rings, in addition to Earth and its moon, Venus and Mars, all together. Image via NASA / JPL-Caltech / SSI. Read more about this image.
View larger. The | Annotated image of Saturn and the view from Saturn, taken by Cassini on July 19, 2013. Image via NASA / JPL-Caltech / SSI.
The occasion defined the first time that people had prior notice that they would be photographed from another world. NASA invited everyone on Earth to turn to the sky and say hello while their image was taken hundreds of millions of miles away. As the day approached, Carolyn Porco, leader of the Cassini imaging team at the Institute for Space Science in Boulder, Colorado, said people should:
... Look up, think about our cosmic place, think about our planet, how unusual it is, how exuberant and life-giving it is, think about your own existence, think about the magnitude of the achievement that this photography session entails. We have a spacecraft on Saturn. We are truly interplanetary explorers. Think about all that and smile.
Thus was born the day the earth smiled. Porco also participated in the planning of the first Pale Blue Orb and Pale Blue Dot images.
NASA said the natural color image is as the human eye would see it, if you had been there with Cassini. Using its wide-angle and narrow-angle cameras, the spacecraft captured a total of 323 photographs over a four-hour period, but only 141 images were used to create this panoramic mosaic. This mosaic is also one of the 33 "footprints" that cover the entire ring system and Saturn itself.
View larger. The | Collage of people on Earth on July 19, 2013. Image via NASA. Read more about this image.
A closer view of some of the many photos that make up the collage. Image via NASA / Gizmodo.
This incredible image, released by NASA on July 23, 2013, spans a distance of 404,880 miles (650,000 km), about twice the distance from Earth to the moon. Cassini was about 898 million miles (1.45 billion km) from Earth at the time. That distance is almost 10 times the distance from the sun to Earth.
Porco also said:
Since we saw Earth between Saturn's rings in September 2006 in a mosaic that has become one of Cassini's most beloved images, I have wanted to do it again, only better. This time, I wanted to turn the entire event into an opportunity for everyone around the world to savor the uniqueness of our planet and the preciousness of life on it.
She accomplished that, and much more.
There is also another very interesting associated image of this day, a collage of people on Earth, created to help celebrate the occasion. More than 1,400 individual photos come together to represent a view of Earth. The same day the image was taken The day the Earth smiled, participants from 40 countries took photos of them waving to Saturn. This impressive collage is the result. The images were transmitted to NASA / JPL-Caltech via Twitter, Facebook, Flickr, Instagram, Google+, and email.
An earlier raw image of Earth and the moon as seen from Saturn by the Cassini spacecraft on July 19, 2013. Earth is the brightest spot; The moon is down on the left. Image via NASA / JPL-Caltech / Space Science Institute / Medium.
This image is known as the Pale Blue Orb. The Cassini spacecraft captured it in 2006, showing Earth and the moon as tiny dots seen through Saturn's rings. Image via NASA / JPL / Space Science Institute.
Cassini's pale blue Orb image, 2006. This was the second image of Earth taken from the outer solar system, taken on February 15, 2006, just two years after Cassini began orbiting Saturn. At the time, the spacecraft was about 930 million miles (1.5 billion km) from Earth. Earth and the moon appear as a small blue dot on the right side of the image, just above the center. When enlarged, you can distinguish the moon as a slight "bulge" on the upper left side of Earth.
As with the 2013 image, the 2006 image was made possible by Saturn passing directly in front of the sun as seen from Cassini.
You can read more about the pale blue Orb image here.
Voyager, 1990 pale blue dot image. The first image taken of Earth from the outer solar system, and the most distant image yet, was acquired by NASA's Voyager 1 spacecraft on February 14, 1990. Its distance from Earth at the time was 4 1 billion miles (6.4 billion km). The image showed Earth as a pale blue dot, hence the name. Earth appears as a very small crescent of only 0.12 pixels in size. Voyager 1 had reached the edge of the solar system, 12 years after its launch, and had completed its primary mission.
This is a photo known as the Pale Blue Dot - the first of only three images of Earth taken from the outer solar system so far. The "dot" - our world, Earth - is on the right side of the photo, about halfway down. Image via NASA / JPL. Read more about this image here.
At the request of astronomer Carl Sagan, NASA ordered the spacecraft to turn around and photograph the planets in the solar system. The mosaic of the solar system was interesting, but this image, the image of our little world in space, surrounded by emptiness, was heartbreaking. About this image, Carl Sagan later said, in part:
Look at that point again. That is here. That's my home. That's us. In it, everyone you love, everyone you know, everyone you've heard of, every human being who ever was, lived their lives. The whole of our joy and suffering, thousands of safe economic religions, ideologies and doctrines, each hunter and gatherer, each hero and coward, each creator and destroyer of civilization, each king and peasant, each young couple in love, each mother and father , a hopeful son, inventor and explorer, every moral teacher, every corrupt politician, every superstar, every supreme leader, every saint and sinner in the history of our species lived there, in a speck of dust suspended in a ray of sunlight.
Carolyn Porco, leader of the Cassini imaging team, who played a pivotal role in planning and taking the three iconic photos. Image via Carolyn Porco.
Read more about the Pale Blue Dot image and what Carl Sagan said.
Bottom line: NASA's Cassini spacecraft, which orbited Saturn until 2017, took the third image of Earth from the outer solar system today, July 19, 2013. The image was renamed The Day Earth Smiled. This followed two previous similar images taken in 1990 and 2006.
