Astronomers just discovered closest known Earth-sized world only 22 light-years away

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In a groundbreaking discovery, scientists in the United States have identified an Earth-sized exoplanet, named LTT 1445 Ac, located merely 22 light-years away from our Solar System.

This artist’s impression shows the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image between the planet and Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface.

This remarkable find, orbiting a small red dwarf star, marks the closest known Earth-sized world outside our solar system, offering a new frontier in the quest to understand extraterrestrial environments.

Unveiling LTT 1445 Ac

LTT 1445 Ac, approximately 1.37 times the mass and around 1.07 times the radius of Earth, presents a unique opportunity for astronomical study. Despite its inhospitable conditions for life, given its extreme heat, the planet’s Earth-like characteristics make it an ideal candidate for researchers to explore planetary evolution and the factors that differentiate Earth-like worlds.

The Discovery Process

The discovery of LTT 1445 Ac was facilitated by data from the TESS (Transiting Exoplanet Survey Satellite) exoplanet-hunting telescope, gathered in 2021. However, the observation process was not without challenges. The exoplanet resides in a trinary system, orbiting one of three gravitationally bound stars. This complex arrangement posed difficulties in accurately determining the planet’s properties due to the influence of stellar companions on the host star’s light.

A diagram of the changes in a star’s light as an exoplanet orbits. (J. Winn, arXiv, 2014)

Understanding Exoplanet Properties

To comprehend the nature of an exoplanet like LTT 1445 Ac, scientists rely on two critical types of measurement: transit data and radial velocity data. Transit data involves observing the minute dips in a star’s light as an exoplanet passes between the star and Earth, revealing the planet’s radius. Radial velocity data, on the other hand, measures the gravitational pull of an exoplanet on its star, providing insights into the planet’s mass.

Animation showing how radial velocity is measured, one of the ways a planet can affect the light of its star. (Alysa Obertas/Wikimedia Commons, CC BY-SA 4.0)

Combining these measurements allows astronomers to calculate the exoplanet’s density, which in turn sheds light on its composition. For instance, a low-density planet might resemble a gas giant, while a higher-density planet indicates a rocky surface, akin to Earth, Venus, Mars, or Mercury.

Implications and Future Research

The discovery of LTT 1445 Ac opens new avenues for understanding the formation and evolution of Earth-sized exoplanets. Its proximity and size provide an unprecedented opportunity for detailed study, potentially unlocking secrets about the conditions necessary for life and the diversity of planetary systems in our galaxy.

As astronomical technology and methods continue to advance, discoveries like LTT 1445 Ac not only deepen our understanding of the cosmos but also bring us closer to answering the age-old question: Are we alone in the universe?

Reference(s): Research Paper

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