India, Sept. 12 -- For decades, astronomers have wondered why the solar system looks so different from many planetary systems found elsewhere in the galaxy. Super-Earths, worlds larger than Earth but smaller than Neptune, appear frequently around other stars, yet none exists in our solar system. NASA describes super-Earths as planets that can be up to about 10 times Earth's mass, and they can be rocky, gaseous or a mixture of both.

Now, a new study offers an extraordinary explanation. The young Sun may have swallowed one.

Researchers led by Professor Mutlu Yildiz of Ege University in Turkey used stellar-evolution models to investigate whether consuming a planet early in the Sun's history could explain some of the differences between wha...