Pinwheel Galaxy facts | Top 10 FAQs

Get the answers to frequently asked questions about one of the most interesting infinite space objects, the Pinwheel Galaxy.

The gigantic composition of the universe stretches over 10 billion light-years and contains a huge number of galaxies, which are composed of different shapes and sizes. What is a galaxy? It is a mysterious nebula of gas and light clouds, dust, and billions of stars and their solar systems, all tied together by gravity. Scientists identify various types of galaxies. Spiral-shaped galaxies account for over half of all known galaxies.

1.      What is the backstory of the Pinwheel Galaxy?

The Pinwheel Galaxy was discovered as a face on spiral galaxy in 1781 by a French astronomer Pierre Méchain.

This celestial capture was included that year in the Messier Catalog as one of its final celestial objects.

Lord Ross, an Irish astronomer, naturalist, and engineer who constructed several giant telescopes, was the first to give an extensive description of the spiral structure in 1784. In his writings, he laid out objective Pinwheel Galaxy facts and made several graphic drawings.

2.      What kind of galaxy is the Pinwheel?

So the Pinwheel Galaxy, also known as Messier 101, M101, or NGC 5457, represents a giant spiral disk of stars, dust, and gas with extensive rotating “fan blades”—the Pinwheel Galaxy’s spiral arms. This giant celestial fan is 170,000 light years across, nearly twice the diameter of our own Milky Way galaxy. M101 has an unusual shape: a fairly small central bulge with loosely rolled up spiral arms. Some astronomers define the Pinwheel Galaxy as a weakly-barred spiral galaxy.

3.      How old is the Pinwheel Galaxy?

M101 is visible at magnitude 7.86 and is about 21 million light years from Earth. This finding suggests that this star formation has existed for about 21 million years. According to some statistics, M101 embraces at least one trillion stars. In cosmic terms, however, the Pinwheel Galaxy is still fairly close (see the Pinwheel Galaxy profile designation).

4.       What part of the sky is the Pinwheel Galaxy?

It is not difficult to find the location of the Pinwheel Galaxy, but at least a simple type of optical telescope is required.

Although this celestial object is huge and emits a very bright light, a long way to M101 makes it impossible to see the Pinwheel Galaxy with the naked eye.

But still, the Pinwheel Galaxy’s spiral structure is observed in the constellation Ursa Major (the Great Bear) near the famous asterism Big Dipper. 

5.      Are there any detailed images of the Pinwheel Galaxy?

Although relatively bright and close to us, the Pinwheel Galaxy is rather faint because its light is spread out over a vast piece of sky. Thanks to the cooperation between the European Space Agency and NASA, we have a real opportunity to see the most spectacular and accurate image of the Pinwheel Galaxy spiral structure ever captured. The complex and detailed image was composed of 51 individual shots taken by the Hubble Space Telescope.

6.      What makes the geometry of the Pinwheel Galaxy so special?

The representation of the Pinwheel Galaxy confuses us by presenting to our imagination the perfect symmetrical forms of this celestial object.

In reality, the geometry of the Pinwheel Galaxy is a little disturbed by the gravitational pull of its companion galaxies.

It is assumed that most galaxies undergo at least one significant collision in their lifetimes.

7.      Why is the Pinwheel Galaxy important?

The Pinwheel Galaxy is one of the many spiral galaxies in the universe. And we certainly must pay tribute to this cosmic wonder, M101, as it is a great star-maker, with over 3,000 cluster areas where stars are born within its closely draped spiral arms. These clusters are called “HII regions”. HII literally explodes with extraordinary amounts of hydrogen gas in these clusters that exist because the stellar material is primarily hydrogen gas and helium.

8.      What is unique about the Pinwheel Galaxy?

The Pinwheel Galaxy is a unique galaxy because, unlike most spiral galaxies that typically spin around a supermassive black hole, there are virtually no stars or a black hole in the center of it. Instead of a massive black hole in its core, the Pinwheel Galaxy has a speck of tiny black holes. Moreover, there is an enormous concentration of X-ray sources termed stellar mass black holes. When stars die, all their stuff drops into the stellar mass black holes, where they are heated by emanating X-ray vision.

9.      What about supernovae in the space of the Pinwheel Galaxy?

A supernova is a powerful and luminous explosion of a star. Actually, it is a star’s funeral march. This last blast of exploded stars is so bright that it can even hinder light from other galaxies. M101 demonstrates a high level of activity. Astronomers have noted four supernovae since the early 20th century.

A luminous red nova, the most remarkable one, was observed in the Pinwheel Galaxy on February 10, 2015.

This list has increased by five points since then. On May 19, Japanese amateur astronomer Koichi Itagaki discovered a new supernova located in the Pinwheel Galaxy within Ursa Major.

10.  How do I find the Pinwheel Galaxy in the night sky?

Under really dark skies, among other galaxies and stellar mass black holes, it is observable through a pair of binoculars as a really faint patch of light.

Now it is your turn to observe:

Step 1: Find the constellation Ursa Major (near the asterism Big Dipper).

Step 2: Find Mizar.

Step 3: Find 81 UMa with the help of Alcor.

Step 4: Find 83 UMa.

Step 5: Find 84 UMa.

Step 6: Find 86 UMa.

Step 7: Find M 101 using the star hopping method.

Step 8: Observe!

 TABLE*

PINWHEEL GALAXY PROFILE DESIGNATION:

Type	Diameter	Distance from Earth’s orbit	Mass	Associated Constellation	Group	Apparent dimensions	Apparent magnitude	Estimated number of stars
Spiral Galaxy	About 170,000 light years	21 million light years	1,000 billion M	Ursa Major constellation (Big Dipper, Great Bear)	Local Group	28’8 x 26’9	7.86	1 trillion

Throughout this giant spiral galaxy exploration period, the researchers have documented lots of curious Pinwheel Galaxy facts. But many questions about its nature have yet to be answered.

The most interesting is still to come!