He is an expert in astrophysics.

A quark is a type of elementary particle, and it is a component of protons and neutrons.

An astronomical unit represents the average distance from the Earth to the Sun.

The concept of topological space plays an important role in many fields of mathematics.

He is facing the problem of impotence.

Over time, this word underwent a figurative extension of meaning and came to have a new meaning.

The Sugawara no Michizane is the oldest anthology in Japan.

It is said that the lunar palace is the dwelling of the Hindu god Chandra.

The statue of Avalokiteshvara is known for its beauty and elegance.

They launched a surface-to-air missile.