A star chart, also known as a star map, is a tool used to map the night sky. For thousands of years, people have studied the stars, dividing the night sky into grids. These grids allow people to identify and locate stars, constellations, galaxies and more. By turning the night sky into a readable map, humans have been able to navigate and travel the world just by simply using the stars.
However, a star chart is not the same as an astronomical catalogue. An astronomical catalogue as a catalogue that lists astronomical objects as a star chart is a visual tool used to aid in the observation of the night sky. Star charts are especially useful when used in combination with an astrolabe and a planisphere.
Interestingly, the oldest known star chart may be 32,500 years old. Discovered in Germany in 1979, an ivory Mammoth tusk has a carving that resembles the constellation Orion. Although this example is a bit of an outlier, the answer to “What is a star chart?” is typically straightforward. Here’s more about how star charts work, and a comparison between a few popular products.
How to Read a Star Chart
If you’re interested in astronomy, you should absolutely invest in a star chart. By simply using the date, time, and your current location you have everything you need to find the brightest stars and constellations.
However, if you’ve never used a star chart, learning how to use and read one may seem a little daunting. Here’s a bit of the basics. Imagine that when you look at the star chart, you’re peering up into the night sky. The edges of the star chart represent the horizon while the center of the star chart is the zenith – the point directly overhead.
Before you begin using the star chart, you’ll need to prepare using the following tips:
- Find the darkest part of the night sky away from light pollution such as city light and streetlights. Why? The brighter it is the harder it will be see the stars. This is also true during a Full Moon when the night sky is a bit too bright to see many stars.
- Once outside, you’ll need to let your eyes adjust to the darkness. Try it! You’ll see that you’ll suddenly be able to see many more stars, and maybe even the Milky Way!
- While some star charts glow in the dark, you’ll likely need a red LED flashlight to see the chart. You’ll want red to dim the brightness of the white light. Alternatively, if you only have a white flashlight, you can cover the end with red plastic or tape.
Once you have this all in place, you’ll want to know how to actually read the chart.
- If you’re looking South, you’ll want to rotate the chart so that South is at the bottom. When you hold the chart up, you’ll see that the directions correlate to the correct directions in the sky.
- Choose a small portion of the map (one with bright stars will be easier). Starting with bright, easy to see constellations such as Orion or Ursa Major is a great place to start.
- Relate that portion of the sky to that area on the map. This may seem difficult at first, but once you find the right spot, you’ll be able to perfectly match the pattern on the star chart with the pattern you see in the night sky.
- From here, it will become easier to find, locate and learn stars in the night sky.
- Depending on how long you’re outside, you may need to adjust your chart according to the time. For example, after about three hours, the stars will have moved approximately 1/8 further along the ecliptic. After 6 hours, they will have moved 1/4 away around the sky.
- Keep in mind, if you see a bright star that doesn’t fit with the star chart, you’re likely viewing a planet! You’ll need to do a bit more research to find out exactly which one.
Star Chart Comparison
Guide to the Stars
The Guide to the Stars chart is a great tool that allows you to identify stars and constellations. The Guide to the Stars includes 70 Constellations, 55 Stars, 54 favorite Double Stars, the location of the Milky Way and Ecliptic (the path of the Sun, Moon and Planets), 56 Galaxies, and more.
The large size (16-inch diameter) of this star chart makes it easy to read, even for seniors. With pertinent information on the back, this chart is ideal for students, teachers or the family. Additionally, the chart is available in a smaller 11-inch diameter, along with a less expensive kids version.
On the back of the star chart, helpful information such as the phases of the Moon, the history of Astronomy and facts about planets can be found. This is definitely a fact packed star chart that offers tons of educational content for adults and children alike.
More information includes, but is not limited to:
- Meteor Showers
- Moon Map
- The 10 Brightest Stars
- Why Stars Twinkle
However, to use this chart, you will need a red flashlight and you should be located between latitudes 30 and 60 degrees North. This area includes the US and Canada, England, Europe, Northern China and Japan.
The Night Sky 30°- 40°
This full-sized sky chart is suitable for those who reside in the 30° – 40° latitude zone (the southern half of the US, the north of Africa and the Middle East, primarily). The reverse side of this star chart is equipped with a helpful key that details what symbols represent which of the objects on the chart. Additionally, there are editions available for other latitude zones, as well as the southern hemisphere. Make sure you’re aware of what latitude zone you are in before purchasing a sky chart. For example, if you are in Northern United States and Europe, you will need the 40°- 50° zone star chart instead.
The night sky is available in two sizes, large and small. The large size is 8 inch in diameter and is more suited to beginners who are learning the constellations as it is easier to read and offers educational content. The small version is 5 inches in diameter and is better served as a pocket reference for those who are already familiar with the constellations. Whichever you choose, both sizes are available in each latitude zone.
Although there is a lot of information on this chart, the print is fairly small, making it difficult to read. This star chart also does not offer a glow-in-the-dark option. The best alternative is to use a red flashlight to minimise light pollution, making the chart easier to read.
Orion 04110 Star Target Planisphere
This Orion planisphere is an easy to use accessory for finding stars and constellations. To find the correct constellations, all you need to do is change the dial until it aligns with the current date and time. Designed for use in the 30° – 50° latitude zone (If you’re not sure which latitude you’re in, check out this list), simply match the chart with north and you’ll see a detailed map of the current night sky. This planisphere is ideal to use with binoculars and telescopes for beginners as it’s easy to read and provides tons of information.
At 8.5 inches in diameter, this sky chart is large enough to easily read the information on it. Although there is a lot of information on the backside of the chart, but good eyesight or glasses are preferred due to the size of the text. However, this product does not have glow-in-the-dark text therefore a flashlight is required to read it, preferably with a red filter or dimmer. This chart is also made of cardboard, not plastic, so be sure to take that into consideration.
Night Sky® Star Wheel
One of the most basic star wheels in the list, this product is best suited for beginners or young children as a starter tool to learn how to use a star chart as well as basic information on the stars and constellations. All that is required is to adjust the wheel to the date and time and the wheel will show you what stars are visible.
At just 7.2 x 7.9 inches in diameter, this product is smaller than the others, which is best used as a reference guide that can fit in the pocket. There is little information available on this chart that is also difficult to read in the dark as there is no glow-in-the-dark option, thus a flashlight is preferred. Due to its small size, there isn’t much information on the chart itself, but provides a link on where to find information. Those who are already knowledgeable in the night sky can use it to simply find the constellations they are viewing. Made from thin cardboard that isn’t water resistant, this product will likely have a shorter lifetime.