What Planet Kicker Actually Is
Planet Kicker is a desktop application used primarily for planning telescope observations of solar system bodies. It helps you figure out when planets, asteroids, and moons will be visible from your location, with enough detail that you don't waste a clear night chasing something that's already set or too close to the sun. It's not a fancy GUI-heavy product. The interface is functional, almost utilitarian. You enter your location, pick your target list, and it generates time windows based on altitude, airmass, and elongation from the sun. That's the core of it.
Downloading and Installing Planet Kicker
The official source is planetskicker.org. The download page has versions for Windows and Linux. There's no Mac native build, though the Linux version runs under Wine on macOS with some configuration. The file is roughly 45MB for the full package, including the ephemeris data. Installation on Windows is straightforward — run the installer, it drops everything into Program Files. On Linux, you'll want to extract it and run the included script from a terminal. Make sure you have Python 3.8 or later. Older Python versions cause library conflicts with the astrometry backend.
Setting It Up for Your First Observation
First thing you do after installing is set your observing location. Latitude, longitude, and elevation matter more than you'd think. I once entered the wrong longitude for my observatory — off by about 3 degrees because I read the coordinate backwards. The software still calculated visibility windows, but they were completely wrong for where I actually was. Took me two nights to realize what happened. The workaround is simple: verify your coordinates against GPS or Google Earth before saving them in the settings file. After that, build your target list. Planet Kicker supports JPL Small-Body Database object names directly. You can type "Mars" or "2024 PT5" and it resolves through its internal orbital element database. For objects without good ephemerides — newly discovered asteroids, for example — you need to import a TLE or OCB file first. The software won't compute positions for arbitrary inputs without that data.
Get the Full Details
Understanding the Output Windows
The main output is a series of observation windows. Each entry shows start time, end time, peak altitude, airmass at culmination, and solar elongation. The columns are sortable. What most people miss is that airmass and altitude are computed independently. A target might reach 60 degrees altitude but still have poor airmass if atmospheric refraction and local horizon obstructions aren't modeled correctly. Planet Kicker uses a flat-horizon approximation by default. If your site has mountains or buildings nearby, you need to input a custom horizon profile or accept that the software is optimistic about your viewing windows. I learned this the hard way with a Kuiper belt candidate observation. The software gave me a 3-hour window at reasonable airmass. In reality, the target dipped below the mountain ridge behind my observatory within 40 minutes. After that, I built a simple horizon mask using a digital level and imported it into the site config. The revised windows matched actual conditions almost exactly.
Common Pitfalls and Workarounds
One issue people run into regularly is orbital element freshness. Planet Kicker ships with a default ephemeris file that gets updated monthly. If you're tracking near-Earth objects or trans-Neptunian objects, that default file can be weeks old. The positional error compounds over time. For fast-moving objects, even a 7-day-old orbit can shift the predicted position by arcminutes. The fix is downloading the latest elements from the Minor Planet Center before each run and importing them via the Elements menu. It takes about three minutes and prevents half the frustration I see in forum complaints. Another quirk: the software doesn't handle timezone changes well if you switch locations mid-project. If you're observing from two different sites in one month, close the current project first, then load the new site. Otherwise you'll get offset timestamps that look like calculation errors but are actually just timezone drift.
When Planet Kicker Falls Short
Here's the honest part. Planet Kicker is solid for planets and well-established minor bodies. It struggles with very faint objects below magnitude 18 and doesn't integrate well with automated telescope control. If you need sequence generation for an unattended run, you'll want to pair it with a tool like TheSkyX or Cartes du Ciel for the scheduling layer. Planet Kicker alone won't talk to your mount or camera. It tells you when something is up. It doesn't tell your equipment what to do. For deep asteroid photometry work, the positional precision is adequate but not class-leading. JPL Horizons gives better accuracy if you need sub-arcsecond predictions. Use Planet Kicker for visibility planning, Horizons for precision ephemerides, and move between them as the task demands.
Practical Workflow
A typical Saturday night prep goes like this. Check the MPEC updates. Download any new orbital elements for targets on your list. Open Planet Kicker, load your site config, pull up the target list, and sort by peak altitude. Run the window generator for the next 72 hours. Filter for airmass below 2.0 and solar elongation above 30 degrees. That gives you a short list of viable windows. Cross-reference with the cloud forecast. If everything lines up, you're set for the night. The whole process takes about 15 minutes once you're familiar with it. The first few times, expect closer to 40 minutes while you figure out where the settings are and why certain targets aren't showing up. It's not the most polished software available. The interface hasn't changed much in years. But for what it does — calculating when solar system objects are observable from a given location — it works reliably once you know its limitations. Plan accordingly, keep your orbital data current, and it saves you from driving out to the telescope on nights where nothing relevant is actually up.
