Exoplanets Archives

January 7, 2014December 23, 2015 by Nancy Atkinson

The Most Common Exoplanets Might be “Mini-Neptunes”

Chart of Kepler planet candidates as of January 2014. Image Credit: NASA Ames

If the dataset from the Kepler mission is any indication, the most common type of exoplanets in our galaxy aren’t Earth-sized rocky worlds or hot Jupiters. In fact, the most common type of exoplanet isn’t one that we see in our own neighborhood at all.

“Perhaps the most remarkable discovery by Kepler is the amount of planets between the size of Earth to four times the size of Earth,” said Geoff Marcy, professor of astronomy at University of California, speaking at the American Astronomical Society meeting this week in Washington D.C. “This is a size range that dominates the planet inventory from Kepler and it a size range not represented in our own Solar System. We don’t know for sure what these planets are made of and we don’t know how they form.”

These “mini-Neptunes” as Marcy called them, represent a huge sample in the Kepler data; about 75% of the planets found by Kepler vary in size between the Earth and Neptune, and for four years since the Kepler data have been rolling in, scientists have been trying to understand these planets.

“There’s been an enormous amount of measurements and quantitative work by the NASA Ames Kepler team,” Marcy said.

While masses and planet densities emerged from the work, astronomers still aren’t certain how they form or if they are made of rock, water or gas.

Mini Neptunian planets range in size from about 1.5 to 4 times the size of Earth and have a rocky core and puffy gaseous shell of varying thickness. Credit: Geoff Marcy — Mini Neptunian planets range in size from about 1.5 to 4 times the size of Earth and have a rocky core and puffy gaseous shell of varying thickness.
Credit: Geoff Marcy

The team focused on about 42 of these planets. Two planets highlighted by Marcy in his presentation are thought to be rocky, and are named Kepler-99b and Kepler-406b. Both are forty percent larger in size than Earth and have a density similar to lead. The planets orbit their host stars in less than five and three days respectively, making these worlds too hot for life as we know it.

The team used Doppler measurements of the planets’ host stars to measure the reflex wobble of the host star, caused by the gravitational tug on the star exerted by the orbiting planet. The measured wobble reveals the mass of the planet: the higher the mass of the planet, the greater the gravitational tug on the star and hence the greater the wobble.

They also the measured transit timing variations (TTV) to determine how much neighboring planets can tug on one another causing one planet to accelerate and another planet to decelerate along its orbit.

These measurements allow for computing mass and densities of the planets, as well as figuring out the possible chemical composition of these worlds. The majority of the measurements suggest that the mini-Neptunes have a rocky core but some may have a gaseous outer shell of hydrogen or helium. Some might just be rocky with no outer envelope at all.

“What we think is happening is that some of these planets may have water on top of a rocky core,” Marcy said. “Larger planets might have the same rocky core with added gas. That’s how you get planets measuring from 1 to 4 earth radii. The planets with lower densities imply increasing amounts of gas on top of a rocky core.”

Illustration of the Kepler spacecraft (NASA/Kepler mission/Wendy Stenzel)

“Kepler’s primary objective is to determine the prevalence of planets of varying sizes and orbits. Of particular interest to the search for life is the prevalence of Earth-sized planets in the habitable zone,” said Natalie Batalha, Kepler mission scientist at NASA’s Ames Research Center. “But the question in the back of our minds is: are all planets the size of Earth rocky? Might some be scaled-down versions of icy Neptunes or steamy water worlds? What fraction are recognizable as kin of our rocky, terrestrial globe?”

The team said that the mass measurements produced by Doppler and TTV will help to answer these questions. The results hint that a large fraction of planets smaller than 1.5 times the radius of Earth may be comprised of the silicates, iron, nickel and magnesium that are found in the terrestrial planets here in the Solar System.

Armed with this type of information, scientists will be able to turn the fraction of stars harboring Earth-sizes planets into the fraction of stars harboring bona-fide rocky planets. And that’s a step closer to finding a habitable environment beyond the Solar System.

Marcy added later in the discussion that there’s one type of telescope that would most helpful: a Terrestrial Planet Finder type mission that would measure the temperature, size, and the orbital parameters of planets as small as our Earth in the habitable zones of distant solar systems. Alas, TPF was canceled.

Read more about the study of mini-Neptunes here.

January 7, 2014December 23, 2015 by Jason Major

Super-sensitive Camera Captures a Direct Image of an Exoplanet

The Gemini Planet Imager’s first light image of Beta Pictoris b (Processing by Christian Marois, NRC Canada)

The world’s newest and most powerful exoplanet imaging instrument, the recently-installed Gemini Planet Imager (GPI) on the 8-meter Gemini South telescope, has captured its first-light infrared image of an exoplanet: Beta Pictoris b, which orbits the star Beta Pictoris, the second-brightest star in the southern constellation Pictor. The planet is pretty obvious in the image above as a bright clump of pixels just to the lower right of the star in the middle (which is physically covered by a small opaque disk to block glare.) But that cluster of pixels is really a distant planet 63 light-years away and several times more massive — as well as 60% larger — than Jupiter!

And this is only the beginning.

GPI installed on the Gemini South 8m telescope. GPI is the boxed suite mounted under the platform. (Gemini Observatory) — GPI installed on the Gemini South 8m telescope. GPI is the boxed suite mounted beneath the platform. (Gemini Observatory)

While many exoplanets have been discovered and confirmed over the past couple of decades using various techniques, very few have actually been directly imaged. It’s extremely difficult to resolve the faint glow of a planet’s reflected light from within the brilliant glare of its star — but GPI was designed to do just that.

“Most planets that we know about to date are only known because of indirect methods that tell us a planet is there, a bit about its orbit and mass, but not much else,” said Bruce Macintosh of the Lawrence Livermore National Laboratory, who led the team that built the instrument. “With GPI we directly image planets around stars – it’s a bit like being able to dissect the system and really dive into the planet’s atmospheric makeup and characteristics.”

And GPI doesn’t just image distant Jupiter-sized exoplanets; it images them quickly.

“Even these early first-light images are almost a factor of ten better than the previous generation of instruments,” said Macintosh. ” In one minute, we were seeing planets that used to take us an hour to detect.”

Despite its large size, Beta Pictoris b is a very young planet — estimated to be less than 10 million years old (the star itself is only about 12 million.) Its presence is a testament to the ability of large planets to form rapidly and soon around newly-formed stars.

“Seeing a planet close to a star after just one minute, was a thrill, and we saw this on only the first week after the instrument was put on the telescope!” added Fredrik Rantakyro a Gemini staff scientist working on the instrument. “Imagine what it will be able to do once we tweak and completely tune its performance.”

Another of GPI’s first-light images captured light scattered by a ring of dust that surrounds the young star HR4796A , about 237 light-years away:

GPI first-light images of HR4796A. (Processing by Marshall Perrin, Space Telescope Science Institute.)

The left image shows shows normal light, including both the dust ring and the residual light from the central star scattered by turbulence in Earth’s atmosphere. The right image shows only polarized light. Leftover starlight is unpolarized and hence removed. The light from the back edge of the disk (to the right of the star) is strongly polarized as it reflects towards Earth, and thus it appears brighter than the forward-facing edge.

It’s thought that the reflective ring could be from a belt of asteroids or comets orbiting HR4796A, and possibly shaped (or “shepherded,” like the rings of Saturn) by as-yet unseen planets. GPI’s advanced capabilities allowed for the full circumference of the ring to be imaged.

The GPI integration team celebrates after obtaining first light images (Gemini Observatory) — The GPI integration team celebrating after obtaining first light images (Gemini Observatory)

GPI’s success in imaging previously-known systems like Beta Pictoris and HR4796A can only indicate many more exciting exoplanet discoveries to come.

“The entire exoplanet community is excited for GPI to usher in a whole new era of planet finding,” says physicist and exoplanet expert Sara Seager of the Massachusetts Institute of Technology. “Each exoplanet detection technique has its heyday. First it was the radial velocity technique (ground-based planet searches that started the whole field). Second it was the transit technique (namely Kepler). Now, it is the ‘direct imaging’ planet-finding technique’s turn to make waves.”

This year the GPI team will begin a large-scale survey, looking at 600 young stars to see what giant planets may be orbiting them.

“Some day, there will be an instrument that will look a lot like GPI, on a telescope in space. And the images and spectra that will come out of that instrument will show a little blue dot that is another Earth.”

– Bruce Macintosh, GPI team leader

The observations above were conducted last November during an “extremely trouble-free debut.” The Gemini South telescope is located near the summit of Cerro Pachon in central Chile, at an altitude of 2,722 meters.

Source: Gemini Observatory press release

January 6, 2014December 23, 2015 by Jason Major

Kepler Finds an Earth-Sized “Gas Giant”

Artist's impression of KOI-xxx, fjkdshfkdsajhkfdkfd

Gas planets aren’t always bloated, monstrous worlds the size of Jupiter or Saturn (or larger) they can also apparently be just barely bigger than Earth. This was the discovery announced earlier today during the 223rd meeting of the American Astronomical Society in Washington, DC, when findings regarding the gassy (but surprisingly small) exoplanet KOI-314c were presented.

“This planet might have the same mass as Earth, but it is certainly not Earth-like,” said David Kipping of the Harvard-Smithsonian Center for Astrophysics (CfA), lead author of the discovery. “It proves that there is no clear dividing line between rocky worlds like Earth and fluffier planets like water worlds or gas giants.”

Discovered by the Kepler space telescope — ironically, during a hunt for exomoons — KOI-314c was found transiting a red dwarf star only 200 light-years away — “a stone’s throw by Kepler’s standards,” according to Kipping. (Kepler’s observation depth is about 3000 light-years.)

Relative size comparison of KOI-314c and Earth; both have similar mass. (J. Major)

Kipping used a technique called transit timing variations (TTV) to study two of three exoplanets found orbiting KOI-314. Both are about 60% larger than Earth in diameter but their respective masses are very different. KOI-314b is a dense, rocky world four times the mass of Earth, while KOI-314c’s lighter, Earthlike mass indicates a planet with a thick “puffy” atmosphere… similar to what’s found on Neptune or Uranus.

Unlike those chilly worlds, though, this newfound exoplanet turns up the heat. Orbiting its star every 23 days, temperatures on KOI-314c reach 220ºF (104ºC)… too hot for water to exist in liquid form and thus too hot for life as we know it.

In fact Kipping’s team found KOI-314c to only be 30 percent denser than water, suggesting that it has a “significant atmosphere hundreds of miles thick,” likely composed of hydrogen and helium.

It’s thought that KOI-314c may have originally been a “mini-Neptune” gas planet and has since lost some of its atmosphere, boiled off by the star’s intense radiation.

Not only is KOI-314c the lightest exoplanet to have both its mass and diameter measured but it’s also a testament to the success and sensitivity of the relatively new TTV method, which is particularly useful in multiple-planet systems where the tiniest gravitational wobbles reveal the presence and details of neighboring bodies.

(Watch the latest Kepler Orrery video here)

“We are bringing transit timing variations to maturity,” Kipping said. He added during the closing remarks of his presentation at AAS223: “It’s actually recycling the way Neptune was discovered by watching Uranus’ wobbles 150 years ago. I think it’s a method you’ll be hearing more about. We may be able to detect even the first Earth 2.0 Earth-mass/Earth-radius using this technique in the future.”

Source: Harvard Smithsonian CfA press release

December 17, 2013December 23, 2015 by Elizabeth Howell

How Scientists Confirmed The Mass Of An Invisible Exoplanet

Artist's conception of Kepler-88. Credit: Center for Astrophysics of the University of Porto

Planets are so very tiny next to stars outside of the solar system, making it really hard to spot exoplanets unless they transit across the face of their star (or if they are very, very big). Often, astronomers can only infer the existence of planets by their effect on the host star or other stars.

That’s especially true of the curious case of Kepler-88 c, which researchers using the Kepler space telescope said was a possible planet due to its effects on the orbit of Kepler-88 b, a planet that goes across the host of its host star. European astronomers just confirmed the Kepler data using the SOPHIE spectrograph at France’s Haute-Provence Observatory.

It’s the first time scientists have successfully used a technique to independently verify a planet’s mass based on what was found from the transit timing variation, or how a planet’s orbit varies from what is expected as it goes across the face of its sun. That means TTV can likely be used as a strong method on its own, advocates say.

SOPHIE’s technique relies on measuring star velocity, which also can reveal a planet’s mass by seeing its effect on the star.

“This independent confirmation is a very important contribution to the statistical analyzes of the Kepler multiple planet systems,” stated Magali Deleuil, an exoplanet researcher at Aix-Marseille University who participated in the research. “It helps to better understand the dynamical interactions and the formation of planetary systems.”

Actually, the two planets behave similarly to Earth and Mars in our own solar system in terms of orbits, according to work from a previous team (led by David Nesvorny of the Southwest Research Institute). They predicted the planets have a two-to-one resonance, which is approximately true of our own solar system since Mars takes about two Earth years to orbit the sun.

The new research was led by S.C.C. Barros at Aix-Marseille University in France. You can read the study in the Dec. 17 edition of Astronomy & Astrophysics, or in preprint version on Arxiv.

Source: Center for Astrophysics at the University of Porto

December 13, 2013December 23, 2015 by Elizabeth Howell

Why Exoplanet-Hunting Is ‘Like Seeing A Flea In A Lightbulb’

Artist's conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech

Exoplanets are really tiny compared to their host star, and it’s hard to imagine sometimes how astronomers can even find one of these worlds — let alone thousands of them. This nifty two-part series from PBS explains how it’s possible in an easy-to-understand and hilarious way. As an example, this is how they describe the Kepler space telescope’s capabilities:

“It can’t actually see those exoplanets because the stars that they surround are so big and bright. Instead, it looks for the tiny shadow of the planet as it passes in front of its parent star. If that sounds hard, that’s because it is. It’s like seeing a flea in a lightbulb in Los Angeles from New York City,” said host Joe Hanson in the video.

Near the end, he provides an interesting segway into the question of life beyond Earth: “The question we’re really interested in is not how common are planets, but how common are we.” That gets tackled in part 2 of the video, which you can see below the jump.

Remember that 2014 will be an interesting year for Kepler as NASA figures out what to do next with the observatory. It isn’t able to perform its primary mission (seeking exoplanets in Cygnus) because two of its four reaction wheels or pointing devices are malfunctioning. NASA, however, has an innovative fix on the books that could allow it to swing different fields of view during the year — check out this infographic for more details.

December 6, 2013December 23, 2015 by Elizabeth Howell

This Exoplanet Is Turning Planetary Formation Scenarios Upside Down

Artist's conception of a planet like HD106906 b. Visible in the picture is a debris disk and its distant host star. Credit: NASA/JPL-Caltech

What the heck is that giant exoplanet doing so far away from its star? Astronomers are still trying to figure out the curious case of HD 106906 b, a newly found gas giant that orbits at an astounding 650 astronomical units or Earth-sun distances from its host star. For comparison, that’s more than 20 times farther from its star than Neptune is from the sun.

“This system is especially fascinating because no model of either planet or star formation fully explains what we see,” stated Vanessa Bailey, a graduate astronomy student at the University of Arizona who led the research.

HD 106906 b is 11 times the size of Jupiter, throwing conventional planetary formation theory for a loop. Astronomers believe that planets gradually form from clumps of gas and dust that circle around young stars, but that process would take too long for this exoplanet to form — the system is just 13 million years old. (Our own planetary system is about 4.5 billion years old, by comparison.)

The discovery image of HD 106906 b, shown in thermal infrared light from instruments on the Magellan telescope at the European Southern Observatory in Chile. The image has been changed to take out light from its very bright host star. The planet orbits more than 20 times farther from its host star than Neptune does from the sun. (AU = astronomical units, or Earth-sun distances). Credit: Vanessa Bailey

Another theory is that if the disc collapses quickly, perhaps it could spawn a huge planet — but it’s improbable that there is enough mass in the system for that to happen. Perhaps, the team says, this system is like a “mini binary star system”, with HD 106906 b being more or less a failed star of some sort. Yet there is at least one problem with that theory as well; the mass ratio of the planet and star is something like 1 to 100, and usually these scenarios occur in ratios of 1 to 10 or less.

“A binary star system can be formed when two adjacent clumps of gas collapse more or less independently to form stars, and these stars are close enough to each other to exert a mutual gravitation attraction and bind them together in an orbit,” Bailey stated.

“It is possible that in the case of the HD 106906 system the star and planet collapsed independently from clumps of gas, but for some reason the planet’s progenitor clump was starved for material and never grew large enough to ignite and become a star.”

Young binarys stars: Image credit: NASA — Young binary stars: Image credit: NASA

Besides puzzling out how HD 106906 b came to be, astronomers are also interested in the system because they can clearly see leftovers or a debris disk from the system’s formation. By studying this system further, astronomers hope to figure out more about how young planets evolve.

At 2,700 degrees Fahrenheit (1,500 degrees Celsius), the planet is most easily visible in infrared. The heat is from when the planet was first coalescing, astronomers said.

The astronomers spotted the planet using the Magellan telescope at the European Southern Observatory’s Atacama Desert in Chile. It was visible in both the Magellan Adaptive Optics (MagAO) system and Clio2 thermal infrared camera on the telescope. The planet was confirmed using Hubble Space Telescope images from eight years ago, as well as the FIRE spectrograph on Magellan that revealed more about the planet’s “nature and composition”, a press release stated.

The research paper is now available on the prepublishing site Arxiv and will be published in a future issue of Astrophysical Journal Letters.

Source: University of Arizona

December 5, 2013December 23, 2015 by Elizabeth Howell

How Do We Learn About An Alien Planet’s Size And Atmosphere?

More than 1,000 exoplanets have been confirmed and cataloged (PHL @ UPR Arecibo)

The fun and challenge of exoplanet science is the planets are so far away and so tiny. Figuring out what they look like isn’t as simple as just pointing a telescope and observing. This new video from NASA explains how astronomers use the parent star to figure out the planet’s size, mass, atmosphere and more.

Alien planets are generally detected through blocking the light of their parent star (from the vantage point of Earth) or through their gravitational effects that cause the star to slightly “wobble” during each orbit. These methods can reveal the mass and size of the planet. As for the atmosphere, that takes a bit more work.

“As the planet crosses its star, its atmosphere absorbs certain wavelengths of light or colors, while allowing other wavelengths of light to pass through,” the video stated.

“Because each molecule absorbs distinct wavelengths, astronomers spread the light into its spectrum of colors to see which wavelengths have been absorbed. The dark absorption bands act as molecular fingerprints, revealing the atmosphere’s chemical makeup.”

And this science can reveal amazing things, such as the recent Hubble find of a “clear signal” of water in five exoplanet atmospheres. The video has more detail on how individual elements are identified, so be sure to check it out.

December 3, 2013December 23, 2015 by Nancy Atkinson

Hubble Finds ‘Clear Signal’ of Water in 5 Exoplanet Atmospheres

To determine what’s in the atmosphere of an exoplanet, astronomers watch the planet pass in front of its host star and look at which wavelengths of light are transmitted and which are partially absorbed. Credit: NASA's Goddard Space Flight Center

For the first time, astronomers have found conclusive evidence of water in the hazy atmospheres of planets orbiting other stars. Using the Hubble Space Telescope, two teams of scientists found faint but clear signatures of water in the atmospheres of five exoplanets. All five are so-called ‘hot Jupiters,’ massive worlds that orbit close to their host stars.

“To actually detect the atmosphere of an exoplanet is extraordinarily difficult. But we were able to pull out a very clear signal, and it is water,” said Drake Deming from the University of Maryland, who led a study characterizing the atmospheres of two of the five planets.

“We’re very confident that we see a water signature for multiple planets,” said Avi Mandell, a planetary scientist at NASA’s Goddard Space Flight Center, and lead author of another paper on the remaining three exoplanets. “This work really opens the door for comparing how much water is present in atmospheres on different kinds of exoplanets, for example hotter versus cooler ones.”

The five planets are all well-studied, and would not be friendly places for life as we know it — with blazing temperatures and unusual conditions. WASP-17b is an unusual planet in a retrograde orbit, and sodium had already been detected in its atmosphere.

HD209458b is much-studied windy world, with raging storms, and organic molecules and water had already been detected on this planet in previous studies.

The atmosphere of WASP-12b already has been found to hold vast amounts of carbon as well as water. WASP-19b orbits a nearby star, and has one of the shortest orbital periods of any known planetary body, about 0.7888399 days or approximately 18.932 hours. XO-1b has the distinction of being discovered by amateur astronomers

The astronomers involved in the new studies say the strengths of the water signatures in each world varied, with WASP-17b and HD209458b having the strongest signals.

Currently, studying exoplanet atmospheres can be done when the planets are passing in front of their stars. Researchers can identify the gases in a planet’s atmosphere by determining which wavelengths of the star’s light are transmitted and which are partially absorbed. Deming’s team employed a new technique with longer exposure times, which increased the sensitivity of their measurements.

In both studies, scientists used Hubble’s Wide Field Camera 3 to explore the details of absorption of light through the planets’ atmospheres. The observations were made in a range of infrared wavelengths where a pattern that signifies the presence of water would appear if water were present. The teams compared the shapes and intensities of the absorption profiles, and the consistency of the signatures gave them confidence they saw water.

“These studies, combined with other Hubble observations, are showing us that there are a surprisingly large number of systems for which the signal of water is either attenuated or completely absent,” said Heather Knutson of the California Institute of Technology, a co-author on Deming’s paper. “This suggests that cloudy or hazy atmospheres may in fact be rather common for hot Jupiters.”

Read the teams paper: Deming et al, Mandell et al.

Sources: HubbleSite, University of Maryland.

November 27, 2013December 23, 2015 by Elizabeth Howell

Kepler May Go Planet-Hunting Again! Infographic Shows How That Would Work

Infographic showing how the Kepler space telescope could continue searching for planets despite two busted reaction wheels. Credit: NASA Ames/W Stenzel

The planet-seeking Kepler space telescope had to stop its primary mission this summer after the failure of a second of its four reaction wheels, the devices that keep it pointing at a spot in the constellation Cygnus. NASA, however, has a backup plan. It’s considering stabilizing the spacecraft using the sun! You can see the details in this infographic.

The plan is still preliminary as it needs testing, and it also needs budgetary approval while NASA is fighting to keep other programs going at the funding levels the agency wants. But if it works, this is what NASA is proposing:

Keep the spacecraft oriented almost parallel to its orbit around the sun.
Gaze at a particular part of the sky for 83 days.
When the sun is close to coming into the telescope, move the spacecraft and do another 83-day observation period.
This would mean the spacecraft will have 4.5 “unique viewing periods” a year, NASA says.

“With the failure of a second reaction wheel, the spacecraft can no longer precisely point at the mission’s original field of view. The culprit is none other than our own sun,” NASA stated in a recent press release.

“The very body that provides Kepler with its energy needs also pushes the spacecraft around by the pressure exerted when the photons of sunlight strike the spacecraft. Without a third wheel to help counteract the solar pressure, the spacecraft’s ultra-precise pointing capability cannot be controlled in all directions.”

But this could be a way to counteract it. Mission managers put Kepler through a 30-minute test in October where the telescope looked at a spot in the constellation Sagittarius, which “produced an image quality within five percent of the primary mission image quality,” NASA stated. More testing is underway.

NASA should have more details at the end of this year as to whether to proceed to a 2014 Senior Review, which is held every two years to review current missions and decide which ones are still worth funding.

Source: NASA

November 27, 2013December 23, 2015 by Shannon Hall

Second Planetary System Like Ours Discovered

A comparison between our solar system and a second solar system: KOI-351. Image Credit:

A team of European astronomers has discovered a second planetary system, the closest parallel to our own solar system yet found. It includes seven exoplanets orbiting a star with the small rocky planets close to their host star and the gas giant planets further away. The system was hidden within the wealth of data from the Kepler Space Telescope.

KOI-351 is “the first system with a significant number of planets (not just two or three, where random fluctuations can play a role) that shows a clear hierarchy like the solar system — with small, probably rocky, planets in the interior and gas giants in the (exterior),” Dr. Juan Cabrera, of the Institute of Planetary Research at the German Aerospace Center, told Universe Today.

Three of the seven planets orbiting KOI-351 were detected earlier this year, and have periods of 59, 210 and 331 days — similar to the periods of Mercury, Venus and Earth.

But the orbital periods of these planets vary by as much as 25.7 hours. This is the highest variation detected in an exoplanet’s orbital period so far, hinting that there are more planets than meets the eye.

In closely packed systems, the gravitational pull of nearby planets can cause the acceleration or deceleration of a planet along its orbit. These “tugs” cause the variations in orbital periods.

They also provide indirect evidence of further planets. Using advanced computer algorithms, Cabrera and his team detected four new planets orbiting KOI-351.

But these planets are much closer to their host star than Mercury is to our Sun, with orbital periods of 7, 9, 92 and 125 days. The system is extremely compact — with the outermost planet having an orbital period less than the Earth’s. Yes, the entire system orbits within 1 AU.

While astronomers have discovered over 1000 exoplanets, this is the first solar system analogue detected to date. Not only are there seven planets, but they display the same architecture — rocky small planets orbiting close to the sun and gas giants orbiting further away — as our own solar system.

Most exoplanets are strikingly different from the planets in our own solar system. “We find planets in any order, at any distance, of any size; even planetary classes that don’t exist in the solar system,” Cabrera said.

Several theories including planet migration and planet-planet scattering have been proposed to explain these differences. But the fact of the matter is planet formation is still poorly understood.

“We don’t know yet why this system formed this way, but we have the feeling that this is a key system in understanding planetary formation in general and the formation of the solar system in particular,” Cabrera told Universe Today.

The team is extremely hopeful that the upcoming mission PLATO will receive funding. If so, it will allow them to take a second look at this system — determining the radius and mass of each planet and even analyzing their compositions.

Follow-up observations will not only allow astronomers to determine how this planetary system formed, it will provide hints as to how our own solar system formed.

The paper has been accepted for publication in the Astrophysical Journal and is available for download here.