The 10 Most Unique Celestial Objects in the Universe

The universe is full of incredible celestial objects, from lone planets hurtling through space to colorful explosions from massive stars. As scientists continue to explore the universe using ever more advanced telescopes, they are stumbling on some incredible and quirky discoveries. In fact, some of the unique celestial objects are even changing the way we think of the universe and our place within it. 

1. The TRAPPIST-1 System

While over 4000 exoplanets have been identified throughout the universe, the TRAPPIST-1 system is particularly unique. Not only does it have a planet similar in size and density to Earth within its habitable zone — it has seven. These planets are all remarkably similar to one another, as well as Earth, in terms of size. One Earth-like planet is exceptionally rare, so the possibility of seven potentially habitable worlds in a single star system is truly incredible. 

Located a relatively short 40 light years away, TRAPPIST-1 itself is a red dwarf star, so it is much smaller and cooler than the Sun. Luckily, its seven planets all have orbits even shorter than that of Mercury. The longest “year” in the TRAPPIST-1 system is less than a month on Earth.

TRAPPIST-1e is currently considered the most Earth-like planet in the system but all of the TRAPPIST-1 planets could have liquid water on them, making this system top of the list for interstellar exploration. 

2. Rogue Planets

Rogue planets are some of the saddest and most interesting celestial bodies humans have discovered to date. These unique planets orbit no star. They have no solar system or “home” in the universe. Rather, rogue planets hurtle through space completely alone. Scientists believe this is the result of gravitational forces essentially catapulting a planet from its original orbit. 

Recently, astronomers discovered a groundbreaking cluster of over 70 rogue planets just within the Milky Way galaxy alone. There could be billions of them scattered around the universe. While it is unlikely that rogue planets could harbor life since they have no star for warmth, it isn’t impossible.

A thick ice shell for insulation and geothermal heating from within the planet’s core could potentially allow life to form, although it would look nothing like life as we know it on Earth. For example, this life would exist in complete darkness in the absence of any sun.

3. Hypernovas

Supernovae might be rare but hypernovae are far more so. Originating from stars at least 30 times more massive than the Sun, hypernovae are among the most unique celestial bodies in the entire universe, though they are more a type of celestial event. When these mammoth stars collapse, they create an explosion 10 times greater than a normal supernova. 

For a star to generate this kind of explosion at the end of its life cycle, it would have to be spinning at incredibly high velocity and have an extremely powerful magnetic field. The physics of these features amplify the explosion of the star, creating a hypernova.

However, scientists also believe the collision of two stars in a binary star system could result in a hypernova, as well. Either way, the result of the hypernova is a tremendous gamma-ray burst and the formation of a new black hole where the star once was. 

In 2021, astronomers recorded the first potential hypernova remnants in the Milky Way galaxy. The star that created this hypernova is one of the oldest ever identified, originating from less than one billion years after the Big Bang. 

4. The “Double Quasar” 

Quasars themselves are a type of extremely bright young galaxy. While astronomers have yet to determine for certain what a quasar is, current theories suggest that these celestial bodies are the nuclei of newly-forming galaxies, potentially highly active black holes.

Astronomers believe a quasar phase may even be a common part of a galaxy’s life cycle. All of the potential quasars identified so far exist on the edge of the visible universe, billions of light years away, which indicates that they are shining on average 27 trillion times brighter than our Sun. 

Double quasars are one of the rarest celestial objects in the universe, accounting for only one out of every 1000 quasars. These twin quasars are formed by two galaxies merging together. Eventually, the supermassive black holes at the center of the twin galaxies will collide and form an even more massive black hole.

Interestingly, this has likely already occurred in all of the double quasars observed due to the time it would take for light from the quasars to reach Earth. 

5. Exoplanet KOI-5Ab

The second planet ever found by the famed Kepler Space Telescope is also one of the most baffling celestial objects in the universe. The Transiting Exoplanet Survey Satellite (TESS) was recently able to collect data on KOI-5Ab that revealed it is the only planet in a system with not one but three stars. 

Believed to be a gas giant similar to Saturn or Jupiter, KOI-5Ab orbits Star A in the KOI-5 system alongside KOI-5B, which also orbits Star A in a sort of binary system. The gravitational forces of this second star are believed to be responsible for KOI-5Ab’s abnormally skewed orbit.

Even stranger, though, is the third star that orbits both Star A and Star B. This star, KOI-5C, takes an estimated 300 Earth years to complete one orbit around the two binary stars. While KOI-5Ab is unlikely to have any solid surface like Earth, a sunset from this world would have three stars. In fact, a day on KOI-5Ab would be highly irregular since it receives sunlight from three different stars. 

6. Omega Centauri

Omega Centauri is a massive globular cluster, a cloud of ancient stars all at least 10 billion years old. In fact, Omega Centauri contains almost 10 million stars. It is unique among globular clusters, though, because the ages of these stars do not all match. One of the features of globular clusters are crowds of stars around the same age.

Omega Centauri’s stars are members of at least two distinct age camps, though. This suggests that Omega Centauri contains the remnants of another galaxy that may have once merged with it. In fact, astronomers have theorized that Omega Centauri may even be a dwarf galaxy, rather than a globular cluster. 

7. The Necklace Nebula

This fascinating nebula earns its place as one of the most unique celestial objects in the universe due to its strange origins. The “Necklace Nebula”, technically named PN G054.2-03.4, is the result of two binary stars colliding with each other. One of the two stars expanded until it enveloped the second star, but the pair continued spinning around each other at incredibly high velocities. In fact, they orbit one another in just over one Earth day. 

The centrifugal force of this rotation caused the gaseous explosion of the larger star to spread out in a massive oval, creating the necklace-like shape the nebula is named for. This ring is an estimated 12 trillion miles across at its longest ends. 

8. Tabby’s Star

While the transit method of hunting for exoplanets has turned up many fascinating celestial objects, one of the most unique so far is a system known as “Tabby’s Star”. This star, KIC 8462852, gets its name from scientist Tabitha Boyajian who studied its strange behavior in 2017.

The transit observation method is used to find exoplanets by looking for slight dips in a star’s light, indicating that something, hopefully an exoplanet, passed in front of the star. However, this was not what astronomers observed with Tabby’s Star.

Unlike any other star observed so far, Tabby’s Star displays rapid and extreme dips in light, much more than any exoplanet could cause. To make matters more baffling, the star’s light has been dimming consistently over the last several decades.

This behavior led many to suggest that an intelligent civilization was responsible, possibly using a megastructure to draw power from the star. However, scientists have since determined that the most likely cause is irregular, massive clouds of debris orbiting the star. 

9. The “IGR J17091-3624” Black Hole

The binary star system IGR J17091-3624 contains the smallest black hole humans have discovered so far. This black hole is a stunning celestial body unlike any other black hole we know of. Estimated to be less than three times the mass of the Sun, this black hole barely makes the cut to qualify as such.

Despite its small size, though, it is home to the universe’s fastest known cosmic winds for a stellar-mass category black hole. In fact, the winds generated by IGR J17091-3624’s black hole are comparable to those of average black holes billions of times more massive.

This is a binary system with a star orbiting the powerful little black hole, which was identified using the x-ray pulses the black hole emits. It is located in the Milky Way galaxy, about 28,000 light years from Earth. 

10. The DF2 Galaxy

The galaxy NGC 1052-DF2, or “DF2” for short, is changing the way astronomers think of galaxies and the universe itself. This perplexing celestial object breaks the rules of cosmic physics as we know them. It contains a mere 1/400th the amount of dark matter scientists expected. Also, it may not contain any dark matter.

Prior to DF2, physicists believed that it was impossible for galaxies to form without dark matter. No galaxy had ever been found before without this invisible matter that is considered the “glue” of the universe. Despite being comparable in size to the Milky Way galaxy, DF2 contains only 1/200th the number of stars.

These stars are hypothesized to account for most, if not all, of the galaxy’s mass. That further confirms the alarming absence of dark matter. Scientists are still figuring out how DF2 formed. 

2023: New Discoveries From the Webb Space Telescope

In July 2022, the world got to see the first images from the revolutionary James Webb Space Telescope. Ever since the telescope went online, it has been helping scientists make incredible new discoveries about our universe. Among these discoveries are some of the most fascinating celestial objects scientists have ever observed.

With the help of the JWST’s advanced array of sensors and imaging equipment, scientists are getting data that was previously inaccessible. For example, the JWST can see further from Earth than any other telescope. This isn’t just giving us data about distant worlds. It is also allowing scientists to learn more about the formation of the universe.

Images of Ancient Galaxies

Due to the way light travels through space, the further an object is from Earth, the older the image of it is. Light from objects that are billions of lightyears away takes so long to reach telescopes like the JWST that what we see is actually an image from millions of years ago. So, when astronomers look into the far reaches of space, they are also looking back in time. 

Thanks to the JWST, the oldest observed galaxies are now among the most unique celestial objects in the universe. In December 2022, the JWST captured images of JADES-GS-z13-0, one of four galaxies located about 33 billion lightyears from Earth. These ancient galaxies are so far away the images we have of them are 13.5 billion years old, according to redshift data collected by the JWST. 

The Cartwheel Galaxy

The JWST captures images of thousands of galaxies all over the universe. A few have gained fame online for their unique traits, including the “Cartwheel Galaxy”, also known as ESO 350-40. This galaxy is composed of an incredible peach-colored spiral. The Cartwheel Galaxy’s famous shape is the result of a cosmic accident, a collision between a large spiral galaxy and a much smaller nearby galaxy. 

This collision sent the outer ring of the new Cartwheel Galaxy in motion, causing it to expand for over 400 million years. At the heart of the galaxy is a bright star cluster. While previous telescopes observed this galaxy, the JWST has given astronomers more data and images than ever before. 

The Pillars of Creation

In a far-flung corner of the universe, the JWST gave us a glimpse at a truly stunning scene. Known as the Pillars of Creation, this region of space is only about 7000 lightyears away. It was originally discovered in 1920 then famously photographed by the Hubble Space Telescope in 1995. The JWST renewed fascination with the Pillars of Creation in 2022 with the most jaw-dropping photo of it yet. 

The Pillars of Creation is a star nursery, an area where many young stars are forming, creating the brilliant arcs of color seen in photos. The rust red pillars, which to some look like the fingers of a giant hand, are formed by combinations of gas and dust. New photos of the Pillars of Creation reveal it in incredible detail thanks to the JWST’s near-infrared-light camera, or NIRCam.

A Fascinating Universe Full of Celestial Objects

These celestial objects are only the tip of the iceberg. The universe is so vast that humans may never finish discovering new phenomena, worlds, and cosmic events. While humanity is still just beginning to explore our small corner of the universe, today’s astronomers continue to give us glimpses into the most distant galaxies, nebulae, supernovae, and more. The more we discover, the more we will learn about the fascinating universe we call home.

Editor’s Note: This article was originally published on January 13, 2022 and was updated on March 29, 2023 to provide readers with more updated information.