Meet the New Interactive Sky Chart!

At long last, I’m proud to announce the release of Sky & Telescope’s much-loved Interactive Sky Chart! We worked with Chris Peat ( to make a number of changes — the vast majority of them under the hood — so that you’ll have a reliable sky chart that you can take with you into the night.

The biggest development is that we’ve moved the code base that runs the Interactive Sky Chart from a Java-based platform to an HTML5 platform. We made the move because Java was never supported on iPhones or iPads, and some browsers, such as Chrome and Firefox, have also stopped supporting the software plugin. The new version of the Interactive Sky Chart runs natively in the browser, no plugin required.

What that means for you, the user, is that there won’t be any more hoops to jump through just to get the sky chart to work. And when you call up the Interactive Sky Chart on your mobile device, it’ll work there too.

As before, the Interactive Sky Chart shows two customizable views of the naked-eye night sky for any date, time, and location: A full-sky view shows the Moon, as well as all the bright stars and planets visible to the naked eye for a given time and location. A selected view appears on the left that shows a section of sky (via stereographic projection, to minimize distortion) along the horizon. The selected view is designed to mimic what you actually see when you head outside at night, so that you don’t have to rotate star patterns in your head. You can change the selected view by moving the green-outlined box on the full sky chart.

Also as before, you have the option to customize your sky chart: show constellation lines and boundaries, label stars and planets, and more. There are a couple of new options that weren’t there before, too. My favorite is the daytime option: turn off the Sun and see what stars are up during the daytime. (Among other things, the option is useful for viewing star positions during a total solar eclipse!)

The PDF print option (icon in the upper right-hand corner) now works seamlessly, rendering a beautiful black-on-white sky chart for ease of printing. This option is great for star parties and other astronomy outreach.

Finally, we’ve updated the look and feel of the sky chart, matching it as closely as makes sense to the central sky chart available in every month’s issue of Sky & Telescope.

Note: We are releasing this new-and-improved sky chart as a beta. If you have questions or wish to report bugs, please email us at

Clear skies!

2 thoughts on “Meet the New Interactive Sky Chart!


    Since its beta I’m hoping some of these ideas will help make it into a better version when released to “production”. 😉

    1 – It wasn’t obvious how to move the green quadrilateral around, maybe a hint somewhere on the site would help first time users.

    2- Hard to use the green triangle when trying to cover the sky near the zenith. If that can be fixed you’ll need a way to rotate it since you can be looking at the zenith from multiple directions on the ground depending on which way your feet are pointing.

    3 – Can you make the sky&tel logo disappear (maybe make than another option) as it covers up a good portion of the top left hand corner of the selected view.

    4 – It would be great if we could zoom in/out of the selected view making the quadrilateral larger or smaller. It was impossible to get the full view of some of the larger constellations like Andromeda and Ursa Major. Especially if you are using it at a start party and want to show something in the sky to beginners.

    5 – Could we possibly have the option to pick different projections for the selected view? I personally like the Gnomic projection when showing small areas of the sky. It is really great for showing individual constellations realistically.

    6 – There should be a different icon for the different types of DSOs (like used in Sky&Tel). Also would be great to indicate which stars are doubles.

    7 – If you hover over something in the chart it would be great for a little tooltip bubble to popup giving the basic details of the object and a link to a longer article somewhere either in sky&tel or wikipedia.

    8 – For those of us in less than ideal viewing conditions can you put a magnitude limiter in here so it only shows stars that are not greater than the magnitude chosen? So if I choose 3.5 it won’t show any starts greater than magnitude 3.5.

    Hope that’s enough to keep the developers busy!

    Orlando, FL

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