Comet Zhu-Balam is a long-period comet first identified by David D. Balam

David D. Balam

David D. Balam is a Canadian astronomer and a research associate with University of Victoria's Department of Physics and Astronomy, in Victoria, British Columbia. Specializing in the search for Near-Earth objects, Balam is one of the world's most prolific contributors to this research; only two...

 on June 8, 1997 and originally photographed by Gin Zhu on June 3, 1997. The comet is estimated at 10 kilometres in diameter with a period of approximately 36,800 years.

Given the orbital eccentricity

Orbital eccentricity

The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...

 of this object, different epochs

Epoch (astronomy)

In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as celestial coordinates, or elliptical orbital elements of a celestial body, where these are subject to perturbations and vary with time...

 can generate quite different heliocentric unperturbed two-body

Two-body problem

In classical mechanics, the two-body problem is to determine the motion of two point particles that interact only with each other. Common examples include a satellite orbiting a planet, a planet orbiting a star, two stars orbiting each other , and a classical electron orbiting an atomic nucleus In...

 best-fit

Curve fitting

Curve fitting is the process of constructing a curve, or mathematical function, that has the best fit to a series of data points, possibly subject to constraints. Curve fitting can involve either interpolation, where an exact fit to the data is required, or smoothing, in which a "smooth" function...

 solutions to the aphelion distance (maximum distance) of this object. For objects at such high eccentricity, the Suns barycentric coordinates

Barycentric coordinates (astronomy)

In astronomy, barycentric coordinates are non-rotating coordinates with origin at the center of mass of two or more bodies.The barycenter is the point between two objects where they balance each other. For example, it is the center of mass where two or more celestial bodies orbit each other...

 are more stable than heliocentric coordinates. Using JPL Horizons the barycentric orbital elements for epoch 2015-Jan-01 generate a semi-major axis

Semi-major axis

The major axis of an ellipse is its longest diameter, a line that runs through the centre and both foci, its ends being at the widest points of the shape...

of 1100 AU and a period of approximately 36,800 years.