The goal of this blog is to create a list of super facts. Important facts that are true with very high certainty and yet surprising, misunderstood, or disputed by many. This blog aims to be challenging, educational, and fun, without it being clickbait. I determine veracity using evidence, data from reputable sources and longstanding scientific consensus. Prepare to be challenged (I am). Intentionally seek the truth not confirmation of your belief.
Superfact 105: The Sun is white, but the Sky steals its Blue is a poetic way of saying that the sun’s light is scattered by the atmosphere giving the Sun a yellowish tint as well as giving us our blue sky. From space the sun looks completely white.
Sunset from the International Space Station by NASA
Viewed from space the sun is entirely white. White light consists of a mix of all the colors of the rainbow. However, viewed from earth the sun has a yellow tint, which gets more pronounced, it even dips into orange, as the sun nears sunset. That does not happen in space as can be seen below in the one minute sunset timelapse video taken from the International Space Station.
Sunset Timelapse from the International Space Station
On earth the sunset looks more like something in the picture below.
The sky dusk has a dramatic background featuring a summer season golden sunset landscape. The light is at the horizon is an orange and yellow color with blue sky above. Shutterstock asset id: 2670235703 by Nature Peaceful
The sun is a so called yellow dwarf star, or a G-type main-sequence star. The term yellow dwarf is a bit of a misnomer, because they range in color from white, for more luminous G-types like the Sun, to only very slightly yellowish for less massive and less luminous G-type main-sequence stars. The sun emits all the colors of the rainbow simultaneously, but the most dominant color is green. However, this looks white to us.
When sunlight enters Earth’s atmosphere, tiny air molecules scatter shorter, blue wavelengths of light in all directions. This scattering is what makes the sky look blue. This is called Rayleigh scattering. Because much of the blue light is removed, the remaining wavelengths of light that reach your eyes combine to make the sun appear yellow. This is a super fact because it is a basic but surprising fact, and we know it is true.
Rayleigh Scattering
The blue color of the sky is caused by Rayleigh scattering of sunlight by the gases in the Earth’s atmosphere. The image below shows the degree to which Rayleigh scattering occurs at different wavelengths / frequencies of light. Blue has the shortest wavelength (highest frequency) for visible light and red the longest (lowest frequency). The curve shows that blue light scatters more than red light. It should be noted that UV light (not shown) scatter even more. The scattering curve shown is calculated for sunlight passing vertically through the atmosphere.
Figure showing the greater proportion of blue light scattered by the atmosphere relative to red light. Robert A. Rohde derivative work:KES47 (talk) (converted to SVG)., CC BY-SA 3.0 http://creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons.
Super fact 103: The moon is always turning the same side towards us. This side is often referred to as the near side of the moon. The back side, which we can’t see from Earth, is often referred to as the far side of the moon. However, there is no side of the moon that is always dark. The near side of the moon and the far side of the moon both have day and night (in a 29.5 day cycle). Another interesting fact is that even though the near side and the far side of the moon get the same amount of light they are very different.
The near side of the Moon on the left and the far side of the Moon on the right. They are both full about once a month but at different times. They look quite different and are quite different. Elements of this image were furnished by NASA. Stock Photo ID: 2157518223 by Claudio Caridi.
Below is a youTube video showing an animation composed of actual satellite photos by NASA. It shows the far side of the moon, illuminated by the sun, as it crosses between the DSCOVR spacecraft’s Earth Polychromatic Imaging Camera (EPIC) and telescope, and the Earth – one million miles away.
The video has frequently been shown on social media, and I’ve seen many comments stating that it is fake because the back side / far side of the moon is not dark in the video. However, the sun is behind us in the video and shining on both Earth and the far side of the moon. The far side is not always dark.
This is a super fact because many people mistakenly think there is a permanently dark side of the moon, which we know is incorrect and understanding the basics about the moon, the most prominent celestial object in the sky, aside from the sun, is kind of important.
Moon Photos
This is a close up photo of the near side of the moon. It is a full moon. Free picture from Pexels by Jay Brand.This is also a close up photo of the near side of the moon, but it is a crescent moon, which means that the far side, or the back side, is the side that is mostly lit up. In other words, the far side of the moon has day. Free picture from Pexels by Sevde.
I took the photo below with my phone a few minutes ago this evening. The little dot on the left (it is not twinkling) is the planet Venus. The moon is currently a crescent, which means that at the moment of my writing this the back side / far side of the moon has day. The sun is shining down on the far side, and it is reflecting light back into space. The back side / far side is almost a full moon right now, but we can’t see that from Earth.
The dot on the left is Venus. On the right is the crescent moon. This photo is taken with my phone a few minutes ago (as of this posting).This is a zoomed out photo taken at the same time as the photo above. I zoomed out to capture a second dot up in the left corner. That’s another planet, the planet Jupiter (also not twinkling).
Interesting Moon Facts
I thought I might as well mention a few interesting facts about the moon.
The Moon’s nearside and farside Image: NASA LRO / Jatan Mehta
The far side of the moon is different. As you can see in the YouTube video and photo above, the far side looks different from the nearside and it is different in appearance and terrain. The near side of the moon has large, dark, flat-lying basins called maria. They look like oceans. The far side is a lot more rugged and covered by lots of craters. Another difference is that the far side of the moon has a much thicker crust compared to the near side.
The moon is drifting away from earth at about 3.8 centimeters per year. The moon is moving away from earth due to the gravitational forces between the moon and earth, which also causes tidal bulges in the Earth’s oceans and the moon. Back in high school I took a difficult physics test for a competition and one of the questions was to show that the moon was moving away from earth due to gravitational forces and calculate by how much. I did not solve that one.
The moon was likely created by a celestial collision. The most widely accepted explanation for the existence of the moon is that the Moon was created when a planet-like object, the size of Mars slammed into Earth, soon after the solar system began forming. That was about 4.5 billion years ago.
NASA found water on the moon. In 2020, NASA announced the discovery of water on the surface of the Moon. The NASA video below features more interesting facts about the moon.
If you visit this link you’ll find an interactive 3D animation using the NASA Visualization Technology Applications and Development (VTAD) technology. By using your mouse, you can view the moon from many different angles and positions (both the near side and the far side of course).
Super fact 67 : The Edge of the Observable Universe is 46.5 billion light years away despite the age of the Universe being 13.8 billion years. We can see 3.4 times further than light can travel in 13.8 billion years.
That sounds impossible at first. The age of the universe is 13.8 billion years. How can we see something that is farther away than 13.8 billion light-years if that’s how long the light had to travel. The reason it works is that space itself has been expanding the entire time that the light has been traveling toward us. The light we see today from the most distant regions of the universe was emitted 13.8 billion years ago, but the space between us and the origin of that light has stretched enormously. You can say that the light hitched a ride on the expanding space.
An overview of the last 13.8 billion years. This file is in the public domain in the United States because it was solely created by NASA. From Wikimedia commons.
As mentioned, the edge of the observable universe is now about 46.5 billion light-years away in every direction, which means that the observable universe is about 93 billion light-years across (46.5 billion light years times 2) vastly larger than what you’d expect if you just multiplied the age of the universe by the speed of light. Beyond that observable edge there may be much more—possibly an infinite Universe, but it is forever hidden from us because light hasn’t had time to reach us yet and will never reach us.
The speed of light in vacuum is a universal constant and nothing can travel faster then the speed of light. However, space itself can expand faster than the speed of light if measured across large enough distances. The distance between two points in space can expand faster than the speed of light if that distance is large enough. This is possible because there is nothing material that is traveling faster than light. It is just the space of the Universe itself expanding because of dark energy.
Space is expanding right where you are standing too. Can you feel space expanding around you? Well, probably not but it is. I consider this a super fact because it is an important aspect of our view of the universe, it is surprising to those who did not know it before, and it is true.
Galaxies are Moving Beyond the Observable Universe
In the future the far away galaxies will continue to move away from us faster and faster, and beyond a certain distance their light will no longer ever reach us again. Therefore, more and more galaxies will disappear from our view. They won’t vanish physically; they’ll just slip beyond our observable horizon. In about 100 billion years, observers in the Milky Way (or what is left of it) may only see the Local Group of galaxies (Milky Way, Andromeda, etc.). Everything else will have faded out of visibility.
Our Local Group of galaxies consists of 80 galaxies compared to the estimated two trillion galaxies in the current observable universe. That means that the observable universe at that point will have 25 billion times fewer galaxies than now, or in other words only 0.000000004% of the galaxies in the observable universe will remain observable.
Large-scale structure of Multiple Galaxies in Deep Universe. When will all these galaxies forever disappear beyond the edge of the observable universe. Asset id: 389006449 by vchal
The Cosmological Event Horizon Another Edge of the Universe
Beyond roughly 16 billion light-years, galaxies recede faster than light due to the expansion of space. Again, that’s allowed in relativity because it’s space expanding, not them moving through space faster than light. Eventually, most of them will cross a boundary called the cosmic event horizon. Once they do, their light will never be able to reach us, not even given infinite time. We can still see these galaxies because of the light they emitted in the past, but the light they emit now will never reach us.
The cosmological event horizon, not to be confused with the event horizon for a black hole, is 16 billion light years away. That is another limit, or edge of the universe. Below is a 10 minute video explaining both the horizon / edge of the observable universe and the cosmological event horizon for those who are interested.
Black Holes Edges of the Universe
3D illustration of giant Black hole in deep space. High quality digital space art in 5K – realistic visualization. Stock Illustration ID: 2476711459 by Vadim Sadovski.
A black hole is a region of spacetime where gravity is so strong that nothing, including light, can escape it. The boundary of no escape is called the event horizon. If you pass the event horizon you cannot come back out no matter how much energy you use. Nothing can escape, no matter, no radiation, not light, or other electromagnetic radiation, and no information. Nothing at all can escape. The curvature of time and space itself forbids it.
I should add that right at the event horizon, there is so called Hawking radiation, but without complicating things it is not the same thing as escaping a black hole. You can guess from physical laws what might be inside, but you can never observe and report what is inside to planet Earth. In a sense, the event horizon of a black hole is another edge of the Universe. You can read about different types of black holes here. You can read more about black holes here, or here.
Black hole devouring a planet. Black Hole Stock Photo ID: 2024419973 by Elena11Realistic spaceship approaching a black hole. This content was generated by an Artificial Intelligence (AI) system. Stock AI-generated image ID: 2448481683 AI-generated image Contributor Shutterstock AI Generator.AI-generated image Description : This image depicts what a black hole is doing to space around it. Gravity bends space time depicted as a grid. Stock AI-generated image ID: 2457551367 by AI-generated image Contributor Shutterstock.AIThe photo of the supermassive black hole at the center of the galaxy M87 taken by the event horizon telescope in 2017. CC BY 4.0, Event Horizon Telescope, uploader cropped and converted TIF to JPG, CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons.Quasar in deep space (a huge black hole emitting an energy beam). Elements of this image furnished by NASA. Asset id: 1758938918. by NASA images.
The Kuiper Belt is a vast torus/donut shaped region of space beyond Neptune, filled with icy, rocky bodies, including dwarf planets like Pluto. It shares a lot of similarities with the Asteroid belt, but it is much larger, and further out. The Kuiper belt is 20 times wider than the Asteroid belt, 1,000 larger by volume, and 20 to 200 times more massive than the Asteroid belt. It extends from roughly 30 to 50 astronomical units (AU) from the Sun.
I can add that one Astronomical Unit (AU) is the distance from the sun to Earth.
I drew this illustration of the solar system and the Kuiper belt. It is not entirely to scale, and in reality, Mercury and Venus are not attached to the sun.
The Kuiper belt is like a giant Asteroid belt located further out, beyond Neptune. The Kuiper Object Pluto, formerly known as the Planet Pluto, is the most admired, the cutest and most beloved of all planets, and it was the first Kuiper object discovered in 1930. However, we did not know of the existence of the Kuiper belt at the time. The Kuiper belt was discovered in 1992 and predicted to possibly exist by Astronomer Gerard Kuiper in 1951. The discovery of the Kuiper belt was one of the reasons Pluto was demoted from its planet status in 2006. There are other dwarf planets in the Kuiper belt similar Pluto, including Makemake, Haumea, and Eris. However, there could be hundreds. Ceres is a dwarf planet located in the Asteroid belt. To read more about the Kuiper belt and verify the facts above, click here, or here, or here.
Pluto and its moon Charon from NASA/JHUAPL/SwRI. NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute, Public domain, via Wikimedia Commons. NASA’s New Horizons spacecraft captured this high-resolution enhanced color view of Pluto in 2015.
I selected this to be a super fact because the existence of the Kuiper belt drastically changed our view of our Solar system, so it is important, we know it exists, so it is a true fact, and despite its enormous size the Kuiper belt is much less known than the Asteroid belt, and its existence often comes as a surprise to people.
The Kuiper Belt Resides in Darkness
You may wonder why the Kuiper belt was discovered so late whilst the Asteroid belt has been known since the beginning of the 19th century (Ceres 1801, Pallas 1802, Vesta 1807, etc.) The reason is that the Kuiper belt resides in darkness. The Asteroid belt is 2.2AU to 3.2AU from the sun whereas the Kuiper belt is between 30 to 50AU from the sun.
Let’s say you take an object that is 2.5AU from the sun and place it at a distance that is 40AU from the sun. Due to the spreading of the light the object will now receive 16 X 16 = 256 times less sunlight. This is called Geometric dilution. In addition, this light needs to be reflected back to earth for us to see the object, and once again the light will spread resulting in 256 X 256 = 65,536 times less light reaching our telescopes. The Kuiper belt is huge, but it resides in darkness. Despite this fact, we have now discovered and catalogued more than 2,000 Kuiper belt objects. However, it is estimated that there are hundreds of thousands of Kuiper belt objects wider than 100 kilometers.
What is a Dwarf Planet?
A planet as well as dwarf planet is a celestial body that orbits the Sun and is nearly round due to its own gravity. Basically, it must be large enough to have compressed itself to a near spherical shape. To be classified as a planet and not a dwarf planet it must also have cleared its orbit of debris. So, a dwarf planet is therefore a celestial body that orbits the Sun, is nearly round due to its own gravity, but has not cleared the neighborhood around its orbit. Obviously, a planet in the Asteroid belt or the Kuiper belt is a dwarf planet. Just to make this complicated Astronomers have found giant exoplanets that have not cleared their orbit of debris . I wonder, are these exo-planets giant dwarf planets?
Oort Cloud
Astronomer and Author David Lee Summers (blog here) reminded me of the Oort cloud, which could be interesting to bring up in this context. The Oort Cloud is a vast spherical cloud of icy bodies, which is hypothesized to surround the solar system, extending from about 2,000 to 200,000 AU. It is thus thousands of times further out and wide than the Kuiper belt. I say hypothesized because the objects are so small, there’s really no direct observation of them and there’s some variation in numbers for its distance and extent, meaning it’s still not well defined yet. Still, its outer edge is believed to be the boundary between where the sun’s gravity dominates and the galaxy’s gravity dominates.
The Oort cloud is generally considered to be the outer edge of the solar system and believed to be the origin of most long period comets. The Oort cloud is thought to encompass two regions: a disc-shaped inner Oort cloud aligned with the solar ecliptic (also called its Hills cloud) and a spherical outer Oort cloud enclosing the entire Solar System.
NASA This SVG image was created by Medium69.Cette image SVG a été créée par Medium69.Please credit this : William Crochot, Public domain, via Wikimedia Commons.
Kevin’s artistic picture above reminds me of a Quasar, a supermassive black hole emitting enormous amounts of energy.
What is a Quasar ?
A Quasar is a supermassive black hole at the center of a galaxy that is emitting enormous amounts of energy. The quasar is the supermassive black hole plus its accretion disk, the gas it is feeding on and the radiation it emits. The quasar is actively feeding on gas and stars and emitting enormous amounts of radiation in the process. The radiant energy of quasars is enormous; the most powerful quasars have luminosities thousands of times greater than that of a galaxy such as the Milky Way, and millions of times greater than the largest and most luminous stars in the known universe.
Supermassive black hole at the center of a quasar. Singularity in space devouring matter and light. From Shutterstock Asset id: 2484018599 by Nazarii Neshcherenskyi.
TON 618
TON 618 is a hyper luminous Quasar known to house one of the most massive black holes ever discovered, with an estimated mass of around 40 to 60 billion solar masses. Its luminosity is estimated to be 140 trillion times that of the Sun. The diameter of TON 618 is 780 billion kilometers or 82.6 light-years. Keep in mind that the distance to the moon is 1.3 light seconds and 82.6 light years is more than two billion times larger than that. Our sun is gigantic with a diameter 109 times larger than the diameter of earth. 1.3 million earths could fit inside the volume of our sun. However, in comparison to TON 618, our sun is a lot less than tiny. The diameter of TON 618 is 561 million times larger than that of the sun’s diameter and 177 octillion (an octillion is 27 zeros) suns could fit inside the volume of TON 618. In other words, we are comparing a dust particle to planet earth size wise. I am pretty sure you are not going to be able to imagine this.
Quasar in deep space. Elements of this image furnished by NASA. Asset id: 1758938918. by NASA images.
When TON 618 was discovered in 1957, quasars and supermassive black holes were not yet recognized and understood by astronomers. The word quasar inspired shock and awe in every nerd on the planet. The concept of quasars, or quasi-stellar radio sources, wasn’t fully recognized until 1963. When I was a kid in the 1970’s there was a lot of speculation as to what these gigantic ultra bright but far away objects could be. TON 618 is located 18.2 billion light years away. Considering that the reachable limit of the Universe is 16.5 billion light years even if you travel at the speed of light, you could never travel to TON 618 (barring the warp drive in Star Trek).
The Event Horizon
When we are talking about the diameter of a black hole we are not talking about a sphere with a solid surface. The black hole is a sphere, or an oval, wherein gravity is so strong that nothing can escape, not light, not anything. It’s truly black. As you approach the event horizon you become invisible, space deforms, and from the perspective of an outside observer, time appears to stop for someone reaching the event horizon of a black hole. Time will continue for someone falling in, well in some sense. You’ll be transported beyond our universe and time as we know it. We can guess but we can’t really know.
When this spaceship reaches the event horizon the time will stop from our perspective, and they will never enter the black hole. From their perspective they will enter right through the event horizon, and they will be transported infinitely far into a future beyond time. Stock AI-generated image ID: 2448481683 AI-generated image Contributor Shutterstock AI Generator.
Black Holes
Black holes are invisible. They are truly black. However, we can see them if they are consuming matter. The matter close to black holes will heat up and glow. The closer to the event horizon the redder it is. It is called an accretion disk as in the depiction above. There are an estimated 100 million black holes in our galaxy, the Milky Way. At the center of the Milky Way is a super massive black hole called Sagittarius A-star. It is 4 million times more massive than our sun. There are supermassive black holes located at the center of most large galaxies. The supermassive black holes are considered to play a crucial role in the formation of galaxies.
3D illustration of giant Black hole in deep space. High quality digital space art in 5K – realistic visualization. Stock Illustration ID: 2476711459 by Vadim Sadovski.
Note : Today March 14 is Albert Einstein’s birthday, the man who gave us the General Theory of Relativity, which mathematically describes black holes. It is also Pi Day (first 10 digits 3.1415926535), and there’s a rare moon eclipse tonight called a blood moon or a worm moon. Also, Dallas is under a fire warning. Be careful.
Important Note : I am going on a ski vacation tomorrow and I will take a one-week break from blogging as well as a break from reading other people’s blogs.
Super Facts 