FAQ

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Excellent question since, without a sense of scale, it’s hard to find what you’re looking for. The image below shows a scale of degrees superimposed over the standard sky chart you see in pre-2014 Sky Lights. The use of the human hand to measure degrees is surprisingly accurate. Sure, some people have larger hands, but then, they also tend to have longer arms, so the difference cancels out. This is still a useful way for estimating distances in the sky, even though in early 2014 we switched to using Cartes du Ciel (Sky Chart) to do all our mapping. It automatically overlays a degree grid to provide scale information.

Sky Lights was originally written primarily for Arizona skies. Now that Sky Lights is online with readers from other locations, that can cause a problem with some sky charts. There are several websites that can compute your exact sky map for any location. See, for example: http://space.jpl.nasa.gov/. But there’s a simple correction you can make to my charts, as long as you know your latitude.

Arizona is at a latitude of 34° north of the Equator. If you’re at latitude 44°, 10° farther north than Arizona, everything in my charts will be shifted 10° south. If you are at latitude 24°, 10° farther south than Arizona, everything in my charts will be shifted 10° north.

Whatever your location, posted clock times will be correct for most celestial events. Check the Local Time & UT page on this website. Sunset times, however, will vary depending on your latitude. Here’s one of many online sunset/sunrise time calculators: http://www.calendar-updates.com/sun.asp. All you have to do is enter your postal code.

There really aren’t that many to learn. Here’s a graphic summary explaining my labeling format for pre-2014 posts when all the charts were done by hand:

Newer charts are created with Cartes du Ciel (Sky Chart) which uses its own symbols. Here’s an example:

And here’s the key:

  • Constellation names are in yellow.
  • All other labels are in white (stars, planets, Moon, extended objects).
  • The Moon is shown with its correct size and phase.
  • Stars and planets are small white discs with larger sizes corresponding to greater brightness.
  • Extended objects (star clusters, galaxies, asterisms, nebulae) are large colored discs or ellipses.
  • The Milky Way is shown in a lighter blue compared to the rest of the sky.

Additional annotations are added as needed: star names, indicator circles or arrows, photographs of objects. Sometimes so many objects are displayed that readers might need a little help finding what’s relevant.

If you’re using an older browser, that could happen. Displaying those special symbols requires UTF-8, a way to encode many more characters than those available on your keyboard. Upgrade to any of the latest browsers, and you should be able to see those special symbols you’ve been missing.

Sky Lights started out as a printed newspaper column, and it’s hard to justify the cost of color printing (unless you’re a widely syndicated cartoonist). So I started out with grayscale images, and just accepted the limitations that imposed. Later, when I made the transition to a local newspaper’s website, color became possible. Now, as an online blog, I use color whenever I can, as well as animations where needed. Some of the older posts will be re-released in color if the topic comes up again. But even now, especially for sky charts, sometimes grayscale is all I need.

Newer animations are in the HTML5-compliant MP4 format, using the H.264 codec. They should play well on all modern devices. Some of the older animations are in FLV format. Those are likely the ones you’re having trouble playing. To fix this, you need to have the latest version of Adobe’s Shockwave Flash Player plug-in installed. It’s available online for almost all operating systems and browsers. We are in the process of converting all our video content to MP4. Patience grasshopper.

The other possibility is that the video was embedded from an outside source, like Vimeo, and subsequently moved or deleted. That’s always a risk with external links. In that case, just do a search with the relevant key words and you’ll probably find it out there somewhere.

If you’re an educator, you already have my permission. Sky Lights is an educational resource that can be freely used by teachers, whether in formal institutions, or in home schooling. Posts may be printed and distributed in a classroom as needed. They may not be altered, reproduced for sale, or converted into any other form for distribution over the internet or on digital media. Sky Lights sometimes uses photos or graphics credited to other individuals, but only after receiving written permission. These images may not be used elsewhere without securing equivalent permission. All images from NASA, NOAA, and USGS are in the public domain except where noted — your tax dollars at work.