Spotting the Pinwheel Galaxy

Here in mid-autumn in the northern latitudes, there are some beautiful things to point your telescope at during these extended, chilly nights. Two of our closest galactic neighbors climb higher in the sky in the evening this time of year. While viewing galaxies can be challenging due to light pollution from a city or moonlight, catching a glimpse of these faint fuzzies is pretty amazing! Seeing a distant group of stars millions of light years away helps to put the universe’s immense size into perspective, and really can get the thoughts wondering if we are really alone out there. In this edition, we’ll have a look at M33, the Triangulum Galaxy.

M33 Triangulum Galaxy

M33 is the third largest galaxy in the Local Group behind the massive Andromeda Galaxy and the Milky Way. Also known as the Pinwheel Galaxy due to its spiral shape, it lies between 2.5 and 3 million light years from Earth, and has a diameter of about 60,000 light years. As with the Andromeda Galaxy, M33 is also moving towards us, at a rate of about 60,000 mph. M33 may have interacted with the Andromeda Galaxy in the distant past, and may do so again in the distant future. Since M33 is at an angle which we can view it more “face-on”, we can see more of its spiral structure with fewer gas and dust obstructions of galaxies facing “edge-on”.

Where to look for M33. “Down” in this image is east towards the horizon.

To find M33, you must first find the Great Square of Pegasus and Cassiopeia. Following the bottom right point of the “W” of Cassiopeia will lead you to the Andromeda Galaxy. To the east of that area will be a slightly dimmer triangle pattern of stars. That is the constellation Triangulum. To find M33, find Triangulum, point your telescope towards the south-facing point of the triangle, then move the telescope slightly west (or up, if Triangulum is above the eastern horizon).

An idea of what to expect when you view M33 in a telescope

Under exceptionally dark skies, you can spot M33, making it one of the most distant objects you can see with your naked eye. It is also possible to find M33 with binoculars as well. It appears as a cloudy smudge with little detail. Any size telescope will also allow you to see M33. The larger the telescope, the better you will be able to make out the spiral arms of the galaxy. At around 30x magnification, M33 will become large in the eyepiece and you should be able to make out its famous pinwheel shape. M33 looks surprisingly faint in a telescope. This is because M33 is more diffuse and its core isnt as densely packed as some other galaxies. Thanks to its face-on orientation, there are some features you may be able to spot within M33, such as one of the largest nebulae known to us.

Some visible features within M33, including the location of NGC-604

Visible to the northeast of the core of M33 is the stellar nursery nebula NGC-604. While viewing with a telescope, NGC-604 may be confused as a regular star. Using magnifications around 100-150x will help. It is even visible in 6 inch telescopes. Using larger telescopes will permit more magnification. NGC-604 spans 1,500 light years, making it one of the largest nebulae discovered. If it were the same distance from Earth as the Orion Nebula, it would be as bright as Venus and span nearly one quarter of the night sky! Spotting a nebula in another galaxy with amateur equipment is pretty amazing, and is definitely worth the effort to try and find! There are other features visible in M33 as well, like globular star clusters. Those require very steady seeing conditions as well as telescopes with diameters of 12 inches or more.

Hubble Space Telescope view of NGC-604

Spotting M33 is a treat during these chilly fall nights. Remember, light pollution and the moon will make M33 very difficult, if not impossible to spot, so wait for a clear dark night so you can appreciate the view in full. From seeing the pinwheel structure of a spiral galaxy to seeing objects within another galaxy, M33 is a great target. Be sure to check this galaxy out when you’re out gazing at the stars!

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