TESS Telescope Finds First Earth-Like Exoplanet Inside Its Stars Habitable Zone

According to NASA, TOI 700 d is one of only a few Earth-size planets found in a star's habitable zone so far.

According to reports, NASA’s TESS space telescope has discovered an alien world that seems to be eerily similar to Earth, orbiting its host star within the so-called Goldilocks or habitable zone, that is, at the perfect distance away from its stars that would allow the planet to have liquid water on its surface and even potentially life.

Meet TOI 700 d

According to a recent statement from NASA, the new alien world called TOI 700 d and is located 101.5 light-years from Earth, in the southern constellation of Dorado, making it a good candidate for future observations by other instruments.

“TESS was designed and launched specifically to find Earth-sized planets orbiting nearby stars,” revealed Paul Hertz, astrophysics division director at NASA Headquarters in Washington.

“Planets around nearby stars are easiest to follow-up with larger telescopes in space and on Earth. Discovering TOI 700 d is a key science finding for TESS. Confirming the planet’s size and habitable zone status with Spitzer is another win for Spitzer as it approaches the end of science operations this January.”

According to experts, TOI 700 d is only one of a few Earth-sized planets that orbit nearby stars, others include several planets in the TRAPPIST-1 system and another smaller collection of exoplanets discovered by NASA’s Kepler Space Telescope.

TESS, which launched in April 2018, is a planet hunter telescope who uses the so-called “transit” method that consists of observing the decreases in brightness caused by potential planets that cross the front of their stars from the perspective of the satellite.

This same strategy was successfully used by the Kepler space telescope, which discovered about 70% of the approximately 4,000 known exoplanets in our catalog today.

Advertisement

TESS is able to successfully monitor large parts of the sky which are dubbed sectors for 27 days at a time.  This prolonged observation time allows the telescope to accurately track changes in the brightness of distant stars which may be caused by planets crossing the front of the stars from our perspective.

The star around which TOI 700 d is a small, cool M dwarf roughly 40% of our Sun’s mass and size, with only about half its surface temperature.

TOI 700 was initially misclassified by experts in the TESS database as a star much more similar to our Sun. This suggested that the planets were larger and much hotter than what the actually are. However, the error was identified after experts working with the TESS team reanalyzed the data.

An artists rendering of the three alien worlds of the TOI 700 system, orbiting a small, cool M dwarf. Image Credit: NASA's Goddard Space Flight Center.
An artists rendering of the three alien worlds of the TOI 700 system, orbiting a small, cool M dwarf. Image Credit: NASA’s Goddard Space Flight Center.

“When we corrected the star’s parameters, the sizes of its planets dropped, and we realized the outermost one was about the size of Earth and in the habitable zone,” explained Emily Gilbert, a graduate student at the University of Chicago.

“Additionally, in 11 months of data, we saw no flares from the star, which improves the chances TOI 700 d is habitable and makes it easier to model its atmospheric and surface conditions.”

There are three known planets orbiting TOI 700. The innermost planet dubbed TOI 700 b is nearly the exact same size as our planet, it is most likely rocky in nature, and orbits its star every 10 days. The middle planet, TOI 700 c is 2.6 more massive than Earth and orbits around its star every 16 days. This planet is most likely a gas-giant ranging in size somewhere between Earth and Neptune.

The outermost world orbiting the star is the exoplanet TOI 700 d. It’s the only one in the star’s habitable zone. It measures around 20% larger than Earth and completes a single orbit around its star every 37 days. It is believed to receive from its star around 86% of the energy that our planet receives from the Sun.

Astronomers theorize that all three exoplanets are tidally locked to their host stars, which means they rotate once per orbit so that one side is constantly bated in daylight, while the other in complete darkness, reveals NASA.

Experts further revealed that since the star around which this exoplanet orbits–TOI 700–is bright, nearby, and so far shows no sign of stellar flares, the system is an excellent candidate for careful mass measurements by current ground-based observatories.