Viewed from [
http://space.jpl.na…] Earth, the solar system's [
http://solarsystem.…planetsfeat.html ] planets do a cosmic dance that is hard to appreciate on any single night. But consider this well planned animated sequence combining 23 pictures taken at approximately 2 week intervals from June 2000 through May 2001. It reveals the graceful looping or retrograde motion [
http://alpha.lasall…retrograd.html ] of bright wanderers [
http://spacekids.hq…mac.html ] Jupiter (leftmost) and Saturn. Loitering among the background stars are the familiar Pleiades (above right) and V-shaped Hyades (below left) star clusters [
http://hou.lbl.gov/…StarHop/hyades_pleia des.html ]. The planets didn't actually loop [
http://antwrp.gsfc.…] by reversing the direction of their orbits, though. Their apparent retrograde motion [
http://www.scienceu…retro/retro.html ] is a reflection of the motion [
http://faculty.full…] of the Earth itself. Retrograde motion [
http://csep10.phys.…retrograde.html ] can be seen each time Earth overtakes and laps [
http://www.physics.…AstroPage.html ] planets orbiting farther from the Sun, Earth moving more rapidly through its own relatively close-in orbit. Astronomer Tunc Tezel captured Jupiter and Saturn's "paired" retrograde loop in this remarkable series made after the close alignment [
http://antwrp.gsfc.…] of these gas giants in May 2000. The next opportunity to see these two planets dance such a pas de deux will be in the year 2020.
Explanation
Viewed from [
http://space.jpl.na…] Earth, the solar system's [
http://solarsystem.…planetsfeat.html ] planets do a cosmic dance that is hard to appreciate on any single night. But consider this well planned animated sequence combining 23 pictures taken at approximately 2 week intervals from June 2000 through May 2001. It reveals the graceful looping or retrograde motion [
http://alpha.lasall…retrograd.html ] of bright wanderers [
http://spacekids.hq…mac.html ] Jupiter (leftmost) and Saturn. Loitering among the background stars are the familiar Pleiades (above right) and V-shaped Hyades (below left) star clusters [
http://hou.lbl.gov/…StarHop/hyades_pleia des.html ]. The planets didn't actually loop [
http://antwrp.gsfc.…] by reversing the direction of their orbits, though. Their apparent retrograde motion [
http://www.scienceu…retro/retro.html ] is a reflection of the motion [
http://faculty.full…] of the Earth itself. Retrograde motion [
http://csep10.phys.…retrograde.html ] can be seen each time Earth overtakes and laps [
http://www.physics.…AstroPage.html ] planets orbiting farther from the Sun, Earth moving more rapidly through its own relatively close-in orbit. Astronomer Tunc Tezel captured Jupiter and Saturn's "paired" retrograde loop in this remarkable series made after the close alignment [
http://antwrp.gsfc.…] of these gas giants in May 2000. The next opportunity to see these two planets dance such a pas de deux will be in the year 2020.
Explanation
