Messier 24

2014-10-18 Ophiucus Sagittarius 35mm 4x30sec f1.8 ISO4000 25.1 x 37.7 deg M24

The Small Sagittarius Star Cloud

Magnitude: +4.6
Apparent size:1.5°
Image date:2014-10-18.
Field of View:25.1° x 37.7°
Exposure:4 x 30sec, f1.8, ISO4000.
Camera:Canon 60D, 35mm lens.

This is Messier 24, which is the only star cloud in the Messier List. It can be seen in the above image of the galactic centre, which I took with my DSLR camera in 2014. It’s somewhat of a mystery why Messier included this star cloud on his 18th century list of fuzzy objects which were not comets. Most of them are globular clusters, galaxies, planetary nebulae or open star clusters.

My Sky Safari app describes M24 as “a pseudo-cluster of stars spread thousands of light years along our line of sight, perceived through a ‘tunnel’ in the Milky Way’s interstellar dust.”

It is actually “a section of a far interior spiral arm of our galaxy, the Norma Spiral Arm, which we see framed by the dust clouds of the nearer Sagittarius-Carina Spiral Arm.”

The following wonderful public domain map of the Milky Way Galaxy, by Cmglee, shows where we are (red dot) and shows the two above-mentioned spiral arms located between us and the central galactic bar. Note that the coordinates in the diagram are based on the Solar System, not the Milky Way.

After amateur astronomers acquire their first serious telescope, many become a bit obsessed with picking out as many of the Messier objects visible from their latitude as possible. Most could be viewed through an eyepiece within the first twelve months.

I followed the same path – but since I stopped using an eyepiece and moved into astro-imaging, I found that ticking objects off a list by imaging them is a much slower business!

I’ve set myself an eventual target of posting images on Cosmic Focus all of the Messier and Caldwell objects that I can, a total of 219 objects (not all of which are visible here).

This image from six years ago brings me up to 72 Messier/Caldwell objects imaged. 🙃

The Seven Best Southern Sky Objects


  1. Fascinating map of the galaxy and in particular the Sun’s orbit. If I recall, the Sun’s orbit around the galaxy’s centre is 250 million Earth years. That means the Sun has, roughly, 12 to 16 orbits before Milky Way and Andromeda collide. Not a lot of time from that perspective. Yes, nothing will “collide” per se, but that nice map will have to be redrawn.

    And the Sun will probably be expiring around that time anyway.


  2. Thanks for the flashing circle to highlight M24. Now that I know where it is, I can see the different texture of stars in the cluster, but without the spotlight, it would have blended in with the larger stream of stars.

    Liked by 1 person

    1. You’re quite right. It doesn’t look all that remarkable and it needs to be highlighted. However, this Messier object is different from all the rest, it’s not a regular nearby star cluster but a gap in a spiral arm of the galaxy revealing a second spiral arm far beyond. Charles Messier didn’t realise it at the time but he picked out an unspectacular gem!

      Liked by 1 person

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