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Astronomers discover more evidence of Earth-like exoplanets



A recent study suggests that an exoplanet – a planet outside the solar system that is 500 light-years distant and similar to Earth – is orbiting a star, SciTechDaily.com reported.

Kepler-186f is the first Earth-like planetary xoplanet orbiting a star in the habitable zone. This means that it is the right distance from its host star to collect liquid water on the surface.

The Georgia Tech study used simulations to analyze and identify the spin axis dynamics of the exoplanet. This dynamics determines how strongly a planet is tilted about its axis and how that angle of inclination develops over time. Axial inclination contributes to seasons and climate because it affects how sunlight strikes the planet's surface.

The researchers suggest that the axial tilt of Kepler-1

86f is very stable, similar to the Earth, allowing for regular seasons and a stable climate. The Georgia Tech team believes that this is also the case for Kepler-62f, a Super Earth planet orbiting around a star about 1200 light-years away.

How important is the axial slope for the climate? A large variability of axial tilt could be a major reason why Mars has transformed from an aquatic landscape billions of years ago into today's barren desert.

"Mars is in the habitable zone of our solar system, but its axial slope was very unstable." "We go from 0 to 60 degrees," said Georgji Tech Assistant Professor Gongjie Li, who led the study along with graduate student Yutong Shan from the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts. "This instability has probably contributed to the decay of the Martian atmosphere and the evaporation of surface water."

By comparison, the Earth's axial tilt oscillates milder – between 22.1 and 24.5 degrees, about every 10,000 years from one extreme to the other, SciTechDaily.com reported.

The orientation angle of the orbit of a planet around its host star can be vibrated by gravitational interaction with other planets in the same system. If the orbit were oscillating at the same speed as the precession of the planet's axis of rotation (similar to the circular motion of a top or gyro's axis of rotation), the axis of rotation would also wobble, sometimes dramatically. 19659003] Mars and Earth interact strongly with each other, as well as with Mercury and Venus. As a result, their axes of rotation would precess even at the same speed as the orbital vibration, which could cause large variations in their axial tilt. Fortunately, the moon keeps the earth's fluctuations in check. The Moon increases the rate of precession of the axis of rotation of our planet and differentiates it from the orbital vibration rate. Mars, on the other hand, does not have enough satellites to stabilize its axial tilt.

"It seems that both exoplanets are very different from Mars and Earth because they have a weaker connection to their sibling planet." said Li, a faculty member in the School of Physics. "We do not know if they own moons, but our calculations show that even without satellites, Kepler-186f and 62f's rotational axes would have remained constant for tens of millions of years."

Kepler-186f is less than 10 percent larger in radius than Earth, but its mass, composition and density remain a mystery. He circles his star every 130 days. According to NASA, the brightness of this star at lunchtime, while it was at 186f, would appear as bright as the sun on Earth just before sunset. Kepler-186f is in the constellation Cygnus as part of a five-planet star system.

Kepler-62f was the most earth-like exoplanet until scientists noticed 186f in 2014. It is about 40 percent larger than our planet and probably a terrestrial or ocean-covered world. It is in the constellation Lyra and is the outermost planet among the five exoplanets orbiting a single star, SciTechDaily.com reported.

That does not mean that either exoplanet has water, let alone life. Both are relatively good candidates.

"Our study is one of the first to study the climate stability of exoplanets and contribute to the growing understanding of these potentially habitable nearby worlds," Li said.

"I do not think we understand enough about the origin of life, to exclude the possibility of his presence on planets with irregular seasons, "added the Shan to the CfA. "Even on Earth, life is remarkably diverse and has proven incredibly resilient in exceptionally hostile environments."

"But a climatically stable planet could be a more comfortable starting point. "


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