M33 (Triangulum Galaxy) 

10/13/2023, 3:00AM (UTC)

M33 is the smallest spiral galaxy (type SA(s)cd) in the Local Group and about 3 million light years from Earth. The most noticeable characteristic of this spiral galaxy is its HII regions. HII is hydrogen that has been ionized by young, hot, massive stars. Its nucleus is also primarily HII. By using a Ha filter (Hydrogen alpha spectral line), you are able to see the HII regions in red.

M33 has a long history of human observation, dating back to ancient times. Giovanni Battista Hodierna, the Italian astronomer, made an early discovery of what we now know as the Triangulum Galaxy (M33) before 1654. In his work "De systemate orbis cometici; deque admirandis coeli caracteribus," he observed and documented this celestial object. He described M33 as a cloud-like nebulosity or obscuration "near the Triangle hinc inde." The reference to "the Triangle" likely indicated its proximity to the constellation Triangulum.

It was officially cataloged by the French astronomer Charles Messier in 1764 as Messier 33 in his famous Messier Catalog, where it is described as a "nebula." However, Messier didn't recognize it as a separate galaxy.The identification of M33 as a separate galaxy, distinct from our Milky Way, was a significant development in the early 20th century. American astronomer Edwin Hubble played a crucial role in this discovery, along with others. In 1926, Hubble used the newly discovered Cepheid variable stars in M33 to accurately determine its distance, confirming that it was a galaxy far beyond the Milky Way.

In 2004, researchers found evidence that M33 in the past may have tidally interacted with Andromeda. The evidence was a clumpy stream of hydrogen gas linking the two galaxies.I love this galaxy, and I can’t wait to capture more data in the near future. Every time I look at this image or the other amazing images by my fellow astronomers, I feel a sense of awe. It’s incredible that the universe’s beauty and its secrets are right at our fingertips. 

(UV/IR Cut) 60 x 120 second exposures
(Ha/Oiii) 30 x 120 second exposures