Solar eclipse by Saturn in 2006. Read more here.
From Earth’s surface, it’s very hard to visualize how much empty space surrounds us. If we could capture photos of Earth from a distant vantage point – say, the outer solar system – we could perhaps begin to picture it, but those opportunities are rare. We humans have acquired only two images of Earth from the outer solar system – ever. The first and most distant was taken 23 years ago by NASA’s Voyager 1 spacecraft from 4 billion miles (6 billion kilometers) away, showing Earth as a pale blue dot . The other opportunity was Cassini’s image in 2006 from 926 million miles (1.49 billion kilometers). But today another opportunity will occur. On July 19, 2013, NASA’s Cassini spacecraft, now orbiting Saturn and weaving in and among its moons, will be aligned in such a way that Saturn will eclipse the sun as seen from the spacecraft. With the sun’s light blocked, space scientists will capture the third-ever picture of Earth from the outer solar system, hundreds of millions of miles away.
Earth will appear as a small, pale blue dot between the rings of Saturn in the image, which will be part of a mosaic, or multi-image portrait, of the Saturn system Cassini is composing, NASA says.
This simulated view from NASA’s Cassini spacecraft shows the expected positions of Saturn and Earth on July 19, 2013, around the time Cassini will take Earth’s picture. Cassini will be about 898 million miles (1.44 billion kilometers) away from Earth at the time. That distance is nearly 10 times the distance from the sun to Earth. Image credit: NASA/JPL-Caltech
North America and part of the Atlantic Ocean are expected to be illuminated when NASA’s Cassini spacecraft takes a snapshot of Earth on July 19, 2013. This view is a close-up simulation. Image credit: NASA/JPL-Caltech
Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California said:
While Earth will be only about a pixel in size from Cassini’s vantage point 898 million [1.44 billion kilometers] away, the team is looking forward to giving the world a chance to see what their home looks like from Saturn.
Cassini will start obtaining the Earth part of the mosaic at 2:27 p.m. PDT (5:27 p.m. EDT or 21:27 UTC) on July 19 and end about 15 minutes later, all while Saturn is eclipsing the sun from Cassini’s point of view. The spacecraft’s unique vantage point in Saturn’s shadow will provide a special scientific opportunity to look at the planet’s rings. At the time of the photo, North America and part of the Atlantic Ocean will be in sunlight.
This is a photo known as the Pale Blue Dot – one of only two images of Earth taken from the outer solar system. The “dot” – our world, Earth – is on the right side of the photo, about halfway down. The Voyager 1 spacecraft acquired this image in 1990, from a record distance of about 6 billion kilometers (3.7 billion miles) from Earth. Voyager was, and still is, heading out of the solar system at the time. NASA engineers commanded it to turn back toward Earth and acquire this image at the request of the late Carl Sagan. Image via NASA/JPL. Read more about this image here.
Carolyn Porco, Cassini imaging team lead at the Space Science Institute in Boulder, Colorado said:
Ever since we caught sight of the Earth among the rings of Saturn in September 2006 in a mosaic that has become one of Cassini’s most beloved images, I have wanted to do it all over again, only better. This time, I wanted to turn the entire event into an opportunity for everyone around the globe to savor the uniqueness of our planet and the preciousness of the life on it.
Porco and her imaging team associates examined Cassini’s planned flight path for the remainder of its Saturn mission in search of a time when Earth would not be obstructed by Saturn or its rings. Working with other Cassini team members, they found the July 19 opportunity would permit the spacecraft to spend time in Saturn’s shadow to duplicate the views from earlier in the mission to collect both visible and infrared imagery of the planet and its ring system.
This image is known as the Pale Blue Orb. The Cassini spacecraft – which has been orbiting Saturn since 2004 – captured it in 2006 when the spacecraft was nearly 930 million miles from Earth.. This image was made possible by the passing of Saturn directly in front of the sun as seen from Cassini. A similar geometry between the Earth, the sun and the Cassini spacecraft will let Cassini take another image of Earth on July 19, 2013. It’ll be only the third such image of Earth ever to be acquired from the outer solar system. Image Credit: NASA/JPL/Space Science Institute. Read more about this image here.
Matt Hedman, a Cassini science team member based at Cornell University in Ithaca, N.Y., and a member of the rings working group, said:
Looking back towards the sun through the rings highlights the tiniest of ring particles, whose width is comparable to the thickness of hair and which are difficult to see from ground-based telescopes. We’re particularly interested in seeing the structures within Saturn’s dusty E ring, which is sculpted by the activity of the geysers on the moon Enceladus, Saturn’s magnetic field and even solar radiation pressure.
Bottom line: NASA’s Cassini spacecraft, now orbiting Saturn, will take a third picture of Earth from the outer solar system on July 19, 2013. The other two pictures were taken in 1990 and 2006.