Astronomers Discover Small, Uninhabitable Planets Near Our Star

Topic: Space

Scientists from the University of Cambridge studied the planetary system around Barnard's Star and found four small planets that are not suitable for life. The planets are rich in magnesium but lack atmospheres and have extreme temperatures.

A team of scientists from the University of Cambridge has created a detailed portrait of the planetary system orbiting Barnard's Star, our closest neighbor after Alpha Centauri.

The four planets in this system are smaller than Earth and Venus but larger than Mars. They were discovered in 2025 and are located just under six light-years from us.

By analyzing the chemical makeup of Barnard's Star, the researchers found that its planets are rich in a rare mineral called periclase. This is because the star has an enormous amount of magnesium compared to other stars, which makes its planets likely to be rich in magnesium too.

However, this abundance of magnesium creates huge quantities of periclase, which does not store water as well as other minerals do. To make matters worse, the researchers found that Barnard's Star's planets are unlikely to have atmospheres because they are so close to their star and have very little gravity.

The planets could have held on to their atmospheres for at most 2 billion years, which is much shorter than the system's 10-billion-year age. This means that the planets would be hostile environments even if they did have atmospheres.

Another consequence of being so close to the star is that the planets are all tidally locked. This means that each planet shows only one face to its star, resulting in extreme temperatures and making them uninhabitable.

Why It Matters

This discovery helps us understand how planetary systems form and evolve, which can inform our search for life beyond Earth. It also highlights the importance of studying small planets, which are harder to detect but may be more similar to Earth than we think.

Key Facts

• The four planets in the Barnard's Star system are smaller than Earth and Venus but larger than Mars.
• The planets were discovered in 2025 and are located just under six light-years from us.
• Barnard's Star has an enormous amount of magnesium compared to other stars, making its planets rich in magnesium too.
• The abundance of magnesium creates huge quantities of periclase, which does not store water as well as other minerals do.
• The planets are unlikely to have atmospheres because they are so close to their star and have very little gravity.

Key Terms

Periclase

A rare mineral that is created when magnesium reacts with oxygen in the presence of water.

Tidally locked

When a planet's rotation is synchronized with its orbit around its star, resulting in one side always facing the star.

Implications

This discovery helps us understand how planetary systems form and evolve, which can inform our search for life beyond Earth. It also highlights the importance of studying small planets, which are harder to detect but may be more similar to Earth than we think.