Tag Archives: pale blue dot

Pale Blue 2Dot0


Thanks to the prodding of Carl Sagan, just over 25 years ago, on February 14, 1990 to be exact, the Voyager 1 spacecraft turned its camera towards Earth and snapped what has since become an iconic image. It showed our home planet as a very small, very pale blue dot — much as you’d expect from a distance of around 3.7 billion miles.

Though much closer to Earth, the Cassini spacecraft snapped a similar shot of our planet in 2013. Cassini is in its seemingly never-ending orbits of discovery around the Saturnian system, which it began over 10 years ago. It took the image in 2013: Earth in the distance at the center right is dwarfed by Saturn’s rings in the foreground. A rare, beautiful and remarkable image!

Image: Saturn’s rings and Earth in the same frame. Taken on July 19, 2013, via the wide-angle camera on NASA’s Cassini spacecraft Courtesy: NASA/JPL-Caltech/Space Science Institute.

The View From Saturn

As Carl Sagan would no doubt have had us remember, we are still collectively residents of a very small, very pale blue dot. The image of planet Earth was taken by the Cassini spacecraft, which has been busy circuiting and mapping the Saturnian system over the last several years. Cassini turned the attention of its cameras to our home on July 19, 2013 for this portrait.

From NASA:

Color and black-and-white images of Earth taken by two NASA interplanetary spacecraft on July 19 show our planet and its moon as bright beacons from millions of miles away in space.

NASA’s Cassini spacecraft captured the color images of Earth and the moon from its perch in the Saturn system nearly 900 million miles (1.5 billion kilometers) away. MESSENGER, the first probe to orbit Mercury, took a black-and-white image from a distance of 61 million miles (98 million kilometers) as part of a campaign to search for natural satellites of the planet.

In the Cassini images Earth and the moon appear as mere dots — Earth a pale blue and the moon a stark white, visible between Saturn’s rings. It was the first time Cassini’s highest-resolution camera captured Earth and its moon as two distinct objects.

It also marked the first time people on Earth had advance notice their planet’s portrait was being taken from interplanetary distances. NASA invited the public to celebrate by finding Saturn in their part of the sky, waving at the ringed planet and sharing pictures over the Internet. More than 20,000 people around the world participated.

“We can’t see individual continents or people in this portrait of Earth, but this pale blue dot is a succinct summary of who we were on July 19,” said Linda Spilker, Cassini project scientist, at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Cassini’s picture reminds us how tiny our home planet is in the vastness of space, and also testifies to the ingenuity of the citizens of this tiny planet to send a robotic spacecraft so far away from home to study Saturn and take a look-back photo of Earth.”

Pictures of Earth from the outer solar system are rare because from that distance, Earth appears very close to our sun. A camera’s sensitive detectors can be damaged by looking directly at the sun, just as a human being can damage his or her retina by doing the same. Cassini was able to take this image because the sun had temporarily moved behind Saturn from the spacecraft’s point of view and most of the light was blocked.

A wide-angle image of Earth will become part of a multi-image picture, or mosaic, of Saturn’s rings, which scientists are assembling. This image is not expected to be available for several weeks because of the time-consuming challenges involved in blending images taken in changing geometry and at vastly different light levels, with faint and extraordinarily bright targets side by side.

“It thrills me to no end that people all over the world took a break from their normal activities to go outside and celebrate the interplanetary salute between robot and maker that these images represent,” said Carolyn Porco, Cassini imaging team lead at the Space Science Institute in Boulder, Colo. “The whole event underscores for me our ‘coming of age’ as planetary explorers.”

Read the entire article here.

Image: In this rare image taken on July 19, 2013, the wide-angle camera on NASA’s Cassini spacecraft has captured Saturn’s rings and our planet Earth and its moon in the same frame. Courtesy: NASA/JPL-Caltech/Space Science Institute.

Cosmic portrait

Make a note in your calendar if you are so inclined: you’ll be photographed from space on July 19, 2013, sometime between 9.27 and 9.42 pm (GMT).

No, this is not another wacky mapping stunt courtesy of Google. Rather, NASA’s Cassini spacecraft, which will be somewhere in the vicinity of Saturn, will train its cameras on us for a global family portrait.

From NASA:

NASA’s Cassini spacecraft, now exploring Saturn, will take a picture of our home planet from a distance of hundreds of millions of miles on July 19. NASA is inviting the public to help acknowledge the historic interplanetary portrait as it is being taken.

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.

“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,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “We hope you’ll join us in waving at Saturn from Earth, so we can commemorate this special opportunity.”

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) 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.

Unlike two previous Cassini eclipse mosaics of the Saturn system in 2006, which captured Earth, and another in 2012, the July 19 image will be the first to capture the Saturn system with Earth in natural color, as human eyes would see it. It also will be the first to capture Earth and its moon with Cassini’s highest-resolution camera. The probe’s position will allow it to turn its cameras in the direction of the sun, where Earth will be, without damaging the spacecraft’s sensitive detectors.

“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,” said Carolyn Porco, Cassini imaging team lead at the Space Science Institute in Boulder, Colo. “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.

“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,” said Matt Hedman, a Cassini science team member based at Cornell University in Ithaca, N.Y., and a member of the rings working group. “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.”

This latest image will continue a NASA legacy of space-based images of our fragile home, including the 1968 “Earthrise” image taken by the Apollo 8 moon mission from about 240,000 miles (380,000 kilometers) away and the 1990 “Pale Blue Dot” image taken by Voyager 1 from about 4 billion miles (6 billion kilometers) away.

Read the entire article here.

Image: 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. Courtesy: NASA/JPL-Caltech

One Pale Blue Dot, 55 Languages and 11 Billion Miles

It was Carl Sagan’s birthday last week (November 9, to be precise). He would have been 77 years old — he returned to “star-stuff” in 1996. Thoughts of this charming astronomer and cosmologist reminded us of a project with which he was intimately involved — the Voyager program.

In 1977, NASA launched two spacecraft to explore Jupiter and Saturn. The spacecraft performed so well that their missions were extended several times: first, to journey farther in the outer reaches of our solar system and explore the planets Neptune and Uranus; and second, to fly beyond our solar system into interstellar space. And, by all accounts both craft are now close to this boundary. The farthest, Voyager I, is currently over 11 billion miles away. For a real-time check on its distance, visit  JPL’s Voyager site here. JPL is NASA’s Jet Propulsion Lab in Pasadena, CA.

Some may recall that Carl Sagan presided over the selection and installation of content from the Earth onto a gold plated disk that each Voyager carries on its continuing mission. The disk contains symbolic explanations of our planet and solar system, as well as images of its inhabitants and greetings spoken in 55 languages. After much wrangling over concerns about damaging Voyager’s imaging instruments by peering back at the Sun, Sagan was instrumental in having NASA reorient Voyager I’s camera back towards the Earth. This enabled the craft to snap one last set of images of our planet from its vantage point in deep space. One poignant image became know as the “Pale Blue Dot”, and Sagan penned some characteristically eloquent and philosophical words about this image in his book, Pale Blue Dot: A Vision of the Human Future in Space.

[div class=attrib]From Carl Sagan:[end-div]

From this distant vantage point, the Earth might not seem of any particular interest. But for us, it’s different. Look again at that dot. That’s here, that’s home, that’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.

[div class=attrib]About the image from NASA:[end-div]

From Voyager’s great distance Earth is a mere point of light, less than the size of a picture element even in the narrow-angle camera. Earth was a crescent only 0.12 pixel in size. Coincidentally, Earth lies right in the center of one of the scattered light rays resulting from taking the image so close to the sun. This blown-up image of the Earth was taken through three color filters – violet, blue and green – and recombined to produce the color image. The background features in the image are artifacts resulting from the magnification.

To ease identification we have drawn a gray circle around the image of the Earth.

[div class=attrib]Image courtesy of NASA / JPL.[end-div]