Three planets survived where they should have vanished: What does it mean for Earth and what did the Chinese scientists discover?

A planet sitting close to an ageing star sounds like a world with little time left. As the star expands, its outer layers can reach the planet’s orbit. Even before it contacts the planet, there could be some tidal waves in spaces which can drag the planets inward. However, scientists in China have found 3 systems that did not meet the fate they were expected to have. Instead, they survived. The planets remain close to stars that have already passed through their dramatic expansion.

What did the Chinese research team discover?

The team identified a survival puzzle involving 24 Boo b and HD 12648 b, alongside TYC 4282-605-1 b, as per a report by Global Times.


The findings are very startling for the scientists. They found that each of the planets has actually passed through an expansion stage and they have helium in their core. They are all a red-clump giant. This raises questions about Earth and our solar system.

Yunnan University astronomer Sheng-Bang Qian did a study which appeared in the Proceedings of the National Academy of Sciences on October 22. In his study, he did not just announce that there could be three new worlds; instead, he studied what they are and how difficult it is for them to exist in the first place.

Why should these planets have disappeared?

Stars like the Sun spend much of their lives turning hydrogen into helium in their cores. After that core hydrogen runs out, their structure changes. They eventually expand into red giants.

Planets that are close to such stars can be swallowed up by the expanding star. Tidal forces can also alter their orbits and pull them towards destruction. The team reconstructed the stars’ earlier growth using computer models. Those calculations placed the planets’ present orbits inside the regions the stars should previously have occupied.

The puzzle is therefore about their history. Being outside a star today does not explain how a planet avoided destruction earlier.

How did NASA’s TESS help investigate?

The researchers used observations from NASA’s Transiting Exoplanet Survey Satellite, known as TESS. Tiny brightness variations reveal vibrations within stars. Studying those vibrations is called asteroseismology.

Think of it as listening for clues about a star’s interior. Two stars can look similar from outside while occupying different stages of life.

Identifying the hosts as helium-burning stars established that their major expansion had already happened.

Which planet presents the strongest puzzle?

The standout is 24 Boo b. It completes an orbit in roughly 30 days. Its orbital distance is about 0.183 astronomical units. One astronomical unit is approximately the distance between Earth and the Sun. The researchers describe it as the closest known planet orbiting a red-clump giant. So will there be a time when the Sun will swallow up the Earth?

Could Earth survive the Sun’s red-giant phase?

The discovery does not establish that Earth will escape. NASA says the Sun will expand into a red giant in about five billion years. Mercury and Venus are expected to be engulfed. Earth may be swallowed too.

Avoiding engulfment would not guarantee habitability. A planet can remain in existence while becoming unsuitable for life. The new systems suggest that models may be missing important interactions. They do not demonstrate which mechanism operated or whether it could apply to Earth.