Sky
Star Chart for Tonight's Sky
Draw an all-sky map of the stars, Moon, and naked-eye planets over any place on Earth at any date and time.
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Date, time, and location
Any date from 1800 to 2050.
24-hour clock, HH:MM.
-90 to 90, north positive.
-180 to 180, east positive.
Sky chart
Ink dots are stars: the larger the dot, the brighter the star. Brass discs mark the Sun, Moon, and planets, each labelled. The outer ring is the horizon, the dashed rings lie 30 and 60 degrees up, and the centre is the zenith, straight overhead. Hold the chart overhead to match the sky: with north at the top, east appears on the left, exactly as the sky looks when you face up. Thin blue lines sketch a few familiar constellation figures. The table below lists the same sky for screen readers.
| Object | Type | Magnitude | Altitude | Azimuth |
|---|
Azimuth is measured clockwise from true north: 0 north, 90 east, 180 south, 270 west. Altitude is degrees above the horizon. Star magnitudes are catalogue values rounded to a tenth; planet magnitudes are computed approximations. Brighter objects have smaller magnitudes.
Enter a date, time, and location, then select Draw chart.
About this chart
The map is a stereographic projection of the whole sky centred on the zenith, the same layout as a planisphere. It plots 463 stars from the Yale Bright Star Catalogue: every star brighter than visual magnitude 3.0 and nearly all stars to magnitude 4.0, from rounded J2000 positions precessed to your date using the rigorous precession angles of Meeus, Astronomical Algorithms, chapter 21. Sidereal time follows chapter 12 and the altitude and azimuth conversion follows chapter 13. The Sun uses the chapter 25 solar series, the Moon uses the low-precision geocentric series from the Astronomical Almanac with a topocentric parallax correction in altitude, and the five naked-eye planets use the JPL approximate Keplerian elements of Standish, fitted for the years 1800 to 2050, which is why dates are limited to that range.
Accuracy is honest chart accuracy, not almanac precision: star positions are good to a few tenths of a degree, the Sun to about 0.01 degrees, planets usually to a tenth or two of a degree and always well under half a degree, and the Moon to about 0.3 degrees. Atmospheric refraction is ignored, which lifts objects near the horizon by up to about half a degree; light time, aberration, nutation, and stellar proper motion are also neglected, each below a few hundredths of a degree at this scale. When the Sun is up the chart still draws the stars so you can see what lies behind the daylight, and the summary says so plainly. Everything is computed in your browser; coordinates from the optional location button never leave this page. The chart is for planning and education, not for navigation or any safety-critical use.