About Planets Tonight
Many people buy a first telescope, take it outside once, see nothing and put it away. The telescope usually works fine; what's missing is knowing what to point it at, where to look, and which eyepiece to use.
PlanetsTonight.com answers those three questions for your exact location and night, in plain language: compass direction, height above the horizon, the best time window, an interactive 180° sky radar, and a through-the-eyepiece optical simulator.
How it works
- Sky positions are calculated in your browser using Astronomy Engine (VSOP87 planetary theory), an open-source library accurate to well under an arcminute for planets.
- Cloud and seeing forecasts come from MET Norway (the Norwegian Meteorological Institute) and 7Timer!, averaged over the hours when the sky is actually dark.
- Optics guidance uses real optical formulas: magnification = telescope focal length ÷ eyepiece focal length, with a practical maximum of about 2× the aperture in millimetres.
Our principles
- Honest limits: we would rather tell you a target is too faint or over-magnified than send you outside for nothing.
- Night-vision friendly: a matte dark interface plus a dedicated Red Mode for use at the eyepiece.
- Free to use. The site is supported by clearly labelled advertising and, where noted, affiliate links that never change what we recommend.
Questions or corrections? Contact us.