First light Guides: Orion Points to...

Constellations found near Orion

Orion is an extremely distinctive constellation found in the southeast, south, and southwestern sky during the evenings of cooler months from the Northern Hemisphere. To people of many cultures, the chance shape of these stars from the perspective of Earth gives the appearance of a large human shape, with three "belt" stars bisecting four similarly bright stars in a quadrangle around them. 

The belt stars are all nearly equal brightness. The upper left "shoulder" star is the somewhat orange-hued red giant star Betelgeuse. The "knee" star to the lower right is the blue giant star Rigel. The upraised club overhead and shield extended towards the west (right) are difficult to see from light polluted locations. 

Check out the graphic below to help you identify this shape:

Orion constellation chart 



Find Canis Major from Orion

A constellation easily found from Orion is Canis Major (the Large Dog), as it contains the next brightest star in the sky after the Sun: Sirius. Make a mental note of the distance between the stars Betelgeuse and Rigel. That distance is about 20 degrees of sky, or two "fist-widths" held at arm's length. Now draw an imaginary line from the belt stars, down and to the left (east), a similar distance of about 20 degrees. This line will take the observer to the -1.4 magnitude star Sirius (negative magnitudes are brighter than positive ones) in Canis Major, allowing the observer to locate the constellation shape. There are several other first and second magnitude stars here, that trace the shape of the large dog. See the chart below to find Canis Major:

Orion to Canis Major chart



Find Taurus from Orion

Going the opposite direction from the belt stars of Orion, the amateur astronomer can trace an imaginary line up a similar distance 20 degrees to the red-giant (and orange-appearing) star of Aldebaran in Taurus the Bull. The bull shape is rather easy to see for most people; Aldebaran marks the red "eye" of the bull. 

Two horns extend towards the east (left) over Orion's head. There are two wonderful open cluster that are best seen with binoculars in Taurus: One is the Hyades, that forms a "V" shape near Aldebaran. The other is the Pleiades, found by continuing the "belt to Aldebaran" line to a tiny "dipper" shape. The line extending up and away from the "s" of Taurus in the graphic leads right to the Pleiades. 

See how to find the bull here:

Orion to Taurus chart


Finding Lepus from Orion

Lepus the Hare is a smaller and often-overlooked constellation, but it does contain First Light Guide object #23. And fortunately the constellation is easy to find. Just look below Orion! Beneath first magnitude Rigel to the lower right and second magnitude Saiph to the lower left, the hare has several 2-nd and 3-rd magnitude stars, though darker skies that reveal 4-th magnitude stars are required to see the "bunny ears" just under Rigel. The brighter "mid-section" stars of Lepus are half the Betelgeuse-Rigel distance. Here's how the hare looks under the hunter's feet:

Orion to Lepus the Hare chart



Finding Auriga from Orion

Auriga is found from Orion by going in the opposite direction of Lepus, and locating it is easier too, though not because it is easily identified as a charioteer from its shape! Rather, it is simpler because Auriga is closer to overhead for many northern hemisphere observers, thereby making for less atmosphere to look through and a clearer view. Also, Auriga contains one of the brightest stars in the night sky: Capella. At magnitude zero, it is the sixth brightest in the entire night sky. Given that Rigel to Betelgeuse is 20 degrees of angular distance, look double that distance straight up and through the hunter from Orion's head 40 degrees to reach Capella. See this chart for a better idea of this:

Orion to Auriga chart


How to find Gemini from Orion

Gemini represents twins in the sky. The two bright stars of Gemini - Pollux and Castor - can be found by generally tracing a line from Rigel - the lower right "knee" star of Orion - through Betelgeuse - the upper left "shoulder" star, and continuing it. Continue past Betelgeuse about double the Rigel-Betelgeuse distance, and the observer will be looking at the two "twin" stars. The shape of the twins then extends back towards the head of Orion, but those are dimmer stars; look for the two "twin" stars first, then find your way back. Here's a chart to help:

Orion to Gemini chart



And that is how to find 5 constellations from the Orion! 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 Canis Major, Taurus, Lepus, Auriga and Gemini from Orion.