Dimensions and Distances

Left: The Earth compared to our Sun.
Right: Our sun (one pixel) compared to VV Cephei

Our universe is vast, however, from our little area of space, we can assume that what we can see is the biggest that there is out there. This is not true, our sun for example is an average size star in comparison to some of the biggest stars out there like UY Scuti. The UY Scuti star is approximately 30 times our sun’s mass. The Voyager 1 Spacecraft is another example, heading out of our solar system at 62,000 kilometers per hour, it is still expected that it will take 77,000 years for it to reach the closest star.

To give us a greater perspective, when the Space Shuttle goes into space, it orbits approximately 700 kilometers above the earth. The moon on the other hand is 400,000 kilometers away, which is equivalent to going around the earth about 10 times. The distance between Earth and Mars is 78,000,000 kilometers, and the distance between Neptune and Earth is 4,350,000,000 kilometers.

When we go further into space, we start talking about light years. At this point, kilometers are too small to measure such impressive distances. A light year is the distance light travels in a year. In kilometers, a light year is approximately 9,500,000,000,000 km.

Distance from Earth 

The brightest star in the sky, Sirius, is 8.6 light years away.

The brightest star in the Southern Cross, Acrux. is 321 light years away.

This is a color picture of the Perseus Galaxy Cluster
This is a picture of the Perseus Galaxy Cluster by NASA.

The brightest star in Orion, Rigel, is 777 light years away.

The Center of our galaxy, which hosts Satigarus A*, our black hole, is 27,700 light years away.

Andromeda, the closest galaxy from us, is 2,900,000 light years away.

The Perseus Cluster, composed of thousands of galaxies, is 190,000,000 light years away.

One big myth when it comes to distances in space is that everything is in a straight line. The universe is full of objects and things with mass and energetic quanta. Due to matter and energy, spacetime can be curved because of gravity, therefore the distance between any two points in space depends on the shape of the universe between those two points. This curvature is also not permanent because our universe in itself is not static. It is subject to change also because it is filled with matter and energy and everything is constantly moving and being transformed.

The edge of the universe, the furthest distance at which we can see light, is about 13.26 billion light years away. The very edge is a little further at about 13.8 billion light years. We do not detect light from the edge, though, but we do detect a radio signal which we call the background noise. The size of the universe is said to be even larger than this because the universe is ever expanding. Although it is expected to be finite, we cannot reach it all.

In this article, we will talk about some of the most fascinating distances and dimensions in the universe. Planets, stars, galaxies, and groups of galaxies are all of great mass, distance, and dimensions. The Milky Way Galaxy is 100,000 light years across according to NASA. The biggest galaxies are said to be millions of light years across. What can be observed from our universe is estimated to be 50 billion light years in all directions. Astrophysicists state that about 13.8 billion years should be given for the possible expansion of space. 

The Largest Exoplanet

The small bright dot on the right is GQ Lupi b, an enormous exoplanet or a small dwarf brown star.

GQ Lupi b was discovered in 2005. It is orbiting the star GQ Lupi and it is two and a half times further from its star than Pluto is from the sun (about 100 AU). The status of this exoplanet has been contentious with some speculating that it could be a brown dwarf. If it is indeed an exoplanet, it is the largest exoplanet known with a radius at least 3.5 times bigger than that of Jupiter.

Note: Jupiter is at times considered a failed star as it emits some light, which is one reason it is so bright in our night sky.

The Largest Galaxy

IC 1101 is the largest galaxy discovered. It is 50 times larger than the Milky Way and 2,000 times more massive than our galaxy. We stated that the biggest galaxies are millions of light years across, and IC 1101 is an incredible 5.5 million light years across. This distance is so big, that were it to replace our Milky Way, it would extend past our neighboring galaxy Andromeda.

The Largest Black Hole/s

We cannot talk about distances and dimensions without talking about black holes and specifically supermassive black holes. Black holes are located at the center of galaxies. In our galaxy specifically, there is a black hole 4 million times the mass of our sun. The largest black hole known to man is found in NGC 4889. It is said to be 21 billion times the sun’s mass. Some reports state that the largest black hole is powering a distant quasar. TON 618 is said to have a mass of 66 billion suns according to reports. 

The Largest Quasar Collection

Speaking of quasars, these gargantuan objects were numerous in the early universe and they are the most powerful light and radiation emitters. Some quasars have reportedly come together to form clusters. The largest known cluster being the Huge-LQG aptly abbreviated from Huge Large Quasar Group. Its mass is a whopping 6.1 quintillion suns and it contains 73 quasars. Its distance measures 4 billion light years across. 

The Largest Supercluster 

The Laniakea Supercluster is a collection of several galaxies including our own Milky Way. Astronomers have hypothesized that it contains on average 100,000 galaxies. Its mass is also said to be 100 million billion suns, that’s right 100 million billion suns. Its distance is also measured at 520 million light years across. 

Apart from The Laniakea Supercluster, the biggest supercluster found in the universe is the Hercules-Corona Borealis Great Wall (HCBGW). Found in 2013, it has been the subject of several studies by astronomers who have found that it is 10 billion light years across. This giant has been said to go against basic principles of cosmology that states that matter should be uniform at large scale. Hercules-Corona does not conform to this principle. It is speculated that there could be superclusters that are bigger than HCBGW. It was discovered after gamma rays were found to be concentrated in the area approximately 10 billion light years away close to the Hercules and Corona Borealis constellations. This is considered to be the biggest thing in the entire universe to be discovered so far. 

The Largest Nebula

The Tarantula Nebula is the largest nebula and the most active star-forming region in our neighboring galaxy. At its widest distance, it is 1,800 light years. It is located in the Large Magellan Cloud which is 170,000 light years away from the Sun. 

The Largest Void

The largest empty spot ever found by astronomers was found by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) satellite. The void was found in Eridanus and is completely empty. Neither stars, gas, dust nor dark matter is found within this region. It measures 1.8 billion light years across and the size of it has shocked researchers as to how it was formed. 

The Largest Single Object

Protocluster SPT2349-56 was formed when 14 galaxies crushed into themselves forming a massive cosmic object. This object occupied a space that was only three times the size of our galaxy ultimately forming a galaxy that was 10 trillion times the mass of the sun. 

The Largest Galaxy Collection

In 1930, astronomer Harlow Shapley discovered a huge collection of galaxies and named them Shapley Supercluster. With a mass 10 million billion times our sun, it constituted 8,000 galaxies.

The Largest Galactic Farts 

Galactic farts are bubbles that can only be observed at a certain wavelength of light. The Fermi Bubbles 25,000 light years tall were discovered by the Fermi Space telescope in the year 2010. Researchers claim that after the feeding of the black hole found at the center of our galaxy, there was an enormous release of energy similar to a belch leading to this galactic fart. 

The Largest Objects within our solar system

Jupiter is the largest planet having a diameter of 142, 984 kilometers. This is 11 times bigger than the earth’s diameter.

Ganymede is the largest moon in our solar system. It also orbits the largest planet Jupiter. Only slightly larger than Mercury, it is 5,268 kilometers in diameter.

The largest volcano is found on Mars and is the Olympus Mons. It is also considered to be the highest mountain in our solar system at 25 kilometers high. This is three times Mount Everest.

Valles Marineris found on Mars is 3,000 kilometers high and 600 kilometers wide and with a depth of 8 kilometers and is the largest canyon.

Utopia Planitia is also found on Mars and is the largest crater with a diameter of 3,300 kilometers. Viking 2 landed on this crater in the year 1976.

4 Vesta at 530 kilometers across is the largest asteroid and is located in the asteroid belt between Mars and Jupiter.

Pluto is considered to be the largest dwarf planet in our solar system, just barely ahead of Eris. It is 2,370 kilometers in diameter. 

As fascinating as large distances and sizes are, the smallest objects in the universe are more incredulous and harder to find. Initially, it was assumed that grains of sand were the smallest objects in the universe, then the atom was discovered. An atom is approximately 10-10 meters (or 10-8 centimeters) in size. Atoms were then split into protons, neutrons, and electrons, and these were thought to be the smallest objects until it was discovered that there were three quarks inside both protons and neutrons. 

Some contenders of the smallest things in the universe include:


At the center of a black hole is the singularity. According to physics, black holes are formed when matter is condensed into a small enough area that gravity takes over pulling it inward up to a certain point of density. It has been theorized that black hole singularities are possibly even smaller than quarks. They could be a million times smaller than the distances we have observed so far.


A Planck length is 1.616 × 10-35 meters. This figure is unbelievably small. A Planck length has not been measured by any instruments created. It has however been theorized that it is the shortest measurable length in existence. Below this length, conventional laws of physics no longer give reasonable answers. This distance correlates with the distance at which gravitational pull is so strong that it can start to make black holes and similar creations. At this length, it is expected that quantum gravity takes over.

The smallest things in the universe should be approximately a Planck’s length. 

So how did the Planck scale come about?

Max Planck came up with the Planck length over 100 years ago. He worked with three constants:

  • G – Gravitational constant.
  • ħ – Planck’s constant. The quantum constant of nature.
  • c – The speed of light in a vacuum.

You can combine these in different ways to come up with time, distance, or mass. 

How about smallest time scale?

Interestingly enough, we have not yet found a way to determine the smallest possible amount of time between two points in time. As mentioned earlier, space and time are affected by matter and energy. We have a good handle on both of those. But time has been eluding us so far. We are not even sure how time functions in a black hole.

We use the Planck Time which is the amount of time it takes for like to go between two points separated by exactly one Plank Length. This is around 5.39 × 10-34 seconds. At this point we think that there is no need for us to have a smaller measurement of time. Also, that’s the smallest amount of time between two intervals that we can ever hope to measure.

Fun Fact

Two very important aspects of distances which are very badly interpreted in science fiction movies:

  • The rocks and ice forming the rings around Saturn, Jupiter, and Uranus; they do look like a solid flat ring, like a flatten planet—the truth is that each piece is separated by very large gaps. These rocks do not touch each other. The distances, for a human, are really large.
  • The asteroid belt is another example where we show it as a very difficult area to navigate. We even have video games where you have to drive a spaceship through such asteroid barriers. The truth is, you are unlikely to notice even one asteroid. The distances between each asteroid are such, to bump into one would take skills (yes! that’s the other way around). We’ve landed a space ship on one asteroid and it succeeded only because we now have the necessary technology to do so.
  • Interstellar travel comes with ships that have ways to communicate back with people on Earth. In most science fiction movies, those conversations are done in real time. People have conversations as if they were sitting across each others. Yet, the closest star is 4 years away at the speed of light. To communicate from that closest star, it will take 4 years to send a message and another 4 years to get the reply. So if you sent a message with a picture of your baby, by the time you get the answer, your baby will be an 8 years old.

With these figures in mind, you can imagine just how big our universe is. Everything on Earth is pretty small in the grand scheme of things. When light leaves the nearest star Proximus Centauri it takes four years to reach earth. Things observed in the universe are seen as they were in the past. When seeing Andromeda, you can guess that you are probably viewing it as it was 2.5 million years ago. We cannot completely comprehend how big the universe is, and it is constantly growing, and that is the beauty of astronomy!

ʻOumuamua a special asteroid that gave us a surprise visit in 2017

Is 'Oumuamua a fragment of a shattered super-Earth? | Space | EarthSky

In October 2017, an astronomer observed an object zooming past our sun at an incredible speed. The astronomer was Robert J. Weryk and he noticed this bizarre object while he was recording images at the Haleakala observatory in Hawaii. This object was then named ʻOumuamua which loosely translates to a messenger from afar arriving first or scout. Apart from its drastic speed of 94,800 km/h (58,900 mph), its strange inclination clued astronomers to the fact that it was not from our solar system. It had traveled on a U-shaped hyperbolic orbit around the sun and was going back into interstellar space. The object was observed by the PAN-STARRS-1, 40 days after it made its closest journey to the sun, this was at 0.25 AU. It was also observed to be spinning rapidly. 

The following drawing shows ʻOumuamua’s position during its visit to our solar system. It came closer to the Sun than Mercury. The closest it got to the Earth was 0.22 AU, which represents a distance light travels in roughly 1.7 minutes. The sun in comparison is about a full AU from the earth (8.32 min.). While it came close, it was not a threat to us. Albeit pretty fast as it reached an incredible 87.71 meters per second (315,756 km/h) while passing the Sun, ʻOumuamua would still have taken 1 hour and 37 minutes to reach Earth at that speed from the closest point from Earth it traveled by.

ʻOumuamua trajectory in the solar system.

There had been a long-standing belief among astronomers that such objects existed, but this was the first concrete proof that this was true. Planetary scientist Alan Stern, among others, predicted as far back as 1997, that we would one day see such interstellar visitors. Especially since we can detect asteroids and comets being periodically ejected from our solar system, it would make sense that one day we would receive the visit of interstellar asteroids and comets from other systems. On its discovery, observatories and telescopes all around and above the world clamored to learn more about this interstellar interloper. NASA’s Hubble Space Telescope as well as numerous ground-based observatories were used to create data around this mysterious object. ʻOumuamua was found to be between 1,300 feet and 2,600 feet. It was also said to be approximately 0.5 miles. Its width is reportedly six times smaller than its length. The object was also a dark red color.

Though this discovery was expected,  ʻOumuamua was not what it was expected to be. Astronomers had expected the first interstellar object spotted to be a comet similar to the recently discovered 2I/Borisov. Nothing about this object was ordinary, and this drew a lot of speculation and theory. From its outward appearance, ʻOumuamua strikes out as an asteroid. 

The object has caused a lot of controversy among astronomers. There have been different takes on just what exactly ʻOumuamua is. Initially, it was reported that the object was a comet. This is because of its high speed. They theorized this high speed to be due to the object outgassing material and ultimately creating a jet that pushed it along. If it is a comet, ʻOumuamua is 10 times more reflective than the comets found within our solar system maybe because of its outgassing nature that leaves streaks of ice underneath it. Some astronomers have been quick to debunk this theory since it did not leave a puffy coma behind it when it moved as comets do. There was just no tail at all. Supporters of this theory stated that the released gas could have contained very few tiny dust particles that they were practically invisible. 

It was also noted that comets have more of an icy appearance, ʻOumuamua on the other hand has a dry and rocky appearance that is not consistent with comets and is more consistent with asteroids. It was also speculated to be an asteroid, but there wasn’t enough evidence to prove that. Although interesting, these theories have their supporters and debunkers in equal measure. 

So what really is ʻOumuamua?

This answer is very murky and there are several theories and beliefs. Retracing its steps is an astronomical task. Information left behind by this interstellar visitor is limited.

  • A longstanding belief is that ʻOumuamua is a rock from another planet and due to gravitational forces, it was thrown away from its original star system. It has also been presumed to be remnants of a comet that disintegrated as it approached the sun. Yun Zhang and Douglas N. C. Lin created computer simulations to prove that objects similar to ʻOumuamua could be created if tidal (created by gravitational pull) from its star were exerted on larger objects. Saturn’s rings, for example, are said to have been created after moons broke apart due to gravitational forces. The two also stated that tidal forces could also throw objects out of their natural systems. Using computer modeling, they also demonstrated the amount of heat involved during this process. This demonstration showed that the original body of the piece that broke apart would melt a short distance away from the original body, it would then re-condense further away creating the elongated crust that is similar to ʻOumuamua’s. This theory, the scientists said, could account for many similar asteroid-like interstellar objects present in our Milky Way.  In a nutshell, they proved that when an object comes close to its star, approximately 354,000 km (220,000 miles), the star’s gravity exerts a force on it that throws it out, stretches it and shreds it. This is known as tidal disruption. For smaller objects, they have to be very close to their star before this disruption occurs. The formation of objects similar to ʻOumuamua would depend on the composition of the parent rock. The violence and sheer force of this process would result in many shards that would be thrown into space, never to be seen again. 

    This simulation also showed that the heat from the star would vaporize any liquid on the surface of the parent planet. Ice within the rock would still be present and this would explain the water vapor that propelled ʻOumuamua when it approached our Sun. Once they melt and become solid once again, they form a stronger crust and this would also explain why it didn’t crumble when it approached the Sun.

    Other researchers have agreed with this theory stating that tidal forces could be the force behind debris-disks, comets, and perhaps even Super-Earths forming ʻOumuamua-like objects during encounters with stars. 
  • The most fascinating theory yet is that ʻOumuamua could come from an advanced and distant civilization. Shmuel Bialy and Avi Loeb from the Harvard Smithsonian Centre for Astrophysics have speculated that the object could be a gossamer-thin LightSail. They were of the idea that the object was a piece of space junk that found its way into our solar system by accident. Or it could be a ship sent on an exploratory mission to find out more about our world. This theory supports the fact that there could be aliens among us and few astrophysicists have been quick to support these claims.Extraterrestrial The First Sign of Intelligent Life Beyond Earth by Avi Loeb Loeb, however, contends that this is a very plausible theory and should be investigated (see his book: Extraterrestrial). Another theory that supports the fact that ʻOumuamua could be sent by aliens was because of its strangely elongated shape and its path in and out of our solar system. Some astronomers even theorized that the object could have been from an alien probe. They have debunked the theory that ʻOumuamua could be a comet. This is because if ʻOumuamua’s trajectory was to be because of its outgassing, it would have caused a rapid change in the way the object was spinning and this was not observed. If the object is indeed a LightSail, Loeb says that radiation pressure could be the cause of its propulsion. “We explain the excess acceleration of ʻOumuamua away from the sun as the result of the force that the sunlight exerts on its surface. For this force to explain measured excess acceleration, the object needs to be extremely thin, of order a fraction of a millimeter in thickness but tens of meters in size. This makes the object lightweight for its surface area and allows it to act as a LightSail. Its origin could be either natural (in the interstellar medium or proto-planetary disks) or artificial (as a probe sent for a reconnaissance mission into the inner region of the solar system).” Professor Loeb was quoted to have said. After calculations, they found that a sail that was 0.3-0.9 millimeters would be enough for a sheet of solid material to survive a journey throughout the galaxy. However, they did not know ʻOumuamua’s mass density, which would also be a determining factor. This sail could survive collisions with gas and dust grain as well and also hold out against tidal and centrifugal forces.

    Also supporting their theory is the fact that ʻOumuamua orbited at 0.25 AU from the sun, which is close enough to earth while still far enough from the sun’s radiation. He further stated that many of these probes could have been sent before until one finally came close enough to earth.

Continuing to Learn About ʻOumuamua

With ʻOumuamua disappearing into space, it is becoming progressively difficult to observe it. Many have thought perhaps we should send a spacecraft to intercept it. A British Nonprofit Initiative for Interstellar Studies (i4is) came up with Project Lyra. This project was meant to be a mission that would take astronomers to the stars.

They noted that ʻOumuamua was moving away from our solar system at double the speed of Voyager 1, the fastest spacecraft created by man. ʻOumuamua travels at about 800 million kilometers (500 million miles) per year meaning that in the 2030s it will enter interstellar space. The founders of the project suggested that by launching a spacecraft using one of the world’s most powerful rockets, they could propel the spacecraft to the object. This would be assisted by gravity from Jupiter and the Sun. Their proposal would see the spacecraft launched in 2030 and it would meet ʻOumuamua in 2049. It would travel 32 billion kilometers (20 billion miles) in approximately 20 years. Voyager 1 in comparison, covered 64 billion kilometers (40 billion miles) in double the years. This journey would most likely face challenges, one of them being simply finding ʻOumuamua in the vast interstellar space.

Astrophysicists have pointed out that visiting an interstellar object would bring about both technical and huge financial challenges. It would be much easier for astronomers to wait for these objects to come to us instead of going to them. Intercepting such an object would come down to timing. Had we had a spacecraft waiting when ʻOumuamua was observed, it would have been possible. Hopefully, with the new generation of telescopes, intercepting interstellar objects would be more common since we would be able to see them better. 

Our Cosmic Ancestry in the StarsBefore ʻOumuamua, there was already a belief that these objects were present and after its citing, it has been theorized that there could be trillions upon trillions of similar entities within our galaxy. There is also a belief that microbes could have attached themselves to ʻOumuamua-like objects and spread everywhere through space. This being referred to as panspermia (See the book Our Cosmic Ancestry in the Stars for more details about this theory). 

Adding on to the mystery surrounding ʻOumuamua, Michele Bannister from the University of Canterbury in New Zealand states that ʻOumuamua most likely came from a comet and not a Super-Earth. They were also skeptical of its shape stating that observations that it was cigar-shaped could be false. They cited a paper published last year that concluded that the interstellar interloper may have very well been pancake-like in shape instead. This shape would be similar to Arrokoth (MU69—often referenced as the Space Snowman).

Arrokoth old view and real shape
Arrokoth (MU69) was first thought to be a spherical binary. In 2019, we found out that they are actually quite flat.

ʻOumuamua is still shrouded in mystery, much like a lot of matters concerning space. Is it an asteroid? Is it a Comet? Is it a piece of a parent rock from another world? Or is it an alien probe? If it is indeed an asteroid, how would you explain its orbit which is similar to that of a comet? If it is a comet, what happened to its tail? I’d like to think that it’s an alien spacecraft, but with limited scientific evidence, this might just be a dream. Until a similar object is observed, we might never have concrete answers. Let us know what you think in the comments below. 

What Are Black Holes?

Image of a black hole

Black holes are one of the most fascinating aspects of space. They have such an extreme gravitational pull that not even light can escape. They are so phenomenal that they are said to have the ability to alter entire galaxies.

Black holes are severely curved off that it can be considered pinched off from the rest of the universe. Within a black hole, the laws of physics as we know them no longer apply. Using Einstein’s theory of relativity, physicists such as Karl Schwarzschild theorized that any mass can become a black hole if it was compressed into a space small enough. Black holes were first predicted by Einstein in 1916, however, it was only until 1971 that the first black hole was physically discovered. Continue reading “What Are Black Holes?”

Handheld Telescope (a.k.a. Pirate Brass Telescope with a Wooden Box)

With Pirate Movies we have seen a come back of those old Telescopes that navigators used for centuries before the GPS was publicly available.

Although often referenced as Pirate Telescope, those were regular captain navigation telescopes and pirates happened to steal them along other treasures. Not like pirates invented them… Continue reading “Handheld Telescope (a.k.a. Pirate Brass Telescope with a Wooden Box)”

Why Do You Want a Case for Your Telescope?

Cleaning a Telescope Mirrors and Eye Pieces

As I explained in my post Advice on Buying a Telescope Online, there are two types of telescopes. Both have a different set of needs when it comes to maintenance.

The maintenance is an important part if you do want your telescope to continue to perform well and who wouldn’t want such?! In most cases you’ll just have a small dust problem, but dust on your mirror is not easy to clean (well… it’s not that hard, but it’s a bit of work) so if there was a way to make it easy on you, wouldn’t that be great? Continue reading “Why Do You Want a Case for Your Telescope?”