dione, photographed 29 times by cassini, 11th april 2015.
i’m not sure, but i think the smaller moon passing in the last sequence is rhea.
image credit: nasa/jpl/ssi. animation & composite: ageofdestruction.
The Movement of Barnard’s Star
The fourth closest known star to our Sun (following the Alpha Centauri stars), Barnard’s Star is famous for having the largest known proper motion of any star. Proper motion is the measure of the observed changes in a star’s position against the distant background stars and in 1916, E. E. Barnard measured this star’s proper motion to be 10.3 arcseconds per year. This corresponds to a speed of 90 km/s across our line of sight.
This movie by RickJ, posted in the CosmoQuest forums, shows the movement of Barnard’s Star over 9 years. Each frame represents one year between 2007 and 2015.
Image: The proper motion of Barnard’s Star over the last 9 years. (Credit: RickJ)
Johnny Bruck
