Linked astronomy tools
Quick start (3 steps)
- Set location, date, and timezone.
- Select a planet and define visibility constraints.
- Compute to view rise/set/transit, best window, chart bands, and CSV.
Inputs
Summary
Altitude chart
Ephemeris table
| Local time | Planet alt (deg) | Planet az (deg) | Sun alt (deg) | Moon alt (deg) | Mag | Diameter (") | Elongation (deg) | Good |
|---|
Definitions & notes
- Azimuth uses north=0°, east=90°, south=180°, west=270°.
- Altitude uses horizon=0° and zenith=+90°.
- Best window uses the longest contiguous interval where both dark-sky and altitude conditions are true.
- CSV column order is fixed for workflow compatibility.
- Magnitude, apparent diameter, and constellation are planning-grade approximations.
How to use this calculator effectively
Use Planet Observation Planner when the main question is which planet is worth observing under one place, date, and horizon rule set. Keep the settings consistent, then compare the planets under that one setup.
Best workflow
Enter the observing site and date, choose the planet, and set the altitude, sky-darkness, or moon constraints that actually matter for your session. After the first result, change only one constraint at a time so you can see why the best window moved.
When to use
This page is best for deciding whether a planet is realistically observable tonight and when it is highest or darkest. Use the linked timing or chart tools only after you know the target is worth following up.
Common mistakes to avoid
- Comparing planets while changing the site, date, and constraint set at the same time.
- Treating planning-grade magnitude or diameter values as a replacement for a full ephemeris workflow.
- Copying a share URL before you finish the final visibility settings.
See also
FAQ
How is the best window selected?
The tool samples the full local day at the chosen step, extracts contiguous intervals that satisfy all conditions, then selects the longest interval. If lengths tie, the earliest start is selected.
Why can rise or set be unavailable?
At high latitudes or specific seasons, a planet may not cross the horizon threshold during the local day. The planner keeps this explicit and still returns the rest of the timeline safely.
Can I reproduce the same setup later?
Yes. Input state is encoded in URL query parameters, so opening the same link restores the same configuration.
What should I enter first for a planet planning run?
Set the observing site, date, and the planet you care about, then review the default visibility constraints before tightening them.
Why does this page differ from another astronomy tool?
This page focuses on planning-grade windows for one planet under one observing setup. A full ephemeris, chart, or imaging tool may use different assumptions or show more specialized detail.