What A Black Hole Is Not!

What A Black Hole Is Not!

by Dr. MMM

Dr. MMM of AstroPicionary has taught astronomy to over 10,000 higher education students over 15 years at a Carnegie Level R1 type University in the USA. The author continues to teach more than 10 classes of astronomy and physics each year at different colleges.

Read on to learn how the above image is NOT a dead star known as a black hole.

The image shown is NOT of a black hole. Hundreds of students that I have taught over the years have come into my astronomy course thinking that this image represents a dead star, which is not true. The fault does not lie with the student: Media often erroneously list the object as a black hole, and astronomers often refer to this object as a type of black hole, not aware that students take these professionals’ words literally. Hence, objects like those shown above should not be referred to as black holes. Read on to learn about this type of object and graduate from this post knowing what black holes are and are not!

What is a stellar mass black hole?

To better understand the definition of a black hole, watch the YouTube video shown below. As shown in the video, the image shown at the top of this post does not look like a black hole (a.k.a., a stellar mass black hole).

What is a supermassive black hole?

The image shown at the top of this post is mostly gasses (orange, yellow, white) falling into the supermassive black hole (within black circle in center) of Messier 87 (see below). Supermassive black holes (SBHs) are not stellar mass black holes. To better understand the definition of an SBH, watch the YouTube video below.

We created these YouTube AstroPictionary videos for a video glossary of astronomy terms to better help learners of astronomy. Astronomy has one of the largest vocabularies of the sciences, if not the largest, and the video library not only gives a definition, but explains the definition using an image, simulation, or animation as an aide. This video glossary is for the Apple Book textbook Astronomy Essentials . This Astronomy Essentials textbook is also published with Morton Publishing/Fountainhead Press/Nelson Publishing/TopHat Publishing. Astronomy Essentials is the first video-based textbook in astronomy; it is designed for the self-learner and a learner who really wants to learn astronomy. I have taught astronomy to over 10,000 higher education students at the University of Central Florida in the United States for over 15 years. Now, I bring this knowledge to those who really want to understand astronomy.

Messier 87: An Example of How A Major Part Of A Galaxy Is NOT A Black Hole

The image shown at the top of this post is an SBH located at the core of Messier 87 (M87). M87 (a.k.a., NGC 4486 and Virgo A) is a giant elliptical galaxy located in the constellation Virgo as viewed from planet Earth. It is located around 53 million light years from Earth; thus, the light we see has taken ~53 million years to reach the telescope. You are observing Messier 87 as it was 53 million years ago! If you want to see what M87 looks like today, you have to wait another 53 million years for that light to reach us!

M87 is one of the most massive galaxies in our Observable Universe. M87 contains trillions of star systems, much more so than in the Milky Way Galaxy; the Milky Way Galaxy has billions of star systems, including the Solar System.

M87 is one of the largest galaxies in our Observable Universe: The diameter of the galaxy is around 980,000 light years. As shown in the Hubble space telescope image below, a blue jet emits from the giant white elliptical galaxy; more specifically, the blue jet emits from the SBH located in the core of the giant elliptical galaxy. The length of the blue jet is around 5,000 light years. The jet indicates that the SBH is active; in other words, the SBH is actively accreting orbiting celestial objects. Celestial objects break apart as they spiral into the SBH. The inspiraling emits light as shown in the image at the top of this page. Some of the energy released goes into ejecting subatomic particles such as electrons, generating the blue jet shown in the image. These subatomic particles are accelerated to speeds up to, and including, the speed of light.

Messier 87 ( courtesy of PD-Hubble under Public Domain

Returning to the image shown at the top of this post (and repeated below, but without the X), this image is the first direct observational evidence of material spiraling into the SBH at an average radius of 350 AU, or about the furthest reach of our Solar System from the Sun (or more specifically, the furthest reach of our heliosphere from our Sun). For the first time, we have observational evidence that an SBH is located in the core of massive galaxies. This image was taken with the Event Horizon Telescope (EHT), which is a large array of radio telescopes. Although the telescopes are not physically connected as they are located in different countries, the data is collected simultaneously at each telescope and processed together to generate this one fantastic image.

SBH at the core of Messier 87 as observed by the Event Horizon Telescope (EHT).

Millimeter (mm) Emission from SBH in M87

This EHT image shown above (without the white X) is light emission that is centered on 1.3 mm, which is in the radio band of the electromagnetic spectrum. Being in the radio band, a band human eyes cannot see in, the image shown is false colored. The false coloring is in units of brightness temperature, with white colors indicating more emission, followed by yellow, orange, red, and black. Being false colored, no 1.3 mm radio emission is coming from outside or inside the brightly colored ring (i.e., the black regions in the image).

If you zoom in to the center of the ring, you will see a black center surrounded by gray annulus before reaching the red/orange ring. The rim edge of black center is the event horizon around the SBH, and the gray annulus that is between the black center and the brightly colored ring is the shadow of this event horizon. The diameter of this black center is around 40 billion km or 267 Astronomical Units (AU), and the gray shadow region is around 2.5 times larger. With a Schwarzschild radius of 20 billion km, the SBH in M87 must be around 6.75 billion solar masses, or 6.75 billion times the mass of the Sun. With this size, the SBH is not infinitely small, as some students believe coming into the higher education astronomy course.

Millimeter (mm) Radiation (in general)

The 1.3 mm radiation from the SBH within the core of galaxy M87 is a wavelength in the Extremely High Frequency (EHF) sub-band of the radio band of the electromagnetic spectrum. Airport screening machines, like that shown below, scan your body in these millimeter wavelengths.

NRW-Verkehrsminister Hendrik Wüst – Vorstellung Easy Security; image ( courtesy of Ramond Spekking under Public Domain

You cannot see these millimeter waves penetrating about 1 mm into your clothes, but airport security personnel can observe your body in images like those shown below. This active millimeter wave body scanner image shows that these millimeter scanners can penetrate through clothing to highlight concealed objects like guns and knives.

image ( courtesy of TSA under Public Domain

5G cell phones also operate within this EHF sub-band of the radio band of the electromagnetic spectrum. Because these millimeter waves penetrate around 1 mm, be sure to hold the cell phone away from your ear when talking and listening on these 5G cell phones!

image ( courtesy of Striker9498 under CC BY-SA 3.0 (

Why BHs are not SBHs

Black holes (BHs) are of stellar mass whereas Supermassive Black Holes (SBHs) contain millions to trillions of stellar masses. A comparison is the mass of an ant to that of a human, which is a million times more. Because BHs and SBHs have vastly different masses, they are not the same type of object.

BH event horizons have diameters of around 30 km whereas SBH event horizons have diameters around 40 billion km. A comparison is the height of the Kingdom tower in Jeddah, Saudi Arabia to the furthest reaches of the Solar System. Because BHs and SBHs have vastly different sizes, they are not the same type of object.

A BH is an end product of a star that once had greater than ~15 solar masses before beginning dying stages of evolution. An SBH is in the core of a massive galaxy. Whereas a BH is typically a stand alone object or one of two objects in a binary, an SBH is a part within a single larger object. An analogy is comparing a flake of dead skin from your body to all of your skin on your body: The flake is a stand alone object whereas skin is an organ (or a part) of the human body. Because BHs and SBHs are different in that one is typically stand alone and the other is a part of a larger object, BHs and SBHs are not the same type of object.

Image ( courtesy of Rjelves under CC BY-SA 4.0 (

As mentioned, BHs are end products of stellar evolution, a type of dead star. BHs do not have enough gravitational force to pull in an SBH to grow more massive and larger. On the other hand, SBHs have enough gravitational force to pull in any orbiting BHs to grow more massive and larger. BHs do not contain SBHs; however SBHs contain BHs. As such, BHs and SBHs are not the same type of object.


Now that you know that Black Holes (BHs) and Supermassive Black Holes (SBHs) have different masses and sizes and are different celestial objects, you know now to not cite an SBH as a (stellar mass) black hole. You now know to not show the image at the top of this post and declare it as a (stellar mass) black hole. With your help, we hope to change the misconception that the image observed by EHT is not a (stellar mass) black hole. Congratulations on passing this learning objective of What a Black Hole is Not!

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About the author

Michele M. Montgomery earned a B.S. Degree in Nuclear/Mechanical Engineering from the Pennsylvania State University, an M.S. Degree in Physics from The University of Alabama with a concentration in Solar Physics, and a Ph.D Degree in Physics from Florida Institute of Technology with a concentration in close binary star systems. She joined the faculty at The University of Central Florida Physics Department in 2004 where she regularly taught astronomy, astrophysics, and cosmology. In 2006, she noticed that a large, urban college nearby to UCF did not teach astronomy at one of their largest campuses. She began teaching astronomy at this East Campus of Valencia College, a college that has more than 60,000 students; she still teaches four courses of astronomy each fall, spring, and summer semesters. The astronomy program atValencia College East has grown significantly with several more faculty added who teach astronomy.

By 2019, Dr. Montgomery has taught astronomy to more than 10,000 college and university students, both online and face-to-face. Many of her students have gone on to take her astrobiology, astrophysics, and space physics courses. 

By 2016, Dr. Montgomery had co-authored several astronomy texts and quiz/exam banks. Her work appears in several domestic and international astronomy text books (e.g., Horizons by Cengage, Universe by Cengage, Foundations of Astronomy by Cengage) that are used both at the higher education as well as at the high school levels. Starting in Fall 2019, Dr. Montgomery switched gears to authoring digital textbooks and research full time, while still teaching 12 courses of astronomy and up to eight conceptual, algebra, and/or calculus-based physics courses each year. Her research interests are numerical simulations using Smoothed Particle Hydrodynamics of close binary star systems. She also regularly is granted telescope time on the NASA's Kepler space telescope for observing eclipsing binary star systems. She has also observed using Gemini South, Keck, and Kitt Peak ground-based telescopes. Her major teaching areas are Astronomy, Astrobiology, Astrophysics, Cosmology, Space Weather/Space Physics.