First Light Guides: Big Dipper points to...

The Big Dipper - or Plough as it is sometimes referred to in some countries - is an easily identified, large shape in the sky. Composed of mostly 2nd magnitude stars, it is visible from most anywhere, and its stars can be used to point to quite a few other areas of the sky. When the Big Dipper is on the meridian, it actually will appear "upside-down" when an observer is facing north. If possible, turn your screen with north (top of graphic) at the bottom of your screen (smartphone/tablet/laptop) in order to see it and shapes to the north if you wish to have it appear in the same orientation as it is in the sky. 

Most observers are able to adjust their orientation of the dipper shape to be able to find objects from it, recognizing the "bowl" and "handle" sections. Here is where the Big Dipper crossing the meridian from an south-facing, all-sky view:

Big Dipper chart



Find the North Star (Polaris) from the Big Dipper

We are fortunate in the northern hemisphere; the 45th brightest star in the entire night sky is about one half of one degree away from the northern celestial pole (the point in the sky around which the sky appears to rotate). So while the myth that "The brightest star in the sky is the north star" is not true, Polaris can be seen from most northern hemisphere locations without much difficulty. It also makes a handy reference if you are ever lost in the woods or backpacking; the height above the horizon provides your latitude, and the star is always at a due-north location. So how can you find it?

Easy. Use the Big Dipper as your guide. The two outer-most stars of the Big Dipper's "bowl" point almost directly at the north star. These two stars are 2nd magnitude; the lower-bowl one just slightly dimmer than the one at the top of the bowl. Trace an imaginary line from them, about 25 to 30 degrees from that upper, brighter star. Then next star the observer will see along that line that is exactly the same magnitude as that upper-bowl star will be Polaris. See the chart below to learn how to find that line:

Big Dipper points to Polaris chart

Once the observer has found Polaris, the shape of the constellation Ursa Minor (the Little Bear) can be traced. From many locations, only the two or three brightest stars will be visible: Polaris (Alpha Ursae Minoris) at the "tail," also 2nd magnitude Beta UMi at the outside, open end of the bowl and 3rd magnitude Gamma UMi at the outside, lower 'bowl' star location. 

Only under darker, less light polluted skies will most observers be able to trace the rest of the constellation, as the remaining stars are dimmer 3-rd and 4-th magnitudes. 



Find Draco from Big Dipper / Polaris

Draco the Dragon is a large, winding constellation. For many amateur astronomers under light polluted skies, it can be hard to see much of it. However, some of it's stars are 3rd magnitude or brighter, and it also contains several of the easy-to-observe First Light Guides objects. After "pointing to Polaris" and identifying Beta Ursa Majoris, look to the northeast for very bright, first magnitude Vega. In between both the Big Dipper / Little Dipper and Vega is Draco. See how it winds back and forth, ending at the "head" somewhat near the star of Vega? The stars at the "head" near Vega, and the two or three bright stars between there and Beta UMi are near where the First Light Guide objects are located. Look for these 2-nd and 3-d magnitude stars between Vega and Beta UMi to find at least the parts of Draco necessary to find the First Light Guides objects:

Big Dipper to find Draco chart



"Arc to Arcturus" to find Bootes from the Big Dipper

One of the well-known ways to find a bright star from the Big Dipper is to trace a line from the handle of the Dipper. Starting at the intersection of the "bowl" and "handle," follow the handle out to the very last handle star. Note how the handle curves slightly. Now continue that curving line about 25 to 30 degrees; the next brightest star seen will be Arcturus of Bootes the Herdsman. While Bootes doesn't resemble much of a herdsman (many people see a mis-shapen ice cream cone!), this is still an important way to find the fourth brightest star in the night sky, Arcturus. And more can be found from here as well (see below). Check this chart to learn how to find Arcturus and Bootes from the Big Dipper:

Big Dipper to Bootes (arc to Arcturus)



Find Libra: Arc to Arcturus, speed on to Spica from the Big Dipper

Libra is a zodiac constellation; no, that's not a reference to astrology, the zodiac constellations are those along the ecliptic, the imaginary line in the sky the Sun traces as Earth revolves around it. The ecliptic is also the line in the sky near where the the planets are seen as they revolve around the Sun as well. First magnitude Spica is very close to this ecliptic line in the sky. To find it, "arc to Arcturus" as you did above, and then continue that arcing line in the sky a similar distance past Arcturus. Not quite as bright, and more bluish-white in appearance is Spica. Compared to the slightly orange red-giant Arcturus what is brighter, Spica may be sometimes joined by a planet nearby or one may be in or near Libra, to the east of Spica. Look for the somewhat dimmer 2nd magnitude stars of Alpha and Beta Librae. These stars form a slight dimmer and flattened "peak" trapezoid shape from the brighter "base" stars of Arcturus and Spica. Check out this chart to help you find Libra:

Find Libra from the Big Dipper chart



Find Leo from the Big Dipper

Leo the Lion is similar to Libra in that it is also a zodiac constellation. The ecliptic passes less than one half of one degree from the brightest star in Leo, first magnitude Regulus. This star is easy to find from the Big Dipper, although the distance to look from the dipper is rather large. Start at the inner two "bowl" stars - the ones opposite from the two used to find Polaris. Also, draw a line in the opposite direction from Polaris, so draw the line from below the "bowl" of the dipper. This line will have to extend a long way - about 1/4 of the entire sky! Measure 45 degrees across the sky using the hand-measuring techniques found in the Stargazing Basics section to locate Regulus in Leo. The Lion's shape can be found from there. See this chart to get an idea of that view of the sky:

Big Dipper to Regulus and Leo the Lion



Find Canes Venatici from the Big Dipper

Canes Venatici - the Hunting Dogs - is a very small constellation not far south from the handle of the Big Dipper. In fact, this constellation is best represented by just two stars! The only one visible from most locations is the brighter one, Alpha Canes Venaticorum. Find it on a line between Arcturus, and the "bottom bowl stars" of the Big Dipper. Alternatively, it sits 'below' the end 'handle' star of the Dipper. At close to magnitude 3, it may take a bit of time to locate it, but it is also the brightest star in this area. This chart below can help in locating it:

Find Canes Venatici from the Big Dipper chart



And that is how to find 6 constellations from the Big Dipper! Don't miss all the great objects you can find and see with a small telescope that reside within these shapes in the sky. 

Check out the First Light Guides starting page to learn what you can find and observe by hopping to Ursa Minor, Draco, Bootes, Libra, Leo and Canes Venatici from the Big Dipper.