Sky maps or star charts help you find celestial bodies with the naked eye. They point to where the planets and constellation sit in the sky at a given date and time. The come digitally as apps on your mobile device or software with your telescope. The manual finder charts, such as planispheres, are useful when you don’t have (or want) access to digital means. Here are some tips on using them.
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.
It pretty much gives you the same information as a chart but a planisphere usually involves two discs joined at the center. You simply to 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.
Tips On Using Sky Maps
- 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.
Interactive Sky Chart
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.
Also, you can find out real time space weather and near Earth asteroids here.