“When NASA’s Juno spacecraft flew past Earth on Oct. 9, 2013, it received a boost in speed of more than 8,800 mph (about 7.3 kilometer per second), which set it on course for a July 4, 2016, rendezvous with Jupiter.
One of Juno’s sensors, a special kind of camera optimized to track faint stars, also had a unique view of the Earth-moon system. The result was an intriguing, low-resolution glimpse of what our world would look like to a visitor from afar.
The cameras that took the images for the movie are located near the pointed tip of one of the spacecraft’s three solar-array arms. They are part of Juno’s Magnetic Field Investigation (MAG) and are normally used to determine the orientation of the magnetic sensors. These cameras look away from the sunlit side of the solar array, so as the spacecraft approached, the system’s four cameras pointed toward Earth. Earth and the moon came into view when Juno was about 600,000 miles (966,000 kilometers) away — about three times the Earth-moon separation.
During the flyby, timing was everything. Juno was traveling about twice as fast as a typical satellite, and the spacecraft itself was spinning at 2 rpm. To assemble a movie that wouldn’t make viewers dizzy, the star tracker had to capture a frame each time the camera was facing Earth at exactly the right instant. The frames were sent to Earth, where they were processed into video format. “
Video and text via NASA Jet Propulsion Laboratory.
“A memo pad that looks as if it has been cut directly out of the earth’s crust. The earth’s surface seems to be whittled away as the pages of the pad are used, and the pattern of the geographical features and the coastal lines changes. A memo pad that lets you enjoy the same kind of sensation you get from diving down into the ocean.”
SANTA AND THE MOON
Peter Barthel, Communicating Astronomy to the Public, May 2012, (12) p13 – 15.
“We have established that illustrators and designers draw moons ad libitum, according to their taste, but often physically incorrect. The most common mistake is the early morning waning moon shown in an evening scene. Our research focussed on Sinterklaas, Santa Claus, and Christmas scenes, with a short side trip to Sint Maarten and Halloween. The apparent lack of knowledge concerning the physics of the moon phases is most likely widespread and not just limited to the countries examined here. Further investigations are however outside the scope of the present research.”
(see more of Popperfont’s Sciencegeek Advent Calendar Extravanganza here)