Sky maps or star charts point to where the planets and constellation sit in the sky at a given date and time. While sky map apps on your mobile device are useful, the manual types, finder charts, planispheres, or the like, are best for a few reasons. This article covers why plus tips on using star charts for beginners learning about astronomy.
What is a planisphere?
A planisphere helps you identify stars and constellations visible on any given night. It is a manual tool that is hand-held. Diagrammatically it shows the planets and constellations with emphasis on the brighter stars.
Also called a sky wheel, a celestial planisphere, or a night sky planisphere. Sky maps and star charts are also names that are used interchangeably.
It pretty much gives you the same information as a chart but a planisphere usually involves two discs joined at the center. You simply turn the discs to align the date and time to show what you can expect in the sky and then orient yourself to match the plane.
Why use manual star charts / sky maps
These are especially important when you don’t have access to digital means of looking up the celestial bodies. You may be in a stargazing location where you can’t get internet coverage, for example. Or you may simply prefer looking at a hard version. You may also be using your mobile device for another purpose and it is inconvenient to toggle between apps.
In any case, I find having a star chart that’s tangible is a handy tool for investigating and finding your way around the night sky. Star charts for beginners are especially great as a learning tool.
Tips on using star charts for beginners
- Make sure your timezone matches the skymap or chart. Daylight Saving and other time shifts may confuse the issue.
- Realize that the limiting magnitude of the stars (5.5) will hinder what you see with the naked eye. You will need to use your binoculars or telescope to see the fainter stars marked on the maps.
- Under dark skies, in areas away from urban light pollution, you should see everything up to that limit.
- Use a distinctive star pattern to orientate yourself and rotate the chart.
- Get to know what the grids on the chart mean. In most, you will have the right ascension (hrs; vertically or N to S) and the declination lines (degrees; running across).
- Look for objects with the same declination (degrees) as your latitude, as these will pass directly overhead (the Zenith). For example, if you were near the Tropic of Cancer, look for the declination +23.5°. In the Southern Hemisphere look for negative declinations, e.g. if you were at the Tropic of Capricorn, look for the declination -23.5°.
- Your chart may also show paths of the planets.
How do you use a sky map?
This video explains it.
Interactive sky chart
More tips on using sky maps and night sky watching
Get to know what’s up there in space.
In viewing the night sky, apart from the constellations, stars and planets, you might come across unexpected sightings or moving objects.
Is that a satellite you’re seeing? Is it the international space station (ISS)? You can find out here.