M38: Open Cluster in Auriga

  Catalogues M38; NGC 1912
  Names Open cluster in Auriga
  Type Open Cluster
  Constellation Auriga
  Season Visible in Evening Winter; November - May
  Conversation Notes Large dense open cluster in Auriga. Several hundred stars - around a hundred visible in a small scope. Compare to the nearby M37 and M35.

Open clusters are easy to find and observe in small telescopes, pretty, and scientifically important. This is a group of stars all born from a common cloud of gas and dust. Since they came from the same gas cloud they are, astronomically speaking, all about the same age and all about the same distance from us. Knowing that they are the same age and at the same distance, the fact that they have different appearances allows us to learn a great deal about stellar evolution - the different appearances can only be a result of the different masses of the different stars.

Finding M38

In mid-winter, look to the South, fairly high in the sky, for the constellation Orion. Image of southern winter sky, near and above Orion
The constellation is easy to find by the distinctive line of 3 close-spaced stars. Southern winter sky with Orion circled
The stars are the belt of Orion, a mythical hunter. Find his shoulders, feet, and head too. Image of constellation Orion, with connecting lines.
Now look straight above Orion's head, a distance about equal to his height, for a pentagon of stars. The top star in this pentagon, Capella, is very bright. Constellation Orion, with 5 stars of constellation Auriga circled above it
The pentagon is part of the constellation Auriga. Constellations Orion and Auriga

Note the two corners that are next-to-closest to Orion and mentally draw a line between them.

Auriga, with a line drawn between two stars next-to-nearest to Orion

Sight your telescope just to the left of the middle of, and just above, this imaginary line.

If you have a wide-angle magnifying finder, you can safely point directly at the middle of the line - the cluster will be in the field of view of the finder.

If you find a small, sparese, uninterestig cluster, you may have found M36 instead, which is just the other side of the imaginary line, a little farther from its centre.

Telescope pointing to the middle of the line between those two stars

In a magnified finder, the cluster should be just visible as a small fuzzy patch of light.

If you don't have a magnifying finder, hunt around carefully with your telescope, fitted with its widest-field eyepiece.

Simulated view of m38 in a 6x finder scope

In a telescope with an eyepiece selected for about 30x - 50x magnification you should be able to resolve individual stars and note their varying brightness and colour.

Compare M38 and the nearby M37 and note the differences in the shape, density, and brightness of the cluster.

Simulated view of m38 in telescope at 30x magnification

All the above images were generated with Starry Night Pro.


 
  140  accesses changed Mar 25, 2008
 
 
Copyright © 2008 Richard McDonald