Messier 93 (M93), also known as the Critter Cluster, is a stunning open star cluster located in the constellation Puppis. Puppis is one of the constellations catalogued by the Greek astronomer Ptolemy in the 2nd century and is part of the larger constellation Argo Navis, which represents the ship of the Argonauts in Greek mythology. Charles Messier added M93 to his famous catalogue of comet-like objects in 1781, where it has remained a popular target for astronomers ever since. The cluster is a beautiful collection of stars that provides insights into stellar formation and evolution.
Physical Characteristics
M93 is located at an approximate distance of 3,400 light-years from Earth, making it relatively close in terms of galactic measurements. With an apparent magnitude of 6.0, it is just visible to the naked eye under ideal viewing conditions, though a telescope or binoculars provide much clearer views. The cluster spans about 20 light-years across, containing around 80 stars of various spectral types, predominantly blue and white stars, which are characteristic of younger clusters.
The age of M93 is estimated to be about 100 million years, making it a relatively young cluster in cosmic terms, indicating that its stars formed during a time of intense star formation in the Milky Way, when large numbers of stars were created in a short period. The cluster is still gravitationally bound, with the stars interacting and moving together as a single entity. The stars of this cluster offer astronomers valuable data on stellar evolution, especially since the cluster is old enough for some of its stars to have reached later stages in their life cycles, but still young enough to retain much of their original composition.
Visual Appearance
When observed through a telescope or binoculars, M93 presents itself as a concentrated group of stars surrounded by a dark backdrop of space. The stars within the cluster are arranged in a somewhat irregular pattern, and some observers have noted that the overall shape resembles a tadpole or a critter, which is the likely origin of its nickname, the “Critter Cluster.” The cluster’s stars appear densely packed together, giving it a bright, shimmering look against the dark expanse of the night sky.
Though M93 is relatively small in terms of its angular size, its rich star density makes it a striking object to observe. The stars are often easily distinguishable, with a few bright blue and white stars standing out from the rest. The irregular formation adds to its unique appeal, making it an enjoyable object for both amateur astronomers and astrophotographers.
Observation Tips
M93 is best observed from the Southern Hemisphere from December to February (summer) when the constellation Puppis is prominently positioned in the night sky. Observers in the Northern Hemisphere can also spot M93, though it will appear lower in the sky, making it harder to observe.
To view M93, a small telescope or even a good pair of binoculars will suffice, especially when observing from locations with dark skies and minimal light pollution. Under these conditions, the cluster’s dense collection of stars is clearly visible, and larger telescopes will offer even more detailed views of the individual stars within the cluster.
As the year progresses into March and April, M93 will begin to move lower in the sky, approaching the horizon as it sets, making it more challenging to observe from the Southern Hemisphere. However, it is still visible in the early spring months, particularly when the cluster is at its highest in the evening sky. For accurate observation times and positioning, it is always helpful to consult a star chart or an astronomy app to get precise details based on your location and the current time of year.