First Light Guide #17: Messier 38

The objects: Messier 38

A detailed guide to finding / observing the open cluster in Auriga

First Light Guide 17 graphicFirst Light Guides #17 is a detailed written and video reference to finding and observing the open cluster Messier 38 in the constellation of Auriga. This guide is ideal for beginners, but many advanced amateur astronomers may find it useful. It is designed to help you locate this double star with almost any telescope. There is a video to using a magnified finderscope, red dot finder, or setting circles along written tips on observing Messier 38.

Visitors who are new to this site may wish to get started here, while more advanced observers can search the First Light Guides by constellation, or by right ascension

Find Messier 38 in the sky

Messier 38 is an open cluster within our own Milky Way galaxy. Different observers see differing patterns within it; some see a Gree letter "pi" shape among the brighter stars, some see an oblique cross shape, and it has even earned the nickname "The Starfish Cluster" by some. Given the various names and shapes seen, it is clearly among the brighter and better of the open clusters visible to telescope owners. At 4,200 light years distant, the light from these stars reaching our eyes today left the cluster around the time the Gilgamesh epic was written, and the period of the historical flood of the Hebrew Bible.   

If you have a magnified finderscope on your telescope, start here to find Messier 38:

If you have a red dot finder on your telescope, start here to find and observe Messier 38:

Observing tips:

From darker sky locations, the "faint fuzzy" of M38 may be visible in some finderscopes. If not, look for the "smiley face" as the magnified finder video above indicates. For red dot finder equipped telescopes, be sure to aim as closely between Iota and Theta as the video shows. Use a low power eyepiece, and slowly and with small movements, spiral around the area if necessary. 

Averted vision is not required to see this cluster as there are a dozen or so 10th magnitude stars, and and several dozen more at 11th magnitude. However, using averted vision may help observers with smaller telescopes see more. A 6 inch telescope under moderate light pollution will see an explosion of stars down to 13-th magnitude!

Useful filter(s): None needed, though a broadband light pollution filter may help darken the sky background for some observers under heavily light polluted conditions. Test to see if the filter helps or not.

What should I see?

Below is an approximate view of Messier 38 a 70mm telescope at 38x magnification, and a 1.4 degree telescopic field of view.  Demonstrates how view would look with objects on the meridian using a refractor telescope and a star diagonal.  Other telescopes or object sky positions may incur a differing view.  Various magnifications, eyepieces, telescope focal lengths and other variables may alter the view compared to this one.  This is a representation only intended to help the observer get some idea what they may see at the eyepiece.  Extreme local light pollution may block the view entirely.

Approximate view of M38 as seen through a small telescope

Details of Messier 38

Type: Open cluster

Distance: 4,200 light years

Apparent dimensions: 21 arc minutes

Apparent magnitude: 6.9 (integrated)

Right ascension: 05h 28m 42s

Declination: +35 51' 18"

Because telescopes and observers are all different, here are some alternate sketched/drawn views of Messier 38:

Mariano Gibaja, 8" SCT at 65x

Unknown artist, M38 w/smiley face in 4 degrees field of view

The constellation: Auriga

General information about Auriga the Charioteer, where Messier 38 is located can be found here.  This will help you know where to find the constellation in the sky and be able to locate and identify its brightest stars.


Name of constellation: Auriga

Abbreviation: Aur

Genetive form: Aurigae

Common names: Charioteer

Associated asterisms: Hexagon, "home plate"

Original 48 of Ptolemy: Yes

Area by size: 657 square degrees

Relative size: 21 out of 88 (Puppis is next larger; Aquila is next smaller)

First Light Guide objects: Messier 36, Messier 37, Messier 38

Brightest stars, in order of magnitude 

First lists the Bayer designation, then the "traditional" star name (often Arabic, but not always - see each star's notes for details). Graphic shows the constellation at culmination on the meridian while facing north from the northern hemisphere.

  • α (alpha) Aurigae (Capella) magnitude 0.08, the 6th brightest star in the sky; it resides at 42 light years distance. The traditional name is from from the diminutive of the Latin capra "goat", hence "little goat".
  • β (beta) Aurigae (Menkalinan) magnitude 1.90 from the combined light of its binary system, the stars are 81 light years away. The traditional name is shortened from the Arabic منكب ذي العنان mankib ðī-l-‘inān "shoulder of the rein-holder".
  • θ (theta) Aurigae is magnitude 2.62, and is about 166 light years distant. 
  • ι (iota) Aurigae magnitude 2.69, and is 490 light years distant.
  • ε (epsilon) Aurigae magnitude 2.98, and is approximately 2,000 light years from Earth.
  • η (eta) Aurigae magnitude 3.18, and is 243 light years distant.