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Are there any data from spacecraft that visited that planet? How large the Earth is when viewed from that planet?

Monty Harder
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Yes!

It's a tiny blue dot of just about 1.6 arc seconds diameter. Cassini made the most famous image of the "In Saturn's Shadow – The Pale Blue Dot", in remembrance of the first such image from Voyager one: a view of Earth and Moon from Saturn (image: NASA/ESA). In Saturn's Shadow – The Pale Blue Dot

The dark side of Saturn, its bright limb, the main rings, the F ring, and the G and E rings are clearly seen; the limb of Saturn and the F ring are overexposed. The ‘breaks’ in the brightness of Saturn’s limb are due to the shadows of the rings on the globe of Saturn, preventing sunlight from shining through the atmosphere in those regions. The E and G rings have been brightened for better visibility.

Earth, 1.44 billion km away in this image, appears as a blue dot at centre right; the Moon can be seen as a fainter protrusion off its right side. The other bright dots nearby are stars.

JPL shows a few more images, including a zoom image taken of the Moon-Earth-system.

See also the wiki entry on "pale blue dot" as part of the impressive "family portrait" series taken by Voyager 1 in 1990 from a distance of about 40 AU which show most of our solar system planets from 6 billion kilometers distance. Also compare with the successor series taken by the messenger spacecraft 20 years later in 2010 from about the orbit of Mercury.

planetmaker
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    Not sure whether the OP wanted an angular or pixel size, but could address that part and provide a size of Earth in arcseconds ? – astrosnapper Nov 29 '23 at 22:07
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    pixel size depends on used camera (and can be checked by following the link to the full-size image), but angular size is fixed for a given distance. I added that. Thanks :) – planetmaker Nov 29 '23 at 22:32
  • So this image is fake ? – An_Elephant Nov 30 '23 at 15:51
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    No, what makes you believe that? – planetmaker Nov 30 '23 at 17:15
  • Wikipedia article about this image: https://en.wikipedia.org/wiki/The_Day_the_Earth_Smiled – Miles Nov 30 '23 at 22:49
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    Just to clearify: Voyagers "pale blue dot" was part of the "family portrait"; it was not taken when Voyager was near Saturn. – Abigail Nov 30 '23 at 23:38
  • @Abigail thanks noted and clarified in the text. – planetmaker Dec 01 '23 at 17:02
  • Maybe @An_Elephant was referring to the fact that the image had been intentionally modified, e.g. "The E and G rings have been brightened for better visibility." I wouldn't call that "fake," though. – LarsH Dec 02 '23 at 02:44
  • As a once-upon-a-time photographer I'm used to thinking in terms of "was this taken with a 50mm lens (human eye comparable for 35mm film format)" or a long lens that can change perspective effects. We've all seen the dramatic moon/landscape photos. What focal length lens was used for the Saturn/Earth photo? – BradV Dec 03 '23 at 23:33
  • Thanks planetmaker for providing this absolutely breathtaking photo! I've long admired the 'Blue Dot' photo that Sagan finally got them to take. I think this Saturn/Earth photo is equally breathtaking. – BradV Dec 03 '23 at 23:40
  • The specs are readily avaliable: "Wide Angle Camera [WAC](20 cm f/3.5 refractor; 380-1100 nm; 18 filters; 3.5°x3.5°)", e. g. on https://science.nasa.gov/mission/cassini/spacecraft/cassini-orbiter/imaging-science-subsystem/ – planetmaker Dec 04 '23 at 00:28