Kepler K2 Mission

This artist concept shows NASA's planet-hunting Kepler spacecraft operating in a new mission profile called K2. In May, the spacecraft began its new mission observing in the ecliptic plane, the orbital path of Earth around the sun, depicted by the grey-blue line marked by opaque cross-like shapes. Each shape represents the field-of-view of an observing campaign.

Using publicly available data collected by the spacecraft in February during the performance concept test to prove K2 would work, astronomers confirmed the first exoplanet detected by the K2 mission. The newly confirmed planet, HIP 116454b, is two-and-a-half times the diameter of Earth, and closely orbits a star smaller and cooler than our sun once every nine days, making the planet too hot for life as we know it. The star and planet are 180 light-years from Earth toward the constellation Pisces.

Illustration credit: NASA/Ames/JPL-Caltech

Note: For more information, see NASA's Kepler Reborn, Makes First Exoplanet Find of New Mission and Reborn Kepler Spacecraft Finds 'Super-Earth'.

Measuring Kepler-93b

Using data from NASA's Kepler and Spitzer Space Telescopes, scientists have made the most precise measurement ever of the size of a world outside our solar system, as illustrated in this artist's conception. The diameter of the exoplanet, dubbed Kepler-93b, is now known with an uncertainty of just one percent.

According to this new study, the diameter of Kepler-93b is about 11,700 miles (18,800 kilometers), plus or minus 150 miles (240 kilometers) -- the approximate distance between Washington, D.C., and Philadelphia, Pennsylvania. Kepler-93b is 1.481 times the width of Earth, the diameter of which is 7,918 miles (12,742 kilometers).

The results confirm that the exoplanet is a "super-Earth." Although super-Earths are common in the galaxy, none exist in our solar system. Exoplanets like Kepler-93b are therefore our only laboratories to study this major class of planet.

With good limits on super-Earths' sizes as well as their masses, scientists can now start to theorize about what makes up these weird worlds. Previous measurements, by the Keck Observatory in Hawaii, had put Kepler-93b's mass at about 3.8 times that of Earth. The density of Kepler-93b, derived from its mass and newly obtained radius, indicates the planet is in fact very likely made of iron and rock, like Earth.

Despite its newfound similarities in composition to Earth, Kepler-93b is far too hot for life. The exoplanet's orbital distance -- only about one-sixth that of Mercury's from the sun -- implies a scorching surface temperature around 1,400 degrees Fahrenheit (760 degrees Celsius).

The methods employed in the new study could help nail down the sizes of other exoplanets, and improve our understanding of alien worlds.

The Spitzer data for this study was obtained during the "warm mission" phase using its Infrared Array Camera. The lead author of the paper describing these findings is Sarah Ballard, a NASA Carl Sagan Fellow at the University of Washington in Seattle.

Illustration credit: NASA/JPL-Caltech

Note: For more information, see The Most Precise Measurement of an Alien World's Size.

55 Cancri e

NASA's Spitzer Space Telescope has, for the first time, captured the light emanating from a distant super Earth, a planet more massive than Earth but lighter than Neptune. Super Earths can be either rocky or gaseous. In this case, theorists propose that the planet, called 55 Cancri e, has a rocky core surrounded by a layer of water in a "supercritical" state, where it is both liquid and gas. Topping it all off is thought to be a blanket of steam. It's as if Neptune were somehow dragged closer to the Sun and stripped of its large atmosphere.

This artist's animation depicts 55 Cancri e as it orbits its star. The planet whips around the star closely and quickly: It is 25 times closer to the star than Mercury is to our Sun and completes one orbit -- its year -- in a mere 18 hours.

The view starts off showing the system in visible light then switches to show how Spitzer saw it in infrared light. In infrared, the planet stands out more relative to its star -- it is brighter when viewed in infrared light and the star is dimmer. This is partly because the planet's sizzling heat causes it to glow brightly at infrared wavelengths.

The planet is too close to its star to be seen separately on the sky, so Spitzer used a specialized trick to see its light. As the planet slipped behind the star in what is called an occultation, the infrared telescope observed how much the total light from the system dropped. The data are shown on a graph that appears in front of the star system.

By measuring the amount of total light before, during and after this drop, astronomers can then calculate how much light is coming directly from the planet itself. The information revealed that the planet's sun-facing side is more than a scorching 2,000 kelvins (3,140 degrees Fahrenheit), or hot enough to melt steel. The data also indicated that the planet does not reflect much visible light; in other words, it is very dark.

The observations are an important milestone in the search for life in the universe. NASA's upcoming James Webb Space Telescope will use a similar technique to probe the atmospheres of even smaller, potentially habitable planets for signs of life.

Video credit: NASA/JPL-Caltech; infographic credit: NASA/JPL-Caltech

Note: This is today's big story. For more information, see:
* NASA's Spitzer Sees the Light of Alien 'Super Earth'
* NASA Space Telescope Sees the Light from an Alien Super-Earth
* PIA15621: Magician of a Planet Disappears to Reveal Itself
* PIA15622: First-of-Its-Kind Glimpse at a Super Earth

Super-Earth Gliese 667 Cc

This artist’s impression shows a sunset seen from the super-Earth Gliese 667 Cc. The brightest star in the sky is the red dwarf Gliese 667 C, which is part of a triple star system. The other two more distant stars, Gliese 667 A and B appear in the sky also to the right. Astronomers have estimated that there are tens of billions of such rocky worlds orbiting faint red dwarf stars in the Milky Way alone.

Illustration credit: ESO/L. Calçada

Note: For more information, see Many Billions of Rocky Planets in the Habitable Zones around Red Dwarfs in the Milky Way.

Exoplanet GJ 1214b

GJ 1214b, shown in this artist's view, is a super-Earth orbiting a red dwarf star 40 light-years from Earth. New observations from the NASA/ESA Hubble Space Telescope show that it is a waterworld enshrouded by a thick, steamy atmosphere. GJ 1214b represents a new type of planet, like nothing seen in the Solar System or any other planetary system currently known.

Image credit: NASA, ESA, and D. Aguilar (Harvard-Smithsonian Center for Astrophysics)

Note: For more information, see Hubble Reveals a New Class of Extrasolar Planet [heic1204].

Re-Thinking an Alien World

Forty light years from Earth, a rocky world named "55 Cancri e" circles perilously close to a stellar inferno. Completing one orbit in only 18 hours, the alien planet is 26 times closer to its parent star than Mercury is to the Sun. If Earth were in the same position, the soil beneath our feet would heat up to about 3200 F. Researchers have long thought that 55 Cancri e must be a wasteland of parched rock.

Now they’re thinking again. New observations by NASA's Spitzer Space Telescope suggest that 55 Cancri e may be wetter and weirder than anyone imagined.

Spitzer recently measured the extraordinarily small amount of light 55 Cancri e blocks when it crosses in front of its star. These transits occur every 18 hours, giving researchers repeated opportunities to gather the data they need to estimate the width, volume and density of the planet.

According to the new observations, 55 Cancri e has a mass 7.8 times and a radius just over twice that of Earth. Those properties place 55 Cancri e in the "super-Earth" class of exoplanets, a few dozen of which have been found. Only a handful of known super-Earths, however, cross the face of their stars as viewed from our vantage point in the cosmos, so 55 Cancri e is better understood than most.

When 55 Cancri e was discovered in 2004, initial estimates of its size and mass were consistent with a dense planet of solid rock. Spitzer data suggest otherwise: About a fifth of the planet's mass must be made of light elements and compounds--including water. Given the intense heat and high pressure these materials likely experience, researchers think the compounds likely exist in a "supercritical" fluid state.

A supercritical fluid is a high-pressure, high-temperature state of matter best described as a liquid-like gas, and a marvelous solvent. Water becomes supercritical in some steam turbines--and it tends to dissolve the tips of the turbine blades. Supercritical carbon dioxide is used to remove caffeine from coffee beans, and sometimes to dry-clean clothes. Liquid-fueled rocket propellant is also supercritical when it emerges from the tail of a spaceship.

On 55 Cancri e, this stuff may be literally oozing--or is it steaming?--out of the rocks.

With supercritical solvents rising from the planet’s surface, a star of terrifying proportions filling much of the daytime sky, and whole years rushing past in a matter of hours, 55 Cancri e teaches a valuable lesson: Just because a planet is similar in size to Earth does not mean the planet is like Earth.

It’s something to re-think about.

Video credit: NASA; text credit: NASA