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.
I was delighted when I saw the post above. Sally from Smorgasbord Blog Magazine shared my super-fact 69:
Super fact 69 : Polar nights happen in the regions north of the Arctic Circle and south of the Antarctic Circle. Together the two polar regions cover an area double as large as the United States, and it includes a population of millions of people. During a polar night the sun does not rise for days, or months, up to six months. The polar nights are special, not just for the daytime darkness, but for the spectacular aurora borealis, the starlit skies, the extremely clear air, and the fact that people often lose track of time during polar nights.
In addition, she is promoting my Leonberger dog book for which Diana Wallace Peach wrote a great review. Thank you so much Sally and Diana. Please visit her post above at the Smorgasbord blog magazine and read it.
Aurora Borealis are often spectacular in the polar regions, especially during the polar night. Asset id: 2499746583 by HappyVibeArt
Super fact 108 : A Pulsar is a rapidly rotating neutron star that emits beams of electromagnetic radiation from its magnetic poles. The radioactive beam from a pulsar that is located where the sun is located would heat earth’s surface to tens of thousands of degrees. The pulsar may rotate hundreds of times per second, and we only detect the beam when it crosses our line of sight. A neutron star, or a pulsar, is vastly denser than the Sun, typically hundreds of trillions of times denser.
As mentioned, a pulsar is a rapidly rotating neutron star that emits beams of radiation from its magnetic poles. A neutron star is an ultra-dense remnant left behind when a massive supergiant star runs out of fuel and collapses. You can read more about neutron stars in my post here and you can read about neutron stars that act like super magnets called magnetars here. This web page feature a calculation of what the intensity of a pulsar beam would be if it hit Earth and the pulsar is located where the sun is.
The beam from a pulsar hits earth causing destruction. This is an AI picture generated by me and ChatGPT.
I consider this a super fact because pulsars are a very extreme type of star, which existence I believe comes as a surprise to many people.
Pulsar with energetic jets in space. Shutterstock asset id: 2697475389 by Nazarii_Neshcherenskyi
Below is a one and a half minute NASA video explaining what a pulsar is. It is taken from this website.
Different Types of Neutron Stars and Different types of Pulsars
Courtesy NASA/JPL-Caltech, Attribution, via Wikimedia Commons
Neutron stars are extreme stars. They are small super dense stars with extreme gravitational fields. They are in a sense like a gigantic atomic nucleus. Perhaps it is not surprising that they are extreme in other ways as well. There are pulsars, neutron stars which emit twin beams of radiation from their magnetic poles. Those poles may not be precisely aligned with the neutron star’s rotation axis, so as the neutron star spins, the beams sweep across the sky, like beams from a lighthouse. To observers on Earth, this can make it look as though the pulsar’s light is pulsing on and off.
There are different types of pulsars. Some spin extremely fast. They rotate hundreds of times per second, even 700 times per second. They are called Millisecond Pulsars. There are pulsars that emit beams of radio waves and pulsars that emit only gamma rays. A black widow pulsar a star system consisting of a rapidly spinning pulsar and a companion star that is being consumed by the pulsar like a black widow spider eats its mate. This link feature animation videos from NASA showing a star being consumed by a black widow pulsar.
Finally, there are magnetars, neutron stars with extremely powerful magnetic fields trillions and quadrillion times stronger than Earth’s magnetic field at the surface. You can read about them here.
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 102: Stars twinkle but planets do not. Planets reflect sunlight, like the moon, whereas stars emit intense light like the sun. However, stars are thousands of times further away.
The light from stars is intense allowing stars to have much smaller discs in the sky for the same amount of light as a planet. Shutter Stock Illustration ID: 566774353 by Nostalgia for Infinity.
The Sun and the Moon appear to have roughly the same sized disk in the sky, about 0.5 degrees of arc, because the Sun is roughly 400 times wider than the Moon but also about 400 times farther away. However, the moon, which reflects sunlight but does that emit any, is much fainter than the sun in our sky. The Sun provides approximately 400,000 times more light to Earth than the full Moon. If you were to move the sun farther away until it provided the same amount of light as the moon you would have to move the sun 632 times farther away until it became a tiny point in comparison to the moon.
The planets in our solar system, Venus, Jupiter, Mars, Mercury, Saturn, etc., appear in the sky as small discs reflecting light whereas the stars appear as intense points of light with a disc diameter that is thousands of times smaller than that of the planets. However, we can’t see the difference with the naked eye. Both planets and stars appear like points of lights to us, but the difference in disc size in the sky is very big.
Planets reflect light whereas the stars appear as intense points. Shutterstock asset id: 2709145593 by buradaki
Because stars are tiny intense points of light Earth’s atmosphere can easily refract (bend) their light. This is known as scintillation. I can add that the light from stars that are low in sky go through more atmosphere and therefore twinkle more. Since planets appear as tiny discs rather than tiny points, planets create a steadier beam of light, which averages out atmospheric turbulence. In addition, dust particles in space and in the atmosphere can more easily block the light from stars compared to that of planets, because the planets have much larger discs in the sky (thousands of times larger).
To the naked eye a planet and a star point look light points of light. In a telescope the planet will turn into a disc, but the star will remain a bright point of light. For example, a piece of space dust can easily make the star twinkle by moving in front of it but won’t do that to the planet. Note: planets are much smaller than stars, but they are much closer and can look bigger.
Since this fact is not scientifically under question, a lot of people don’t know it, and it is kind of important to anyone interested in the night sky, I consider it a super fact. I should say that I borrowed this super fact from Jacqui Murray’s blog worddreams.
Planets Reflect Light like the Moon
Planets reflect light. They don’t shine and emit light like the sun or the stars.
Jupiter in true color, taken by the Hubble Space Telescope in January 2024Saturn and its prominent rings, as captured by the Cassini orbiter. This natural color view of the planet Saturn was created from images collected shortly after Cassini began its extended Equinox Mission in July 2008.Pluto 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.
Super fact 79 : Distant galaxies appear redder (redshifted) because of the universe’s expansion. The farther away the galaxy, the redder it is. This cosmological redshift is also increasing because the Universe’s expansion is accelerating. Our Universe is getting more and more red every day.
Many people are aware that the Universe is expanding but may not know that this results in a measurable redshift. The faster a galaxy is moving away from us the redder it appears. This is called the cosmological redshift. Measuring these redshifts was how we discovered that our Universe is expanding.
As the Universe expands and galaxies are moving away from each other the light will be stretched. Stretched light with longer wavelengths are more red. The phenomenon is called redshift. Shutterstock Asset id: 1180828402 by VectorMine.
At the end of the 1990’s it was also discovered that the Universe’s expansion was accelerating. This discovery came from measuring the redshifts (and apparent dimness) of distant Type Ia supernovae. I should add that measuring the increase in the cosmological redshift directly is difficult. However, it is expected to be possible when the Extremely Large Telescope (ELT) starts gathering data in 2027. I can add that there are also other types of evidence showing that the Universe’s expansion is accelerating.
Another surprising aspect is, if the Big Bang was like an explosion, gravity would pull back the galaxies making the expansion slow down and perhaps eventually even reverse. However, the opposite is happening. A common explanation is that a repulsive force, a sort of anti-gravity, referred to as dark energy, is responsible for this acceleration.
I call this a super fact because this is an observed phenomenon, it is important knowledge for how we view the world, and it is surprising. Many people have heard bits and pieces of this but do not have the fuller picture.
The Doppler Effect
The cosmological redshift is an example of the so called doppler effect. The doppler effect is the change in the frequency or wavelength of a wave in relation to an observer if the origin of the wave and the observer are moving compared to each other. If an object is moving towards you, let say an ambulance, the frequency of its sound will be higher (wavelength shorter).
After it passes you and moves away from the frequency will be lower (wavelength longer). In other words, the sound changes when the ambulance passes you. The same is true for other kinds of waves, including waves on the water, and light. If a light is travelling towards you at a high speed, it will look bluer. If a light is travelling away from you at a high speed it will look redder. The latter is what is called a redshift, cosmological redshift in our case.
Change of wavelength caused by motion of the source. When an object moves toward you the wavelengths get shorter and the frequency higher. When an object moves away from you the wavelengths get longer and the frequency lower. Original: Tkarcher Vector: Tatoute, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia CommonsThe Doppler effect causes a car engine or siren to sound higher in pitch when it is approaching than when it is receding. The red circles represent sound waves. Charly Whisky 18:20, 27 January 2007, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia Commons
Below is a three minute video explaining the doppler effect and redshift.
I can add that the constancy of the speed of light in vacuum changes the exact size of the doppler effect. The doppler effect remains as is for the most part but the formulas for the classical doppler effect, which you would use for sound, and the relativistic doppler effect, which you would use for light in space, are different. It is just to pick the right formula.
The classical formula for the doppler effect. There is a medium (air) but you don’t need to consider the constancy of the speed of light in vacuum. You use it for sound and water waves. Shutterstock Asset id: 2365938267 by Sasha701.The relativistic formula for the doppler effect considers the constancy of the speed of light in vacuum but there is no medium to worry about. You use this formula for the doppler effect of light in space. Shutterstock Asset id: 2416786951 by Sasha701.
Measuring redshift
A common misconception is that astronomers take pictures of distant galaxies and somehow measure the “redness” of them, but that is not the case. When you take a spectrum of a heated element (such as hydrogen or helium in stars) it creates characteristic dark lines in the spectrum — like a fingerprint. Everything on the periodic table has its own characteristic fingerprint of lines at characteristic frequencies. In addition to measuring the cosmological redshift it makes it possible to identify the elements in a star and their proportions. See the picture below.
Visualization of redshifted absorption lines are redshifted due to velocity away from observer. Top lines are for an object at rest and in the bottom picture the object is moving away. Maxmath12, CC0, via Wikimedia Commons. This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.
Expanding Universe Hazy IPA
Expanding Universe is a Hazy IPA, or a so called New England style IPA from First State Brewing, ABV 6.5%, IBU 25 (IBU = International Bitter Units). The fact that it is an IPA (India Pale Ale) means that it is Ale and therefore not a Lager. The fact that it is an IPA means that it is hop-forward and has an intense flavor and aroma. The fact that it is a Hazy / New England style IPA means that it is more fruity than bitter and looks cloudy, hazy, like juice. The flavor of Expanding Universe is mango, pineapple, and grapefruit. It has a low bitterness, it is fruity, juicy, and it is great if you like New England IPAs.
