Saturday May 16th the outer planets Mars and Jupiter will reach a point in their respective orbit that has them at nearly the same heliocentric coordinates. This a system of tracking the planets as they make their 360o orbit around the Sun. Each Sun orbiting object’s orbital position is measured using degrees, minutes, and seconds of heliocentric longitude. Each object orbits the Sun at a daily rate determined by dividing 360o by the number of days an object takes to complete one orbit around the Sun.
As the above graphic shows the two planets are arranged in a straight line out from the Sun. The Earth is not part of the line-up. This is a heliocentric view of their orbital positions with the Sun at the Center. A heliocntric longitude based view is not the same as a view from the surface of the Earth where there is a distinctly different view of the two planets.
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