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VirtualSky

VirtualSky a browser-based planetarium that lets you see what is visible in the sky from any location on Earth. It can be customized and included on your own website, blog etc. It is provided freely for educational and non-profit use.

Contents

• What's new?
• Keyboard shortcuts
• Instructions for embedding
  • Example 1
  • Example 2
  • Example 3
  • Example 4
  • Example 5
  • Example 6
  • Example 7
  • Example 8
  • Example 9
  • Example 10
• Options
• Technical details

What's new?

Version 0.7.4 / 15 September 2019

Changes:

• Update links
• Make sure atmosphere gradient displays on first draw #63
• Improve the size of the keyboard shortcuts
• Fix bug with time input

Version 0.7.3 / 6 August 2019

There have been some improvements to the code:

• Fixed issue #52 to improve touch move handling
• Improved performance of drawing
• Fixed part of issue #25 to get RA/dec of cursor position

Version 0.7.0 / 15 October 2018

There has been a major overhaul to remove the need for jQuery (replaced with stuQuery). This has reduced the initial page load from 337kB to 200kB so it should hopefully load more quickly and save bandwidth. Also:

• Can set the width of gridlines (gridlineswidth=5) #46
• Can set the width of constellation lines (constellationwidth=5)
• Can set the width of constellation boundaries (constellationboundarieswidth=5)
• Can set the width of the galaxy (galaxywidth=5)
• Help screen can be accessed with the mouse
• The place-search API was deprecated by Yahoo so the place lookup now uses static files split by starting letter (to keep it quick)
• Switched to date/time input fields to make date selection easier with controls native to the browser
• Bug fix: manually set constellation boundaries work again. #41

Please report any bugs on Github giving your browser make/version. You can also suggest new features there (although they may not happen for ages or at all as this is an entirely spare time project).

Keyboard shortcuts

Press the "?" key (with your mouse over VirtualSky) to see the full list of keyboard controls.

Instructions for embedding

The easiest way to include VirtualSky on your website is to use the custom form to create an embed link (uses an <iframe>).

Sometimes an <iframe> just doesn't give you the flexibility you need (or you might want to include it in an offline page during a public talk). In that case you could download a copy of the source from GitHub and include VirtualSky in your page using Javascript. You will need to include the following in your page:

That is a version of VirtualSky with all the default options. However, one of the great things about VirtualSky is that it can be customised. Here are some examples to give you some ideas:

1. A stereo projection set for Santa Barbara's lat/long:
2. A lambert projection, with constellations shown, no keyboard control and a black-on-white view. It is based in Manchester,UK and facing north:
3. A stereo projection with no keyboard or mouse input and with a Galactic grid and the Meridian line displayed. The view is facing south east from Hill Valley, California at 1:21 am on October 25, 1985.
4. A mollweide projection with with star labels drawn and the ground blocking half the sky.
5. A default view with a stereo projection, constellation lines and two manually specified constellation boundaries (note that RA/Dec for boundaries are assumed to be in B1875).
6. A default view using stereo projection with a place marker
7. A default view using gnomic-tan projection centred on M42
8. A default view using gnomic-tan projection centred on Orion with a button to move, and a handler for contextmenu (try the right mouse button...)
   Move to The Pleiades Move to M1 Move to M82 Move to M42
9. A default view using stereo projection in Arabic
10. A default view using stereo projection showing objects (in this case the Messier catalogue) included from a local JSON file:

    If you have multiple files of objects you can separate them with semi-colons e.g. objects: 'messier.json;caldwell.json'.

Options

There are a range of options to try (default values in brackets):

• id ('starmap') - The ID for the HTML element where you want the sky inserted
• projection ('polar') - The projection type as 'polar', 'stereo', 'lambert', 'ortho', 'equirectangular', 'mollweide', 'planechart' or 'fisheye'
• width (500) - Set the width of the sky unless you've set the width of the element
• height (250) - Set the height of the sky unless you've set the height of the element
• planets - either an object containing an array of planets or a JSON file
• magnitude (5) - the magnitude limit of displayed stars
• longitude (53.0) - the longitude of the observer
• latitude (-2.5) - the latitude of the observer
• clock (now) - a Javascript Date() object with the starting date/time
• background ('rgba(0,0,0,0)') - the background colour
• transparent (false) - make the background transparent
• color ('rgb(255,255,255)') - the text colour
• az (180) - an azimuthal offset with 0 = north and 90 = east
• negative (false) - invert the default colours i.e. to black on white
• gradient (true) - reduce the brightness of stars near the horizon
• ground (false) - show/hide the local ground (for full sky projections)
• keyboard (true) - allow keyboard controls
• mouse (true) - allow mouse controls
• cardinalpoints (true) - show/hide the N/E/S/W labels
• constellations (false) - show/hide the constellation lines
• constellationlabels (false) - show/hide the constellation labels
• constellationwidth (0.7) - set the width of the constellations in pixels
• constellationboundaries (false) - show/hide the constellation boundaries
• constellationboundarieswidth (0.7) - set the width of the constellation boundaries in pixels
• meteorshowers (false) - show/hide current meteor shower radiants
• showplanets (true) - show/hide the planets
• showplanetlabels (true) - show/hide the planet labels
• showorbits (false) - show/hide the orbits of the planets
• showstars (true) - show/hide the stars
• showstarlabels (false) - show/hide the star labels for the brightest stars
• scalestars (1) - the factor by which to scale the star sizes
• showdate (true) - show/hide the date and time
• showposition (true) - show/hide the latitude and longitude
• gridlines_az (false) - show/hide the azimuth/elevation grid lines
• gridlines_eq (false) - show/hide the RA/Dec grid lines
• gridlines_gal (false) - show/hide the Galactic grid lines
• gridlineswidth (0.7) - set the width of the gridlines in pixels
• gridstep (30) - the size of the grid step when showing grid lines
• ecliptic (false) - show the line of the Ecliptic
• meridian (false) - show the line of the Meridian
• showgalaxy (false) - show an outline of the Milky Way
• galaxywidth (0.7) - set the width of the Milky Way outline in pixels
• live (false) - update the display in real time
• fontsize - if, from a design point of view, you need a very specific font size (currently only in pixels), this is how you override the automatic font scaling. e.g. "10px"
• fontfamily - VirtualSky inherits the font family when it is added to an element on a page but can't when using an iframe. To solve that situation, you can provide a CSS font-family string.
• lang - VirtualSky will attempt to auto-detect the preferred language of the person's browser but you can specify a language explicitly
• callback.contextmenu - VirtualSky will invoke the given callback on right click or long press on the map. The event sent to the callback includes the RA,DEC coordinates in the skyPos property, if applicable.

Technical details

Virtual Sky uses the <canvas> element - part of the HTML5 proposal - so should work in most modern browsers such as Firefox (there are issues in Firefox 3.0 on Ubuntu), Opera, Chrome and Safari. It should also work in Internet Explorer 7.0 and 8.0 through the use of the excanvas.js library. The code can be found on Github.

Alternatives

There are other browser-based planetaria available online e.g. Ivan Boldyrev's Starchartjs, Luther Huffman's StarAtlas and Thomas Boch's All Sky Map. On the desktop, Stellarium is a highly featured planetarium program that works on Windows, Mac and Linux platforms (VirtualSky uses many of the same keyboard shortcuts).