Space is full of strange and weird things, and we are still in the process of investigating them. Below is the list of the fascinating things in space that we have discovered so far.
21. Haumea’s Rings
Artist’s concept of Haumea at the center with its two moons Hiʻiaka (above) and Namaka (below) | Image Courtesy: NASA/Agência FAPESP.
Fastest Rotating Object In Our Solar System
Haumea, previously designated as 2003 EL61, is a dwarf planet located in the Kuiper Belt beyond the orbit of Neptune. It is the most massive dwarf planet in this region, after Pluto and Eris, and is peculiar in several ways.
With about 3.9 hours rotation period, Haumea is the fastest rotating body known in the solar system, with a diameter of more than 100 kilometers. Due to its insanely fast rotation, Haumea has been deformed into an ellipsoid (similar to a rugby ball). If Haumea was rotating more rapidly than it is now, it would have been split (distorted) into two pieces.
However, what makes Haumea really unique is the presence of a faint ring around it. Haumea is the first trans-Neptunian Object to feature a ring system. The existence of a ring around Haumea was first discovered in 2017 during a stellar occultation and is yet to be directly observed.
20. Moon of a Moon
An artist’s concept of exomoon Kepler-1625b-i orbiting its mother planet | Image courtesy: NASA/ESA
Satellite orbiting another natural satellite
A “moon of a moon” is a common term used to describe a satellite (natural or man-made) that orbits another natural satellite. They are also called subsatellites or submoon. Theoretically, the existence of a significant natural subsatellite is almost impossible as the tidal effects of the planet would make such a system unstable.
Though no natural subsatellites are currently known, there are a few instances in which such systems have been inferred or predicted within our Solar system and beyond.
In October 2018, while observing Kepler 1625, a distant star in the constellation Cygnus, researchers uncovered strong evidence of a Neptune-sized exomoon (moon outside of the solar system) orbiting the only planet in the star system, Kepler 1625b. Later, it was speculated that the exomoon might have its own moon.
There had been speculations of a possible ring system and at least one subsatellite revolving around Rhea, the second-largest natural satellite of Saturn. However, the Cassini spacecraft could not find any evidence of a subsatellite around Rhea during its mission. It is also hypothesized that Iapetus, Saturn’s third-largest moon, may have had a subsatellite in the past.
19. Flattest Star – Achernar
Artist’s concept of Achernar star | Image Courtesy: Wikimedia Commons
The least Spherical Star in the Milky Way
Most stars, including the Sun, are spherical or nearly spherical in shape. But there are some exceptions. As we know, stars are made of hot gas (plasma) and are supported by their internal pressure to remain in the state of equilibrium. Thus, creating a spherical shape.
Stars also rotate on their axis at different speeds. Depending on the rotation speed, the spinning gas on the star’s surface affects its shape to become flattened, i.e., wider at the equator and shorter on the axis.
One such flattened star is Achernar. In fact, it is the flattest or least spherical star in the Milky Way galaxy, with an equatorial radius at least 55 percent greater than the polar radius. However, it is impossible to distinguish the exact shape of a star with the naked eye.
Achernar is located about 139 light-years away from the Earth at the Eridanus constellation. It is as much as seven times more massive than the Sun and 3,150 times more luminous.
18. Rogue Stars
Stars Without a Galactic Home
Stars that are gravitationally not bound to a galaxy are known as rogue stars. These are outcast stars that were tossed out of their home galaxies at some point during their lifetime. Since rogue stars are not associated with any galaxy, they are often called intergalactic stars.
The first group of rogue stars was discovered in 1997 by the Hubble telescope in the Virgo cluster of galaxies about 60 million light-years away from Earth. The finding also suggested that such stars occupy about 10 percent of the Virgo cluster’s mass. Another large group of rogue stars was discovered a few years later in the Fornax cluster.
Though rogue stars are now believed to be most likely to have been born inside the galaxies, like other stars, the exact mechanism behind their expulsion from home galaxies is still a mystery.
To explain such a phenomenon, physicists have proposed a few credible scientific hypotheses. The most favored among them is a galactic collision. The collision between two or more galaxies can lead to gravitational disturbances that can expel some of the stars in intergalactic space.
A proposed mechanism for rogue stars | Image Courtesy: NASA
Another popular hypothesis is that such stars were initially part of a multi-star system and were ejected violently out of their galaxies after a close encounter with the supermassive black hole (located at the center of most large galaxies.)
In 2019, a team of astronomers discovered a fast-moving rogue star in the constellation Grus (crane) about 29,000 light-years away. The star, designated S5-HVS1, is believed to be moving at a speed of 3,930,000 mph (1,755 km/s), about ten times faster than most stars in the Milky Way galaxy.
According to the researchers, the star was originally part of a binary system and interacted with the supermassive black hole at the galaxy’s center (Sagittarius A*) before getting kicked out. Due to its extremely high speed, the S5-HVS1 is usually categorized as unbound hypervelocity stars (HVSs).
17. Rogue Planets
Planets Without a Parent Star
Most planets outside the solar system, also known as exoplanets, orbit at least one star and are in a planetary system (circumbinary planets that orbit two stars have also been found). However, researchers have also discovered several confirmed and possible rogue planets that are wandering without a parent (star) in space.
It is believed that such planets have been either ejected from their planetary system or were never a part of one. In some cases, rogue planets are part of a stellar association, such as moving groups, i.e., a group of stars that share a common origin and motion through space.
PSO J318.5−22 is one such planet. It was discovered in 2013 and is located about 80 light-years away from Earth. The rogue planet is at least six times more massive than Jupiter and has a surface temperature of 1275 K.
Scientists believe that there are likely millions or maybe billions of rogue planets in the Milky Way alone. NASA’s Nancy Grace Roman Space Telescope, which is expected to be launched in early 2027, will enable astronomers to find such planets more efficiently.
16. Tabby’s Star
Artist’s concept of Tabby’s Star surrounded by a ring of interstellar dust | Image Courtesy: NASA/JPL-Caltech
A Star with mysterious fluctuations in brightness
Tabby’s star, also known as the WTF star, is a popular target among amateur astronomers due to its unusual and mysterious fluctuations in brightness. The star is located about 1,470 light-years away from Earth in the constellation Cygnus and was first observed in the year 1890.
Both the short-term and long-term fluctuations in the luminosity of Tabby’s Star have been observed by Kepler Space Telescope. The first significant dip was recorded on March 5 2011, when the star’s brightness was reduced by 15 percent. Then after the next 726 days (almost two years), it went up by 22 percent. The next dimming event (8 percent reduced brightness) was recorded just 48 days later. Moreover, a long-term study of the star indicates that it has faded by about 20 percent in the last century.
Over the years, researchers have tried to explain the fluctuations in the star’s brightness through various means. Some of the proposed explanations include – the presence of an interstellar dust ring, an asteroid field, planetary debris, and even a large swarm of comets that could obstruct the star’s light.
Another, perhaps a more fascinating, speculation behind the Tabby Star’s mysterious behavior is the presence of an artificial megastructure built by an alien civilization. This hypothesis argues that an advanced extraterrestrial civilization might have built a massive structure around the star to harness its energy.
Though an initial study by the SETI Institute found no telltale sign of any alien life near the star, it remains an important target for SETI since no satisfactory explanation for the star’s dimming has been provided yet.
15. Hoag’s Object
Hoag’s Object | Image Courtesy: NASA’s Hubble Space Telescope/Ray A. Lucas (STScI/AURA)
Perhaps the Most Mysterious Galaxy in the Universe
Hoag’s Object is one of the fascinating galaxies known in the universe. When it was first discovered by astronomer Arthur Hoag in 1950, he mistook it for a planetary nebula, a bright shell made of gas ejected from red giant stars near the end of their lives (nothing related to planets).
Hoag’s Object is unique in terms of morphology. Unlike the Milky Way galaxy, it has a nearly perfect ring-like structure and has two separate stellar populations. The center of this galaxy is occupied by a closely packed group of redder stars. Encircling them is a ring of younger and brighter blue color stars.
The gap that separates the two stellar populations is almost entirely dark, though it may contain some extremely faint star clusters. The galaxy is located about 600 million light-years away in the constellation Serpens. It has an estimated diameter of 100,000 light-years and contains 8 billion stars.
Though ring galaxies like Hoag’s Object are exceptionally rare, a similar galaxy can be seen behind it in the distant space on the upper right corner.
14. The Largest and Most Distant Water Reservior
Artist’s concept of quasar APM 08279+5255 | Image Courtesy: NASA/ESA
The largest reserve of water in the observable universe is found around a quasar or active galactic nucleus located about 12 billion light-years away in the Lynx constellation. The quasar, called APM 08279+5255, is powered by a massive black hole with 20 billion times more mass than the Sun.
To measure the amount of water present in distant space objects, including galaxies, astronomers essentially look for water vapor in their atmosphere through spectroscopy. According to the astronomers, the amount of water present around the quasar is 140 trillion times of all water in Earth’s oceans and 4,000 times of that in the entire Milky Way galaxy (most of the water in our galaxy is in the form of ice).
An artist’s concept of quasar ULAS J1120+0641 and its surrounding accretion disc | Image Courtesy: ESO/M. Kornmesser
One of the Brightest and Densest Objects in the Universe
When quasars were first discovered in the 1950s, they were identified as stars. That’s how they got the name — quasi-stellar (star-like). However, they are far from being stars. Today, astronomers identify quasars as galactic nuclei located in the center of many galaxies.
A quasar is powered by at least one supermassive black hole with mass hundreds of million times more than that of the Sun. They are found at vast distances. The nearest quasar, Markarian 231, is located at 600 million light-years away and is powered by two supermassive black holes.
Despite being relatively distant objects, quasars have a bright appearance. It is due to their high luminosities. Since they are powered by supermassive black holes, quasars are surrounded by accretion discs that produce insane amounts of energy.
The brightest quasar in the universe, 3C 273, has an apparent magnitude of 12.8 and can be observed using intermediate amateur telescopes. Its luminosity is estimated to be 100 times more than all the light in the Milky Way galaxy combined and as much as 4 trillion times than our Sun.
So far, about 750,000 quasars have been discovered. Compared to the hundreds of billions of estimated galaxies in the universe, this number is quite insignificant. Not all galaxies with supermassive black holes at the center feature an active nucleus or quasar. The Milky Way galaxy is one of them.
It is now believed that galaxies that don’t feature active nucleus, despite having supermassive black holes, most likely to have run out of matter to feed the black hole and generate radiation.
12. Space Cannibalism
A composite image of galaxy NGC 3393 | Image Courtesy: X-ray: NASA/CXC/SAO/G.Fabbiano et al; Optical: NASA/STScI
Sun-like stars can eat planets in space, larger galaxies can “eat” the smaller ones, and a black hole can devour other black holes. According to a recent study published in the journal of Nature Astronomy, between 20-35 percent of all Sun-like stars consume planets orbiting around them. Fortunately, our Sun is neither in the process of eating a planet nor it has done so (most probably) in the past.
Cannibalism on a galactic scale has been observed since the 1990s. With the help of NASA’s Hubble Space Telescope, a group of astronomers in 1999 discovered several small and faint star clusters near the center of a lenticular galaxy, NGC 1316, located at the edge of the Fornax constellation more than 60 million light-years away.
According to the researchers, these small clusters are remnants of a former galaxy that was eaten by NGC 1316 a few billion years ago. Further distinct evidence of the cannibalistic past of NGC 1316 is the dust patches and lanes that suggest its previous collision with a gas-rich galaxy.
If that’s not freakish enough, astronomers have now found clear evidence of a black hole eating away a smaller black hole. NGC 3393, a barred spiral galaxy (similar to the Milky Way), located about 180 million light-years away in the Hydra constellation, hosts not one but two supermassive black holes at its center.
Interestingly, one of these SMBH is significantly more massive than the other and is actively devouring the smaller one. The distance between the two supermassive black holes is only about 490 light-years. Researchers have concluded that the current structure of NGC 3393 is a result of a merger between two galaxies of unequal mass more than a billion years ago.
Artist’s concept of a magnetar | Image Courtesy: ESO/L. Calçada
Stars with the Most Powerful Magnetic Fields
Magnetars can be simply defined as the most magnetic stars in the universe. They are also one of the most freakish things found in space. Magnetars are a type of neutron star.
When a massive star explodes into a supernova during the last stages of its evolutionary cycle, it leaves behind an extremely dense core, known as a neutron star. Neutron stars that have exceptionally strong magnetic fields are called magnetars. They have a mass between 1.4 and 2.6 times the Sun and a diameter of no more than 20 miles.
The magnetic field of magnetars is about a trillion times stronger than the field around Earth (0.5 gauss). It would make any lifeform impossible within a distance of 620 miles (1,000 km) from its surface by obliterating them at an atomic level. Magnetars are rare as well. So far, about 3,000 neutron stars have been discovered; out of them, only 31 are recognized as magnetars.
The first magnetar was discovered back in March 1979 after multiple satellites operating in the inner solar system, including some of which were orbiting earth, were hit by an extremely powerful blast of gamma radiation. It was the most intense extra-solar gamma radiation burst yet, about 100 times more powerful than anything before that.
Researchers were able to pinpoint the source of a bright supernova remnant, known as N49, located in the Large Magellanic Cloud about 160,000 light-years away. The suspected magnetar is designated as SGR 0525−66.
10. Three Merging Supermassive Black Holes
In 2019, an international group of astronomers discovered that three massive black holes are in a collision course with each other at about one billion light-years away from Earth. The discovery was made by combining data from the Sloan Digital Sky Survey (SDSS), NASA’s Wide-field Infrared Survey Explorer (WISE), and Chandra Observatory.
Dual and triple massive black holes are extremely rare. However, it can occur due to galactic mergers. In this case, three closely rotating galaxies, each with a supermassive black hole, are about to collide and merge into one. The system of three galaxies is designated as SDSS J084905.51+111447.2.
Studies show that the system exhibits intense brightness when observed in the infrared wavelength. It is indicative of one or more rapidly feeding black holes.
9. Cosmic Microwave Background
The Remnant Radiation From The Early Universe
The cosmic microwave background or CMB is the ultimate evidence of the Big Bang origin of the universe. It is essentially the leftover electromagnetic radiation from the earliest stage of the universe, which is believed to have transpired some 380,000 years after the Big Bang.
The CMB is observed using sensitive radio telescopes that are able to detect faint glow or background noise not related to any star, galaxy, or other astronomical objects. It is visible at a distance of about 13.8 billion light-years in all directions, which also led scientists to estimate the accurate age of the universe. CMB is critical to the Lambda-CDM model, our current understanding of the Big Bang cosmology.
The 15 meter Holmdel Horn Antenna that led to the discovery of the CMB in 1965 | Image Courtesy: NASA
Believe it or not, the cosmic microwave background was accidentally discovered by radio astronomers Robert Wilson and Arno Penzias in 1965 while working on their newly built sensitive microwave antenna. For their groundbreaking discovery, both were awarded the Nobel Prize in Physics in 1978.
The First Observed Interstellar Object
On October 19, 2017, the discovery of an asteroid made headlines not only in the scientific community but also among the general public. The reason was quite apparent. It was the first-ever interstellar object seen passing through the solar system.
Designated as 1I/2017 U1, or ‘Oumuamua, the object is estimated to be no longer than 3,000 ft (1,000 meters) and 550 ft (167 meters) in width.
Interestingly, when ‘Oumuamua was first found, it was identified as a comet. However, due to the lack of visible comet-like features, it was re-classified as an asteroid. To rectify this confusion, a new designation — I was created to identify newly found interstellar objects.
7. Diamond Planets
Planets That Are Mostly Made of Diamonds
55 Cancri e, an exoplanet orbiting around a Sun-like star, 55 Cancri A, about 41 light-years away, is believed to be filled with diamonds. The exoplanet is eight times more massive than the earth and is twice as large. Due to its density (6.66 g cm3), some researchers suspect that 55 Cancri e is made of carbon-rich materials, most possibly diamond, due to high internal temperature and pressure.
A recent study published in The Planetary Science Journal revealed that diamond-rich planets might be more common in space than we think. The study stated that carbon-rich planets, also known as carbide exoplanets also containing water, could form diamonds in large quantities.
6. Himiko – Lyman-alpha blob
A Newborn Galaxy From the Dawn Of the Universe
Himiko is a famous Lyman-alpha blob, a giant gas structure filled with mostly hydrogen or helium, located about 12.9 billion light-years from the earth in the constellation Cetus. It is the most massive object found in the early universe, with a mass of about 40 million times the Sun. At 55,000 light-years across, Himiko is almost half the size of the Milky Way.
What makes Himiko unique is that it predates all known Lyman-alpha blobs. Researchers believe that what we are seeing now is a protogalaxy from the reionization epoch, a cosmological phase that existed between 200 million and 1 billion years after the Big Bang, in its formation. It was named after a 3rd-century Japanese queen.
5. O-type stars
One Of The Rarest And Brightest Type Of Stars
Stars can be classified into several types and sub-types based on their spectral characteristics. Out of all spectral types, perhaps the most intriguing is spectral type O. The O-type stars are hot, luminous, and have a bluish-white appearance.
The surface temperature of these stars can reach up to 52,000 K (Sun’s surface temperature is 5,778 K), while their luminosities could be anywhere between 100,000 to 1 million times the Sun (for O-type main sequence stars).
Due to their extreme brightness, O-type stars can be seen with naked eyes at great distances. However, they are very rare. Out of 90 brightest stars observed from the earth, only four belong to spectral type-O. Only about 0.00003% of main-sequence stars near the solar system are O-type.
This is because O-type stars have shorter lives and tend to go supernova relatively faster than less massive and cooler stars.
4. Interacting Galaxies
Hubble Space Telescope image of Antennae Galaxies | Image Courtesy: ESA/Hubble & NASA
When two galaxies are close enough to make disturbances in each other’s gravitational fields, they are identified as interacting galaxies. This interaction may also lead to a complete galactic merger. One of the famous examples of interacting galaxies is NGC 4038/NGC 4039 or Antennae Galaxies, which are currently in process of merging.
The two components in this galactic merger are NGC 4038 (a barred spiral galaxy) and larger NGC 4039 (a spiral galaxy). Researchers believe that the two galaxies started interacting with each other about 900 million years ago. The Milky Way galaxy will also encounter a collision with a more massive Andromeda Galaxy in about 4.5 billion years or so.
Another, more common type of interacting galaxy is when a giant galaxy creates tidal disturbances in its nearby satellite galaxies.
3. Seven-star System
A Complex Star System With Seven Stars Orbiting Each Other
A multi-star system is a stellar system in which two or more stars are gravitationally bound to each other. It doesn’t include any planets, thus not to be confused with the planetary system. Most of the observed multi-star systems are triple stars, including Alpha Centauri, the closest stars to the earth. Star systems with more than three stars are rare, but they do exist.
The highest number of stars in a single star system discovered to date is seven, dubbed as the septuple star system. Nu Scorpii, located at a distance of 470 light-years, and AR Cassiopeiae, at 620 light-years, are the only two-star systems suspected to have seven stellar components.
2. KBC void
Artist’s concept of KBC void | Image Courtesy: Pablo Carlos Budassi/Wikimedia Commons
One Of The Largest Objects In The Universe
A cosmic void is a vast region in space with an unusually low number of massive galaxies and galaxy clusters. Larger voids that are characterized by a lack of notable superclusters are known as supervoids. Voids can be anywhere between 30 and 300 light-years (10-100 megaparsecs) in diameter.
In 2013, a study conducted by a team of astronomers revealed that our Earth and the Milky Way galaxy are part of the largest void in space. Labeled as the KBC void, named after astronomers Keenan, Barger, and Cowie, it is the largest cosmic void observed to date with a diameter of 2 billion light-years.
Like all cosmic voids, the KBC void features a few massive galaxies and galaxy clusters. It includes large parts of the Laniakea supercluster, home to the Local Group, which includes the Milky Way and Andromeda galaxy.
According to the researchers, the void is nearly spherical in shape, surrounded by a clump of galaxies and other objects. The location of the Milky Way is relatively close to the void’s center.
1. Supermassive Black Holes
The first-ever direct image of a supermassive black hole located at the center of supergiant galaxy Messier 87 | Image courtesy: ESO/EHT (Event Horizon Telescope) Collaboration
The Largest, Most Massive Type Of Black Hole Observed Yet
Scientists have come to a conclusion that four types of black holes exist in the universe. They are — micro black holes, stellar black holes, intermediate-mass black holes, and supermassive black holes.
Though yet to be observed, the micro black holes are the smallest black hole type and are believed to have a mass similar to the moon. Stellar black holes are created by the gravitational collapse of massive stars that have a mass between 5 and 20 solar masses. The third type, intermediate-mass black holes, is significantly more massive than stellar black holes. Their mass is estimated to be anywhere between 100 to 100,000 (105) solar masses.
Black holes with a mass above 100,000 solar masses are known as supermassive black (SMBH). They are the largest type of black holes observed in the universe, with an upper mass limit of 10 billion solar masses. The supermassive black holes are found in the center of nearly every large galaxy, including the Milky Way. The supermassive black hole in the center of the Milky Way galaxy is called Sagittarius A*.
To gain a perspective of their massiveness, the supermassive black hole powering a distant quasar, named TON 618, is believed to be at least 66 billion times more massive than the Sun. It is also more massive than all the stars in the Milky Way combined and about 15,000 times that of Sagittarius A*.
However, due to its exceptional mass, many researchers believe that TON 618 supermassive black hole belongs to a new group of black holes, called ultramassive black holes.