Keck Observatory Exoplanet Imaginarium


W. M. Keck Observatory is bringing alien worlds to life, embarking on a deep space virtual “journey” to exoplanets that have either been discovered or characterized using Keck Observatory data.

Serving as an interface between science, technology, and the arts, the Exoplanet Imaginarium is designed to fulfill the ultimate dream of anyone who has ever wondered what extrasolar planets look like, to imagine ourselves on board a spacecraft flying by a strange world, or standing on an alien moon’s surface looking at a giant planet rising above the horizon.

This project is the result of a collaboration between Keck Observatory and award-winning exoplanet artist Adam Makarenko. Our mission was to go on a virtual “trip” to 12 different exoplanets throughout 2018. Together, we created an artistic rendering of an exoplanet scene every month based on available scientific data as well as calculations from Keck Observatory Astronomer Carlos Alvarez.

JANUARY: Gliese 876b

We begin this special series with the very first exoplanet that Keck Observatory discovered. Gliese 876b is a gas giant that’s two times more massive than Jupiter, as seen from a hypothetical moon.

While there is currently no scientific evidence of moons, this planet likely has moons based on the gas giants we see in our own solar system.

Gliese 876b is not alone; it is one of four known planets that orbits one of the closest stars to our sun – a red dwarf located just 15 light years away.

This extrasolar system is extremely compact; all four planets are squeezed in a space that is smaller than Mercury’s orbit around the Sun. As such, in the distance we see planet Gliese 876c, another gas giant, in a waning crescent. 

Scene inspired by scientific data published on Marcy et al. (1998), ApJL, 505, 147.

FEBRUARY: HD 209458b

HD 209458b, also known as “Osiris,” its unofficial nickname, was discovered in 1999 using Keck Observatory’s HIRES instrument. This exoplanet is a “hot Jupiter,” a gas giant that is 30 percent less massive and 40 percent larger than Jupiter. HD 209458b is unlike any planet in our Solar System. What makes it exotic? This alien world is so close to its star that its atmosphere is evaporating!

A mere 4 million miles from its parent star (that’s 8 times closer than Mercury is to the Sun), the scorched dayside of the planet’s lower atmosphere boils up to a blazing 2,000 degrees Fahrenheit; that’s as hot as the magma melting within Kilauea Volcano on Hawaii Island.

The intense heat excites the atmospheric gases to a point where they build up enough speed to escape the planet’s gravitational pull; some gases reach velocities as high as 130,000 miles per hour! The stripped atmosphere leaves behind a giant trailing gaseous tail, similar to a comet. Because HD 209458b orbits extremely close to the star, one year there lasts only 3.5 Earth days. The exoplanet is located 150 light years away in the constellation Pegasus.

Scene inspired by scientific data published on Mazeh et al. (2000), ApJL, 532, 55.

MARCH: 55 Cancri f

55 Cancri f, or “55 Cnc f” for short, also known as “Harriot,” its official and proper name.

It is the fourth known exoplanet in the 55 Cancri system, which consists of two stars circling around each other (called a binary star system). Discovered in 2008 using Keck Observatory’s HIRES instrument, this exoplanet’s mass is similar to Saturn.

Though there is no scientific proof that Harriot has rings, it is possible given that the four giant planets in our own Solar System have rings.

Of the two stars in this binary system, Harriot orbits the brightest one; its sun is “55 Cnc A” shown here rising behind the planet. The second star in the binary system, “55 Cnc B,” is the red dwarf star shown to the upper right of Harriot.

The two bright objects to the left of Harriot’s parent star are its planetary siblings, “55 Cnc b” and “55 Cnc c.” Planet b is nearly the size of Jupiter; it has 84% the mass of the largest planet in our Solar System, while Planet c is about half as massive as Saturn.

This entire system is located 41 light years away in the constellation of Cancer, the Crab.

Scene inspired by scientific data published on Fischer et al. (2008), ApJ, 675, 790.

APRIL: HD 179079b

Shown here is HD 179079b as seen from a hypothetical rocky moon that is orbiting the planet.

Discovered in 2009 using Keck Observatory’s HIRES instrument, HD 179079b is classified as a ‘hot Neptune.’

It’s similar to our Solar System’s blue planet – about twice the mass of Neptune – but its weather is the polar opposite of Neptune’s icy cold conditions. HD 179079b’s equilibrium temperature is at a scorching 1,400 degrees Farenheit – hot enough to burn your bones to ash!

This is because the planet orbits its parent star, HD 179079, very closely – just one fourth the distance between Mercury and our Sun.

HD 179079b appears to be an only child; it is the only known planet orbiting this star, which is much older than our Sun. HD 179079 is 7 billion years old whereas the Sun’s age is 4.5 billion years.

HD 179079 is a sub-giant star. In star years, this phase is between adulthood (Main Sequence phase) and retirement age (Red Giant phase).

This entire system is located 207 light years away from Earth in the constellation Aquila.

Scene inspired by scientific data published on Valenti et al. (2009), ApJ, 702, 989.

BEHIND THE SCENES VIDEO: Check out why the hypothetical rocky moon shown in the image of HD 179079b looks so realistic! The secret? Adam Makarenko combines digital photography with modeling. That’s right…this moon is handmade!

MAY: OGLE-2007-BLG-368Lb

OGLE-2007-BLG-368Lb is shown partially illuminated by its star, which you can see as the dim light right above this alien world.

This ice giant is 30 percent more massive than Neptune. Based on the distance from its star, OGLE-2007-BLG-368Lb’s temperature is at a bone-chilling -280 degrees Fahrenheit. That’s more than two times colder than the coldest place on Earth! The lowest temperature ever recorded on our planet is at the East Antarctic Plateau, where the climate has dropped as low as -135 degrees Fahrenheit.

The discovery of OGLE-2007-BLG-368Lb was reported in 2010; its mass, the mass of its star, and the distance between the two were confirmed using Keck Observatory’s NIRC2 instrument.

OGLE-2007-BLG-368Lb was discovered using gravitational microlensing. This is a phenomenon that acts as nature’s magnifying glass. When an exoplanet and its star pass in front of a more distant star, the duo’s gravity bends and focuses the light of the distant star behind them. Astronomers can’t directly see the light from the exoplanet and its star, but they can measure their masses by looking at how they amplify the light from the star moving behind them.

OGLE-2007-BLG-368Lb is named after the experiment that was specifically designed to find these microlensing events: the Optical Gravitational Lensing Experiment (OGLE). OGLE consists of a camera with a wide field-of-view that covers the entire Moon, mounted on the 1.3-meter Warsaw University Telescope at the Las Campanas Observatory in Chile.

The microlensing method allows astronomers to detect other planetary worlds that are extremely far away. The OGLE-2007-BLG-368L system is located at a jaw-dropping 19,200 light years away from Earth!

Scene inspired by scientific data published on Sumi et al. (2010), ApJ, 710, 1641.


HAT-P-11b is a scary world given how close it is to its star! Imagine looking up into the sky and seeing our Sun enlarged 15 times – that’s how close HAT-P-11b is to its star, HAT-P-11, which is colder and less luminous than the Sun. This gives it an orange color.

Our Sun has sunspots. But this star has starspots! They look bigger and are more abundant that sunspots because HAT-P-11 is more magnetically active than the Sun. Sunspots are cooler areas on the surface of the sun produced by high concentrations of magnetic fields. They appear darker because they are surrounded by brighter, hotter regions of the Sun’s photosphere.

What’s just as striking about HAT-P-11b are its lightning storms, as shown by the bright blue spots scattered on the dark side of this “hot Neptune.” The electrifying weather is one possible scientific interpretation of the radio waves that astronomers have detected coming from HAT-P-11b.

Compared to Neptune, HAT-P-11b is 50% more massive and has a radius that’s 25% larger. Its atmosphere is expected to contain methane, which would make it look blue.

The discovery of HAT-P-11b was reported in 2010 using Keck Observatory’s HIRES instrument. The HAT-P-11 system is located 124 light years away from us.

Scene inspired by scientific data published on Bakos et al. (2010), ApJ, 710, 1724.

JULY: EPIC 220674823 b

Here’s an alien world that is fitting for summer – EPIC 220674823 b. This lava planet is living up to its name, with “epic” surface temperatures that are so hot, it is expected to be covered in molten lava. In the second image, we see a lava ocean with some solid pieces of land floating on the planet’s surface, which is estimated to be a fiery 3,000 to 4,000 degrees Fahrenheit!

EPIC 220674823 b’s extreme environment is due to its searing proximity to its star, EPIC 220674823; the planet is 35 times closer to its star than Mercury is to the Sun! If you had a burn-proof spaceship that could visit this planet, you would need ultra-protective sunglasses to look at its monster-sized star – it is 76 times bigger than the Sun as seen from Earth!

EPIC 220674823 b is a super-Earth; it has a radius that is 46 percent larger and is between 2.4 to 4.5 times more massive than our planet. It is an Ultra-Short-Period (USP) planet, which is a class of exoplanets that orbit their stars in less than one Earth day. One year on EPIC 220674823 b lasts only 13 hours!

The discovery of EPIC 220674823 b was announced in 2017 using data from NASA’s Kepler Space Telescope K2 mission. Keck Observatory’s NIRC2 instrument using Adaptive Optics was key to determining that EPIC 220674823 b’s star is single, not a binary. This observation was critical in calculating the planet’s radius.

The EPIC 220674823 system is located 825 light years away from Earth. 

Scene inspired by scientific data published on Adams et al. (2017), ApJ, 153, 82.


This exoplanet has astronomers seeing double. 2MASS 0249 c is the doppelganger to a famous exoplanet, beta Pictoris b. As with twins, they look similar, but do have differences.

Unlike its sibling, which orbits a star, 2MASS 0249 c surprised astronomers when they discovered the planet orbits a pair of brown dwarfs – a binary system seen here as two dim red points of light in the upper-right side of 2MASS 0249 c.

They seem tiny due to their distance from the planet – about 67 times farther away than Neptune is from the Sun!

But the brown dwarfs are actually huge; each one has a radius that is 80 percent larger and over 40 times more massive than Jupiter.

Why the burning red glow? 2MASS 0249 c is still young, only about 22 million years old. Keiki planets start their lives with temperatures of several thousands of degrees, then cool down as they get older. 2MASS 0249 c’s temperature is currently at about 2,800 degrees Fahrenheit.

Also, its atmosphere is fully convective. Just like a saucepan full of boiling water, heat from the interior of the planet bubbles up to outer space in the form of rising gas, cools down in the upper atmosphere, then sinks as it becomes cooler and denser.

As such, the lower layers of 2MASS 0249 c’s atmosphere consist of turbulent, red-glowing gas that carries up heat by convection, blanketed by dark clouds in the upper atmosphere.

The discovery of 2MASS 0249 c was announced this past July. A team led by Trent Dupuy, an astronomer at Gemini Observatory, and collaborator Michael Liu of the University of Hawaii Institute for Astronomy, identified this alien world using Canada-France-Hawaii Telescope, then characterized its host binary dwarf system using Keck Observatory.

Scene inspired by scientific data published on Dupuy et al. (2018), AJ,156, 57.

SEPTEMBER: Kepler-1649b

Venus, named after the Roman Goddess of Love and Beauty, may be a bit jealous of our next exoplanet of the month. Kepler-1649b is just as pretty! Although its planet mass has not been measured, scientists speculate Kepler-1649b is very likely a Venus-twin. It is extremely close to its star – 8 times closer than Mercury is to the Sun.

But this Venus doppelgänger is receiving only twice as much radiation as the Earth is receiving from the Sun. This is because Kepler-1649b’s star is 50 percent colder and 90 percent less luminous compared to the Sun, giving it a redder color.

This planet was discovered with the Kepler space telescope. Keck Observatory was used to rule out the possibility that its star is a binary, which is critical in determining the planet’s radius. Kepler-1649b’s radius is 8 percent larger than Earth. Because Kepler-1649b is so close to its star, one year on this beautiful alien world lasts only 8.7 days!

Scene inspired by scientific data published on Angelo et al. (2017), AJ, 153, 162.

OCTOBER: Kepler 186f

Is there life on other planets? We don’t have an answer yet, but we do know that Earth-sized planets do exist! Our October exoplanet of the month is one of the best examples of this.

Kepler 186f is similar in size with a radius that is just 10% larger than Earth’s. Its mass has not been measured but astronomers who discovered Kepler 186f report in their published scientific paper that the planet is likely rocky and has similar environmental conditions as our own planet: an atmosphere with water clouds, liquid water on the surface, and large bodies of solid rock.

It is the first confirmed exoplanet with a size nearly identical to Earth’s that is orbiting within the Goldilocks Zone – meaning it orbits the habitable zone of its star where the temperature is not too hot and not too cold, but just right for liquid water to exist on the planet.

The discovery, announced in 2014, was made by the Kepler Space Telescope, then validated by Keck Observatory. Observations with the NIRC2 instrument combined with the powerful Adaptive Optics system on the Keck II telescope were critical in ruling out the possibility that a background star or stellar companion could be mimicking what Kepler detected, thereby confirming it is indeed an exoplanet.

Kepler 186f is one of five planets orbiting its host star, Kepler 186. The other four planets – Kepler 186b, c, d, and e – have radii similar to Earth’s and are also thought to be rocky planets. However, they are not in the habitable zone; the four planets orbit too close to their star to sustain liquid water.

Pictured here is a scene that shows Kepler 186f in the foreground, with its continents, oceans and clouds. The other planets in the system are shown as unresolved points of light, except for Kepler 186e, which appears as a thin crescent as seen from Kepler 186f.

One difference between Earth and our featured exoplanet? If you lived on this Earth-twin, your birthday would come around faster – one year there lasts only 130 days!

Kepler 186f is located 492 light years from Earth.

Scene inspired by scientific data published on Quintana et al. (2014), Sci, 344, 6181.

NOVEMBER: Kepler 22b

Here’s an ocean world that mirrors our own. Kepler 22b is the first confirmed planet in the habitable zone of its host star where liquid water could exist on a planet’s surface.

This water world is not nearly as close to Earth’s size as October’s featured exoplanet, Kepler 186f; in comparison, Kepler 22b’s radius is 2.3 times larger than our own planet.

But this Super-Earth resembles our world in other ways. In addition to its ocean surface, its star, Kepler 22, is very similar to our Sun; it is only 3% less massive and 2% smaller than the Sun and is also the same type of star – both are yellow dwarfs (whereas Kepler 186f’s star is a red dwarf).

Plus, Kepler 22b receives nearly the same amount of radiation from its star as what the Earth receives from the Sun. Also, one year on this planet is almost the same as Earth’s – Kepler 22b orbits around its sun-like star in 290 days.

Here, we show the planet being illuminated by its star from the left, covered mostly by liquid water and cloud formations.

The discovery of Kepler 22b was announced in 2011. It was first detected by NASA’s Kepler Space Telescope; its existence was then validated using data from Keck Observatory’s HIRES instrument.

Kepler 22b is located 619 light years from Earth.

Scene inspired by scientific data published on Borucki et al. (2012), ApJ, 745, 120.

DECEMBER: Kepler-62f

This icy world is fitting for December. Kepler-62f is a winter wonderland located on the outer edge of the habitable zone of its star. Though this Super-Earth may be a rocky ocean planet, it may be completely covered in ice.

This is due to its distance from its host star, along with the lack of CO2 in the exoplanet’s atmosphere. Also, Kepler-62f’s star is cooler and smaller than our Sun, with a radius that’s 37 percent smaller and 31 percent less massive than the Sun.

Kepler-62f is one of five known planets in this system located 1200 light-years from Earth. One year on this frosty world lasts 267 Earth days.

Scene inspired by scientific data published on Borucki et al. (2013), Sci, 340, 587.


(Left) Adam creates alien planetary surfaces like this volcanic landscape using a variety of materials such as foam insulation, plaster, and sand.

(Middle) To create the cloud formations on August’s image of 2MASS 0249c, Adam applied a mixture of baking soda and graphite over a translucent red sphere.

(Right) Adam used cotton to give the spiral cyclones featured in November’s image of Kepler 22b a realistic touch. 


We are inspired by scientific facts about these extraordinary worlds, which are published in peer-reviewed journals. Published values of the separation between exoplanets and their host stars, combined with stellar radii and measured or inferred planet radii, are used to estimate the angular size of the planets and host stars as seen by a privileged observer located close to the exoplanets. Other planetary data extracted from the literature, when available, such as effective temperature, density, atmospheric composition, and classification, are also used to create photo-realistic scenes.

Since science facts can only go so far in revealing the full nature of exoplanets, we explore the ‘unknowns’ with creativity and imagination by way of artistic conceptions.

This artistic work is comprised of hand-crafted planetary models made from half spheres of plaster, plastic, or foam. The models are painted with a variety of different paint mixtures to achieve the desired effect, e.g. a gas giant, or a rocky world. Afterwards, the completed planets are suspended in front of a black backdrop, illuminated by a single light source, and then photographed.

The result of this technique gives the work a tangible quality, instantly transporting the viewer to distant worlds outside of our solar system, far, far away.

Resources: The Extrasolar Planets Encyclopedia, NASA Abstract Service, and arXiv.