by APOD Robot » Tue Oct 28, 2014 4:06 am
Retrograde Mars
Explanation: Why would Mars appear to move backwards? Most of the time, the apparent motion of
Mars in
Earth's sky is in one direction, slow but steady in front of the far distant stars. About every two years, however, the
Earth passes Mars as they orbit around the Sun. During the most recent such pass starting late last year,
Mars as usual, loomed
large and bright. Also during this time, Mars appeared to move backwards in the sky, a phenomenon called
retrograde motion.
Featured here is a series of images digitally stacked so that all of the stars coincide. Here, Mars appears to
trace out a narrow loop in the sky. At the center of the loop, Earth passed Mars and the
retrograde motion was the highest.
Retrograde motion can also be seen for other
Solar System planets.
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[url=http://apod.nasa.gov/apod/ap141028.html][img]http://apod.nasa.gov/apod/calendar/S_141028.jpg[/img] [size=150]Retrograde Mars[/size][/url]
[b] Explanation: [/b] Why would Mars appear to move backwards? Most of the time, the apparent motion of [url=http://en.wikipedia.org/wiki/Mars]Mars[/url] in [url=http://apod.nasa.gov/apod/ap010827.html]Earth's sky[/url] is in one direction, slow but steady in front of the far distant stars. About every two years, however, the [url=http://apod.nasa.gov/apod/ap030902.html]Earth passes Mars[/url] as they orbit around the Sun. During the most recent such pass starting late last year, [url=http://apod.nasa.gov/apod/ap030828.html]Mars[/url] as usual, loomed [url=http://apod.nasa.gov/apod/ap030827.html]large and bright[/url]. Also during this time, Mars appeared to move backwards in the sky, a phenomenon called [url=http://alpha.lasalle.edu/~smithsc/Astronomy/retrograd.html]retrograde motion[/url]. [url=http://www.twanight.org/newTWAN/photos.asp?ID=3004740]Featured here[/url] is a series of images digitally stacked so that all of the stars coincide. Here, Mars appears to [url=http://twanight.org/newTWAN/photos.asp?ID=3004739]trace out a narrow loop[/url] in the sky. At the center of the loop, Earth passed Mars and the [url=http://apod.nasa.gov/apod/ap080511.html]retrograde motion[/url] was the highest. [url=http://apod.nasa.gov/apod/ap060422.html]Retrograde motion[/url] can also be seen for other [url=https://solarsystem.nasa.gov/planets/]Solar System[/url] planets.
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