NEO Planner Orbit View screen - Close Approach of the asteroid (99942) Aphopis on Friday, April 13, 2029
The NEO passes Earth almost in the plane of the ecliptic. Europe and Africa have the best viewing conditions
at the object during its flyby of Earth, visible to the naked eye.
View direction from the north towards the ecliptic. The white area is Greenland.
Starting with version 6, NEO Planner supplements the existing "Execute Search" screen—which displays planned objects
with their paths and star/deep-sky backgrounds within the equipment's field of view—by offering heliocentric and geocentric orbit viewers for the planned objects.
These views are presented from a perspective looking down onto the ecliptic orbital plane from the north when the Orbit Viewer is launched. The vernal equinox ♈ is located on the left.
The display is supplemented by planning data. In addition, various zoom and video options are available.
In addition to comets and asteroids, the orbits of NEOCP objects can also be displayed.
When externally distributing videos or hardcopies of any kind from the Orbit View screen, the origin as a function of NEO Planner should be indicated.
The orbit viewer relies exclusively on data from JPL Horizons and Scout, displaying trajectories based on the accuracy of the calculated orbital elements.
Orbits for known and numbered objects are depicted with high precision. Notably, the geocentric orbits of NEOCP objects are plotted according to their 1-sigma deviation
as reported by Scout; consequently—especially with short orbital arcs—these may show significant deviations compared to the orbits calculated after the objects have been officially numbered.
Please take this into account.
Calculation basis from data of HORIZONS API Quantities and
JPL Scout APIgo to top
Heliocentric mode
all objects
Starting Orbit View In heliocentric mode, a 2D view of the planets and objects projected onto the ecliptic is displayed from a northern perspective and the vernal equinox ♈ on the left.
To suggest a 3D view of the object, its "z-line" is drawn with the specification of a positive or negative value in kilometers.
This line represents the object's position either above the ecliptic (positive/northern value) or below it (negative/southern value).
NEO Planner Orbit View start screen - Atira 2019 LF6 in heliocentric mode in 2026
Control functions
Simulation controls are located at the bottom left and operate like a cassette player.
A trackbar
above them allows for the selection of speed increments from -12 to +12, relative to the time interval set via the adjacent buttons.
These buttons allow simulation steps in increments of minutes, hours, days, weeks, or months.
A reset button situated between them returns the time to the current time.
To the right of the bottom center, there is a toggle buttonfor switching between heliocentric and geocentric modes.
Next to this, the CA (Close Approach) button
allows you to set the simulation time to the point of closest approach to Earth in the current observing season.
Like the mouse wheel, the +/- buttons control the zoom factor;
an adjacent button allows the zoom to be reset to the initial value.
The button toggles the display of basic help topics.
The camera button captures a screenshot of the current display and saves it to the archive folder.
Special features of the helio mode
The lowest zoom level (factor 0.05) provides an overview of the solar system extending beyond Neptune's orbit.
The button displays grid lines spaced at half an astronomical unit, extending as far as Jupiter's orbit.
As the view zooms out to the outer solar system, the orbits, positions, and labels of the inner planets appear smaller.
This graphical adjustment ensures a legible view of the situation within the inner solar system. NEO Planner Orbit View start screen - Atira 2019 LF6 in heliocentric mode with 3D Axis
The button helps visualize spatial orientation.
The line extending to the left from the Sun indicates the astronomical vernal equinox, marked by RA 0h and the ♈ Aries symbol.
The non-tilted “Orbit View” start screen is directed at the ecliptic from the north, which is why the label "NORTH (Z+)" appears right next to the Sun.
The dashed line pointing downwards indicates the summer solstice position (RA 6h).
Moving the mouse in 3D mode causes the axis lines to adjust accordingly, aiding in the orientation of the displayed graphical elements. NEO Planner Orbit View start screen - Atira 2019 LF6 in heliocentric mode with 3D Axis tilted by 90 degrees
Clicking and holding the left mouse button while dragging the mouse backwards shifts the view of the solar system into 3D mode.
Once the mouse has been fully dragged back, a 90-degree perspective relative to the ecliptic plane is displayed.
This reveals the object's orbit and its current inclination—highlighted by a gray dashed line that begins at the object and extends to Earth's orbit—with the inclination expressed
as a vertical displacement (z-value) in kilometers. An orange line pointing downwards now indicates the orientation of the ecliptic axis.
By dragging the mouse in any direction, you can then view the solar system from any desired perspective.
It is also possible to zoom in and out, ranging from the Sun to the orbit of Neptune. NEO Planner Orbit View start screen - Atira 2019 LF6 in heliocentric mode with with curtain
Pressing the button draws shaded lines from the object's orbit down to the ecliptic plane.
These represent the object's varying orbital inclination over the course of its path.
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Geocentric mode
Asteroids and comets with provisional or final numbering
These objects are displayed in Geo-mode with high precision, based on orbital elements for 500 (Earth) from JPL Horizons.
The orbital paths are plotted based on daily orbital elements, which are loaded as discrete points for each day and subsequently smoothed using a curve fit.
The curved path of an object from the perspective of a moving observer is called an epicycloid.
By default, the trajectory is plotted for a period extending +30/-40 days from the current date, provided the close approach (CA) falls within this timeframe.
If the CA lies outside this period, the line is extended to the date of the CA plus 10 days, depending on whether the CA occurs in the past or the future.
The maximum duration of the path is limited to +/- 8 months, which roughly corresponds to an observation period for the current season.
The distinct curves for each object arise primarily from perspective effects caused by the continuous revolution of the Earth-Moon system around the Sun
and the objects' own unique elliptical or hyperbolic orbits around the Sun.
"Orbit View" displays the objects' apparent paths as viewed from "500" (the Earth's center of mass)—paths that can also be traced in planetarium software
by observing the objects' prograde and retrograde motion—but it presents these trajectories as curves without a background of stars.
The direction of the sun is dynamically indicated by a line pointing towards the sun. The displayed descriptions of the object are self-explanatory.
Swapping the polar view of the Earth when the sign of z (the object's distance from the ecliptic) changes at high zoom levels.
NEO Planner Orbit View screen
(1980) Tezcatlipoca in heliocentric mode in 2026
NEO Planner Orbit View screen
(1980) Tezcatlipoca in geocentric mode in 2026
The trajectories in heliocentric and geocentric modes differ substantially from one another.
While the image on the left shows the object's heliocentric Keplerian orbit around the Sun, the geocentric mode displays an epicycloidal curve;
this represents the Earth's perspective on the object—combined with the object's distinct orbit—over a specific period as Earth itself orbits the Sun.
In geocentric mode, it becomes clear how the forward and backward paths of the solar system's non-planetary planned objects behave from an Earth-based perspective.
NEO Planner Orbit View screen, Amor 2026 MO1 in geocentric mode.
The position grid in R.A. and Decl., the 3D orientation axis,
and the curtain relative to the ecliptic are activated via buttons.
The trajectory relative to the Earth-Moon system can be easily assessed in the geocentric orbit view,
particularly for newly discovered NEOs or those currently passing close to Earth at relatively high speeds.
User-friendly controls allow for the optional display of features such as a position grid, orientation axes for 3D mode,
or a "curtain" projection of the object's orbit onto the ecliptic.
The view can be freely rotated, zoomed in, or zoomed out using mouse movements.
Control functions
The most control functions essentially correspond to those in helio mode.
Special features of the geo mode
The lowest zoom level (factor 0.05) provides an overview of the solar system extending beyond Neptune's orbit.
The maximum zoom factor of 40,000 shows the Earth in full size from a northern perspective.
The button displays the object's coordinates—Right Ascension along the left edge and Declination along the top edge—at the simulation time.
These coordinates are referenced to the Earth's center of mass (IAU code 500) rather than the active observatory.
The grid lines and their coordinate labels update dynamically as the simulation progresses via the control buttons. Additionally, the grid lines and values adjust when zooming in or out.
The accuracy of the coordinate values corresponds to the JPL Horizons ephemerides for IAU code 500.
The button helps visualize spatial orientation.
The line extending to the left from the Earth indicates the astronomical vernal equinox, marked by RA 0h and the ♈ Aries symbol.
The non-tilted “Orbit View” start screen is directed at the ecliptic from the north, which is why the label "NORTH (Z+)" appears right next to the Earth.
The dashed line pointing downwards indicates the summer solstice position (RA 6h).
Moving the mouse in 3D mode causes the axis lines to adjust accordingly, aiding in the orientation of the displayed graphical elements.
Clicking and holding the left mouse button while dragging the mouse backwards shifts the view of the Earth-Moon system
into 3D mode.
Once the mouse has been fully dragged back, a 90-degree perspective relative to the ecliptic plane is displayed.
This reveals the object's orbit and its current inclination—highlighted by a gray dashed line that begins at the object and extends to Earth's orbit—with the inclination expressed
as a vertical displacement (z-value) in kilometers. An orange line pointing downwards now indicates the orientation of the ecliptic axis.
By dragging the mouse in any direction, you can then view the the region around the Earth-Moon system from any desired perspective.
It is also possible to zoom in and out, ranging from the Erath to the orbit of Neptune.
Pressing the button draws shaded lines from the object's orbit down to the ecliptic plane.
These represent the object's varying orbital inclination over the course of its path.
Optimal starting position of an object
for using the video zoom function.
Additionally, the checkbox allows the object to be automatically switched to a video mode
that begins recording from the current position in any direction by pressing the
or buttons.
Before starting the video, I recommend zooming the view to cover the entire length of the object's path and positioning the object at its maximum starting position.
Let the video run for hour
An algorithm triggers a zoom-in on the Earth-Moon system as the object approaches and passes through the "close approach zone,"
with the inner viewing area automatically expanding based on the object's proximity to Earth.
For nearby objects, this function enables the creation of dramatic videos that can be made available to the public for free educational use via personal screen-recording software.
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Asteroids and comets from NEOCP or PCCP
These objects are displayed in Geo-mode with precision, based on orbital elements for 500 (Earth) from JPL Scout.
In GEO mode, OrbitView plots the geocentric orbital segment (trajectory) of the NEOCP object over a total period of 7 days
(spanning from 4 days prior to the current planning date to 3 days ahead).
The geometric nature of this arc is determined by the eccentricity e: for solutions with e > 1, the plotted line segment corresponds to a hyperbolic arc, whereas for closed orbits (e < 1),
it represents an elliptical arc.
In this process, the entire orbit is calculated based on the orbital elements provided by Scout for the observation period (epoch).
The best 68.27% of the 1,000 supplied orbital elements are filtered out according to the 1-sigma criterion, and mean orbital elements are calculated for each individual day from this subset.
NEOCP object ST26G03 in geocentric mode, close approach with 3d Axis orientation lines
As in heliocentric mode, a 2D view of the Earth-Moon system and the object is displayed in perspective onto the ecliptic from a northern viewpoint upon the first activation of geo mode.
To provide a 3D preview of an object, its "z-line" is drawn, indicating a positive or negative value in kilometers;
this line represents the object's position either above the ecliptic (positive/northern value) or below it (negative/southern value).
All control functions available for GEO mode—including video zoom and full 3D mode—are also available for NEOCP/PCCP objects.
Interpretation of the display
The accuracy with which the display reflects the object's actual position and trajectory depends on the length of the orbital arc covered by the measurements.
For extremely short arcs of less than one hour, the graphical representation bears little resemblance to reality.
Arcs of under three hours provide only a rough indication of the object's path.
Once the arc extends beyond three hours—and leading up to the assignment of a provisional designation—the
display becomes significantly more precise and warrants greater attention.
Typically, NEOCP objects with orbital arcs exceeding one day receive a provisional designation and are removed from the NEOCP page.
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are located at the bottom left and operate like a cassette player. 
above them allows for the selection of speed increments from -12 to +12, relative to the time interval set via the adjacent buttons. 
allow simulation steps in increments of minutes, hours, days, weeks, or months. 
situated between them returns the time to the current time.
for switching between heliocentric and geocentric modes.
allows you to set the simulation time to the point of closest approach to Earth in the current observing season.
control the zoom factor;
an adjacent button allows the zoom to be reset to the initial value.
button toggles the display of basic help topics.
captures a screenshot of the current display and saves it to the archive folder.
displays grid lines spaced at half an astronomical unit, extending as far as Jupiter's orbit.
As the view zooms out to the outer solar system, the orbits, positions, and labels of the inner planets appear smaller.
This graphical adjustment ensures a legible view of the situation within the inner solar system.
helps visualize spatial orientation.
The line extending to the left from the Sun indicates the astronomical vernal equinox, marked by RA 0h and the ♈ Aries symbol.
The non-tilted “Orbit View” start screen is directed at the ecliptic from the north, which is why the label "NORTH (Z+)" appears right next to the Sun.
The dashed line pointing downwards indicates the summer solstice position (RA 6h).
Moving the mouse in 3D mode causes the axis lines to adjust accordingly, aiding in the orientation of the displayed graphical elements.
while dragging the mouse backwards shifts the view of the solar system into 3D mode.
Once the mouse has been fully dragged back, a 90-degree perspective relative to the ecliptic plane is displayed.
This reveals the object's orbit and its current inclination—highlighted by a gray dashed line that begins at the object and extends to Earth's orbit—with the inclination expressed
as a vertical displacement (z-value) in kilometers. An orange line pointing downwards now indicates the orientation of the ecliptic axis.
By dragging the mouse in any direction, you can then view the solar system from any desired perspective.
button draws shaded lines from the object's orbit down to the ecliptic plane.
These represent the object's varying orbital inclination over the course of its path.
go to top
checkbox allows the object to be automatically switched to a video mode
that begins recording from the current position in any direction by pressing the
or 
buttons.
Before starting the video, I recommend zooming the view to cover the entire length of the object's path and positioning the object at its maximum starting position.
Let the video run for hour 
