Astronomers Spotted 'Mirror-Image' Exoplanet Only 3,000 Light-Years Away

The exoplanet KOI-456.04 orbits within its host star Kepler-160's habitable zone, and basks in roughly 93% of the amount of light Earth receives from the Sun.

A new "mirror-Earth" exoplanet called KOI-456.04 was discovered in orbit of the Sun-like star Kepler-160 and could be the best-yet candidate for a habitable exoplanet beyond the reaches of our solar system, according to a study recently published in the journal Astronomy & Astrophysics.

The new Earth-like exoplanet — called KOI-456.04 — is roughly 3,000 light-years from Earth.


Redefining search parameters for habitable exoplanets

Most exoplanets probably orbit red dwarf stars. This is partly because red dwarf stars are the most common type of star in the universe, but also because the relative faintness of red dwarfs makes it easier to observe an exoplanet through stellar transit — when it passes in front of a host star and blocks a fraction of its emitted light.

While exoplanets orbiting red dwarf stars are easier to spot, the discovery of KOI-456.04 has sent the scientific community abuzz on the importance of looking for planets orbiting stars like Kepler-160 (and our Sun).

NASA Flaring Red Dwarf Star
An illustration of a flaring red dwarf star. Source: NASA/ESA/G. Bacon (STScI)

The problem with red dwarf stars

Red dwarf stars present big obstacles to habitability: they emit a large number of high-energy flares and radiation, and their relative dimness compared to our Sun means that a habitable planet would have to be so close to the star that stellar gravity would warp and deform it.

This is why scientists are calling for greater focus on the search for planets orbiting stars like our own, like Kepler 160. Data on the new exoplanet orbiting Kepler 160 is a case-in-point. Kepler 160 and KOI-456.04's great resemblance to our Earth and Sun means that the pair are more likely to foster conditions amenable to life.

While researchers say KOI-456.04 is probably nearly twice Earth's size, it orbits Kepler-160 at about the same distance as Earth from the Sun, completing an orbit in 378 days. Crucially, the researchers say, the exoplanet basks in roughly 93% of the same amount of light that Earth receives from the Sun.

Astronomers' search for the Earth-like KOI-456.04

The researchers found KOI-456.04 via another iteration of analysis on old data previously collected by NASA’s Kepler mission, the MIT Technology Review explains. Kepler-160 was discovered roughly six years ago alongside two exoplanets, called Kepler-160b and Kepler-160c. Both of these are substantially larger than Earth, and their proximity to their host star means that life on those planets is likely untenable.

By employing two new algorithms to analyze the stellar brightness observed from Kepler-160, the transatlantic team of scientists from NASA, MPS, the Sonneberg Observatory, the University of Göttingen, and the University of California in Santa Cruz looked at dimming patterns on a more granular and gradual level. This allowed them to find the third exoplanet orbiting Kepler-160 — now dubbed KOI-456.04.

NASA Goddard James Webb Space Telescope
The James Webb Telescope, due to launch in 2021, can help to verify the existence of KOI-456.04. Source: NASA

NASA could confirm the Earth-like exoplanet

MPS scientist and lead author of the new study René Heller along with colleagues have found a total of 18 exoplanets in old Kepler data.

As of writing, the team says it is still not confirmed whether KOI-456.04 is definitely a planet. While there is an 85% probability that their findings were not in error, there is also a small probability that the dimming in light could be an artifact of Kepler's instruments or a statistical fluke. In order to be certain about KOI-456.04's status as a viable exoplanet — an exoplanet candidate needs to pass a threshold of 99% — more observation is needed.

In the meantime, NASA’s upcoming James Webb Space Telescope mission is one of several ways the team's findings regarding KOI-456.04 might be confirmed. Regardless, the search continues for habitable exoplanets capable of fostering life as we know it, and also the holy grail of exobiology: intelligent life itself.

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