Story highlights
- Planet Nine has an orbit that's "about 20 times farther from the sun" than Neptune
- "We hope that other people are going to get inspired and start searching," researcher says
(CNN)You might have a replacement, Pluto. There could be another planet in our solar system.
Researchers at the California Institute of Technology have found evidence in the outer solar system of an object that could be a real ninth planet.

Photos: Wonders of the universe

Photos: Wonders of the universe
The NASA/ESA Hubble Space Telescope is celebrating its 28th anniversary in space with this stunning and colorful image of the Lagoon Nebula 4,000 light-years from Earth. While the whole nebula is 55 light-years across, this image only reveals a portion of about four light-years.
Hide Caption
1 of 56

Photos: Wonders of the universe
This is a more star-filled view of the Lagoon Nebula, using Hubble's infrared capabilities. The reason you can see more stars is because infrared is able to cut through the dust and gas clouds to reveal the abundance of both young stars within the nebula, as well as more distant stars in the background.
Hide Caption
2 of 56

Photos: Wonders of the universe
The Rosette Nebula is 5,000 light-years from Earth. The distinctive nebula, which some claim looks more like a skull, has a hole in the middle that creates the illusion of its rose-like shape.
Hide Caption
3 of 56

Photos: Wonders of the universe
An illustration depicts the detection of a repeating fast radio burst from a mysterious source 3 billion light-years from Earth.
Hide Caption
4 of 56

Photos: Wonders of the universe
KIC 8462852, also known as Boyajian's Star or Tabby's Star, is 1,000 light-years from us. It's 50% bigger than our sun and 1,000 degrees hotter. And it doesn't behave like any other star, dimming and brightening sporadically. Dust around the star, depicted here in an artist's illustration, may be the most likely cause of its strange behavior.
Hide Caption
5 of 56

Photos: Wonders of the universe
This inner slope of a Martian crater has several of the seasonal dark streaks called "recurrent slope lineae," or RSL, that a November 2017 report interprets as granular flows, rather than darkening due to flowing water. The image is from the HiRISE camera on NASA's Mars Reconnaissance Orbiter.
Hide Caption
6 of 56

Photos: Wonders of the universe
'Oumuamua, the first observed interstellar asteroid, is shown in an artist's illustration. It is longer and varies more in brightness than any asteroid to be formed in our solar system.
Hide Caption
7 of 56

Photos: Wonders of the universe
This artist's impression shows a supernova explosion, which contains the luminosity of 100 million suns. Supernova iPTF14hls, which has exploded multiple times, may be the most massive and longest-lasting ever observed.
Hide Caption
8 of 56

Photos: Wonders of the universe
This illustration shows hydrocarbon compounds splitting into carbon and hydrogen inside ice giants, such as Neptune, turning into a "diamond (rain) shower."
Hide Caption
9 of 56

Photos: Wonders of the universe
This striking image is the stellar nursery in the Orion Nebula, where stars are born. The red filament is a stretch of ammonia molecules measuring 50 light-years long. The blue represents the gas of the Orion Nebula. This image is a composite of observation from the Robert C. Byrd Green Bank Telescope and NASA's Wide-field Infrared Survey Explore telescope. "We still don't understand in detail how large clouds of gas in our Galaxy collapse to form new stars," said Rachel Friesen, one of the collaboration's co-Principal Investigators. "But ammonia is an excellent tracer of dense, star-forming gas."
Hide Caption
10 of 56

Photos: Wonders of the universe
This is an illustration of the Parker Solar Probe spacecraft approaching the sun. The NASA probe will explore the sun's atmosphere in a mission that begins in the summer of 2018.
Hide Caption
11 of 56

Photos: Wonders of the universe
See that tiny dot between Saturn's rings? That's Earth, as seen by the Cassini mission on April 12, 2017. "Cassini was 870 million miles away from Earth when the image was taken," according to NASA. "Although far too small to be visible in the image, the part of Earth facing Cassini at the time was the southern Atlantic Ocean." Much like the famous "pale blue dot" image captured by Voyager 1 in 1990, we are but a point of light when viewed from the furthest planet in the solar system.
Hide Caption
12 of 56

Photos: Wonders of the universe
NASA's Hubble Space Telescope, using infrared technology, reveals the density of stars in the Milky Way. According to NASA, the photo -- stitched together from nine images -- contains more than a half-million stars. The star cluster is the densest in the galaxy.
Hide Caption
13 of 56

Photos: Wonders of the universe
This photo of Saturn's large icy moon, Tethys, was taken by NASA's Cassini spacecraft, which sent back some jaw-dropping images from the ringed planet.
Hide Caption
14 of 56

Photos: Wonders of the universe
This is what Earth and its moon look like from Mars. The image is a composite of the best Earth image and the best moon image taken on November 20, 2016, by NASA's Mars Reconnaissance Orbiter. The orbiter's camera takes images in three wavelength bands: infrared, red and blue-green. Mars was about 127 million miles from Earth when the images were taken.
Hide Caption
15 of 56

Photos: Wonders of the universe
PGC 1000714 was initially thought to be a common elliptical galaxy, but a closer analysis revealed the incredibly rare discovery of a Hoag-type galaxy. It has a round core encircled by two detached rings.
Hide Caption
16 of 56

Photos: Wonders of the universe
NASA's Cassini spacecraft took these images of the planet's mysterious hexagon-shaped jetstream in December 2016. The hexagon was discovered in images taken by the Voyager spacecraft in the early 1980s. It's estimated to have a diameter wider than two Earths.
Hide Caption
17 of 56

Photos: Wonders of the universe
A dead star gives off a greenish glow in this Hubble Space Telescope image of the Crab Nebula, located about 6,500 light years from Earth in the constellation Taurus. NASA released the image for Halloween 2016 and played up the theme in its press release. The agency said the "ghoulish-looking object still has a pulse." At the center of the Crab Nebula is the crushed core, or "heart" of an exploded star. The heart is spinning 30 times per second and producing a magnetic field that generates 1 trillion volts, NASA said.
Hide Caption
18 of 56

Photos: Wonders of the universe
Peering through the thick dust clouds of the galactic bulge, an international team of astronomers revealed the unusual mix of stars in the stellar cluster known as Terzan 5. The new results indicate that Terzan 5 is one of the bulge's primordial building blocks, most likely the relic of the very early days of the Milky Way.
Hide Caption
19 of 56

Photos: Wonders of the universe
An artist's conception of Planet Nine, which would be the farthest planet within our solar system. The similar cluster orbits of extreme objects on the edge of our solar system suggest a massive planet is located there.
Hide Caption
20 of 56

Photos: Wonders of the universe
An illustration of the orbits of the new and previously known extremely distant Solar System objects. The clustering of most of their orbits indicates that they are likely be influenced by something massive and very distant, the proposed Planet X.
Hide Caption
21 of 56

Photos: Wonders of the universe
Say hello to dark galaxy Dragonfly 44. Like our Milky Way, it has a halo of spherical clusters of stars around its core.
Hide Caption
22 of 56

Photos: Wonders of the universe
A classical nova occurs when a white dwarf star gains matter from its secondary star (a red dwarf) over a period of time, causing a thermonuclear reaction on the surface that eventually erupts in a single visible outburst. This creates a 10,000-fold increase in brightness, depicted here in an artist's rendering.
Hide Caption
23 of 56

Photos: Wonders of the universe
Gravitational lensing and space warping are visible in this image of near and distant galaxies captured by Hubble.
Hide Caption
24 of 56

Photos: Wonders of the universe
At the center of our galaxy, the Milky Way, researchers discovered an X-shaped structure within a tightly packed group of stars.
Hide Caption
25 of 56

Photos: Wonders of the universe
Meet UGC 1382: What astronomers thought was a normal elliptical galaxy (left) was actually revealed to be a massive disc galaxy made up of different parts when viewed with ultraviolet and deep optical data (center and right). In a complete reversal of normal galaxy structure, the center is younger than its outer spiral disk.
Hide Caption
26 of 56

Photos: Wonders of the universe
NASA's Hubble Space Telescope captured this image of the Crab Nebula and its "beating heart," which is a neutron star at the right of the two bright stars in the center of this image. The neutron star pulses 30 times a second. The rainbow colors are visible due to the movement of materials in the nebula occurring during the time-lapse of the image.
Hide Caption
27 of 56

Photos: Wonders of the universe
The Hubble Space Telescope captured an image of a hidden galaxy that is fainter than Andromeda or the Milky Way. This low surface brightness galaxy, called UGC 477, is over 110 million light-years away in the constellation of Pisces.
Hide Caption
28 of 56

Photos: Wonders of the universe
On April 19, NASA released new images of bright craters on Ceres. This photo shows the Haulani Crater, which has evidence of landslides from its rim. Scientists believe some craters on the dwarf planet are bright because they are relatively new.
Hide Caption
29 of 56

Photos: Wonders of the universe
This illustration shows the millions of dust grains NASA's Cassini spacecraft has sampled near Saturn. A few dozen of them appear to have come from beyond our solar system.
Hide Caption
30 of 56

Photos: Wonders of the universe
This image from the VLT Survey Telescope at ESO's Paranal Observatory in Chile shows a stunning concentration of galaxies known as the Fornax Cluster, which can be found in the Southern Hemisphere. At the center of this cluster, in the middle of the three bright blobs on the left side of the image, lies a cD galaxy -- a galactic cannibal that has grown in size by consuming smaller galaxies.
Hide Caption
31 of 56

Photos: Wonders of the universe
This image shows the central region of the Tarantula Nebula in the Large Magellanic Cloud. The young and dense star cluster R136, which contains hundreds of massive stars, is visible in the lower right of the image taken by the Hubble Space Telescope.
Hide Caption
32 of 56

Photos: Wonders of the universe
In March 2016, astronomers published a paper on powerful red flashes coming from binary system V404 Cygni in 2015. This illustration shows a black hole, similar to the one in V404 Cygni, devouring material from an orbiting star.
Hide Caption
33 of 56

Photos: Wonders of the universe
A new map of the Milky Way was released February 24, 2016, giving astronomers a full census of the star-forming regions within our own galaxy. The APEX telescope in Chile captured this survey.
Hide Caption
34 of 56

Photos: Wonders of the universe
This image shows the elliptical galaxy NGC 4889, deeply embedded within the Coma galaxy cluster. There is a gigantic supermassive black hole at the center of the galaxy.
Hide Caption
35 of 56

Photos: Wonders of the universe
An artist's impression of 2MASS J2126, which takens 900,000 years to orbit its star, 1 trillion kilometers away.
Hide Caption
36 of 56

Photos: Wonders of the universe
Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system. The object, nicknamed Planet Nine, has a mass about 10 times that of Earth and orbits about 20 times farther from the sun on average than does Neptune.
Hide Caption
37 of 56

Photos: Wonders of the universe
An international team of astronomers may have discovered the biggest and brightest supernova ever. The explosion was 570 billion times brighter than the sun and 20 times brighter than all the stars in the Milky Way galaxy combined, according to a statement from The Ohio State University, which is leading the study. Scientists are straining to define the supernova's strength. This image shows an artist's impression of the supernova as it would appear from an exoplanet located about 10,000 light years away.
Hide Caption
38 of 56

Photos: Wonders of the universe
Astronomers noticed huge waves of gas being "burped" by the black hole at the center of NGC 5195, a small galaxy 26 million light years from Earth. The team believes the outburst is a consequence of the interaction of NGC 5195 with a nearby galaxy.
Hide Caption
39 of 56

Photos: Wonders of the universe
An artist's illustration shows a binary black hole found in the quasar at the center of the Markarian 231 galaxy. Astronomers using NASA's Hubble Space Telescope discovered the galaxy being powered by two black holes "furiously whirling about each other," the space agency said in a news release.
Hide Caption
40 of 56

Photos: Wonders of the universe
An artist's impression of what a black hole might look like. In February, researchers in China said they had spotted a super-massive black hole 12 billion times the size of the sun.
Hide Caption
41 of 56

Photos: Wonders of the universe
Are there are oceans on any of Jupiter's moons? The Juice probe shown in this artist's impression aims to find out. Picture courtesy of ESA/AOES
Hide Caption
42 of 56

Photos: Wonders of the universe
Astronomers have discovered powerful auroras on a brown dwarf that is 20 light-years away. This is an artist's concept of the phenomenon.
Hide Caption
43 of 56

Photos: Wonders of the universe
Venus, bottom, and Jupiter shine brightly above Matthews, North Carolina, on Monday, June 29. The apparent close encounter, called a conjunction, has been giving a dazzling display in the summer sky. Although the two planets appear to be close together, in reality they are millions of miles apart.
Hide Caption
44 of 56

Photos: Wonders of the universe
Jupiter's icy moon Europa may be the best place in the solar system to look for extraterrestrial life, according to NASA. The moon is about the size of Earth's moon, and there is evidence it has an ocean beneath its frozen crust that may hold twice as much water as Earth. NASA's 2016 budget includes a request for $30 million to plan a mission to investigate Europa. The image above was taken by the Galileo spacecraft on November 25, 1999. It's a 12-frame mosaic and is considered the the best image yet of the side of Europa that faces Jupiter.
Hide Caption
45 of 56

Photos: Wonders of the universe
This nebula, or cloud of gas and dust, is called RCW 34 or Gum 19. The brightest areas you can see are where the gas is being heated by young stars. Eventually the gas burst outward like champagne after a bottle is uncorked. Scientists call this champagne flow. This new image of the nebula was captured by the European Space Organization's Very Large Telescope in Chile. RCW 34 is in the constellation Vela in the southern sky. The name means "sails of a ship" in Latin.
Hide Caption
46 of 56

Photos: Wonders of the universe
The Hubble Space Telescope captured images of Jupiter's three great moons -- Io, Callisto, and Europa -- passing by at once.
Hide Caption
47 of 56

Photos: Wonders of the universe
A massive galaxy cluster known as SDSS J1038+4849 looks like a smiley face in an image captured by the Hubble Telescope. The two glowing eyes are actually two distant galaxies. And what of the smile and the round face? That's a result of what astronomers call "strong gravitational lensing." That happens because the gravitational pull between the two galaxy clusters is so strong it distorts time and space around them.
Hide Caption
48 of 56

Photos: Wonders of the universe
Using powerful optics, astronomers have found a planet-like body, J1407b, with rings 200 times the size of Saturn's. This is an artist's depiction of the rings of planet J1407b, which are eclipsing a star.
Hide Caption
49 of 56

Photos: Wonders of the universe
A patch of stars appears to be missing in this image from the La Silla Observatory in Chile. But the stars are actually still there behind a cloud of gas and dust called Lynds Dark Nebula 483. The cloud is about 700 light years from Earth in the constellation Serpens (The Serpent).
Hide Caption
50 of 56

Photos: Wonders of the universe
This is the largest Hubble Space Telescope image ever assembled. It's a portion of the galaxy next door, Andromeda (M31).
Hide Caption
51 of 56

Photos: Wonders of the universe
NASA has captured a stunning new image of the so-called "Pillars of Creation," one of the space agency's most iconic discoveries. The giant columns of cold gas, in a small region of the Eagle Nebula, were popularized by a similar image taken by the Hubble Space Telescope in 1995.
Hide Caption
52 of 56

Photos: Wonders of the universe
Astronomers using the Hubble Space pieced together this picture that shows a small section of space in the southern-hemisphere constellation Fornax. Within this deep-space image are 10,000 galaxies, going back in time as far as a few hundred million years after the Big Bang.
Hide Caption
53 of 56

Photos: Wonders of the universe
Planetary nebula Abell 33 appears ring-like in this image, taken using the European Southern Observatory's Very Large Telescope. The blue bubble was created when an aging star shed its outer layers and a star in the foreground happened to align with it to create a "diamond engagement ring" effect.
Hide Caption
54 of 56

Photos: Wonders of the universe
This long-exposure image from the Hubble Telescope is the deepest-ever picture taken of a cluster of galaxies. The cluster, called Abell 2744, contains several hundred galaxies as they looked 3.5 billion years ago; the more distant galaxies appear as they did more than 12 billion years ago, not long after the Big Bang.
Hide Caption
55 of 56

Photos: Wonders of the universe
This Hubble image looks a floating marble or a maybe a giant, disembodied eye. But it's actually a nebula with a giant star at its center. Scientists think the star used to be 20 times more massive than our sun, but it's dying and is destined to go supernova.
Hide Caption
56 of 56
























































Nicknamed Planet Nine, it "has a mass about 10 times that of Earth and orbits about 20 times farther from the sun" than Neptune. That means "it would take this new planet between 10,000 and 20,000 years to make just one full orbit around the sun," according to Caltech.
Researchers Konstantin Batygin and Mike Brown haven't actually seen the planet, but other research helped lead them to conclude that there is one. Basically, they found that certain objects in the Kuiper Belt -- the field of icy objects and debris beyond Neptune -- had orbits that peculiarly pointed in the same direction.
Over time, mathematical modeling and computer simulation led them to the conclusion that a planet was exerting the gravity necessary to shape these orbits.
Read More
Brown says "there have only been two true planets discovered since ancient times, and this would be a third. It's a pretty substantial chunk of our solar system that's still out there to be found, which is pretty exciting."
Already, Caltech is pretty confident Planet Nine is large enough to rule out any debate about whether it's a true planet -- unlike Pluto, which got the boot in 2006.
Brown, who played a role in Pluto's demotion to a dwarf planet, says "all those people who are mad that Pluto is no longer a planet can be thrilled to know that there is a real planet out there still to be found. Now we can go and find this planet and make the solar system have nine planets once again."
Depending on where Planet Nine is in its "bizarre, highly elongated orbit," many telescopes have a shot at finding it. Brown would love to find a planet he helped discover, "but I'd also be perfectly happy if someone else found it. That is why we're publishing this paper. We hope that other people are going to get inspired and start searching."