Fetching the stars…
The sky tonight
Look up
Drag to look round. Touch a star.
Up now
Working it out…
How to use it
The picture shows the sky as you would see it standing outside, facing the way written on the ground at the foot of the view. Drag the picture to turn round or to look higher. Pinch, or roll the mouse wheel, to look closer.
Slide the bar to move through the night and watch the sky turn. Touch any bright star, a planet or the Moon to find out what it is.
"Whole sky" tips the view straight up, so the point overhead is in the middle and the horizon runs round the edge. East is then on the left and west on the right, the other way round from a map of the ground, because you are looking up and not down.
A bigger dot is a brighter star. The colours are real: blue-white stars are the hottest and orange ones the coolest. Things close to the ground may be hidden by houses, trees or haze.
Meet a star has a page for every star on the map.
How it is worked out
Nothing here is looked up from a service. The page works out the sky itself from your place and the time on your device.
- Stars: places, distances, brightness and colour from the HYG star database by David Nash (CC BY-SA 4.0), the same stars the 3D view uses.
- Planets and the Sun: orbits from NASA/JPL Solar System Dynamics, the same sums as the rest of this site.
- The Moon: the largest terms of the series in Jean Meeus, Astronomical Algorithms, chapter 47.
- Constellation figures: from d3-celestial by Olaf Frohn.
Checked against NASA's JPL Horizons service, the planets land within a fifth of a degree and the Moon within a tenth. A fifth of a degree is less than half the width of the full Moon. The colour of the sky and the glow at dusk are drawn to give the feel of the hour, and are not measurements. If you use "where I am", your position stays on your device. See Sources for the files and their licences.