Nearby Exoplanet May Be Smaller Than Earth

An extra-solar candidate around 67 percent the size of Earth was recently detected close to our own solar system. Researchers say that the discovery was only made possible through the use of the NASA Spitzer Space Telescope.

According to experts, the object is located around 33 light-years from Earth, which makes it the closest known alien world that is smaller than our own planet. Provisionally, experts have named it UCF-1.01.

Even though more than 770 exoplanets have been identified to date, and thousands of other candidates are currently in the process of being confirmed, scientists have yet to uncover any worlds that are much smaller than Earth.

There are some which may be of equal size, but the fact of the matter is that our planet is in many ways unique, at least at this time. Finding an Earth-analog is the main goal of exoplanetary research, since such a body could potentially hold life.

Interestingly, this is the first exoplanet that Spitzer helped discover. This could point at a new role for the long-lived telescope, which has long since concluded its primary science mission. UCF-1.01 was found around the dwarf star GJ 436.

Experts were studying the Neptune-sized gas giant GJ 436b, which was already known to orbit this star, when they observed another set of small dips in the brightness level of the object. Subsequent studies were able to pinpoint the new planet.

“We have found strong evidence for a very small, very hot and very near planet with the help of the Spitzer Space Telescope. Identifying nearby small planets such as UCF-1.01 may one day lead to their characterization using future instruments,” says expert Kevin Stevenson.

He is the lead author of a new paper detailing the findings, which will be published in an upcoming issue of the esteemed Astrophysical Journal. The investigator is based at the University of Central Florida, in Orlando.

It is very unlikely that UCF-1.01 has an atmosphere, the UCF team says. Since it orbits so close to its parent star – a full year lasts just 1.4 days – the object's surface is heated to more than 1,000 degrees Fahrenheit (almost 600 degrees Celsius), and may have long since melted.

The planet has a diameter of around 5,200 miles (8,400 kilometers), and may resemble Mercury from our own solar system. It may be accompanied in orbit by another small planet, tentatively named UCF-1.02, but the latter has not yet been confirmed.

“I hope future observations will confirm these exciting results, which show Spitzer may be able to discover exoplanets as small as Mars. Even after almost nine years in space, Spitzer's observations continue to take us in new and important scientific directions,” Michael Werner adds.

The expert holds an appointment as a Spitzer project scientist at the NASA Jet Propulsion Laboratory (JPL), in Pasadena, California. The Lab manages the telescope for the NASA Science Mission Directorate.