A Brief History of Galactic Observation

The Andromeda Galaxy, the closest large galaxy to our own Milky Way, has been visible to the naked eye for as long as humans have gazed at the stars. The first recorded observation dates back to 964 CE when the Persian astronomer Al-Sufi described it as a “little cloud.” For centuries, observers believed it was simply a cloud or a smudge in the sky.

In the 1700s, French astronomer Charles Messier cataloged many deep-space objects, 40 of which are now known to be galaxies. However, Andromeda, which he designated M31, along with the other galaxies he documented, were cataloged as a nebula. It wasn’t until the 20th century that astronomers began to understand the true nature of these objects. Using advancements in telescopes and spectrometry, astronomers discovered that these “nebulae” were far beyond the Milky Way.

In 1924, Edwin Hubble solved the mystery once and for all when he identified Cepheid variable stars in Andromeda. These stars allowed him to calculate that Andromeda was much farther away than anything in our Milky Way, proving that it was an entirely separate galaxy. His discovery, along with numerous other astronomical advancements, opened the door to the vast universe we know today.

What is a Galaxy?

A galaxy is a massive system of stars, gas, dust, and dark matter bound together by gravity. Galaxies come in various shapes—spiral, elliptical, and irregular—and can contain billions to trillions of stars. The Milky Way, our home galaxy, is just one of these immense cosmic structures. Thanks to powerful telescopes like the Hubble Space Telescope and the James Webb Space Telescope, we now estimate there are at least two trillion galaxies in the observable universe.

How Do Galaxies Form?

Galaxies form over millions to billions of years as gas and dust collapse under gravity, triggering star formation. The early universe contained vast clouds of hydrogen and helium, which gradually coalesced into the first galaxies. Over time, galaxies merged and evolved, forming complex structures with diverse characteristics.

Gravity plays a crucial role in shaping galaxies, with dark matter—an invisible form of matter—providing additional mass that influences their structure and motion. Many galaxies also contain supermassive black holes at their centers, which can regulate star formation and drive energetic phenomena like quasars and active galactic nuclei.

Why Do Galaxies Have Different Shapes?

A galaxy’s shape is influenced by its history and environment. Spiral galaxies, like the Milky Way, maintain their shape due to their rotational motion, with new stars forming in their spiral arms. Elliptical galaxies, which tend to have older star populations, likely formed from galaxy mergers that disrupted their original structure. Irregular galaxies often result from gravitational interactions or collisions with other galaxies, leaving them without a defined shape.

Why Do Galaxies Seem to Cluster Together?

Galaxies rarely exist alone; they tend to cluster together due to gravity. These galaxy groups can range in size from small clusters containing a few dozen galaxies to enormous superclusters stretching hundreds of millions of light-years across.

The Virgo Supercluster, for example, is a vast collection of galaxy clusters, including our own Local Group, which contains the Milky Way, the Andromeda Galaxy (M31), and the Triangulum Galaxy (M33). The entire Virgo Supercluster spans approximately 110 million light-years and contains thousands of galaxies. It is part of an even larger structure called the Laniakea Supercluster, a galactic web spanning 520 million light-years, within which our Milky Way is just a tiny piece.

These enormous structures are interconnected, forming the large-scale cosmic web that defines the structure of the universe. Understanding galaxies and their distribution helps astronomers unravel the history and fate of the cosmos itself.

What is Galaxy Season?

Astronomers call the time of year from March through mid-May “Galaxy Season.” During these months, Earth’s nighttime view shifts away from the bright band of the Milky Way, due to Earth’s and our solar system’s position in our own galaxy. The Milky Way is a barred spiral galaxy, and our solar system is located on one of its outer arms. During the summer months, the densest part of the Milky Way—its galactic core—is positioned high in the night sky, making it difficult to see past the thick clouds of gas and dust within our own galaxy. However, in the spring, Earth’s nighttime sky faces away from the plane of the Milky Way, allowing for an unobstructed view into intergalactic space and toward the Virgo supercluster, which contains many of the galaxies readily visible in small telescopes.. This means we can see a greater number of galaxies, particularly in constellations like Leo, Virgo, Coma Berenices, Hydra, and Ursa Major.

Our 20 Favorite Galaxy Season Objects

The Andromeda Galaxy, which is observable with the naked eye, is only visible in the early morning hours before sunrise during the spring. However, there are numerous galaxies that are easily seen through binoculars or a modest telescope throughout the spring in dark evening skies. Below are our 20 favorite galaxies to observe during Galaxy Season with beautiful photos from either the DAS Astrophotography Special Interest Group or NASA/Hubble Space Telescope. These galaxies are all within 60 Million light-years away and each have a magnitude brighter than or equal to 9.3. They all are from the Messier catalog, which means Charles Messier observed all of these galaxies through a four-inch refractor in the 1700s.  For your convenience, you can download this target list in either a CSV format (with names, constellation, coordinates, etc.) or in a SkySafari skylist format, that you can import directly into the app, by simply downloading it to your device and opening it.

Image	Name	Catalog Numbers	Constellation	Apparent Magnitude	Distance (Million Light-Years)	Description
	Bode’s Galaxy	M81 / NGC 3031	Ursa Major	6.9	12	A bright spiral galaxy, easily seen in small telescopes.
	Southern Pinwheel Galaxy	M83 / NGC 5236	Hydra	7.5	15	A stunning barred spiral galaxy.
	Pinwheel Galaxy	M101 / NGC 5457	Ursa Major	7.9	21	A large face-on spiral galaxy.
	Sombrero Galaxy	M104 / NGC 4594	Virgo	8.0	29	Famous for its bright nucleus and dark dust lane.
	Croc’s Eye Galaxy	M94 / NGC 4736	Canes Venatici	8.2	17	A compact and bright spiral galaxy.
	M106	M106 / NGC 4258	Canes Venatici	8.3	23	Features an active supermassive black hole.
	M49	M49 / NGC 4472	Virgo	8.4	56	The brightest galaxy in the Virgo Cluster.
	Whirlpool Galaxy	M51 / NGC 5194	Canes Venatici	8.4	23	A stunning interacting spiral galaxy.
	Cigar Galaxy	M82 / NGC 3034	Ursa Major	8.4	12	A starburst galaxy with intense star formation.
	Black Eye Galaxy	M64 / NGC 4826	Coma Berenices	8.5	24	Known for its dark, dusty band.
	Sunflower Galaxy	M63 / NGC 5055	Canes Venatici	8.6	29	Named for its bright, patchy spiral arms.
	Virgo Galaxy	M87 / NGC 4486	Virgo	8.6	53	Home to a supermassive black hole.
	M60	M60 / NGC 4649	Virgo	8.8	55	A massive elliptical galaxy.
	Leo Triplet	M66 / NGC 3627	Leo	8.9	35	A group of three interacting galaxies.
	Markarian’s Chain	M86 / NGC 4406	Virgo	8.9	52	Part of a stunning galaxy chain.
	Markarian’s Chain	M84 / NGC 4374	Virgo	9.1	55	Another member of Markarian’s Chain.
	M85	M85 / NGC 4382	Coma Berenices	9.1	60	A bright elliptical galaxy.
	M96	M96 / NGC 3368	Leo	9.3	31	A spiral galaxy with a bright core.
	M105	M105 / NGC 3379	Leo	9.3	32	An elliptical galaxy in the Leo I Group.
	Leo Triplet	M65 / NGC 3623	Leo	9.3	35	Another spiral galaxy in the Leo Triplet.

Keep Looking Up

Galaxy Season is the best time of year to observe some of the most breathtaking objects in the night sky. Whether you’re using binoculars or a telescope, the spring sky is packed with deep-space wonders waiting to be discovered. So grab your star chart, star atlas, or your favorite astronomical app, head to a dark sky site, and get ready to explore the vast universe beyond our own Milky Way.

Clear skies and happy stargazing galaxy-gazing!