Keck Observatory Exoplanet Imaginarium


Maunakea, Hawaii – W. M. Keck Observatory has teamed up with exoplanet artist Adam Makarenko, an award-winning photographer who produces photo-realistic images of distant worlds beyond our own Solar System.

Every month this year, we will feature one artistic conception of an exoplanet discovered or validated by Keck Observatory.

Each image is based on available scientific data as well as calculations from Keck Observatory Astronomer Carlos Alvarez.

Mahalo to Adam and Carlos for taking us on a visual journey to these real-life alien worlds!

Be sure to check back here every month to see which exoplanet we’ll be featuring next.

JANUARY: Gliese 876b

We begin this special series with the very first exoplanet discovered by Keck Observatory – Gliese 876b, 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.

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.

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.

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.

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!


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.

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.