Spiraling exoplanet suggests how Earth might meet its end
An exoplanet known as Kepler-1658b is spiraling closer toward its host star. This is the first time that astronomers have been able to observe the decaying orbit of an exoplanet around an "evolved" or older parent object. The orbital period is decreasing at a rate of about 131 milliseconds per year which indicates that the exoplanet is moving closer to its star.
Why does this story matter?
Kepler-1658b is also called a "hot Jupiter" due to its similarity in size with the giant planet and its proximity to its host star. Its orbiting distance is about an eighth of the space between our Sun and Mercury. It was discovered by the Kepler space telescope in 2009 but was confirmed to be an exoplanet only a decade later, in 2019.
The orbital period is decreasing by 131 milliseconds per year
Orbital decay of exoplanets is a slow process and detecting them is not an easy task. According to the study, Kepler-1658b's orbital period is decreasing at a rate of 131 milliseconds (or thousandths of a second) per year. It was monitored for years by the Kepler space telescope, Palomar Observatory's Hale Telescope in Southern California, and the Transiting Exoplanet Survey Telescope (TESS).
Kepler-1658b orbits its host star every 3.8 days
When an exoplanet crosses the face of its star, it's called a transit and this causes a dimming of the star's brightness when seen from Earth. Kepler-1658b has a short orbital period of 3.8 days, unlike Mercury's 88-day orbit, and astronomers have been able to observe regular transits. The interval between the exoplanet's transits has slightly but steadily declined over the past 13 years.
What is the cause of this orbital decay?
It is predicted that Kepler-1658b's orbital delay is due to the tidal interactions with its host star. The same phenomenon causes the rise and fall of oceans on our planet due to the gravitation effects stemming from Earth and the Moon. Tidal interactions can either bring the orbiting bodies inward, like Kepler-1658b's, or push them outward, like our Moon which is growing distant.
This study can revamp our models of tidal physics
"Now that we have evidence of inspiraling of a planet around an evolved star, we can really start to refine our models of tidal physics," said Shreyas Vissapragada, a planetary astrophysicist. "The Kepler-1658 system can serve as a celestial laboratory in this way for years to come, and with any luck, there will soon be many more of these labs."
Will something like this happen with Earth and Sun?
Kepler-1658 is inching closer and will ultimately collide with its host star. The same "death-by-star" fate is what might befall Earth billions of years from now as the Sun is growing older. When the Sun starts to die, it will expand into a red giant star, large enough that it can engulf Mercury and Venus, and perhaps Earth as well, as explained by NASA.
